main.dart

import 'package:english_words/english_words.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

/// The app extends StatelessWidget, which makes the app itself a widget
/// The Scaffold widget, from the Material library, provides a defaut app bar, a title, and a body
/// Property that holds the widget tree for the home screen.
/// Awidget's main job is to provide a build method that describes how to display the widget in
/// terms of other. lower-level widgets.
class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Startup Name Generator',
      theme: ThemeData(
        appBarTheme: const AppBarTheme(
          backgroundColor: Colors.lightGreen,
          foregroundColor: Colors.white,
        ),
      ),
      home: const RandomWords(),
    );
  }
}

/// Boiler plate code for a stateful widget
class RandomWords extends StatefulWidget {
  const RandomWords({Key? key}) : super(key: key);

  @override
  State<RandomWords> createState() => _RandomWordsState();
}

class _RandomWordsState extends State<RandomWords> {
  // for saving suggested word pairing
  final _suggestions = <WordPair>[];
  // The set stores word pairing that the user favorited
  // Set is preferred to List because a properly implemented Set doesn't allow duplicate entries
  final _saved = <WordPair>{};
  // for making the font size larger
  final _biggerFont = const TextStyle(fontSize: 18);

  Widget _buildRow(WordPair pair) {
    // alreadySaved checks to ensure that a word pairing has not already been added to favorites
    final alreadySaved = _saved.contains(pair);
    return ListTile(
      title: Text(
        pair.asPascalCase,
        style: _biggerFont,
      ),
      // add heart-shaped icons after the text
      trailing: Icon(
        alreadySaved ? Icons.favorite : Icons.favorite_border,
        color: alreadySaved ? Colors.red : null,
        semanticLabel: alreadySaved ? 'Remove from saved' : 'Save',
      ),
      onTap: () {
        setState(() {
          if (alreadySaved) {
            _saved.remove(pair);
          } else {
            _saved.add(pair);
          }
        });
      },
    );
  }

  Widget _buildSuggestions() {
    return ListView.builder(
        padding: const EdgeInsets.all(16),
        // The itemBuilder callback is called once per suggested word pairing,
        // and places each suggestion into a ListTile row.
        // For even rows, the function adds a ListTile row for the word pairing
        // For odd rows, the function adds a Divider widget to visually separate the entries.
        // Note that the divider may be difficult to see on smaller devices.
        itemBuilder: (context, i) {
          // Add a one-pixel-high divider widget before each row in the ListView
          if (i.isOdd) {
            return const Divider();
          }

          // The syntax "i ~/ 2" divides i by 2 and returns an integer result.
          // for example: 1, 2, 3, 4, 5 becomes 0, 1, 1, 2, 2.
          // This calculates the actual number of word pairings in the ListView, minus the divider widgets.
          final index = i ~/ 2;

          // if you've reached the end of the available word pairings
          if (index >= _suggestions.length) {
            // ... then generate 10 more and add them to the suggestions list
            _suggestions.addAll(generateWordPairs().take(10));
          }
          return _buildRow(_suggestions[index]);
        });
  }

  /// changes the screen to display the new route
  void _pushSaved() {
    // push the route to the Navigator's stack
    Navigator.of(context).push(
      MaterialPageRoute(
        builder: (context) {
          final tiles = _saved.map(
            (pair) {
              return ListTile(
                title: Text(
                  pair.asPascalCase,
                  style: _biggerFont,
                ),
              );
            },
          );
          final divided = tiles.isNotEmpty
              ? ListTile.divideTiles(
                  context: context,
                  tiles: tiles,
                ).toList()
              : <Widget>[];

          return Scaffold(
            appBar: AppBar(
              title: const Text('Saved Suggestions'),
            ),
            body: ListView(children: divided),
          );
        },
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    // Scaffold implements the the basic Material Design visual layout
    return Scaffold(
      appBar: AppBar(
        title: const Text('Startup Name Generator'),
        actions: [
          IconButton(
            icon: const Icon(Icons.list),
            onPressed: _pushSaved,
            tooltip: 'Saved Suggestions',
          ),
        ],
      ),
      body: _buildSuggestions(),
    );
  }
}