agent.py

import os
import itertools
from typing import TypedDict, Annotated, Literal

from langchain_openai import ChatOpenAI
from langchain_core.messages import AnyMessage, SystemMessage, HumanMessage, ToolMessage
from langgraph.graph.message import add_messages
from langgraph.graph import MessagesState, StateGraph, START, END
from langchain_core.runnables import RunnableConfig  # for LangSmith tracking

from langchain_community.tools import BraveSearch  # web search
from langchain_experimental.tools.python.tool import PythonAstREPLTool  # for logic/math problems

from tools import (
    calculator_basic, datetime_tools, transcribe_audio,
    transcribe_youtube, query_image, webpage_content, read_excel
)
from prompt import system_prompt

# --------------------------------------------------------------------
# 1. API Key Rotation Setup
# --------------------------------------------------------------------
api_keys = [k for k in [
    os.getenv("OPENROUTER_API_KEY"),
    os.getenv("OPENROUTER_API_KEY_1")
] if k]

if not api_keys:
    raise EnvironmentError("No OpenRouter API keys found in environment variables.")

api_key_cycle = itertools.cycle(api_keys)

def get_next_api_key() -> str:
    """Get the next API key in rotation."""
    return next(api_key_cycle)

class RotatingChatOpenAI(ChatOpenAI):
    """ChatOpenAI wrapper that automatically rotates OpenRouter API keys on failure."""

    def invoke(self, *args, **kwargs):
        for _ in range(len(api_keys)):  # try each key once per call
            current_key = get_next_api_key()
            self.openai_api_key = current_key  # ✅ Correct for ChatOpenAI
            try:
                return super().invoke(*args, **kwargs)
            except Exception as e:
                # Handle rate-limits or auth errors
                if any(code in str(e) for code in ["429", "401", "403"]):
                    print(f"[API Key Rotation] Key {current_key[:5]}... failed, trying next key...")
                    continue
                raise  # Re-raise unexpected errors
        raise RuntimeError("All OpenRouter API keys failed or were rate-limited.")

# --------------------------------------------------------------------
# 2. Initialize LLM with API Key Rotation
# --------------------------------------------------------------------
llm = RotatingChatOpenAI(
    base_url="https://openrouter.ai/api/v1",
    openai_api_key=get_next_api_key(),  # ✅ start with the first key
    model="qwen/qwen3-coder:free",      # must support tool/function calling
    temperature=1
)

# --------------------------------------------------------------------
# 3. Tools Setup
# --------------------------------------------------------------------
python_tool = PythonAstREPLTool()
search_tool = BraveSearch.from_api_key(
    api_key=os.getenv("BRAVE_SEARCH_API"),
    search_kwargs={"count": 4},
    description="Web search using Brave"
)

community_tools = [search_tool, python_tool]
custom_tools = calculator_basic + datetime_tools + [
    transcribe_audio, transcribe_youtube, query_image, webpage_content, read_excel
]

tools = community_tools + custom_tools
llm_with_tools = llm.bind_tools(tools)
tools_by_name = {tool.name: tool for tool in tools}

# --------------------------------------------------------------------
# 4. Define LangGraph State and Nodes
# --------------------------------------------------------------------
class MessagesState(TypedDict):
    messages: Annotated[list[AnyMessage], add_messages]

# LLM Node
def llm_call(state: MessagesState):
    return {
        "messages": [
            llm_with_tools.invoke(
                [SystemMessage(content=system_prompt)] + state["messages"]
            )
        ]
    }

# Tool Node
def tool_node(state: MessagesState):
    """Executes tools requested by the LLM."""
    results = []
    last_message = state["messages"][-1]

    for tool_call in getattr(last_message, "tool_calls", []) or []:
        tool = tools_by_name.get(tool_call["name"])
        if not tool:
            results.append(ToolMessage(content=f"Unknown tool: {tool_call['name']}", tool_call_id=tool_call["id"]))
            continue

        args = tool_call["args"]
        # Handle dict vs positional args safely
        try:
            observation = tool.invoke(**args) if isinstance(args, dict) else tool.invoke(args)
        except Exception as e:
            observation = f"[Tool Error] {str(e)}"

        results.append(ToolMessage(content=observation, tool_call_id=tool_call["id"]))

    return {"messages": results}

# Conditional Routing
def should_continue(state: MessagesState) -> Literal["Action", END]:
    """Route to tools if LLM made a tool call, else end."""
    last_message = state["messages"][-1]
    return "Action" if getattr(last_message, "tool_calls", None) else END

# --------------------------------------------------------------------
# 5. Build LangGraph Agent
# --------------------------------------------------------------------
builder = StateGraph(MessagesState)

builder.add_node("llm_call", llm_call)
builder.add_node("environment", tool_node)

builder.add_edge(START, "llm_call")
builder.add_conditional_edges(
    "llm_call",
    should_continue,
    {"Action": "environment", END: END}
)
builder.add_edge("environment", "llm_call")

gaia_agent = builder.compile()

# --------------------------------------------------------------------
# 6. Agent Wrapper
# --------------------------------------------------------------------
class LangGraphAgent:
    def __init__(self):
        print("LangGraphAgent initialized with API key rotation.")

    def __call__(self, question: str) -> str:
        input_state = {"messages": [HumanMessage(content=question)]}
        print(f"Running LangGraphAgent with input: {question[:150]}...")

        config = RunnableConfig(
            config={
                "run_name": "GAIA Agent",
                "tags": ["gaia", "langgraph", "agent"],
                "metadata": {"user_input": question},
                "recursion_limit": 30,
                "tracing": True
            }
        )

        result = gaia_agent.invoke(input_state, config)
        final_response = result["messages"][-1].content

        # Extract "FINAL ANSWER" if present
        if isinstance(final_response, str):
            return final_response.split("FINAL ANSWER:")[-1].strip()
        else:
            return str(final_response)