langchain_agent.py

from langchain.tools import StructuredTool
from langchain.agents import StructuredChatAgent
import re
from typing import Any, List, Optional, Sequence

from langchain.agents.agent import Agent, AgentOutputParser
from langchain.base_language import BaseLanguageModel
from langchain.callbacks.base import BaseCallbackManager
from langchain.chains.llm import LLMChain
from langchain.prompts.base import BasePromptTemplate
from langchain.prompts.chat import (
    ChatPromptTemplate,
    HumanMessagePromptTemplate,
    SystemMessagePromptTemplate,
)
from langchain.tools import BaseTool, HumanInputRun
from tools import search_apis, search_api_endpoints

PREFIX = """You are IntegrationBuilderGPT. Your objective is to help build an integration between different APIs to meet the user's needs. Your final answer should be syntatically correct and usable Python code that the user can use to build their integration.

In order to help you do this, you have access to the following tools:"""
FORMAT_INSTRUCTIONS = """Use a json blob to specify a tool by providing an action key (tool name) and an action_input key (tool input).

Valid "action" values: "Final Answer" or {tool_names}

Provide only ONE action per $JSON_BLOB, as shown:

```
{{{{
  "action": $TOOL_NAME,
  "action_input": $INPUT
}}}}
```

Follow this format:

Question: input question to answer
Thought: consider previous and subsequent steps
Action:
```
$JSON_BLOB
```
Observation: action result
... (repeat Thought/Action/Observation N times)
Thought: I know what to respond
Action:
```
{{{{
  "action": "Final Answer",
  "action_input": "Final response to human"
}}}}
```"""
SUFFIX = """Begin! Reminder to ALWAYS respond with a valid json blob of a single action. Use tools if necessary. Respond directly if appropriate. Format is Action:```$JSON_BLOB```then Observation:.
Thought:"""


search_apis_tool = StructuredTool.from_function(search_apis)
search_api_endpoints_tool = StructuredTool.from_function(search_api_endpoints)
human_input_tool = HumanInputRun()


class IntegrationBuilderAgent(StructuredChatAgent):
    @classmethod
    def create_prompt(
        cls,
        tools: Sequence[BaseTool],
        prefix: str = PREFIX,
        suffix: str = SUFFIX,
        format_instructions: str = FORMAT_INSTRUCTIONS,
        input_variables: Optional[List[str]] = None,
    ) -> BasePromptTemplate:
        tool_strings = []
        for tool in tools:
            args_schema = re.sub("}", "}}}}", re.sub("{", "{{{{", str(tool.args)))
            tool_strings.append(f"{tool.name}: {tool.description}, args: {args_schema}")
        formatted_tools = "\n".join(tool_strings)
        tool_names = ", ".join([tool.name for tool in tools])
        format_instructions = format_instructions.format(tool_names=tool_names)
        template = "\n\n".join([prefix, formatted_tools, format_instructions, suffix])
        messages = [
            SystemMessagePromptTemplate.from_template(template),
            HumanMessagePromptTemplate.from_template("{input}\n\n{agent_scratchpad}"),
        ]
        if input_variables is None:
            input_variables = ["input", "agent_scratchpad"]
        return ChatPromptTemplate(input_variables=input_variables, messages=messages)

    @classmethod
    def from_llm_and_tools(
        cls,
        llm: BaseLanguageModel,
        tools: Sequence[BaseTool],
        callback_manager: Optional[BaseCallbackManager] = None,
        output_parser: Optional[AgentOutputParser] = None,
        prefix: str = PREFIX,
        suffix: str = SUFFIX,
        format_instructions: str = FORMAT_INSTRUCTIONS,
        input_variables: Optional[List[str]] = None,
        **kwargs: Any,
    ) -> Agent:
        """Construct an agent from an LLM and tools."""
        cls._validate_tools(tools)
        prompt = cls.create_prompt(
            tools,
            prefix=prefix,
            suffix=suffix,
            format_instructions=format_instructions,
            input_variables=input_variables,
        )
        llm_chain = LLMChain(
            llm=llm,
            prompt=prompt,
            callback_manager=callback_manager,
        )
        tool_names = [tool.name for tool in tools]
        _output_parser = output_parser or cls._get_default_output_parser(llm=llm)
        return cls(
            llm_chain=llm_chain,
            allowed_tools=tool_names,
            output_parser=_output_parser,
            **kwargs,
        )