app.py

#pip install langchain_google_genai langgraph gradio
import os
import sys
import typing
from typing import Annotated, Literal, Iterable
from typing_extensions import TypedDict

from langchain_google_genai import ChatGoogleGenerativeAI
from langgraph.graph import StateGraph, START, END
from langgraph.graph.message import add_messages
from langgraph.prebuilt import ToolNode
from langchain_core.tools import tool
from langchain_core.messages import AIMessage, ToolMessage, HumanMessage, BaseMessage, SystemMessage
from random import randint

import requests
from bs4 import BeautifulSoup
import openpyxl
import wikipedia
import pandas as pd

import gradio as gr
import logging

class OrderState(TypedDict):
    """State representing the customer's order conversation."""
    messages: Annotated[list, add_messages]
    order: list[str]
    finished: bool

# System instruction for the Agent
SYSINT = (
    "system",
    "You are a general AI assistant. I will ask you a question."
    "The question requires a tool to solve. You must attempt to use at least one of the available tools before returning an answer."
    "Report your thoughts, and finish your answer with the following template: "
    "FINAL ANSWER: [YOUR FINAL ANSWER]. YOUR FINAL ANSWER should be a number OR as few words as possible OR a comma separated list of numbers and/or strings."
    "If you are asked for a number, don't use comma to write your number neither use units such as $ or percent sign unless specified otherwise."
    "If you are asked for a string, don't use articles, neither abbreviations (e.g. for cities), and write the digits in plain text unless specified otherwise."
    "If you are asked for a comma separated list, apply the above rules depending of whether the element to be put in the list is a number or a string."
    "If a tool required for task completion is not functioning, return 0."
    )

WELCOME_MSG = "Welcome to my general-purpose AI agent. Type `q` to quit. How shall I fail to serve you today?"

# Initialize the Google Gemini LLM
llm = ChatGoogleGenerativeAI(model="gemini-1.5-flash-latest")

@tool
def wikipedia_search_tool(title: str) -> str:
    """Provides an excerpt from a Wikipedia article with the given title."""
    page = wikipedia.page(title, auto_suggest=False)
    return page.content[:3000]

@tool
def media_tool(file_path: str) -> str:
    """Used for deciphering video and audio files."""
    return "This tool hasn't been implemented yet. Please return 0 if the task cannot be solved without knowing the contents of this file."

@tool
def internet_search_tool(search_query: str) -> str:
    """Does a google search with using the input as the search query. Returns a long batch of textual information related to the query."""
    search_tool = DuckDuckGoSearchTool()
    result = search_tool(search_query)
    return result

@tool
def webscraper_tool(url: str) -> str:
    """Returns the page's html content from the input url."""
    response = requests.get(url, stream=True)
    if response.status_code == 200:
        soup = BeautifulSoup(response.content, 'html.parser')
        html_text = soup.get_text()
        return html_text
    else:
        raise Exception(f"Failed to retrieve the webpage. Status code: {response.status_code}")

@tool
def read_excel_tool(file_path: str) -> str:
    """Returns the contents of an Excel file as a Pandas dataframe."""
    df = pd.read_excel(file_path, engine = "openpyxl")
    return df

def agent_node(state: OrderState) -> OrderState:
    """agent with tool handling."""
    print(f"Messagelist sent to agent node: {[msg.content for msg in state.get('messages', [])]}")
    defaults = {"order": [], "finished": False}

    # Ensure we always have at least a system message
    if not state.get("messages", []):
        return defaults | state | {"messages": [SystemMessage(content=SYSINT), new_output]}

    try:
        # Prepend system instruction if not already present
        messages_with_system = [
            SystemMessage(content=SYSINT)
        ] + state.get("messages", [])

        # Process messages through the LLM
        new_output = llm_with_tools.invoke(messages_with_system)

        return defaults | state | {"messages": [new_output]}
    except Exception as e:
        # Fallback if LLM processing fails
        return defaults | state | {"messages": [AIMessage(content=f"I'm having trouble processing that. {str(e)}")]}

def interactive_tools_node(state: OrderState) -> OrderState:
    """Handles interactive tool calls."""
    logging.info("interactive tools node")
    tool_msg = state.get("messages", [])[-1]
    order = state.get("order", [])
    outbound_msgs = []

    for tool_call in tool_msg.tool_calls:
        tool_name = tool_call["name"]
        tool_args = tool_call["args"]

        if tool_name == "wikipedia_search_tool":
            print(f"called wikipedia with {str(tool_args)}")
            page = wikipedia.page(tool_args.get("title"), auto_suggest=False)
            response = page.content[:3000]
        elif tool_name == "media_tool":
            print(f"called media with {str(tool_args)}")
            response = "This tool hasn't been implemented yet. Please return 0 if the task cannot be solved without knowing the contents of this file."
        elif tool_name == "internet_search_tool":
            print(f"called internet with {str(tool_args)}")
            question = tool_args.get("search_query")
            search_tool = DuckDuckGoSearchTool()
            response = search_tool(question)[:3000]
        elif tool_name == "webscraper_tool":
            print(f"called webscraper with {str(tool_args)}")
            url = tool_args.get("url")
            response = requests.get(url, stream=True)
            if response.status_code == 200:
                soup = BeautifulSoup(response.content, 'html.parser')
                html_text = soup.get_text()
                response = html_text
            else:
                response = Exception(f"Failed to retrieve the webpage. Status code: {response.status_code}")
        elif tool_name == "read_excel_tool":
            print(f"called excel with {str(tool_args)}")
            path = tool_args.get("file_path")
            df = pd.read_excel(path, engine = "openpyxl")
            response = df

        else:
            raise NotImplementedError(f'Unknown tool call: {tool_name}')

        outbound_msgs.append(
            ToolMessage(
                content=response,
                name=tool_name,
                tool_call_id=tool_call["id"],
            )
        )

    return {"messages": outbound_msgs, "order": order, "finished": False}
    
def maybe_route_to_tools(state: OrderState) -> str:
    """Route between chat and tool nodes."""
    if not (msgs := state.get("messages", [])):
        raise ValueError(f"No messages found when parsing state: {state}")

    msg = msgs[-1]

    if state.get("finished", False):
        print("from agent GOTO End node")
        return END

    elif hasattr(msg, "tool_calls") and len(msg.tool_calls) > 0:
        if any(tool["name"] in tool_node.tools_by_name.keys() for tool in msg.tool_calls):
            print("from agent GOTO tools node")
            return "tools"
        else:
            logging.info("from chatbot GOTO interactive tools node")
            return "interactive_tools"

    print("tool call failed, quitting")
    return "human"

def human_node(state: OrderState) -> OrderState:
    """Handle user input."""
    logging.info(f"Messagelist sent to human node: {[msg.content for msg in state.get('messages', [])]}")
    last_msg = state["messages"][-1]

    if last_msg.content.lower() in {"q", "quit", "exit", "goodbye"}:
        state["finished"] = True

    return state

def maybe_exit_human_node(state: OrderState) -> Literal["agent", "__end__"]:
    """Determine if conversation should continue."""
    if state.get("finished", False):
        logging.info("from human GOTO End node")
        return END
    last_msg = state["messages"][-1]
    if isinstance(last_msg, AIMessage):
        logging.info("Chatbot response obtained, ending conversation")
        return END
    else:
        logging.info("from human GOTO agent node")
        return "agent"

# Prepare tools
auto_tools = []
tool_node = ToolNode(auto_tools)

interactive_tools = [wikipedia_search_tool, media_tool, internet_search_tool, webscraper_tool, read_excel_tool]

# Bind all tools to the LLM
llm_with_tools = llm.bind_tools(auto_tools + interactive_tools)

# Build the graph
graph_builder = StateGraph(OrderState)

# Add nodes
graph_builder.add_node("agent", agent_node)
graph_builder.add_node("human", human_node)
graph_builder.add_node("tools", tool_node)
graph_builder.add_node("interactive_tools", interactive_tools_node)

# Add edges and routing
graph_builder.add_conditional_edges("agent", maybe_route_to_tools)
graph_builder.add_conditional_edges("human", maybe_exit_human_node)
graph_builder.add_edge("tools", "agent")
graph_builder.add_edge("interactive_tools", "agent")
graph_builder.add_edge(START, "human")

# Compile the graph
chat_graph = graph_builder.compile()

def convert_history_to_messages(history: list) -> list[BaseMessage]:
    """
    Convert Gradio chat history to a list of Langchain messages.
    
    Args:
    - history: Gradio's chat history format
    
    Returns:
    - List of Langchain BaseMessage objects
    """
    messages = []
    for human, ai in history:
        if human:
            messages.append(HumanMessage(content=human))
        if ai:
            messages.append(AIMessage(content=ai))
    return messages

def gradio_chat(message: str, history: list) -> str:
    """
    Gradio-compatible chat function that manages the conversation state.
    
    Args:
    - message: User's input message
    - history: Gradio's chat history
    
    Returns:
    - Bot's response as a string
    """
    logging.info(f"{len(history)} history so far: {history}")
    # Ensure non-empty message
    if not message or message.strip() == "":
        message = "Hello, how can I help you today?"

    # Convert history to Langchain messages
    conversation_messages = []
    for old_message in history:
        if old_message["content"].strip():
            if old_message["role"] == "user":
                conversation_messages.append(HumanMessage(content=old_message["content"]))
            if old_message["role"] == "assistant":
                conversation_messages.append(AIMessage(content=old_message["content"]))
    
    # Add current message
    conversation_messages.append(HumanMessage(content=message))
    
    # Create initial state with conversation history
    conversation_state = {
        "messages": conversation_messages, 
        "order": [], 
        "finished": False
    }
    logging.info(f"Conversation so far: {str(conversation_state)}")
    try:
        # Process the conversation through the graph
        conversation_state = chat_graph.invoke(conversation_state, {"recursion_limit": 10})
        
        # Extract the latest bot message
        latest_message = conversation_state["messages"][-1]
        
        # Return the bot's response content
        logging.info(f"return: {latest_message.content}")
        return latest_message.content
    
    except Exception as e:
        return f"An error occurred: {str(e)}"

# Gradio interface
def launch_agent():
    gr.ChatInterface(
        gradio_chat,
        type="messages",
        title="Agent",
        description="An AI agent (work in progress)",
        theme="ocean"
    ).launch()

if __name__ == "__main__":
    # initiate logging tool
    logging.basicConfig(
                    stream=sys.stdout,
                    level=logging.INFO,
                    format='%(asctime)s - %(levelname)s - %(message)s')
    launch_agent()