hedy.py

import textwrap

import lark
from flask_babel import gettext
from lark import Lark
from lark.exceptions import UnexpectedEOF, UnexpectedCharacters, VisitError
from lark import Tree, Transformer, visitors, v_args
from os import path

import warnings
import hedy
import hedy_translation
from hedy_content import ALL_KEYWORD_LANGUAGES
from collections import namedtuple
import re
import regex
from dataclasses import dataclass, field
import exceptions
import program_repair
import yaml

# Some useful constants
from hedy_content import KEYWORDS
from hedy_sourcemap import SourceMap, source_map_transformer

HEDY_MAX_LEVEL = 18
HEDY_MAX_LEVEL_SKIPPING_FAULTY = 5
MAX_LINES = 100
LEVEL_STARTING_INDENTATION = 8

# Boolean variables to allow code which is under construction to not be executed
local_keywords_enabled = True

# dictionary to store transpilers
TRANSPILER_LOOKUP = {}

# define source-map
source_map = SourceMap()

# builtins taken from 3.11.0 docs: https://docs.python.org/3/library/functions.html
PYTHON_BUILTIN_FUNCTIONS = [
    'abs',
    'aiter',
    'all',
    'any',
    'anext',
    'ascii',
    'bin',
    'bool',
    'breakpoint',
    'bytearray',
    'bytes',
    'callable',
    'chr',
    'classmethod',
    'compile',
    'complex',
    'delattr',
    'dict',
    'dir',
    'divmod',
    'enumerate',
    'eval',
    'exec',
    'filter',
    'float',
    'format',
    'frozenset',
    'getattr',
    'globals',
    'hasattr',
    'hash',
    'help',
    'hex',
    'id',
    'input',
    'int',
    'isinstance',
    'issubclass',
    'iter',
    'len',
    'list',
    'locals',
    'map',
    'max',
    'memoryview',
    'min',
    'next',
    'object',
    'oct',
    'open',
    'ord',
    'pow',
    'print',
    'property',
    'range',
    'repr',
    'reversed',
    'round',
    'set',
    'setattr',
    'slice',
    'sorted',
    'staticmethod',
    'str',
    'sum',
    'super',
    'tuple',
    'type',
    'vars',
    'zip']
PYTHON_KEYWORDS = [
    'and',
    'except',
    'lambda',
    'with',
    'as',
    'finally',
    'nonlocal',
    'while',
    'assert',
    'False',
    'None',
    'yield',
    'break',
    'for',
    'not',
    'class',
    'from',
    'or',
    'continue',
    'global',
    'pass',
    'def',
    'if',
    'raise',
    'del',
    'import',
    'return',
    'elif',
    'in',
    'True',
    'else',
    'is',
    'try',
    'int']
# Python keywords and function names need hashing when used as var names
reserved_words = set(PYTHON_BUILTIN_FUNCTIONS + PYTHON_KEYWORDS)

# Let's retrieve all keywords dynamically from the cached KEYWORDS dictionary
indent_keywords = {}
for lang, keywords in KEYWORDS.items():
    indent_keywords[lang] = []
    for keyword in ['if', 'elif', 'for', 'repeat', 'while', 'else', 'define', 'def']:
        indent_keywords[lang].append(keyword)  # always also check for En
        indent_keywords[lang].append(keywords.get(keyword))

# These are the preprocessor rules that we use to specify changes in the rules that
# are expected to work across several rules
# Example
# for<needs_colon> instead of defining the whole rule again.


def needs_colon(rule):
    pos = rule.find('_EOL (_SPACE command)')
    return f'{rule[0:pos]} _COLON {rule[pos:]}'


PREPROCESS_RULES = {
    'needs_colon': needs_colon
}


class Command:
    print = 'print'
    ask = 'ask'
    echo = 'echo'
    turn = 'turn'
    forward = 'forward'
    sleep = 'sleep'
    color = 'color'
    add_to_list = 'add to list'
    remove_from_list = 'remove from list'
    list_access = 'at random'
    in_list = 'in list'
    equality = 'is (equality)'
    repeat = 'repeat'
    for_list = 'for in'
    for_loop = 'for in range'
    addition = '+'
    subtraction = '-'
    multiplication = '*'
    division = '/'
    smaller = '<'
    smaller_equal = '<='
    bigger = '>'
    bigger_equal = '>='
    not_equal = '!='
    pressed = 'pressed'
    clear = 'clear'
    define = 'define'
    call = 'call'
    returns = 'return'


translatable_commands = {Command.print: ['print'],
                         Command.ask: ['ask'],
                         Command.echo: ['echo'],
                         Command.turn: ['turn'],
                         Command.sleep: ['sleep'],
                         Command.color: ['color'],
                         Command.forward: ['forward'],
                         Command.add_to_list: ['add', 'to_list'],
                         Command.remove_from_list: ['remove', 'from'],
                         Command.list_access: ['at', 'random'],
                         Command.in_list: ['in'],
                         Command.equality: ['is', '=', '=='],
                         Command.repeat: ['repeat', 'times'],
                         Command.for_list: ['for', 'in'],
                         Command.for_loop: ['in', 'range', 'to'],
                         Command.define: ['define'],
                         Command.call: ['call'],
                         Command.returns: ['return'], }


class HedyType:
    any = 'any'
    none = 'none'
    string = 'string'
    integer = 'integer'
    list = 'list'
    float = 'float'
    boolean = 'boolean'
    input = 'input'


# Type promotion rules are used to implicitly convert one type to another, e.g. integer should be auto converted
# to float in 1 + 1.5. Additionally, before level 12, we want to convert numbers to strings, e.g. in equality checks.
int_to_float = (HedyType.integer, HedyType.float)
int_to_string = (HedyType.integer, HedyType.string)
float_to_string = (HedyType.float, HedyType.string)
input_to_int = (HedyType.input, HedyType.integer)
input_to_float = (HedyType.input, HedyType.float)
input_to_string = (HedyType.input, HedyType.string)


def promote_types(types, rules):
    for (from_type, to_type) in rules:
        if to_type in types:
            types = [to_type if t == from_type else t for t in types]
    return types


# Commands per Hedy level which are used to suggest the closest command when kids make a mistake
commands_per_level = {
    1: ['print', 'ask', 'echo', 'turn', 'forward', 'color'],
    2: ['print', 'ask', 'is', 'turn', 'forward', 'color', 'sleep'],
    3: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from'],
    4: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'clear'],
    5: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'clear'],
    6: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'clear'],
    7: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'repeat', 'times', 'clear'],
    8: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'repeat', 'times', 'clear'],
    9: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'repeat', 'times', 'clear'],
    10: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'repeat', 'times', 'for', 'clear'],
    11: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'for', 'range', 'repeat', 'clear'],
    12: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'for', 'range', 'repeat', 'clear', 'define', 'call'],
    13: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'for', 'range', 'repeat', 'and', 'or', 'clear', 'define', 'call'],
    14: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'for', 'range', 'repeat', 'and', 'or', 'clear', 'define', 'call'],
    15: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'for', 'range', 'repeat', 'and', 'or', 'while', 'clear', 'define', 'call'],
    16: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'for', 'range', 'repeat', 'and', 'or', 'while', 'clear', 'define', 'call'],
    17: ['ask', 'is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'not in', 'if', 'else', 'pressed', 'button', 'for', 'range', 'repeat', 'and', 'or', 'while', 'elif', 'clear', 'define', 'call'],
    18: ['is', 'print', 'forward', 'turn', 'color', 'sleep', 'at', 'random', 'add', 'to', 'remove', 'from', 'in', 'if', 'not in', 'else', 'for', 'pressed', 'button', 'range', 'repeat', 'and', 'or', 'while', 'elif', 'input', 'clear', 'define', 'call'],
}

command_turn_literals = ['right', 'left']
command_make_color = ['black', 'blue', 'brown', 'gray', 'green', 'orange', 'pink', 'purple', 'red', 'white', 'yellow']

# Commands and their types per level (only partially filled!)
commands_and_types_per_level = {
    Command.print: {
        1: [HedyType.string, HedyType.integer, HedyType.input],
        12: [HedyType.string, HedyType.integer, HedyType.input, HedyType.float],
        16: [HedyType.string, HedyType.integer, HedyType.input, HedyType.float, HedyType.list]
    },
    Command.ask: {
        1: [HedyType.string, HedyType.integer, HedyType.input],
        12: [HedyType.string, HedyType.integer, HedyType.input, HedyType.float],
        16: [HedyType.string, HedyType.integer, HedyType.input, HedyType.float, HedyType.list]
    },
    Command.turn: {1: command_turn_literals,
                   2: [HedyType.integer, HedyType.input],
                   12: [HedyType.integer, HedyType.input, HedyType.float]
                   },
    Command.color: {1: command_make_color,
                    2: [command_make_color, HedyType.string, HedyType.input]},
    Command.forward: {1: [HedyType.integer, HedyType.input],
                      12: [HedyType.integer, HedyType.input, HedyType.float]
                      },
    Command.sleep: {1: [HedyType.integer, HedyType.input]},
    Command.list_access: {1: [HedyType.list]},
    Command.in_list: {1: [HedyType.list]},
    Command.add_to_list: {1: [HedyType.list]},
    Command.remove_from_list: {1: [HedyType.list]},
    Command.equality: {1: [HedyType.string, HedyType.integer, HedyType.input, HedyType.float],
                       14: [HedyType.string, HedyType.integer, HedyType.input, HedyType.float, HedyType.list]},
    Command.addition: {
        6: [HedyType.integer, HedyType.input],
        12: [HedyType.string, HedyType.integer, HedyType.input, HedyType.float]
    },
    Command.subtraction: {
        1: [HedyType.integer, HedyType.input],
        12: [HedyType.integer, HedyType.float, HedyType.input],
    },
    Command.multiplication: {
        1: [HedyType.integer, HedyType.input],
        12: [HedyType.integer, HedyType.float, HedyType.input],
    },
    Command.division: {
        1: [HedyType.integer, HedyType.input],
        12: [HedyType.integer, HedyType.float, HedyType.input],
    },
    Command.repeat: {7: [HedyType.integer, HedyType.input]},
    Command.for_list: {10: {HedyType.list}},
    Command.for_loop: {11: [HedyType.integer, HedyType.input]},
    Command.smaller: {14: [HedyType.integer, HedyType.float, HedyType.input]},
    Command.smaller_equal: {14: [HedyType.integer, HedyType.float, HedyType.input]},
    Command.bigger: {14: [HedyType.integer, HedyType.float, HedyType.input]},
    Command.bigger_equal: {14: [HedyType.integer, HedyType.float, HedyType.input]},
    Command.not_equal: {14: [HedyType.integer, HedyType.float, HedyType.string, HedyType.input, HedyType.list]},
    Command.pressed: {5: [HedyType.string]}  # TODO: maybe use a seperate type character in the future.
}

# we generate Python strings with ' always, so ' needs to be escaped but " works fine
# \ also needs to be escaped because it eats the next character
characters_that_need_escaping = ["\\", "'"]

character_skulpt_cannot_parse = re.compile('[^a-zA-Z0-9_]')


def get_list_keywords(commands, to_lang):
    """ Returns a list with the local keywords of the argument 'commands'
    """

    translation_commands = []
    dir = path.abspath(path.dirname(__file__))
    path_keywords = dir + "/content/keywords"

    to_yaml_filesname_with_path = path.join(path_keywords, to_lang + '.yaml')
    en_yaml_filesname_with_path = path.join(path_keywords, 'en' + '.yaml')

    with open(en_yaml_filesname_with_path, 'r', encoding='utf-8') as stream:
        en_yaml_dict = yaml.safe_load(stream)

    try:
        with open(to_yaml_filesname_with_path, 'r', encoding='utf-8') as stream:
            to_yaml_dict = yaml.safe_load(stream)
        for command in commands:
            try:
                translation_commands.append(to_yaml_dict[command])
            except Exception:
                translation_commands.append(en_yaml_dict[command])
    except Exception:
        for command in commands:
            translation_commands.append(en_yaml_dict[command])

    return translation_commands


def get_suggestions_for_language(lang, level):
    if not local_keywords_enabled:
        lang = 'en'

    lang_commands = get_list_keywords(commands_per_level[level], lang)

    # if we allow multiple keyword languages:
    en_commands = get_list_keywords(commands_per_level[level], 'en')
    en_lang_commands = list(set(en_commands + lang_commands))

    return en_lang_commands


def escape_var(var):
    var_name = var.name if type(var) is LookupEntry else var
    return "_" + var_name if var_name in reserved_words else var_name


def closest_command(invalid_command, known_commands, threshold=2):
    # closest_command() searches for a similar command (distance smaller than threshold)
    # TODO: make the result value be tuple instead of a ugly None & string mix
    # returns None if the invalid command does not contain any known command.
    # returns 'keyword' if the invalid command is exactly a command (so shoudl not be suggested)

    min_command = closest_command_with_min_distance(invalid_command, known_commands, threshold)

    # Check if we are not returning the found command
    # In that case we have no suggestion
    # This is to prevent "print is not a command in Hedy level 3, did you mean print?" error message

    if min_command == invalid_command:
        return 'keyword'
    return min_command


def style_command(command):
    return f'<span class="command-highlighted">{command}</span>'


def closest_command_with_min_distance(invalid_command, commands, threshold):
    # FH, early 2020: simple string distance, could be more sophisticated MACHINE LEARNING!

    minimum_distance = 1000
    closest_command = None
    for command in commands:
        minimum_distance_for_command = calculate_minimum_distance(command, invalid_command)
        if minimum_distance_for_command < minimum_distance and minimum_distance_for_command <= threshold:
            minimum_distance = minimum_distance_for_command
            closest_command = command

    return closest_command


def calculate_minimum_distance(s1, s2):
    """Return string distance between 2 strings."""
    if len(s1) > len(s2):
        s1, s2 = s2, s1
    distances = range(len(s1) + 1)
    for index2, char2 in enumerate(s2):
        new_distances = [index2 + 1]
        for index1, char1 in enumerate(s1):
            if char1 == char2:
                new_distances.append(distances[index1])
            else:
                new_distances.append(1 + min((distances[index1], distances[index1 + 1], new_distances[-1])))
        distances = new_distances
    return distances[-1]


@dataclass
class InvalidInfo:
    error_type: str
    command: str = ''
    arguments: list = field(default_factory=list)
    line: int = 0
    column: int = 0


# used in to construct lookup table entries and infer their type
@dataclass
class LookupEntry:
    name: str
    tree: Tree
    linenumber: int
    skip_hashing: bool
    type_: str = None
    currently_inferring: bool = False  # used to detect cyclic type inference


class TypedTree(Tree):
    def __init__(self, data, children, meta, type_):
        super().__init__(data, children, meta)
        self.type_ = type_


@v_args(meta=True)
class ExtractAST(Transformer):
    # simplifies the tree: f.e. flattens arguments of text, var and punctuation for further processing
    def text(self, meta, args):
        return Tree('text', [' '.join([str(c) for c in args])], meta)

    def INT(self, args):
        return Tree('integer', [str(args)])

    def NUMBER(self, args):
        return Tree('number', [str(args)])

    def POSITIVE_NUMBER(self, args):
        return Tree('number', [str(args)])

    def NEGATIVE_NUMBER(self, args):
        return Tree('number', [str(args)])

    # level 2
    def var(self, meta, args):
        return Tree('var', [''.join([str(c) for c in args])], meta)

    def list_access(self, meta, args):
        # FH, may 2022 I don't fully understand why we remove INT here and just plemp
        # the number in the tree. should be improved but that requires rewriting the further processing code too (TODO)
        if isinstance(args[1], Tree):
            if "random" in args[1].data:
                return Tree('list_access', [args[0], 'random'], meta)
            elif args[1].data == "var_access":
                return Tree('list_access', [args[0], args[1].children[0]], meta)
            else:
                # convert to latin int
                latin_int_index = str(int(args[1].children[0]))
                return Tree('list_access', [args[0], latin_int_index], meta)
        else:
            return Tree('list_access', [args[0], args[1]], meta)

    # level 5
    def error_unsupported_number(self, meta, args):
        return Tree('unsupported_number', [''.join([str(c) for c in args])], meta)


# This visitor collects all entries that should be part of the lookup table. It only stores the name of the entry
# (e.g. 'animal') and its value as a tree node (e.g. Tree['text', ['cat']]) which is later used to infer the type
# of the entry. This preliminary traversal is needed to avoid issues with loops in which an iterator variable is
# used in the inner commands which are visited before the iterator variable is added to the lookup.

class LookupEntryCollector(visitors.Visitor):
    def __init__(self, level):
        super().__init__()
        self.level = level
        self.lookup = []

    def ask(self, tree):
        # in level 1 there is no variable name on the left side of the ask command
        if self.level > 1:
            self.add_to_lookup(tree.children[0].children[0], tree, tree.meta.line)

    def input_empty_brackets(self, tree):
        self.input(tree)

    def input(self, tree):
        var_name = tree.children[0].children[0]
        self.add_to_lookup(var_name, tree, tree.meta.line)

    def assign(self, tree):
        var_name = tree.children[0].children[0]
        self.add_to_lookup(var_name, tree.children[1], tree.meta.line)

    def assign_list(self, tree):
        var_name = tree.children[0].children[0]
        self.add_to_lookup(var_name, tree, tree.meta.line)

    # list access is added to the lookup table not because it must be escaped
    # for example we print(dieren[1]) not print('dieren[1]')

    def list_access(self, tree):
        list_name = escape_var(tree.children[0].children[0])
        position_name = escape_var(tree.children[1])
        if position_name == 'random':
            name = f'random.choice({list_name})'
        else:
            # We want list access to be 1-based instead of 0-based, hence the -1
            name = f'{list_name}[int({position_name})-1]'
        self.add_to_lookup(name, tree, tree.meta.line, True)

    def change_list_item(self, tree):
        self.add_to_lookup(tree.children[0].children[0], tree, tree.meta.line, True)

    def for_list(self, tree):
        iterator = str(tree.children[0].children[0])
        # the tree is trimmed to skip contain the inner commands of the loop since
        # they are not needed to infer the type of the iterator variable
        trimmed_tree = Tree(tree.data, tree.children[0:2], tree.meta)
        self.add_to_lookup(iterator, trimmed_tree, tree.meta.line)

    def for_loop(self, tree):
        iterator = str(tree.children[0].children[0])
        # the tree is trimmed to skip contain the inner commands of the loop since
        # they are not needed to infer the type of the iterator variable
        trimmed_tree = Tree(tree.data, tree.children[0:3], tree.meta)
        self.add_to_lookup(iterator, trimmed_tree, tree.meta.line)

    def define(self, tree):
        # add function name to lookup
        self.add_to_lookup(str(tree.children[0].children[0]) + "()", tree, tree.meta.line)

        # add arguments to lookup
        if tree.children[1].data == 'arguments':
            for x in (c for c in tree.children[1].children if isinstance(c, Tree)):
                self.add_to_lookup(x.children[0], tree.children[1], tree.meta.line)

    def call(self, tree):
        function_name = tree.children[0].children[0]
        args_str = ""
        if len(tree.children) > 1:
            args_str = ", ".join(str(x.children[0]) if isinstance(x, Tree) else str(x)
                                 for x in tree.children[1].children)
        self.add_to_lookup(f"{function_name}({args_str})", tree, tree.meta.line)

    def add_to_lookup(self, name, tree, linenumber, skip_hashing=False):
        entry = LookupEntry(name, tree, linenumber, skip_hashing)
        hashed_name = escape_var(entry)
        entry.name = hashed_name
        self.lookup.append(entry)


# The transformer traverses the whole AST and infers the type of each node. It alters the lookup table entries with
# their inferred type. It also performs type validation for commands, e.g. 'text' + 1 results in error.
@v_args(tree=True)
class TypeValidator(Transformer):
    def __init__(self, lookup, level, lang, input_string):
        super().__init__()
        self.lookup = lookup
        self.level = level
        self.lang = lang
        self.input_string = input_string

    def print(self, tree):
        self.validate_args_type_allowed(Command.print, tree.children, tree.meta)

        return self.to_typed_tree(tree)

    def ask(self, tree):
        if self.level > 1:
            self.save_type_to_lookup(tree.children[0].children[0], HedyType.input)
        self.validate_args_type_allowed(Command.ask, tree.children[1:], tree.meta)
        return self.to_typed_tree(tree, HedyType.input)

    def input(self, tree):
        self.validate_args_type_allowed(Command.ask, tree.children[1:], tree.meta)
        return self.to_typed_tree(tree, HedyType.input)

    def forward(self, tree):
        if tree.children:
            self.validate_args_type_allowed(Command.forward, tree.children, tree.meta)
        return self.to_typed_tree(tree)

    def color(self, tree):
        if tree.children:
            self.validate_args_type_allowed(Command.color, tree.children, tree.meta)
        return self.to_typed_tree(tree)

    def turn(self, tree):
        if tree.children:
            name = tree.children[0].data
            if self.level > 1 or name not in command_turn_literals:
                self.validate_args_type_allowed(Command.turn, tree.children, tree.meta)
        return self.to_typed_tree(tree)

    def sleep(self, tree):
        if tree.children:
            self.validate_args_type_allowed(Command.sleep, tree.children, tree.meta)
        return self.to_typed_tree(tree)

    def assign(self, tree):
        try:
            type_ = self.get_type(tree.children[1])
            self.save_type_to_lookup(tree.children[0].children[0], type_)
        except hedy.exceptions.UndefinedVarException as ex:
            if self.level >= 12:
                raise hedy.exceptions.UnquotedAssignTextException(
                    text=ex.arguments['name'],
                    line_number=tree.meta.line)
            else:
                raise

        return self.to_typed_tree(tree, HedyType.none)

    def assign_list(self, tree):
        self.save_type_to_lookup(tree.children[0].children[0], HedyType.list)
        return self.to_typed_tree(tree, HedyType.list)

    def list_access(self, tree):
        self.validate_args_type_allowed(Command.list_access, tree.children[0], tree.meta)

        list_name = escape_var(tree.children[0].children[0])
        if tree.children[1] == 'random':
            name = f'random.choice({list_name})'
        else:
            # We want list access to be 1-based instead of 0-based, hence the -1
            name = f'{list_name}[int({tree.children[1]})-1]'
        self.save_type_to_lookup(name, HedyType.any)

        return self.to_typed_tree(tree, HedyType.any)

    def add(self, tree):
        self.validate_args_type_allowed(Command.add_to_list, tree.children[1], tree.meta)
        return self.to_typed_tree(tree)

    def remove(self, tree):
        self.validate_args_type_allowed(Command.remove_from_list, tree.children[1], tree.meta)
        return self.to_typed_tree(tree)

    def in_list_check(self, tree):
        self.validate_args_type_allowed(Command.in_list, tree.children[1], tree.meta)
        return self.to_typed_tree(tree, HedyType.boolean)

    def equality_check(self, tree):
        if self.level < 12:
            rules = [int_to_float, int_to_string, float_to_string, input_to_string, input_to_int, input_to_float]
        else:
            rules = [int_to_float, input_to_string, input_to_int, input_to_float]
        self.validate_binary_command_args_type(Command.equality, tree, rules)
        return self.to_typed_tree(tree, HedyType.boolean)

    def repeat(self, tree):
        command = Command.repeat
        allowed_types = get_allowed_types(command, self.level)
        self.check_type_allowed(command, allowed_types, tree.children[0], tree.meta)
        return self.to_typed_tree(tree, HedyType.none)

    def for_list(self, tree):
        command = Command.for_list
        allowed_types = get_allowed_types(command, self.level)
        self.check_type_allowed(command, allowed_types, tree.children[1], tree.meta)
        self.save_type_to_lookup(tree.children[0].children[0], HedyType.any)
        return self.to_typed_tree(tree, HedyType.none)

    def for_loop(self, tree):
        command = Command.for_loop
        allowed_types = get_allowed_types(command, self.level)

        start_type = self.check_type_allowed(command, allowed_types, tree.children[1], tree.meta)
        self.check_type_allowed(command, allowed_types, tree.children[2], tree.meta)

        iterator = str(tree.children[0])
        self.save_type_to_lookup(iterator, start_type)

        return self.to_typed_tree(tree, HedyType.none)

    def integer(self, tree):
        return self.to_typed_tree(tree, HedyType.integer)

    def text(self, tree):
        # under level 12 integers appear as text, so we parse them
        if self.level < 12:
            type_ = HedyType.integer if ConvertToPython.is_int(tree.children[0]) else HedyType.string
        else:
            type_ = HedyType.string
        return self.to_typed_tree(tree, type_)

    def text_in_quotes(self, tree):
        return self.to_typed_tree(tree.children[0], HedyType.string)

    def var_access(self, tree):
        return self.to_typed_tree(tree, HedyType.string)

    def var_access_print(self, tree):
        return self.var_access(tree)

    def var(self, tree):
        return self.to_typed_tree(tree, HedyType.none)

    def number(self, tree):
        number = tree.children[0]
        if ConvertToPython.is_int(number):
            return self.to_typed_tree(tree, HedyType.integer)
        if ConvertToPython.is_float(number):
            return self.to_typed_tree(tree, HedyType.float)
        # We managed to parse a number that cannot be parsed by python
        raise exceptions.ParseException(level=self.level, location='', found=number)

    def subtraction(self, tree):
        return self.to_sum_typed_tree(tree, Command.subtraction)

    def addition(self, tree):
        return self.to_sum_typed_tree(tree, Command.addition)

    def multiplication(self, tree):
        return self.to_sum_typed_tree(tree, Command.multiplication)

    def division(self, tree):
        return self.to_sum_typed_tree(tree, Command.division)

    def to_sum_typed_tree(self, tree, command):
        rules = [int_to_float, input_to_int, input_to_float]
        prom_left_type, prom_right_type = self.validate_binary_command_args_type(command, tree, rules)
        return TypedTree(tree.data, tree.children, tree.meta, prom_left_type)

    def smaller(self, tree):
        return self.to_comparison_tree(Command.smaller, tree)

    def smaller_equal(self, tree):
        return self.to_comparison_tree(Command.smaller_equal, tree)

    def bigger(self, tree):
        return self.to_comparison_tree(Command.bigger, tree)

    def bigger_equal(self, tree):
        return self.to_comparison_tree(Command.bigger_equal, tree)

    def not_equal(self, tree):
        rules = [int_to_float, input_to_int, input_to_float, input_to_string]
        self.validate_binary_command_args_type(Command.not_equal, tree, rules)
        return self.to_typed_tree(tree, HedyType.boolean)

    def to_comparison_tree(self, command, tree):
        allowed_types = get_allowed_types(command, self.level)
        self.check_type_allowed(command, allowed_types, tree.children[0], tree.meta)
        self.check_type_allowed(command, allowed_types, tree.children[1], tree.meta)
        return self.to_typed_tree(tree, HedyType.boolean)

    def validate_binary_command_args_type(self, command, tree, type_promotion_rules):
        allowed_types = get_allowed_types(command, self.level)

        left_type = self.check_type_allowed(command, allowed_types, tree.children[0], tree.meta)
        right_type = self.check_type_allowed(command, allowed_types, tree.children[1], tree.meta)

        if self.ignore_type(left_type) or self.ignore_type(right_type):
            return HedyType.any, HedyType.any

        prom_left_type, prom_right_type = promote_types([left_type, right_type], type_promotion_rules)

        if prom_left_type != prom_right_type:
            left_arg = tree.children[0].children[0]
            right_arg = tree.children[1].children[0]
            raise hedy.exceptions.InvalidTypeCombinationException(
                command, left_arg, right_arg, left_type, right_type, tree.meta.line)
        return prom_left_type, prom_right_type

    def validate_args_type_allowed(self, command, children, meta):
        allowed_types = get_allowed_types(command, self.level)
        children = children if type(children) is list else [children]
        for child in children:
            self.check_type_allowed(command, allowed_types, child, meta)

    def check_type_allowed(self, command, allowed_types, tree, meta=None):
        arg_type = self.get_type(tree)
        if arg_type not in allowed_types and not self.ignore_type(arg_type):
            variable = tree.children[0]

            if command in translatable_commands:
                keywords = translatable_commands[command]
                result = hedy_translation.find_command_keywords(
                    self.input_string,
                    self.lang,
                    self.level,
                    keywords,
                    meta.line,
                    meta.end_line,
                    meta.column - 1,
                    meta.end_column - 2)
                result = {k: v for k, v in result.items()}
                command = ' '.join([v.strip() for v in result.values() if v is not None])
            raise exceptions.InvalidArgumentTypeException(command=command, invalid_type=arg_type,
                                                          invalid_argument=variable, allowed_types=allowed_types, line_number=meta.line)
        return arg_type

    def get_type(self, tree):
        # The rule var_access is used in the grammars definitions only in places where a variable needs to be accessed.
        # So, if it cannot be found in the lookup table, then it is an undefined variable for sure.
        if tree.data == 'var_access':
            var_name = tree.children[0]
            in_lookup, type_in_lookup = self.try_get_type_from_lookup(var_name)
            if in_lookup:
                return type_in_lookup
            else:
                raise hedy.exceptions.UndefinedVarException(name=var_name, line_number=tree.meta.line)

        if tree.data == 'var_access_print':
            var_name = tree.children[0]
            in_lookup, type_in_lookup = self.try_get_type_from_lookup(var_name)
            if in_lookup:
                return type_in_lookup
            else:
                # is there a variable that is mildly similar?
                # if so, we probably meant that one

                # we first check if the list of vars is empty since that is cheaper than stringdistancing.
                # TODO: Can be removed since fall back handles that now
                if len(self.lookup) == 0:
                    raise hedy.exceptions.UnquotedTextException(
                        level=self.level, unquotedtext=var_name, line_number=tree.meta.line)
                else:
                    # TODO: decide when this runs for a while whether this distance small enough!
                    minimum_distance_allowed = 4
                    for var_in_lookup in self.lookup:
                        if calculate_minimum_distance(var_in_lookup.name, var_name) <= minimum_distance_allowed:
                            raise hedy.exceptions.UndefinedVarException(name=var_name, line_number=tree.meta.line)

                    # nothing found? fall back to UnquotedTextException
                    raise hedy.exceptions.UnquotedTextException(
                        level=self.level, unquotedtext=var_name, line_number=tree.meta.line)

        # TypedTree with type 'None' and 'string' could be in the lookup because of the grammar definitions
        # If the tree has more than 1 child, then it is not a leaf node, so do not search in the lookup
        if tree.type_ in [HedyType.none, HedyType.string] and len(tree.children) == 1:
            in_lookup, type_in_lookup = self.try_get_type_from_lookup(tree.children[0])
            if in_lookup:
                return type_in_lookup
        # If the value is not in the lookup or the type is other than 'None' or 'string', return evaluated type
        return tree.type_

    def ignore_type(self, type_):
        return type_ in [HedyType.any, HedyType.none]

    def save_type_to_lookup(self, name, inferred_type):
        for entry in self.lookup:
            if entry.name == escape_var(name):
                entry.type_ = inferred_type

    # Usually, variable definitions are sequential and by the time we need the type of a lookup entry, it would already
    #  be inferred. However, there are valid cases in which the lookup entries will be accessed before their type
    #  is inferred. This is the case with for loops:
    #      for i in 1 to 10
    #          print i
    #  In the above case, we visit `print i`, before the definition of i in the for cycle. In this case, the tree of
    #  lookup entry is used to infer the type and continue the started validation. This approach might cause issues
    #  in case of cyclic references, e.g. b is b + 1. The flag `inferring` is used as a guard against these cases.
    def try_get_type_from_lookup(self, name):
        matches = [entry for entry in self.lookup if entry.name == escape_var(name)]
        if matches:
            match = matches[0]
            if not match.type_:
                if match.currently_inferring:  # there is a cyclic var reference, e.g. b = b + 1
                    raise exceptions.CyclicVariableDefinitionException(
                        variable=match.name, line_number=match.tree.meta.line)
                else:
                    match.currently_inferring = True
                    try:
                        TypeValidator(self.lookup, self.level, self.lang, self.input_string).transform(match.tree)
                    except VisitError as ex:
                        raise ex.orig_exc
                    match.currently_inferring = False

            return True, self.lookup_type_fallback(matches[0].type_)
        return False, None

    def lookup_type_fallback(self, type_in_lookup):
        # If the entry is in the lookup table but its type has not been evaluated yet, then most probably this is a
        # variable referenced before it is defined. In this case, we rely on python to return an error. For now.
        return HedyType.any if type_in_lookup is None else type_in_lookup

    def to_typed_tree(self, tree, type_=HedyType.none):
        return TypedTree(tree.data, tree.children, tree.meta, type_)

    def __default__(self, data, children, meta):
        return TypedTree(data, children, meta, HedyType.none)


def flatten_list_of_lists_to_list(args):
    flat_list = []
    for element in args:
        if isinstance(
                element,
                str):  # str needs a special case before list because a str is also a list and we don't want to split all letters out
            flat_list.append(element)
        elif isinstance(element, list):
            flat_list += flatten_list_of_lists_to_list(element)
        else:
            flat_list.append(element)
    return flat_list


def are_all_arguments_true(args):
    bool_arguments = [x[0] for x in args]
    arguments_of_false_nodes = flatten_list_of_lists_to_list([x[1] for x in args if not x[0]])
    return all(bool_arguments), arguments_of_false_nodes


# this class contains code shared between IsValid and IsComplete, which are quite similar
# because both filter out some types of 'wrong' nodes
@v_args(meta=True)
class Filter(Transformer):
    def __default__(self, data, children, meta):
        result, args = are_all_arguments_true(children)
        return result, args, meta

    def program(self, meta, args):
        bool_arguments = [x[0] for x in args]
        if all(bool_arguments):
            return [True]  # all complete
        else:
            for a in args:
                if not a[0]:
                    return False, a[1]

    # leafs are treated differently, they are True + their arguments flattened
    def var(self, meta, args):
        return True, ''.join([str(c) for c in args]), meta

    def random(self, meta, args):
        return True, 'random', meta

    def number(self, meta, args):
        return True, ''.join([c for c in args]), meta

    def NEGATIVE_NUMBER(self, args):
        return True, ''.join([c for c in args]), None

    def text(self, meta, args):
        return all(args), ''.join([c for c in args]), meta


class UsesTurtle(Transformer):
    def __default__(self, args, children, meta):
        if len(children) == 0:  # no children? you are a leaf that is not Turn or Forward, so you are no Turtle command
            return False
        else:
            return any(isinstance(c, bool) and c is True for c in children)

    # returns true if Forward or Turn are in the tree, false otherwise
    def forward(self, args):
        return True

    def color(self, args):
        return True

    def turn(self, args):
        return True

    # somehow tokens are not picked up by the default rule so they need their own rule
    def INT(self, args):
        return False

    def NAME(self, args):
        return False

    def NUMBER(self, args):
        return False

    def POSITIVE_NUMBER(self, args):
        return False

    def NEGATIVE_NUMBER(self, args):
        return False


class UsesPyGame(Transformer):
    command_prefix = (f"""\
pygame_end = False
while not pygame_end:
  pygame.display.update()
  event = pygame.event.wait()
  if event.type == pygame.QUIT:
    pygame_end = True
    pygame.quit()
    break""")

    def __default__(self, args, children, meta):
        if len(children) == 0:  # no children? you are a leaf that is not Pressed, so you are no PyGame command
            return False
        else:
            return any(isinstance(c, bool) and c is True for c in children)

    def ifpressed(self, args):
        return True

    def ifpressed_else(self, args):
        return True

    def assign_button(self, args):
        return True


class AllCommands(Transformer):
    def __init__(self, level):
        self.level = level

    def translate_keyword(self, keyword):
        # some keywords have names that are not a valid name for a command
        # that's why we call them differently in the grammar
        # we have to translate them to the regular names here for further communciation
        if keyword in ['assign', 'assign_list']:
            return 'is'
        if keyword == 'ifelse':
            return 'else'
        if keyword == 'ifs':
            return 'if'
        if keyword == 'elifs':
            return 'elif'
        if keyword == 'for_loop':
            return 'for'
        if keyword == 'for_list':
            return 'for'
        if keyword == 'or_condition':
            return 'or'
        if keyword == 'and_condition':
            return 'and'
        if keyword == 'while_loop':
            return 'while'
        if keyword == 'in_list_check':
            return 'in'
        if keyword == 'input_empty_brackets':
            return 'input'
        if keyword == 'print_empty_brackets':
            return 'print'
        return str(keyword)

    def __default__(self, args, children, meta):
        # if we are matching a rule that is a command
        production_rule_name = self.translate_keyword(args)
        leaves = flatten_list_of_lists_to_list(children)
        # for the achievements we want to be able to also detct which operators were used by a kid
        operators = ['addition', 'subtraction', 'multiplication', 'division']

        if production_rule_name in commands_per_level[self.level] or production_rule_name in operators:
            if production_rule_name == 'else':  # use of else also has an if
                return ['if', 'else'] + leaves
            return [production_rule_name] + leaves
        else:
            return leaves  # 'pop up' the children

    def command(self, args):
        return args

    def program(self, args):
        return flatten_list_of_lists_to_list(args)

    # somehow tokens are not picked up by the default rule so they need their own rule
    def INT(self, args):
        return []

    def NAME(self, args):
        return []

    def NUMBER(self, args):
        return []

    def POSITIVE_NUMBER(self, args):
        return []

    def NEGATIVE_NUMBER(self, args):
        return []

    def text(self, args):
        return []


def all_commands(input_string, level, lang='en'):
    input_string = process_input_string(input_string, level, lang)
    program_root = parse_input(input_string, level, lang)

    return AllCommands(level).transform(program_root)


class AllPrintArguments(Transformer):
    def __init__(self, level):
        self.level = level

    def __default__(self, args, children, meta):
        leaves = flatten_list_of_lists_to_list(children)

        if args == 'print':
            return children
        else:
            return leaves  # 'pop up' the children

    def program(self, args):
        return flatten_list_of_lists_to_list(args)

    # somehow tokens are not picked up by the default rule so they need their own rule
    def INT(self, args):
        return []

    def NAME(self, args):
        return []

    def NUMBER(self, args):
        return []

    def POSITIVE_NUMBER(self, args):
        return []

    def NEGATIVE_NUMBER(self, args):
        return []

    def text(self, args):
        return ''.join(args)


def all_print_arguments(input_string, level, lang='en'):
    input_string = process_input_string(input_string, level, lang)
    program_root = parse_input(input_string, level, lang)

    return AllPrintArguments(level).transform(program_root)


@v_args(meta=True)
class IsValid(Filter):
    # all rules are valid except for the "Invalid" production rule
    # this function is used to generate more informative error messages
    # tree is transformed to a node of [Bool, args, command number]

    def error_invalid_space(self, meta, args):
        # return space to indicate that line starts in a space
        return False, InvalidInfo(" ", line=args[0][2].line, column=args[0][2].column), meta

    def error_print_nq(self, meta, args):
        words = [str(x[1]) for x in args]  # second half of the list is the word
        text = ' '.join(words)
        return False, InvalidInfo("print without quotes", arguments=[
                                  text], line=meta.line, column=meta.column), meta

    def error_invalid(self, meta, args):
        # TODO: this will not work for misspelling 'at', needs to be improved!

        error = InvalidInfo('invalid command', command=args[0][1], arguments=[
                            [a[1] for a in args[1:]]], line=meta.line, column=meta.column)
        return False, error, meta

    def error_unsupported_number(self, meta, args):
        error = InvalidInfo('unsupported number', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta

    def error_condition(self, meta, args):
        error = InvalidInfo('invalid condition', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta

    def error_repeat_no_command(self, meta, args):
        error = InvalidInfo('invalid repeat', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta

    def error_repeat_no_print(self, meta, args):
        error = InvalidInfo('repeat missing print', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta

    def error_repeat_no_times(self, meta, args):
        error = InvalidInfo('repeat missing times', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta

    def error_text_no_print(self, meta, args):
        error = InvalidInfo('lonely text', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta

    def error_list_access_at(self, meta, args):
        error = InvalidInfo('invalid at keyword', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta
    # other rules are inherited from Filter

    # flat if no longer allowed in level 8 and up
    def error_ifelse(self, meta, args):
        error = InvalidInfo('flat if', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta

    def error_ifpressed_missing_else(self, meta, args):
        error = InvalidInfo('ifpressed missing else', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta

    def error_nested_define(self, meta, args):
        error = InvalidInfo('nested function', arguments=[str(args[0])], line=meta.line, column=meta.column)
        return False, error, meta
    # other rules are inherited from Filter


@v_args(meta=True)
def valid_echo(ast):
    commands = ast.children
    command_names = [x.children[0].data for x in commands]
    no_echo = 'echo' not in command_names

    # no echo is always ok!

    # otherwise, both have to be in the list and echo should come after
    return no_echo or ('echo' in command_names and 'ask' in command_names) and command_names.index(
        'echo') > command_names.index('ask')


@v_args(meta=True)
class IsComplete(Filter):
    def __init__(self, level):
        self.level = level
    # print, ask and echo can miss arguments and then are not complete
    # used to generate more informative error messages
    # tree is transformed to a node of [True] or [False, args, line_number]

    def ask(self, meta, args):
        # in level 1 ask without arguments means args == []
        # in level 2 and up, ask without arguments is a list of 1, namely the var name
        incomplete = (args == [] and self.level == 1) or (len(args) == 1 and self.level >= 2)
        if meta is not None:
            return not incomplete, ('ask', meta.line)
        else:
            return not incomplete, ('ask', 1)

    def print(self, meta, args):
        return args != [], ('print', meta.line)

    def input(self, meta, args):
        return len(args) > 1, ('input', meta.line)

    def length(self, meta, args):
        return args != [], ('len', meta.line)

    def error_print_nq(self, meta, args):
        return args != [], ('print level 2', meta.line)

    def echo(self, meta, args):
        # echo may miss an argument
        return True, ('echo', meta.line)

    # other rules are inherited from Filter


def process_characters_needing_escape(value):
    # defines what happens if a kids uses ' or \ in in a string
    for c in characters_that_need_escaping:
        value = value.replace(c, f'\\{c}')
    return value


def get_allowed_types(command, level):
    # get only the allowed types of the command for all levels before the requested level
    allowed = [values for key, values in commands_and_types_per_level[command].items() if key <= level]
    # use the allowed types of the highest level available
    return allowed[-1] if allowed else []


# decorator used to store each class in the lookup table
def hedy_transpiler(level):
    def decorator(c):
        TRANSPILER_LOOKUP[level] = c
        c.level = level
        return c
    return decorator


@v_args(meta=True)
class ConvertToPython(Transformer):
    def __init__(self, lookup, numerals_language="Latin"):
        self.lookup = lookup
        self.numerals_language = numerals_language

    # default for line number is max lines so if it is not given, there
    # is no check on whether the var is defined
    def is_variable(self, variable_name, access_line_number=100):
        all_names = [a.name for a in self.lookup]
        all_names_before_access_line = [a.name for a in self.lookup if a.linenumber <= access_line_number]

        if variable_name in all_names and variable_name not in all_names_before_access_line:
            # referenced before assignment!
            definition_line_number = [a.linenumber for a in self.lookup if a.name == variable_name][0]
            raise hedy.exceptions.AccessBeforeAssignException(
                name=variable_name,
                access_line_number=access_line_number,
                definition_line_number=definition_line_number)

        is_function = False
        if isinstance(variable_name, str):
            pattern = r'^([a-zA-Z_][a-zA-Z0-9_]*)\('
            match = re.match(pattern, variable_name)
            is_function = match and [a.name for a in self.lookup if match.group(1) + "()" == a.name]

        return escape_var(variable_name) in all_names_before_access_line or is_function

    def process_variable(self, arg, access_line_number=100):
        # processes a variable by hashing and escaping when needed
        if self.is_variable(arg, access_line_number):
            return escape_var(arg)
        if ConvertToPython.is_quoted(arg):
            arg = arg[1:-1]
        return f"'{process_characters_needing_escape(arg)}'"

    def process_variable_for_fstring(self, variable_name, access_line_number=100):
        if self.is_variable(variable_name, access_line_number):
            return "{" + escape_var(variable_name) + "}"
        else:
            return process_characters_needing_escape(variable_name)

    def process_variable_for_comparisons(self, name):
        # used to transform variables in comparisons
        if self.is_variable(name):
            return f"convert_numerals('{self.numerals_language}', {escape_var(name)})"
        elif ConvertToPython.is_float(name):
            return f"convert_numerals('{self.numerals_language}', {name})"
        elif ConvertToPython.is_quoted(name):
            return f"{name}"

    def make_f_string(self, args):
        argument_string = ''
        for argument in args:
            if self.is_variable(argument):
                # variables are placed in {} in the f string
                argument_string += "{" + escape_var(argument) + "}"
            else:
                # strings are written regularly
                # however we no longer need the enclosing quotes in the f-string
                # the quotes are only left on the argument to check if they are there.
                argument_string += argument.replace("'", '')

        return f"print(f'{argument_string}')"

    def get_fresh_var(self, name):
        while self.is_variable(name):
            name = '_' + name
        return name

    def check_var_usage(self, args, var_access_linenumber=100):
        # this function checks whether arguments are valid
        # we can proceed if all arguments are either quoted OR all variables

        def is_var_candidate(arg) -> bool:
            return not isinstance(arg, Tree) and \
                not ConvertToPython.is_int(arg) and \
                not ConvertToPython.is_float(arg)

        args_to_process = [a for a in args if is_var_candidate(a)]  # we do not check trees (calcs) they are always ok

        unquoted_args = [a for a in args_to_process if not ConvertToPython.is_quoted(a)]
        unquoted_in_lookup = [self.is_variable(a, var_access_linenumber) for a in unquoted_args]

        if unquoted_in_lookup == [] or all(unquoted_in_lookup):
            # all good? return for further processing
            return args
        else:
            # TODO: check whether this is really never raised??
            # return first name with issue
            first_unquoted_var = unquoted_args[0]
            raise exceptions.UndefinedVarException(name=first_unquoted_var, line_number=var_access_linenumber)

    # static methods
    @staticmethod
    def is_quoted(s):
        opening_quotes = ['‘', "'", '"', "“", "«"]
        closing_quotes = ['’', "'", '"', "”", "»"]
        return len(s) > 1 and (s[0] in opening_quotes and s[-1] in closing_quotes)

    @staticmethod
    def is_int(n):
        try:
            int(n)
            return True
        except ValueError:
            return False

    @staticmethod
    def is_float(n):
        try:
            float(n)
            return True
        except ValueError:
            return False

    @staticmethod
    def is_random(s):
        return 'random.choice' in s

    @staticmethod
    def is_list(s):
        return '[' in s and ']' in s

    @staticmethod
    def indent(s, spaces_amount=2):
        lines = s.split('\n')
        return '\n'.join([' ' * spaces_amount + line for line in lines])


@v_args(meta=True)
@hedy_transpiler(level=1)
@source_map_transformer(source_map)
class ConvertToPython_1(ConvertToPython):

    def __init__(self, lookup, numerals_language):
        self.numerals_language = numerals_language
        self.lookup = lookup
        __class__.level = 1

    def program(self, meta, args):
        return '\n'.join([str(c) for c in args])

    def command(self, meta, args):
        return args[0]

    def text(self, meta, args):
        return ''.join([str(c) for c in args])

    def integer(self, meta, args):
        # remove whitespaces
        return str(int(args[0].replace(' ', '')))

    def number(self, meta, args):
        return str(int(args[0]))

    def NEGATIVE_NUMBER(self, meta, args):
        return str(int(args[0]))

    def print(self, meta, args):
        # escape needed characters
        argument = process_characters_needing_escape(args[0])
        return "print('" + argument + "')"

    def ask(self, meta, args):
        argument = process_characters_needing_escape(args[0])
        return "answer = input('" + argument + "')"

    def echo(self, meta, args):
        if len(args) == 0:
            return "print(answer)"  # no arguments, just print answer

        argument = process_characters_needing_escape(args[0])
        return "print('" + argument + " '+answer)"

    def comment(self, meta, args):
        return f"#{''.join(args)}"

    def empty_line(self, meta, args):
        return ''

    def forward(self, meta, args):
        if len(args) == 0:
            return sleep_after('t.forward(50)', False)
        return self.make_forward(int(args[0]))

    def color(self, meta, args):
        if len(args) == 0:
            return "t.pencolor('black')"  # no arguments defaults to black ink

        arg = args[0].data
        if arg in command_make_color:
            return f"t.pencolor('{arg}')"
        else:
            # the TypeValidator should protect against reaching this line:
            raise exceptions.InvalidArgumentTypeException(command=Command.color, invalid_type='', invalid_argument=arg,
                                                          allowed_types=get_allowed_types(Command.color, self.level), line_number=meta.line)

    def turn(self, meta, args):
        if len(args) == 0:
            return "t.right(90)"  # no arguments defaults to a right turn

        arg = args[0].data
        if arg == 'left':
            return "t.left(90)"
        elif arg == 'right':
            return "t.right(90)"
        else:
            # the TypeValidator should protect against reaching this line:
            raise exceptions.InvalidArgumentTypeException(command=Command.turn, invalid_type='', invalid_argument=arg,
                                                          allowed_types=get_allowed_types(Command.turn, self.level), line_number=meta.line)

    def make_turn(self, parameter):
        return self.make_turtle_command(parameter, Command.turn, 'right', False, 'int')

    def make_forward(self, parameter):
        return self.make_turtle_command(parameter, Command.forward, 'forward', True, 'int')

    def make_color(self, parameter):
        return self.make_turtle_color_command(parameter, Command.color, 'pencolor')

    def make_turtle_command(self, parameter, command, command_text, add_sleep, type):
        exception = ''
        if isinstance(parameter, str):
            exception = self.make_catch_exception([parameter])
        variable = self.get_fresh_var('__trtl')
        transpiled = exception + textwrap.dedent(f"""\
            {variable} = {parameter}
            try:
              {variable} = {type}({variable})
            except ValueError:
              raise Exception(f'While running your program the command {style_command(command)} received the value {style_command('{' + variable + '}')} which is not allowed. Try changing the value to a number.')
            t.{command_text}(min(600, {variable}) if {variable} > 0 else max(-600, {variable}))""")
        if add_sleep:
            return sleep_after(transpiled, False)
        return transpiled

    def make_turtle_color_command(self, parameter, command, command_text):
        variable = self.get_fresh_var('__trtl')
        return textwrap.dedent(f"""\
            {variable} = f'{parameter}'
            if {variable} not in {command_make_color}:
              raise Exception(f'While running your program the command {style_command(command)} received the value {style_command('{' + variable + '}')} which is not allowed. Try using another color.')
            t.{command_text}({variable})""")

    def make_catch_exception(self, args):
        lists_names = []
        list_args = []
        var_regex = r"[\p{Lu}\p{Ll}\p{Lt}\p{Lm}\p{Lo}\p{Nl}_]+|[\p{Mn}\p{Mc}\p{Nd}\p{Pc}·]+"
        # List usage comes in indexation and random choice
        list_regex = fr"(({var_regex})+\[int\(({var_regex})\)-1\])|(random\.choice\(({var_regex})\))"
        for arg in args:
            # Expressions come inside a Tree object, so unpack them
            if isinstance(arg, Tree):
                arg = arg.children[0]
            for group in regex.findall(list_regex, arg):
                if group[0] != '':
                    list_args.append(group[0])
                    lists_names.append(group[1])
                else:
                    list_args.append(group[3])
                    lists_names.append(group[4])
        code = ""
        exception_text_template = gettext('catch_index_exception')
        for i, list_name in enumerate(lists_names):
            exception_text = exception_text_template.replace('{list_name}', style_command(list_name))
            code += textwrap.dedent(f"""\
            try:
              {list_args[i]}
            except IndexError:
              raise Exception('{exception_text}')
            """)
        return code


@v_args(meta=True)
@hedy_transpiler(level=2)
@source_map_transformer(source_map)
class ConvertToPython_2(ConvertToPython_1):

    def error_ask_dep_2(self, meta, args):
        # ask is no longer usable this way, raise!
        # ask_needs_var is an entry in lang.yaml in texts where we can add extra info on this error
        raise hedy.exceptions.WrongLevelException(1, 'ask', "ask_needs_var", meta.line)

    def error_echo_dep_2(self, meta, args):
        # echo is no longer usable this way, raise!
        # ask_needs_var is an entry in lang.yaml in texts where we can add extra info on this error
        raise hedy.exceptions.WrongLevelException(1, 'echo', "echo_out", meta.line)

    def color(self, meta, args):
        if len(args) == 0:
            return "t.pencolor('black')"
        arg = args[0]
        if not isinstance(arg, str):
            arg = arg.data

        arg = self.process_variable_for_fstring(arg)

        return self.make_color(arg)

    def turn(self, meta, args):
        if len(args) == 0:
            return "t.right(90)"  # no arguments defaults to a right turn
        arg = args[0]
        if self.is_variable(arg):
            return self.make_turn(escape_var(arg))
        if arg.lstrip("-").isnumeric():
            return self.make_turn(arg)

    def var(self, meta, args):
        name = args[0]
        return escape_var(name)

    def var_access(self, meta, args):
        name = args[0]
        self.check_var_usage(args, meta.line)
        return escape_var(name)

    def var_access_print(self, meta, args):
        return self.var_access(meta, args)

    def print(self, meta, args):
        args_new = []
        for a in args:
            # list access has been already rewritten since it occurs lower in the tree
            # so when we encounter it as a child of print it will not be a subtree, but
            # transpiled code (for example: random.choice(dieren))
            # therefore we should not process it anymore and thread it as a variable:
            # we set the line number to 100 so there is never an issue with variable access before
            # assignment (regular code will not work since random.choice(dieren) is never defined as var as such)
            if "random.choice" in a or "[" in a:
                args_new.append(self.process_variable_for_fstring(a, meta.line))
            else:
                # this regex splits words from non-letter characters, such that name! becomes [name, !]
                res = regex.findall(
                    r"[·\p{Lu}\p{Ll}\p{Lt}\p{Lm}\p{Lo}\p{Nl}\p{Mn}\p{Mc}\p{Nd}\p{Pc}]+|[^·\p{Lu}\p{Ll}\p{Lt}\p{Lm}\p{Lo}\p{Nl}]+", a)
                args_new.append(''.join([self.process_variable_for_fstring(x, meta.line) for x in res]))
        exception = self.make_catch_exception(args)
        argument_string = ' '.join(args_new)
        return exception + f"print(f'{argument_string}')"

    def ask(self, meta, args):
        var = args[0]
        all_parameters = ["'" + process_characters_needing_escape(a) + "'" for a in args[1:]]
        return f'{var} = input(' + '+'.join(all_parameters) + ")"

    def forward(self, meta, args):
        if len(args) == 0:
            return sleep_after('t.forward(50)', False)

        if ConvertToPython.is_int(args[0]):
            parameter = int(args[0])
        else:
            # if not an int, then it is a variable
            parameter = args[0]

        return self.make_forward(parameter)

    def assign(self, meta, args):
        parameter = args[0]
        value = args[1]
        if self.is_random(value) or self.is_list(value):
            exception = self.make_catch_exception([value])
            return exception + parameter + " = " + value
        else:
            if self.is_variable(value):
                value = self.process_variable(value, meta.line)
                return parameter + " = " + value
            else:
                # if the assigned value is not a variable and contains single quotes, escape them
                value = process_characters_needing_escape(value)
                return parameter + " = '" + value + "'"

    def sleep(self, meta, args):
        if not args:
            return "time.sleep(1)"
        else:
            value = f'"{args[0]}"' if self.is_int(args[0]) else args[0]
            exceptions = self.make_catch_exception(args)
            try_prefix = "try:\n" + textwrap.indent(exceptions, "  ")
            code = try_prefix + textwrap.dedent(f"""\
                  time.sleep(int({value}))
                except ValueError:
                  raise Exception(f'While running your program the command {style_command(Command.sleep)} received the value {style_command('{' + value + '}')} which is not allowed. Try changing the value to a number.')""")
            return code


@v_args(meta=True)
@hedy_transpiler(level=3)
@source_map_transformer(source_map)
class ConvertToPython_3(ConvertToPython_2):
    def assign_list(self, meta, args):
        parameter = args[0]
        values = [f"'{process_characters_needing_escape(a)}'" for a in args[1:]]
        return f"{parameter} = [{', '.join(values)}]"

    def list_access(self, meta, args):
        args = [escape_var(a) for a in args]

        # check the arguments (except when they are random or numbers, that is not quoted nor a var but is allowed)
        self.check_var_usage([a for a in args if a != 'random' and not a.isnumeric()], meta.line)

        if args[1] == 'random':
            return 'random.choice(' + args[0] + ')'
        else:
            return args[0] + '[int(' + args[1] + ')-1]'

    def process_argument(self, meta, arg):
        # only call process_variable if arg is a string, else keep as is (ie.
        # don't change 5 into '5', my_list[1] into 'my_list[1]')
        if arg.isnumeric() and isinstance(arg, int):  # is int/float
            return arg
        elif (self.is_list(arg)):  # is list indexing
            before_index, after_index = arg.split(']', 1)
            return before_index + '-1' + ']' + after_index   # account for 1-based indexing
        else:
            return self.process_variable(arg, meta.line)

    def add(self, meta, args):
        value = self.process_argument(meta, args[0])
        list_var = args[1]
        return f"{list_var}.append({value})"

    def remove(self, meta, args):
        value = self.process_argument(meta, args[0])
        list_var = args[1]
        return textwrap.dedent(f"""\
        try:
          {list_var}.remove({value})
        except:
          pass""")


@v_args(meta=True)
@hedy_transpiler(level=4)
@source_map_transformer(source_map)
class ConvertToPython_4(ConvertToPython_3):

    def process_variable_for_fstring(self, name):
        if self.is_variable(name):
            if self.numerals_language == "Latin":
                converted = escape_var(name)
            else:
                converted = f'convert_numerals("{self.numerals_language}",{escape_var(name)})'
            return "{" + converted + "}"
        else:
            if self.is_quoted(name):
                name = name[1:-1]
            return name.replace("'", "\\'")  # at level 4 backslashes are escaped in preprocessing, so we escape only '

    def var_access(self, meta, args):
        name = args[0]
        return escape_var(name)

    def var_access_print(self, meta, args):
        name = args[0]
        return escape_var(name)

    def print_ask_args(self, meta, args):
        args = self.check_var_usage(args, meta.line)
        result = ''
        for argument in args:
            argument = self.process_variable_for_fstring(argument)
            result += argument
        return result

    def print(self, meta, args):
        argument_string = self.print_ask_args(meta, args)
        exceptions = self.make_catch_exception(args)
        return exceptions + f"print(f'{argument_string}')"

    def ask(self, meta, args):
        var = args[0]
        argument_string = self.print_ask_args(meta, args[1:])
        return f"{var} = input(f'{argument_string}')"

    def error_print_nq(self, meta, args):
        return ConvertToPython_2.print(self, meta, args)

    def clear(self, meta, args):
        return f"""extensions.clear()
try:
    # If turtle is being used, reset canvas
    t.hideturtle()
    turtle.resetscreen()
    t.left(90)
    t.showturtle()
except NameError:
    pass"""


@v_args(meta=True)
@hedy_transpiler(level=5)
@source_map_transformer(source_map)
class ConvertToPython_5(ConvertToPython_4):
    def __init__(self, lookup, numerals_language):
        super().__init__(lookup, numerals_language)

    def ifs(self, meta, args):
        return f"""if {args[0]}:
{ConvertToPython.indent(args[1])}"""

    def ifelse(self, meta, args):
        return f"""if {args[0]}:
{ConvertToPython.indent(args[1])}
else:
{ConvertToPython.indent(args[2])}"""

    def condition(self, meta, args):
        return ' and '.join(args)

    def condition_spaces(self, meta, args):
        arg0 = self.process_variable(args[0], meta.line)
        arg1 = self.process_variable(' '.join(args[1:]))
        return f"{arg0} == {arg1}"

    def equality_check(self, meta, args):
        arg0 = self.process_variable(args[0], meta.line)
        arg1 = ' '.join([self.process_variable(a) for a in args[1:]])
        return f"{arg0} == {arg1}"
        # TODO, FH 2021: zelfde change moet ik ook nog ff maken voor equal. check in hogere levels

    def in_list_check(self, meta, args):
        arg0 = self.process_variable(args[0], meta.line)
        arg1 = self.process_variable(args[1], meta.line)
        return f"{arg0} in {arg1}"

    def not_in_list_check(self, meta, args):
        arg0 = self.process_variable(args[0], meta.line)
        arg1 = self.process_variable(args[1], meta.line)
        return f"{arg0} not in {arg1}"

    def assign_button(self, meta, args):
        button_name = self.process_variable(args[0], meta.line)
        return f"""create_button({button_name})"""

    def make_ifpressed_command(self, command, button=False, add_command_prefix=True):
        if button:
            command = f"""\
  if event.type == pygame.USEREVENT:
{ConvertToPython.indent(command, 4)}
    # End of PyGame Event Handler"""
        else:
            command = f"""\
  if event.type == pygame.KEYDOWN:
{ConvertToPython.indent(command, 4)}
    # End of PyGame Event Handler"""

        if add_command_prefix:
            return UsesPyGame.command_prefix + "\n" + command
        else:
            return "\n" + command

    def ifpressed_else(self, meta, args):
        var_or_button = args[0]
        if self.is_variable(var_or_button):
            return self.make_ifpressed_command(f"""\
if event.key == {var_or_button}:
{ConvertToPython.indent(args[1])}
  break
else:
{ConvertToPython.indent(args[2])}
  break""", button=False)
        elif len(var_or_button) > 1:
            button_name = self.process_variable(args[0], meta.line)
            return self.make_ifpressed_command(f"""\
if event.key == {button_name}:
{ConvertToPython.indent(args[1])}
  break
else:
{ConvertToPython.indent(args[2])}
  break""", button=True)
        else:
            return self.make_ifpressed_command(f"""\
if event.unicode == '{args[0]}':
{ConvertToPython.indent(args[1])}
  break
else:
{ConvertToPython.indent(args[2])}
  break""", button=False)


@v_args(meta=True)
@hedy_transpiler(level=6)
@source_map_transformer(source_map)
class ConvertToPython_6(ConvertToPython_5):

    def print_ask_args(self, meta, args):
        # we only check non-Tree (= non calculation) arguments
        self.check_var_usage(args, meta.line)

        # force all to be printed as strings (since there can not be int arguments)
        args_new = []
        for a in args:
            if isinstance(a, Tree):
                if self.numerals_language == "Latin":
                    args_new.append("{" + a.children[0] + "}")
                else:
                    converted = f'convert_numerals("{self.numerals_language}",{a.children[0]})'
                    args_new.append("{" + converted + "}")
            else:
                args_new.append(self.process_variable_for_fstring(a))

        return ''.join(args_new)

    def equality_check(self, meta, args):
        arg0 = self.process_variable(args[0], meta.line)
        remaining_text = ' '.join(args[1:])
        arg1 = self.process_variable(remaining_text, meta.line)

        # FH, 2022 this used to be str but convert_numerals in needed to accept non-latin numbers
        # and works exactly as str for latin numbers (i.e. does nothing on str, makes 3 into '3')
        return f"convert_numerals('{self.numerals_language}', {arg0}) == convert_numerals('{self.numerals_language}', {arg1})"

    def assign(self, meta, args):
        parameter = args[0]
        value = args[1]
        if type(value) is Tree:
            return parameter + " = " + value.children[0]
        else:
            if self.is_variable(value):
                value = self.process_variable(value, meta.line)
                if self.is_list(value) or self.is_random(value):
                    exception = self.make_catch_exception([value])
                    return exception + parameter + " = " + value
                else:
                    return parameter + " = " + value
            else:
                # if the assigned value is not a variable and contains single quotes, escape them
                value = process_characters_needing_escape(value)
                return parameter + " = '" + value + "'"

    def process_token_or_tree(self, argument):
        if type(argument) is Tree:
            return f'{str(argument.children[0])}'
        if argument.isnumeric():
            latin_numeral = int(argument)
            return f'int({latin_numeral})'
        return f'int({argument})'

    def process_calculation(self, args, operator):
        # arguments of a sum are either a token or a
        # tree resulting from earlier processing
        # for trees we need to grap the inner string
        # for tokens we add int around them

        args = [self.process_token_or_tree(a) for a in args]
        return Tree('sum', [f'{args[0]} {operator} {args[1]}'])

    def addition(self, meta, args):
        return self.process_calculation(args, '+')

    def subtraction(self, meta, args):
        return self.process_calculation(args, '-')

    def multiplication(self, meta, args):
        return self.process_calculation(args, '*')

    def division(self, meta, args):
        return self.process_calculation(args, '//')

    def turn(self, meta, args):
        if len(args) == 0:
            return "t.right(90)"  # no arguments defaults to a right turn
        arg = args[0]
        if self.is_variable(arg):
            return self.make_turn(escape_var(arg))
        if isinstance(arg, Tree):
            return self.make_turn(arg.children[0])
        return self.make_turn(int(arg))

    def forward(self, meta, args):
        if len(args) == 0:
            return sleep_after('t.forward(50)', False)
        arg = args[0]
        if self.is_variable(arg):
            return self.make_forward(escape_var(arg))
        if isinstance(arg, Tree):
            return self.make_forward(arg.children[0])
        return self.make_forward(int(args[0]))


def sleep_after(commands, indent=True):
    lines = commands.split()
    if lines[-1] == "time.sleep(0.1)":  # we don't sleep double so skip if final line is a sleep already
        return commands

    sleep_command = "time.sleep(0.1)" if indent is False else "  time.sleep(0.1)"
    return commands + "\n" + sleep_command


@v_args(meta=True)
@hedy_transpiler(level=7)
@source_map_transformer(source_map)
class ConvertToPython_7(ConvertToPython_6):
    def repeat(self, meta, args):
        var_name = self.get_fresh_var('__i__')
        times = self.process_variable(args[0], meta.line)
        command = args[1]
        # in level 7, repeats can only have 1 line as their arguments
        command = sleep_after(command, False)
        return f"""for {var_name} in range(int({str(times)})):
{ConvertToPython.indent(command)}"""


@v_args(meta=True)
@hedy_transpiler(level=8)
@v_args(meta=True)
@hedy_transpiler(level=9)
@source_map_transformer(source_map)
class ConvertToPython_8_9(ConvertToPython_7):

    def command(self, meta, args):
        return "".join(args)

    def repeat(self, meta, args):
        # todo fh, may 2022, could be merged with 7 if we make
        # indent a boolean parameter?

        var_name = self.get_fresh_var('i')
        times = self.process_variable(args[0], meta.line)

        all_lines = [ConvertToPython.indent(x) for x in args[1:]]
        body = "\n".join(all_lines)
        body = sleep_after(body)

        return f"for {var_name} in range(int({times})):\n{body}"

    def ifs(self, meta, args):
        all_lines = [ConvertToPython.indent(x) for x in args[1:]]
        return "if " + args[0] + ":\n" + "\n".join(all_lines)

    def ifpressed(self, met, args):
        args = [a for a in args if a != ""]  # filter out in|dedent tokens

        all_lines = '\n'.join([x for x in args[1:]])
        all_lines = ConvertToPython.indent(all_lines)
        var_or_key = args[0]
        # if this is a variable, we assume it is a key (for now)
        if self.is_variable(var_or_key):
            return self.make_ifpressed_command(f"""\
if event.unicode == {args[0]}:
{all_lines}
  break""", button=False)
        elif len(var_or_key) == 1:  # one character? also a key!
            return self.make_ifpressed_command(f"""\
if event.unicode == '{args[0]}':
{all_lines}
  break""", button=False)
        else:  # otherwise we mean a button
            button_name = self.process_variable(args[0], met.line)
            return self.make_ifpressed_command(f"""\
if event.key == {button_name}:
{all_lines}
  break""", button=True)

    def ifpressed_else(self, met, args):
        args = [a for a in args if a != ""]  # filter out in|dedent tokens

        all_lines = '\n'.join([x for x in args[1:]])
        all_lines = ConvertToPython.indent(all_lines)

        if (len(args[0]) > 1):
            button_name = self.process_variable(args[0], met.line)
            return self.make_ifpressed_command(f"""\
if event.key == {button_name}:
{all_lines}
  break""", button=True)
        else:
            return self.make_ifpressed_command(f"""\
if event.unicode == '{args[0]}':
{all_lines}
  break""", button=False)

    def elses(self, meta, args):
        args = [a for a in args if a != ""]  # filter out in|dedent tokens
        all_lines = [ConvertToPython.indent(x) for x in args]

        return "\nelse:\n" + "\n".join(all_lines)

    def ifpressed_elses(self, meta, args):
        args = [a for a in args if a != ""]  # filter out in|dedent tokens
        args += ["  break"]

        all_lines = "\n".join(
            [ConvertToPython.indent(x, 4) for x in args]
        )

        return all_lines

    def var_access(self, meta, args):
        if len(args) == 1:  # accessing a var
            return escape_var(args[0])
        else:
            # this is list_access
            return escape_var(args[0]) + "[" + str(escape_var(args[1])) + "]" if type(args[1]
                                                                                      ) is not Tree else "random.choice(" + str(escape_var(args[0])) + ")"

    def var_access_print(self, meta, args):
        return self.var_access(meta, args)


@v_args(meta=True)
@hedy_transpiler(level=10)
@source_map_transformer(source_map)
class ConvertToPython_10(ConvertToPython_8_9):
    def for_list(self, meta, args):
        args = [a for a in args if a != ""]  # filter out in|dedent tokens
        times = self.process_variable(args[0], meta.line)

        body = "\n".join([ConvertToPython.indent(x) for x in args[2:]])

        body = sleep_after(body, True)
        return f"for {times} in {args[1]}:\n{body}"


@v_args(meta=True)
@hedy_transpiler(level=11)
@source_map_transformer(source_map)
class ConvertToPython_11(ConvertToPython_10):
    def for_loop(self, meta, args):
        args = [a for a in args if a != ""]  # filter out in|dedent tokens
        iterator = escape_var(args[0])
        body = "\n".join([ConvertToPython.indent(x) for x in args[3:]])
        body = sleep_after(body)
        stepvar_name = self.get_fresh_var('step')
        begin = self.process_token_or_tree(args[1])
        end = self.process_token_or_tree(args[2])
        return f"""{stepvar_name} = 1 if {begin} < {end} else -1
for {iterator} in range({begin}, {end} + {stepvar_name}, {stepvar_name}):
{body}"""


@v_args(meta=True)
@hedy_transpiler(level=12)
@source_map_transformer(source_map)
class ConvertToPython_12(ConvertToPython_11):
    def define(self, meta, args):
        function_name = args[0]
        args_str = ", ".join(str(x) for x in args[1].children) if isinstance(
            args[1], Tree) and args[1].data == "arguments" else ""

        lines = []
        for line in args[1 if args_str == "" else 2:]:
            lines.append(line)
        body = "\n".join(ConvertToPython.indent(x) for x in lines)

        return f"def {function_name}({args_str}):\n{body}"

    def call(self, meta, args):
        args_str = ""
        if len(args) > 1:
            args_str = ", ".join(str(x.children[0]) if isinstance(x, Tree) else str(x) for x in args[1].children)
        return f"{args[0]}({args_str})"

    def returns(self, meta, args):
        argument_string = self.print_ask_args(meta, args)
        exception = self.make_catch_exception(args)
        return exception + f"return f'''{argument_string}'''"

    def number(self, meta, args):
        # try all ints? return ints
        try:
            all_int = [str(int(x)) == x for x in args]
            if all(all_int):
                return ''.join(args)
            else:
                # int succeeds but does not return the same? these are non-latin numbers
                # and need to be casted
                return ''.join([str(int(x)) for x in args])
        except Exception:
            # if not? make into all floats
            numbers = [str(float(x)) for x in args]
            return ''.join(numbers)

    def NEGATIVE_NUMBER(self, meta, args):
        numbers = [str(float(x)) for x in args]
        return ''.join(numbers)

    def text_in_quotes(self, meta, args):
        # We need to re-add the quotes, so that the Python code becomes name = 'Jan' or "Jan's"
        text = args[0]
        if "'" in text:
            return f'"{text}"'
        return f"'{text}'"

    def process_token_or_tree(self, argument):
        if isinstance(argument, Tree):
            return f'{str(argument.children[0])}'
        else:
            return argument

    def print_ask_args(self, meta, args):
        result = super().print_ask_args(meta, args)
        if "'''" in result:
            raise exceptions.UnsupportedStringValue(invalid_value="'''")
        return result

    def print(self, meta, args):
        argument_string = self.print_ask_args(meta, args)
        exception = self.make_catch_exception(args)
        return exception + f"print(f'''{argument_string}''')"

    def ask(self, meta, args):
        var = args[0]
        argument_string = self.print_ask_args(meta, args[1:])
        assign = f"{var} = input(f'''{argument_string}''')"

        return textwrap.dedent(f"""\
        {assign}
        try:
          {var} = int({var})
        except ValueError:
          try:
            {var} = float({var})
          except ValueError:
            pass""")  # no number? leave as string

    def assign_list(self, meta, args):
        parameter = args[0]
        values = args[1:]
        return parameter + " = [" + ", ".join(values) + "]"

    def assign(self, meta, args):
        right_hand_side = args[1]
        left_hand_side = args[0]

        # we now need to check if the right hand side of te assign is
        # either a var or quoted, if it is not (and undefined var is raised)
        # the real issue is probably that the kid forgot quotes
        try:
            # check_var_usage expects a list of arguments so place this one in a list.
            self.check_var_usage([right_hand_side], meta.line)
        except exceptions.UndefinedVarException:
            # is the text a number? then no quotes are fine. if not, raise maar!

            if not (ConvertToPython.is_int(right_hand_side) or ConvertToPython.is_float(
                    right_hand_side) or ConvertToPython.is_random(right_hand_side)):
                raise exceptions.UnquotedAssignTextException(
                    text=args[1],
                    line_number=meta.line)

        if isinstance(right_hand_side, Tree):
            exception = self.make_catch_exception([right_hand_side.children[0]])
            return exception + left_hand_side + " = " + right_hand_side.children[0]
        else:
            # we no longer escape quotes here because they are now needed
            exception = self.make_catch_exception([right_hand_side])
            return exception + left_hand_side + " = " + right_hand_side + ""

    def var(self, meta, args):
        name = args[0]
        self.check_var_usage(args, meta.line)
        return escape_var(name)

    def turn(self, meta, args):
        if len(args) == 0:
            return "t.right(90)"  # no arguments defaults to a right turn
        arg = args[0]
        if self.is_variable(arg):
            return self.make_turn(escape_var(arg))
        if isinstance(arg, Tree):
            return self.make_turn(arg.children[0])
        return self.make_turn(float(arg))

    def forward(self, meta, args):
        if len(args) == 0:
            return sleep_after('t.forward(50)', False)
        arg = args[0]
        if self.is_variable(arg):
            return self.make_forward(escape_var(arg))
        if isinstance(arg, Tree):
            return self.make_forward(arg.children[0])
        return self.make_forward(float(args[0]))

    def make_turn(self, parameter):
        return self.make_turtle_command(parameter, Command.turn, 'right', False, 'float')

    def make_forward(self, parameter):
        return self.make_turtle_command(parameter, Command.forward, 'forward', True, 'float')

    def division(self, meta, args):
        return self.process_calculation(args, '/')


@v_args(meta=True)
@hedy_transpiler(level=13)
@source_map_transformer(source_map)
class ConvertToPython_13(ConvertToPython_12):
    def and_condition(self, meta, args):
        return ' and '.join(args)

    def or_condition(self, meta, args):
        return ' or '.join(args)


@v_args(meta=True)
@hedy_transpiler(level=14)
@source_map_transformer(source_map)
class ConvertToPython_14(ConvertToPython_13):
    def process_comparison(self, meta, args, operator):

        arg0 = self.process_variable_for_comparisons(args[0])
        arg1 = self.process_variable_for_comparisons(args[1])

        simple_comparison = arg0 + operator + arg1

        if len(args) == 2:
            return simple_comparison  # no and statements
        else:
            return f"{simple_comparison} and {args[2]}"

    def equality_check_dequals(self, meta, args):
        return super().equality_check(meta, args)

    def smaller(self, meta, args):
        return self.process_comparison(meta, args, "<")

    def bigger(self, meta, args):
        return self.process_comparison(meta, args, ">")

    def smaller_equal(self, meta, args):
        return self.process_comparison(meta, args, "<=")

    def bigger_equal(self, meta, args):
        return self.process_comparison(meta, args, ">=")

    def not_equal(self, meta, args):
        return self.process_comparison(meta, args, "!=")


@v_args(meta=True)
@hedy_transpiler(level=15)
@source_map_transformer(source_map)
class ConvertToPython_15(ConvertToPython_14):
    def while_loop(self, meta, args):
        args = [a for a in args if a != ""]  # filter out in|dedent tokens
        all_lines = [ConvertToPython.indent(x) for x in args[1:]]
        body = "\n".join(all_lines)
        body = sleep_after(body)
        exceptions = self.make_catch_exception([args[0]])
        return exceptions + "while " + args[0] + ":\n" + body

    def ifpressed(self, meta, args):
        button_name = self.process_variable(args[0], meta.line)
        var_or_button = args[0]
        all_lines = [ConvertToPython.indent(x) for x in args[1:]]
        body = "\n".join(all_lines)

        # for now we assume a var is a letter, we can check this lateron by searching for a ... = button
        if self.is_variable(var_or_button):
            return self.make_ifpressed_command(f"""\
if event.unicode == {args[0]}:
{body}
  break""", button=False)
        elif len(var_or_button) > 1:
            return self.make_ifpressed_command(f"""\
if event.key == {button_name}:
{body}
  break""", button=True)
        else:
            return self.make_ifpressed_command(f"""\
if event.unicode == '{args[0]}':
{body}
  break""", button=False)


@v_args(meta=True)
@hedy_transpiler(level=16)
@source_map_transformer(source_map)
class ConvertToPython_16(ConvertToPython_15):
    def assign_list(self, meta, args):
        parameter = args[0]
        values = [a for a in args[1:]]
        return parameter + " = [" + ", ".join(values) + "]"

    def change_list_item(self, meta, args):
        left_side = args[0] + '[' + args[1] + '-1]'
        right_side = args[2]
        exception_text = gettext('catch_index_exception').replace('{list_name}', style_command(args[0]))
        exception = textwrap.dedent(f"""\
        try:
          {left_side}
        except IndexError:
          raise Exception('{exception_text}')
        """)
        return exception + left_side + ' = ' + right_side

    def ifs(self, meta, args):
        all_lines = [ConvertToPython.indent(x) for x in args[1:]]
        exceptions = self.make_catch_exception([args[0]])
        return exceptions + "if " + args[0] + ":\n" + "\n".join(all_lines)


@v_args(meta=True)
@hedy_transpiler(level=17)
@source_map_transformer(source_map)
class ConvertToPython_17(ConvertToPython_16):
    def elifs(self, meta, args):
        args = [a for a in args if a != ""]  # filter out in|dedent tokens
        all_lines = [ConvertToPython.indent(x) for x in args[1:]]
        return "\nelif " + args[0] + ":\n" + "\n".join(all_lines)

    def ifpressed_elifs(self, meta, args):
        args = [a for a in args if a != ""]  # filter out in|dedent tokens

        all_lines = '\n'.join([x for x in args[1:]])
        all_lines = ConvertToPython.indent(all_lines)
        var_or_key = args[0]
        # if this is a variable, we assume it is a key (for now)
        if self.is_variable(var_or_key):
            return self.make_ifpressed_command(f"""\
if event.unicode == {args[0]}:
{all_lines}
  break""", button=False, add_command_prefix=False)
        elif len(var_or_key) == 1:  # one character? also a key!
            return self.make_ifpressed_command(f"""\
if event.unicode == '{args[0]}':
{all_lines}
  break""", button=False, add_command_prefix=False)
        else:  # otherwise we mean a button
            button_name = self.process_variable(args[0], meta.line)
            return self.make_ifpressed_command(f"""\
if event.key == {button_name}:
{all_lines}
  break""", button=True, add_command_prefix=False)


@v_args(meta=True)
@hedy_transpiler(level=18)
@source_map_transformer(source_map)
class ConvertToPython_18(ConvertToPython_17):
    def input(self, meta, args):
        return self.ask(meta, args)

    def input_is(self, meta, args):
        return self.input(meta, args)

    def input_equals(self, meta, args):
        return self.input(meta, args)

    def input_empty_brackets(self, meta, args):
        return self.input(meta, args)

    def print_empty_brackets(self, meta, args):
        return self.print(meta, args)


def merge_grammars(grammar_text_1, grammar_text_2, level):
    # this function takes two grammar files and merges them into one
    # rules that are redefined in the second file are overridden
    # rules that are new in the second file are added (remaining_rules_grammar_2)
    merged_grammar = []

    rules_grammar_1 = grammar_text_1.split('\n')
    remaining_rules_grammar_2 = grammar_text_2.split('\n')
    for line_1 in rules_grammar_1:
        if line_1 == '' or line_1[0] == '/':  # skip comments and empty lines:
            continue
        parts = line_1.split(':')
        # get part before are after : (this is a join because there can be : in the rule)
        name_1, definition_1 = parts[0], ''.join(parts[1:])

        rules_grammar_2 = grammar_text_2.split('\n')
        override_found = False
        for line_2 in rules_grammar_2:
            if line_2 == '' or line_2[0] == '/':  # skip comments and empty lines:
                continue

            needs_preprocessing = re.match(r'((\w|_)+)<((\w|_)+)>', line_2)
            if needs_preprocessing:
                name_2 = f'{needs_preprocessing.group(1)}'
                processor = needs_preprocessing.group(3)
            else:
                parts = line_2.split(':')
                name_2, definition_2 = parts[0], ''.join(parts[1])  # get part before are after :

            if name_1 == name_2:
                override_found = True
                if needs_preprocessing:
                    definition_2 = PREPROCESS_RULES[processor](definition_1)
                    line_2_processed = f'{name_2}: {definition_2}'
                else:
                    line_2_processed = line_2
                if definition_1.strip() == definition_2.strip():
                    warn_message = f"The rule {name_1} is duplicated on level {level}. Please check!"
                    warnings.warn(warn_message)
                # Used to compute the rules that use the merge operators in the grammar
                # namely +=, -= and >
                new_rule = merge_rules_operator(definition_1, definition_2, name_1, line_2_processed)
                # Already procesed so remove it
                remaining_rules_grammar_2.remove(line_2)
                break
        # new rule found? print that. nothing found? print org rule
        if override_found:
            merged_grammar.append(new_rule)
        else:
            merged_grammar.append(line_1)

    # all rules that were not overlapping are new in the grammar, add these too
    for rule in remaining_rules_grammar_2:
        if not (rule == '' or rule[0] == '/'):
            merged_grammar.append(rule)

    merged_grammar = sorted(merged_grammar)
    return '\n'.join(merged_grammar)


def merge_rules_operator(prev_definition, new_definition, name, complete_line):
    # Check if the rule is adding or substracting new rules
    has_add_op = new_definition.startswith('+=')
    has_sub_op = has_add_op and '-=' in new_definition
    has_last_op = has_add_op and '>' in new_definition
    if has_sub_op:
        # Get the rules we need to substract
        part_list = new_definition.split('-=')
        add_list, sub_list = (part_list[0], part_list[1]) if has_sub_op else (part_list[0], '')
        add_list = add_list[3:]
        # Get the rules that need to be last
        sub_list = sub_list.split('>')
        sub_list, last_list = (sub_list[0], sub_list[1]) if has_last_op else (sub_list[0], '')
        sub_list = sub_list + '|' + last_list
        result_cmd_list = get_remaining_rules(prev_definition, sub_list)
    elif has_add_op:
        # Get the rules that need to be last
        part_list = new_definition.split('>')
        add_list, sub_list = (part_list[0], part_list[1]) if has_last_op else (part_list[0], '')
        add_list = add_list[3:]
        last_list = sub_list
        result_cmd_list = get_remaining_rules(prev_definition, sub_list)
    else:
        result_cmd_list = prev_definition

    if has_last_op:
        new_rule = f"{name}: {result_cmd_list} | {add_list} | {last_list}"
    elif has_add_op:
        new_rule = f"{name}: {result_cmd_list} | {add_list}"
    else:
        new_rule = complete_line
    return new_rule


def get_remaining_rules(orig_def, sub_def):
    orig_cmd_list = [command.strip() for command in orig_def.split('|')]
    unwanted_cmd_list = [command.strip() for command in sub_def.split('|')]
    result_cmd_list = [cmd for cmd in orig_cmd_list if cmd not in unwanted_cmd_list]
    result_cmd_list = ' | '.join(result_cmd_list)  # turn the result list into a string
    return result_cmd_list


def create_grammar(level, lang="en"):
    # start with creating the grammar for level 1
    result = get_full_grammar_for_level(1)
    keywords = get_keywords_for_language(lang)

    result = merge_grammars(result, keywords, 1)
    # then keep merging new grammars in
    for i in range(2, level + 1):
        grammar_text_i = get_additional_rules_for_level(i)
        result = merge_grammars(result, grammar_text_i, i)

    # Change the grammar if skipping faulty is enabled
    if source_map.skip_faulty:
        # Make sure to change the meaning of error_invalid
        # this way more text will be 'catched'
        error_invalid_rules = re.findall(r'^error_invalid.-100:.*?\n', result, re.MULTILINE)
        if len(error_invalid_rules) > 0:
            error_invalid_rule = error_invalid_rules[0]
            error_invalid_rule_changed = 'error_invalid.-100: textwithoutspaces _SPACE* text?\n'
            result = result.replace(error_invalid_rule, error_invalid_rule_changed)

        # from level 12:
        # Make sure that all keywords in the language are added to the rules:
        # textwithspaces & textwithoutspaces, so that these do not fall into the error_invalid rule
        if level > 12:
            textwithspaces_rules = re.findall(r'^textwithspaces:.*?\n', result, re.MULTILINE)
            if len(textwithspaces_rules) > 0:
                textwithspaces_rule = textwithspaces_rules[0]
                textwithspaces_rule_changed = r'textwithspaces: /(?:[^#\n،,，、 ]| (?!SKIP1))+/ -> text' + '\n'
                result = result.replace(textwithspaces_rule, textwithspaces_rule_changed)

            textwithoutspaces_rules = re.findall(r'^textwithoutspaces:.*?\n', result, re.MULTILINE)
            if len(textwithoutspaces_rules) > 0:
                textwithoutspaces_rule = textwithoutspaces_rules[0]
                textwithoutspaces_rule_changed = (
                    r'textwithoutspaces: /(?:[^#\n،,，、 *+\-\/eiіиలేไamfnsbअ否אو]|SKIP2)+/ -> text' + '\n'
                )
                result = result.replace(textwithoutspaces_rule, textwithoutspaces_rule_changed)

            non_allowed_words = re.findall(r'".*?"', keywords)
            non_allowed_words = list(set(non_allowed_words))

            non_allowed_words = [x.replace('"', '') for x in non_allowed_words]
            non_allowed_words_with_space = '|'.join(non_allowed_words)
            result = result.replace('SKIP1', non_allowed_words_with_space)

            letters_done = []
            string_words = ''

            for word in non_allowed_words:
                # go through all words and add them in groups by their first letter
                first_letter = word[0]
                if first_letter not in letters_done:
                    string_words += f'|{first_letter}(?!{word[1:]})'
                    letters_done.append(first_letter)
                else:
                    string_words = string_words.replace(f'|{word[0]}(?!', f'|{word[0]}(?!{word[1:]}|')

            string_words = string_words.replace('|)', ')')  # remove empty regex expressions
            string_words = string_words[1:]  # remove first |

            result = result.replace('SKIP2', string_words)

        # Make sure that the error_invalid is added to the command rule
        # to function as a 'bucket' for faulty text
        command_rules = re.findall(r'^command:.*?\n', result, re.MULTILINE)
        if len(command_rules) > 0:
            command_rule = command_rules[0]
            command_rule_with_error_invalid = command_rule.replace('\n', '') + " | error_invalid\n"
            result = result.replace(command_rule, command_rule_with_error_invalid)

        # Make sure that the error_invalid is added to the if_less_command rule
        # to function as a 'bucket' for faulty if body commands
        if_less_command_rules = re.findall(r'^_if_less_command:.*?\n', result, re.MULTILINE)
        if len(if_less_command_rules) > 0:
            if_less_command_rule = if_less_command_rules[0]
            if_less_command_rule_with_error_invalid = if_less_command_rule.replace('\n', '') + " | error_invalid\n"
            result = result.replace(if_less_command_rule, if_less_command_rule_with_error_invalid)

        # Make sure that the _non_empty_program rule does not contain error_invalid rules
        # so that all errors will be catches by error_invalid instead of _non_empty_program_skipping
        non_empty_program_rules = re.findall(r'^_non_empty_program:.*?\n', result, re.MULTILINE)
        if len(non_empty_program_rules) > 0:
            non_empty_program_rule = non_empty_program_rules[0]
            non_empty_program_rule_changed = (
                '_non_empty_program: _EOL* (command) _SPACE* (_EOL+ command _SPACE*)* _EOL*\n'
            )
            result = result.replace(non_empty_program_rule, non_empty_program_rule_changed)

    # ready? Save to file to ease debugging
    # this could also be done on each merge for performance reasons
    save_total_grammar_file(level, result, lang)
    return result


def save_total_grammar_file(level, grammar, lang):
    # Load Lark grammars relative to directory of current file
    script_dir = path.abspath(path.dirname(__file__))
    filename = "level" + str(level) + "." + lang + "-Total.lark"
    loc = path.join(script_dir, "grammars-Total", filename)
    file = open(loc, "w", encoding="utf-8")
    file.write(grammar)
    file.close()


def get_additional_rules_for_level(level, sub=0):
    script_dir = path.abspath(path.dirname(__file__))
    if sub:
        filename = "level" + str(level) + "-" + str(sub) + "-Additions.lark"
    else:
        filename = "level" + str(level) + "-Additions.lark"
    with open(path.join(script_dir, "grammars", filename), "r", encoding="utf-8") as file:
        grammar_text = file.read()
    return grammar_text


def get_full_grammar_for_level(level):
    script_dir = path.abspath(path.dirname(__file__))
    filename = "level" + str(level) + ".lark"
    with open(path.join(script_dir, "grammars", filename), "r", encoding="utf-8") as file:
        grammar_text = file.read()
    return grammar_text

# TODO FH, May 2022. I feel there are other places in the code where we also do this
# opportunity to combine?


def get_keywords_for_language(language):
    script_dir = path.abspath(path.dirname(__file__))
    try:
        if not local_keywords_enabled:
            raise FileNotFoundError("Local keywords are not enabled")
        filename = "keywords-" + str(language) + ".lark"
        with open(path.join(script_dir, "grammars", filename), "r", encoding="utf-8") as file:
            keywords = file.read()
    except FileNotFoundError:
        filename = "keywords-en.lark"
        with open(path.join(script_dir, "grammars", filename), "r", encoding="utf-8") as file:
            keywords = file.read()
    return keywords


def get_parser(level, lang="en", keep_all_tokens=False):
    """Return the Lark parser for a given level.
    """
    grammar = create_grammar(level, lang)
    return Lark(grammar, regex=True, propagate_positions=True, keep_all_tokens=keep_all_tokens)  # ambiguity='explicit'


ParseResult = namedtuple('ParseResult', ['code', 'source_map', 'has_turtle', 'has_pygame'])


def transpile_inner_with_skipping_faulty(input_string, level, lang="en"):
    def skipping_faulty(meta, args): return [True]

    defined_errors = [method for method in dir(IsValid) if method.startswith('error')]
    defined_errors_original = dict()

    def set_error_to_allowed():
        # override IsValid methods to always be valid & store original
        for error in defined_errors:
            defined_errors_original[error] = getattr(IsValid, error)
            setattr(IsValid, error, skipping_faulty)

    def set_errors_to_original():
        # revert IsValid methods to original
        for error in defined_errors:
            setattr(IsValid, error, defined_errors_original[error])

    try:
        set_error_to_allowed()
        transpile_result = transpile_inner(input_string, level, lang, populate_source_map=True)
    finally:
        # make sure to always revert IsValid methods to original
        set_errors_to_original()

    # If transpiled successfully while allowing errors, transpile mapped code again to get original error
    # If none is found, raise error so that original error will be returned
    at_least_one_error_found = False

    for hedy_source_code, python_source_code in source_map.map.copy().items():
        if hedy_source_code.error is not None or python_source_code.code == 'pass':
            try:
                transpile_inner(hedy_source_code.code, source_map.level, source_map.language)
            except Exception as e:
                hedy_source_code.error = e

            if hedy_source_code.error is not None:
                at_least_one_error_found = True

    if not at_least_one_error_found:
        raise Exception('Could not find original error for skipped code')

    return transpile_result


def transpile(input_string, level, lang="en", skip_faulty=False):
    """
    Function that transpiles the Hedy code to Python

    The first time the client will try to execute the code without skipping faulty code
    If an exception is caught (the Hedy code contains faults) an exception is raised to inform the client

    The second time, after an Error is received by the client, the client will re-POST the code
    with skipping faulty enabled, after that we either return the partially correct code or raise the original error
    """

    if not skip_faulty:
        try:
            source_map.set_skip_faulty(False)
            transpile_result = transpile_inner(input_string, level, lang, populate_source_map=True)
        except Exception as original_error:
            source_map.exception_found_during_parsing = original_error  # store original exception
            raise original_error
    else:
        original_error = source_map.exception_found_during_parsing
        source_map.clear()

        if isinstance(original_error, source_map.exceptions_not_to_skip):
            raise original_error

        try:
            source_map.set_skip_faulty(True)
            transpile_result = transpile_inner_with_skipping_faulty(input_string, level, lang)
        except Exception:
            raise original_error  # we could not skip faulty code, raise original exception

    return transpile_result


def translate_characters(s):
    # this method is used to make it more clear to kids what is meant in error messages
    # for example ' ' is hard to read, space is easier
    commas = [',', "،", "，", "、"]
    if s == ' ':
        return 'space'
    elif s in commas:
        return 'comma'
    elif s == '?':
        return 'question mark'
    elif s == '\n':
        return 'newline'
    elif s == '.':
        return 'period'
    elif s == '!':
        return 'exclamation mark'
    elif s == '*':
        return 'star'
    elif s == "'":
        return 'single quotes'
    elif s == '"':
        return 'double quotes'
    elif s == '/':
        return 'slash'
    elif s == '-':
        return 'dash'
    elif s >= 'a' and s <= 'z' or s >= 'A' and s <= 'Z':
        return s
    else:
        return s


def beautify_parse_error(character_found):
    character_found = translate_characters(character_found)
    return character_found


def find_indent_length(line):
    number_of_spaces = 0
    for x in line:
        if x == ' ':
            number_of_spaces += 1
        else:
            break
    return number_of_spaces


def line_requires_indentation(line, lang):
    # this is done a bit half-assed, clearly *parsing* the one line would be superior
    # because now a line like `repeat is 5` would also require indentation!

    line = line.lstrip()  # remove spaces since also `    for    ` requires indentation
    if lang not in indent_keywords.keys():  # some language like Greek or Czech do not have local keywords
        lang = 'en'

    local_indent_keywords = indent_keywords[lang]

    for k in local_indent_keywords:
        # does the line start with this keyword?
        # We can't just split since some langs like French have keywords containing a space
        # We also have to check space/lineending/: after or forward 100 wil also require indentation
        end_of_line_or_word = (len(line) > len(k) and (
            line[len(k)] == " " or line[len(k)] == ":")) or len(line) == len(k)
        if end_of_line_or_word and line[:len(k)] == k:
            return True
    return False


def preprocess_blocks(code, level, lang):
    processed_code = []
    lines = code.split("\n")
    current_number_of_indents = 0
    previous_number_of_indents = 0
    indent_size = 4  # set at 4 for now
    indent_size_adapted = False  # FH We can remove this now since we changed in indenter a bit in Nov 2022
    line_number = 0
    next_line_needs_indentation = False
    for line in lines:
        if ' _ ' in line or line == '_':
            raise hedy.exceptions.CodePlaceholdersPresentException(line_number=line_number+1)

        leading_spaces = find_indent_length(line)

        line_number += 1

        # ignore whitespace-only lines
        if leading_spaces == len(line):
            processed_code.append('')
            continue

        # first encounter sets indent size for this program
        if not indent_size_adapted and leading_spaces > 0:
            indent_size = leading_spaces
            indent_size_adapted = True

        # indentation size not 4
        if (leading_spaces % indent_size) != 0:
            # there is inconsistent indentation, not sure if that is too much or too little!
            if leading_spaces < current_number_of_indents * indent_size:
                fixed_code = program_repair.fix_indent(code, line_number, leading_spaces, indent_size)
                raise hedy.exceptions.NoIndentationException(line_number=line_number, leading_spaces=leading_spaces,
                                                             indent_size=indent_size, fixed_code=fixed_code)
            else:
                fixed_code = program_repair.fix_indent(code, line_number, leading_spaces, indent_size)
                raise hedy.exceptions.IndentationException(line_number=line_number, leading_spaces=leading_spaces,
                                                           indent_size=indent_size, fixed_code=fixed_code)

        # happy path, multiple of 4 spaces:
        current_number_of_indents = leading_spaces // indent_size
        if current_number_of_indents > 1 and level == hedy.LEVEL_STARTING_INDENTATION:
            raise hedy.exceptions.LockedLanguageFeatureException(concept="nested blocks")

        if current_number_of_indents > previous_number_of_indents and not next_line_needs_indentation:
            # we are indenting, but this line is not following* one that even needs indenting, raise
            # * note that we have not yet updated the value of 'next line needs indenting' so if refers to this line!
            fixed_code = program_repair.fix_indent(code, line_number, leading_spaces, indent_size)
            raise hedy.exceptions.IndentationException(line_number=line_number, leading_spaces=leading_spaces,
                                                       indent_size=indent_size, fixed_code=fixed_code)

        if next_line_needs_indentation and current_number_of_indents <= previous_number_of_indents:
            fixed_code = program_repair.fix_indent(code, line_number, leading_spaces, indent_size)
            raise hedy.exceptions.NoIndentationException(line_number=line_number, leading_spaces=leading_spaces,
                                                         indent_size=indent_size, fixed_code=fixed_code)

        if current_number_of_indents - previous_number_of_indents > 1:
            fixed_code = program_repair.fix_indent(code, line_number, leading_spaces, indent_size)
            raise hedy.exceptions.IndentationException(line_number=line_number, leading_spaces=leading_spaces,
                                                       indent_size=indent_size, fixed_code=fixed_code)

        if current_number_of_indents < previous_number_of_indents:
            # we are dedenting ('jumping back) so we need to and an end-block
            # (multiple if multiple dedents are happening)

            difference_in_indents = (previous_number_of_indents - current_number_of_indents)
            for i in range(difference_in_indents):
                processed_code[-1] += '#ENDBLOCK'

        if line_requires_indentation(line, lang):
            next_line_needs_indentation = True
        else:
            next_line_needs_indentation = False

        # save to compare for next line
        previous_number_of_indents = current_number_of_indents

        # if indent remains the same, do nothing, just add line
        processed_code.append(line)

    # if the last line is indented, the end of the program is also the end of all indents
    # so close all blocks
    for i in range(current_number_of_indents):
        processed_code[-1] += '#ENDBLOCK'
    return "\n".join(processed_code)


def preprocess_ifs(code, lang='en'):
    processed_code = []
    lines = code.split("\n")

    def starts_with(command, line):
        if lang in ALL_KEYWORD_LANGUAGES:
            command_plus_translated_command = [command, KEYWORDS[lang].get(command)]
            for c in command_plus_translated_command:
                #  starts with the keyword and next character is a space
                if line[0:len(c)] == c and (len(c) == len(line) or line[len(c)] == ' '):
                    return True
            return False
        else:
            return line[0:len(command)] == command

    def starts_with_after_repeat(command, line):
        elements_in_line = line.split()
        keywords_in_lang = KEYWORDS.get(lang, KEYWORDS['en'])
        repeat_plus_translated = ['repeat', keywords_in_lang.get('repeat')]
        times_plus_translated = ['times', keywords_in_lang.get('times')]

        if len(elements_in_line) > 2 and elements_in_line[0] in repeat_plus_translated and elements_in_line[2] in times_plus_translated:
            line = ' '.join(elements_in_line[3:])

        if lang in ALL_KEYWORD_LANGUAGES:
            command_plus_translated_command = [command, KEYWORDS[lang].get(command)]
            for c in command_plus_translated_command:
                #  starts with the keyword and next character is a space
                if line[0:len(c)] == c and (len(c) == len(line) or line[len(c)] == ' '):
                    return True
            return False
        else:
            return line[0:len(command)] == command

    def contains(command, line):
        if lang in ALL_KEYWORD_LANGUAGES:
            command_plus_translated_command = [command, KEYWORDS[lang].get(command)]
            for c in command_plus_translated_command:
                if c in line:
                    return True
            return False
        else:
            return command in line

    def contains_two(command, line):
        if lang in ALL_KEYWORD_LANGUAGES:
            command_plus_translated_command = [command, KEYWORDS[lang].get(command)]
            for c in command_plus_translated_command:
                if line.count(' ' + c + ' ') >= 2:  # surround in spaces since we dont want to mathc something like 'dishwasher is sophie'
                    return True
            return False

    def contains_any_of(commands, line):
        # translation is not needed here, happens in contains
        if lang in ALL_KEYWORD_LANGUAGES:
            for c in commands:
                if contains(c, line):
                    return True
            return False
        else:
            for c in commands:
                if contains(c, line):
                    return True
            return False

    for i in range(len(lines) - 1):
        line = lines[i]
        next_line = lines[i + 1]

        # if this line starts with if but does not contain an else, and the next line too is not an else.
        if (starts_with('if', line) or starts_with_after_repeat('if', line)) and (not starts_with('else', next_line)) and (not contains('else', line)):
            # is this line just a condition and no other keyword (because that is no problem)
            commands = ["print", "ask", "forward", "turn"]
            excluded_commands = ["pressed"]

            if (
                (contains_any_of(commands, line) or contains_two('is', line))
                and not contains_any_of(excluded_commands, line)
            ):
                # a second command, but also no else in this line -> check next line!

                # no else in next line?
                # add a nop (like 'Pass' but we just insert a meaningless assign)
                line = line + " else x__x__x__x is 5"

        processed_code.append(line)
    processed_code.append(lines[-1])  # always add the last line (if it has if and no else that is no problem)
    return "\n".join(processed_code)


def location_of_first_blank(code_snippet):
    # returns 0 if the code does not contain _
    # otherwise returns the first location (line) of the blank
    lines = code_snippet.split('\n')
    for i in range(len(lines)):
        code = lines[i]
        if len(code) > 0:
            if (" _" in code) or ("_ " in code) or (code[-1] == "_"):
                return i+1
    return 0


def check_program_size_is_valid(input_string):
    number_of_lines = input_string.count('\n')
    # parser is not made for huge programs!
    if number_of_lines > MAX_LINES:
        raise exceptions.InputTooBigException(lines_of_code=number_of_lines, max_lines=MAX_LINES)


def process_input_string(input_string, level, lang, escape_backslashes=True, preprocess_ifs_enabled=True):
    result = input_string.replace('\r\n', '\n')

    location = location_of_first_blank(result)
    if location > 0:
        raise exceptions.CodePlaceholdersPresentException(line_number=location)

    if escape_backslashes and level >= 4:
        result = result.replace("\\", "\\\\")

    # In levels 5 to 7 we do not allow if without else, we add an empty print to make it possible in the parser
    if level >= 5 and level < 8 and preprocess_ifs_enabled:
        result = preprocess_ifs(result, lang)

    # In level 8 we add indent-dedent blocks to the code before parsing
    if level >= hedy.LEVEL_STARTING_INDENTATION:
        result = preprocess_blocks(result, level, lang)

    return result


def parse_input(input_string, level, lang):
    parser = get_parser(level, lang)
    try:
        parse_result = parser.parse(input_string + '\n')
        return parse_result.children[0]  # getting rid of the root could also be done in the transformer would be nicer
    except lark.UnexpectedEOF:
        lines = input_string.split('\n')
        last_line = len(lines)
        raise exceptions.UnquotedEqualityCheckException(line_number=last_line)
    except UnexpectedCharacters as e:
        try:
            location = e.line, e.column
            # not yet in use, could be used in the future (when our parser rules are
            # better organize, now it says ANON*__12 etc way too often!)
            # characters_expected = str(e.allowed)
            character_found = beautify_parse_error(e.char)
            # print(e.args[0])
            # print(location, character_found, characters_expected)
            fixed_code = program_repair.remove_unexpected_char(input_string, location[0], location[1])
            raise exceptions.ParseException(
                level=level,
                location=location,
                found=character_found,
                fixed_code=fixed_code) from e
        except UnexpectedEOF:
            # this one can't be beautified (for now), so give up :)
            raise e


def is_program_valid(program_root, input_string, level, lang):
    # IsValid returns (True,) or (False, args)
    instance = IsValid()
    instance.level = level  # TODO: could be done in a constructor once we are sure we will go this way
    is_valid = instance.transform(program_root)

    if not is_valid[0]:
        _, invalid_info = is_valid

        # Apparently, sometimes 'args' is a string, sometimes it's a list of
        # strings ( are these production rule names?). If it's a list of
        # strings, just take the first string and proceed.
        if isinstance(invalid_info, list):
            invalid_info = invalid_info[0]

        line = invalid_info.line
        column = invalid_info.column
        if invalid_info.error_type == ' ':

            # the error here is a space at the beginning of a line, we can fix that!
            fixed_code = program_repair.remove_leading_spaces(input_string)
            if fixed_code != input_string:  # only if we have made a successful fix
                try:
                    fixed_result = transpile_inner(fixed_code, level, lang)
                    result = fixed_result
                    raise exceptions.InvalidSpaceException(
                        level=level, line_number=line, fixed_code=fixed_code, fixed_result=result)
                except exceptions.HedyException:
                    invalid_info.error_type = None
                    transpile_inner(fixed_code, level)
                    # The fixed code contains another error. Only report the original error for now.
                    pass
            raise exceptions.InvalidSpaceException(
                level=level, line_number=line, fixed_code=fixed_code, fixed_result=result)
        elif invalid_info.error_type == 'invalid condition':
            raise exceptions.UnquotedEqualityCheckException(line_number=line)
        elif invalid_info.error_type == 'invalid repeat':
            raise exceptions.MissingInnerCommandException(command='repeat', level=level, line_number=line)
        elif invalid_info.error_type == 'repeat missing print':
            raise exceptions.IncompleteRepeatException(command='print', level=level, line_number=line)
        elif invalid_info.error_type == 'repeat missing times':
            raise exceptions.IncompleteRepeatException(command='times', level=level, line_number=line)
        elif invalid_info.error_type == 'print without quotes':
            unquotedtext = invalid_info.arguments[0]
            raise exceptions.UnquotedTextException(
                level=level, unquotedtext=unquotedtext, line_number=invalid_info.line)
        elif invalid_info.error_type == 'unsupported number':
            raise exceptions.UnsupportedFloatException(value=''.join(invalid_info.arguments))
        elif invalid_info.error_type == 'lonely text':
            raise exceptions.LonelyTextException(level=level, line_number=line)
        elif invalid_info.error_type == 'flat if':
            raise exceptions.WrongLevelException(
                offending_keyword='if',
                working_level=7,
                tip='no_more_flat_if',
                line_number=invalid_info.line)
        elif invalid_info.error_type == 'invalid at keyword':
            raise exceptions.InvalidAtCommandException(command='at', level=level, line_number=invalid_info.line)
        elif invalid_info.error_type == 'ifpressed missing else':
            raise exceptions.MissingElseForPressitException(
                command='ifpressed_else', level=level, line_number=invalid_info.line)
        elif invalid_info.error_type == 'nested function':
            raise exceptions.NestedFunctionException()
        else:
            invalid_command = invalid_info.command
            closest = closest_command(invalid_command, get_suggestions_for_language(lang, level))

            if closest == 'keyword':  # we couldn't find a suggestion
                invalid_command_en = hedy_translation.translate_keyword_to_en(invalid_command, lang)
                if invalid_command_en == Command.turn:
                    arg = invalid_info.arguments[0][0]
                    raise hedy.exceptions.InvalidArgumentException(command=invalid_info.command,
                                                                   allowed_types=get_allowed_types(Command.turn, level),
                                                                   invalid_argument=arg,
                                                                   line_number=invalid_info.line)
                # clearly the error message here should be better or it should be a different one!
                raise exceptions.ParseException(level=level, location=[line, column], found=invalid_command)
            elif closest is None:
                raise exceptions.MissingCommandException(level=level, line_number=line)

            else:

                fixed_code = None
                result = None
                fixed_code = input_string.replace(invalid_command, closest)
                if fixed_code != input_string:  # only if we have made a successful fix
                    try:
                        fixed_result = transpile_inner(fixed_code, level)
                        result = fixed_result
                    except exceptions.HedyException:
                        # The fixed code contains another error. Only report the original error for now.
                        pass

            raise exceptions.InvalidCommandException(invalid_command=invalid_command, level=level,
                                                     guessed_command=closest, line_number=line,
                                                     fixed_code=fixed_code, fixed_result=result)


def is_program_complete(abstract_syntax_tree, level):
    is_complete = IsComplete(level).transform(abstract_syntax_tree)
    if not is_complete[0]:
        incomplete_command_and_line = is_complete[1][0]
        incomplete_command = incomplete_command_and_line[0]
        line = incomplete_command_and_line[1]
        raise exceptions.IncompleteCommandException(incomplete_command=incomplete_command, level=level,
                                                    line_number=line)


def create_lookup_table(abstract_syntax_tree, level, lang, input_string):
    visitor = LookupEntryCollector(level)
    visitor.visit_topdown(abstract_syntax_tree)
    entries = visitor.lookup

    TypeValidator(entries, level, lang, input_string).transform(abstract_syntax_tree)

    return entries


def transpile_inner(input_string, level, lang="en", populate_source_map=False):
    check_program_size_is_valid(input_string)

    level = int(level)
    if level > HEDY_MAX_LEVEL:
        raise Exception(f'Levels over {HEDY_MAX_LEVEL} not implemented yet')

    input_string = process_input_string(input_string, level, lang)
    program_root = parse_input(input_string, level, lang)

    if populate_source_map:
        source_map.clear()
        source_map.set_level(level)
        source_map.set_language(lang)
        source_map.set_hedy_input(input_string)

    # checks whether any error production nodes are present in the parse tree
    is_program_valid(program_root, input_string, level, lang)

    try:
        abstract_syntax_tree = ExtractAST().transform(program_root)

        is_program_complete(abstract_syntax_tree, level)

        if not valid_echo(abstract_syntax_tree):
            raise exceptions.LonelyEchoException()

        lookup_table = create_lookup_table(abstract_syntax_tree, level, lang, input_string)

        # FH, may 2022. for now, we just out arabic numerals when the language is ar
        # this can be changed into a profile setting or could be detected
        # in usage of programs
        if lang == "ar":
            numerals_language = "Arabic"
        else:
            numerals_language = "Latin"

        # grab the right transpiler from the lookup
        convertToPython = TRANSPILER_LOOKUP[level]
        python = convertToPython(lookup_table, numerals_language).transform(abstract_syntax_tree)

        uses_turtle = UsesTurtle()
        has_turtle = uses_turtle.transform(abstract_syntax_tree)

        uses_pygame = UsesPyGame()
        has_pygame = uses_pygame.transform(abstract_syntax_tree)

        if populate_source_map:
            source_map.set_python_output(python)

        return ParseResult(python, source_map, has_turtle, has_pygame)
    except VisitError as E:
        if isinstance(E, VisitError):
            # Exceptions raised inside visitors are wrapped inside VisitError. Unwrap it if it is a
            # HedyException to show the intended error message.
            if isinstance(E.orig_exc, exceptions.HedyException):
                raise E.orig_exc
            else:
                raise E


def execute(input_string, level):
    python = transpile(input_string, level)
    if python.has_turtle:
        raise exceptions.HedyException("hedy.execute doesn't support turtle")
    exec(python.code)