import os
import time
import json
import logging
from dotenv import load_dotenv
from langgraph.graph import StateGraph, END
from langchain_google_genai import ChatGoogleGenerativeAI
from langchain_community.tools import DuckDuckGoSearchRun
from langchain_community.document_loaders import WikipediaLoader, ArxivLoader
from langchain_core.messages import SystemMessage, AIMessage, HumanMessage
from langchain_core.tools import tool
from typing import TypedDict, Annotated, Sequence
import operator
import random

# Configure logging
logging.basicConfig(level=logging.INFO)
logger = logging.getLogger("GAIA_Agent")

# Load environment variables
load_dotenv()
google_api_key = os.getenv("GOOGLE_API_KEY") or os.environ.get("GOOGLE_API_KEY")
if not google_api_key:
    raise ValueError("Missing GOOGLE_API_KEY environment variable")

# --- Math Tools ---
@tool
def multiply(a: int, b: int) -> int:
    """Multiply two integers."""
    return a * b

@tool
def add(a: int, b: int) -> int:
    """Add two integers."""
    return a + b

@tool
def subtract(a: int, b: int) -> int:
    """Subtract b from a."""
    return a - b

@tool
def divide(a: int, b: int) -> float:
    """Divide a by b, error on zero."""
    if b == 0:
        raise ValueError("Cannot divide by zero.")
    return a / b

@tool
def modulus(a: int, b: int) -> int:
    """Compute a mod b."""
    return a % b

# --- Browser Tools ---
@tool
def wiki_search(query: str) -> str:
    """Search Wikipedia and return up to 3 relevant documents."""
    try:
        # Ensure query contains "discography" keyword
        if "discography" not in query.lower():
            query = f"{query} discography"
            
        docs = WikipediaLoader(query=query, load_max_docs=3).load()
        if not docs:
            return "No Wikipedia results found."
        
        results = []
        for doc in docs:
            title = doc.metadata.get('title', 'Unknown Title')
            content = doc.page_content[:2000]  # Limit content length
            results.append(f"Title: {title}\nContent: {content}")
        
        return "\n\n---\n\n".join(results)
    except Exception as e:
        return f"Wikipedia search error: {str(e)}"

@tool
def arxiv_search(query: str) -> str:
    """Search Arxiv and return up to 3 relevant papers."""
    try:
        docs = ArxivLoader(query=query, load_max_docs=3).load()
        if not docs:
            return "No arXiv papers found."
        
        results = []
        for doc in docs:
            title = doc.metadata.get('Title', 'Unknown Title')
            authors = ", ".join(doc.metadata.get('Authors', []))
            content = doc.page_content[:2000]  # Limit content length
            results.append(f"Title: {title}\nAuthors: {authors}\nContent: {content}")
        
        return "\n\n---\n\n".join(results)
    except Exception as e:
        return f"arXiv search error: {str(e)}"

@tool
def web_search(query: str) -> str:
    """Search the web using DuckDuckGo and return top results."""
    try:
        search = DuckDuckGoSearchRun()
        result = search.run(query)
        return f"Web search results for '{query}':\n{result[:2000]}"  # Limit content length
    except Exception as e:
        return f"Web search error: {str(e)}"

# --- Load system prompt ---
with open("system_prompt.txt", "r", encoding="utf-8") as f:
    system_prompt = f.read()

# --- Tool Setup ---
tools = [
    multiply,
    add,
    subtract,
    divide,
    modulus,
    wiki_search,
    arxiv_search,
    web_search,
]

# --- Graph Builder ---
def build_graph():
    # Initialize model with Gemini 2.5 Flash
    llm = ChatGoogleGenerativeAI(
        model="gemini-2.5-flash",
        temperature=0.3,
        google_api_key=google_api_key,
        max_retries=0,  # Disable internal retries
        request_timeout=30  # Keep timeout reasonable
    )
    
    # Bind tools to LLM
    llm_with_tools = llm.bind_tools(tools)
    
    # 1. Define state structure
    class AgentState(TypedDict):
        messages: Annotated[Sequence, operator.add]
        step_count: int
        start_time: float
        last_action: str
        api_errors: int  # Track consecutive API errors
    
    # 2. Create graph
    workflow = StateGraph(AgentState)
    
    # 3. Define node functions
    def agent_node(state: AgentState):
        """Main agent node with manual retry handling"""
        # Ensure state has required fields
        state.setdefault("start_time", time.time())
        state.setdefault("step_count", 0)
        state.setdefault("last_action", "start")
        state.setdefault("api_errors", 0)
        
        # Check global timeout (2 minutes)
        if time.time() - state["start_time"] > 120:
            return {
                "messages": [AIMessage(content="AGENT ERROR (GLOBAL_TIMEOUT): Execution exceeded 2-minute limit")],
                "step_count": state["step_count"] + 1,
                "start_time": state["start_time"],
                "last_action": "timeout",
                "api_errors": state["api_errors"]
            }
        
        # Check step limit (max 8 steps)
        if state["step_count"] >= 8:
            return {
                "messages": [AIMessage(content="AGENT ERROR (STEP_LIMIT): Exceeded maximum step count of 8")],
                "step_count": state["step_count"] + 1,
                "start_time": state["start_time"],
                "last_action": "step_limit",
                "api_errors": state["api_errors"]
            }
        
        # Check consecutive API errors
        if state["api_errors"] >= 3:
            return {
                "messages": [AIMessage(content="AGENT ERROR (API_LIMIT): Too many consecutive API errors")],
                "step_count": state["step_count"] + 1,
                "start_time": state["start_time"],
                "last_action": "api_limit",
                "api_errors": state["api_errors"]
            }
        
        try:
            # Add variable delay to avoid rate limiting
            delay = 2 + random.uniform(0, 3)  # 2-5 seconds
            time.sleep(delay)
            
            # Call API without automatic retries
            response = llm_with_tools.invoke(state["messages"])
            
            # Reset error counter on success
            return {
                "messages": [response],
                "step_count": state["step_count"] + 1,
                "start_time": state["start_time"],
                "last_action": "agent",
                "api_errors": 0  # Reset error counter
            }
        
        except Exception as e:
            # Detailed error logging
            error_details = f"Gemini API Error: {type(e).__name__}: {str(e)}"
            logger.error(error_details)
            
            error_type = "UNKNOWN"
            if "429" in str(e) or "ResourceExhausted" in str(e):
                error_type = "RESOURCE_EXHAUSTED"
            elif "400" in str(e):
                error_type = "INVALID_REQUEST"
            elif "503" in str(e):
                error_type = "SERVICE_UNAVAILABLE"
                
            error_msg = f"AGENT ERROR ({error_type}): {error_details[:300]}"
            
            return {
                "messages": [AIMessage(content=error_msg)],
                "step_count": state["step_count"] + 1,
                "start_time": state["start_time"],
                "last_action": "error",
                "api_errors": state["api_errors"] + 1  # Increment error counter
            }
    
    def tool_node(state: AgentState):
        """Tool execution node"""
        # Ensure state has required fields
        state.setdefault("start_time", time.time())
        state.setdefault("step_count", 0)
        state.setdefault("last_action", "start")
        state.setdefault("api_errors", 0)
            
        # Check global timeout (2 minutes)
        if time.time() - state["start_time"] > 120:
            return {
                "messages": [AIMessage(content="AGENT ERROR (GLOBAL_TIMEOUT): Execution exceeded 2-minute limit")],
                "step_count": state["step_count"] + 1,
                "start_time": state["start_time"],
                "last_action": "timeout",
                "api_errors": state["api_errors"]
            }
        
        last_msg = state["messages"][-1]
        tool_calls = last_msg.additional_kwargs.get("tool_calls", [])
        
        responses = []
        for call in tool_calls:
            tool_name = call["function"]["name"]
            tool_args = call["function"].get("arguments", {})
            
            tool_func = next((t for t in tools if t.name == tool_name), None)
            if not tool_func:
                responses.append(f"Tool {tool_name} not available")
                continue
            
            try:
                # Parse arguments
                if isinstance(tool_args, str):
                    try:
                        tool_args = json.loads(tool_args)
                    except json.JSONDecodeError:
                        if "query" in tool_args:
                            tool_args = {"query": tool_args}
                        else:
                            tool_args = {"query": tool_args}
                
                # Execute tool
                result = tool_func.invoke(tool_args)
                responses.append(f"{tool_name} result: {str(result)[:1000]}")
            except Exception as e:
                responses.append(f"{tool_name} error: {str(e)}")
        
        tool_response_content = "\n".join(responses)
        return {
            "messages": [AIMessage(content=tool_response_content)],
            "step_count": state["step_count"] + 1,
            "start_time": state["start_time"],
            "last_action": "tool",
            "api_errors": state["api_errors"]  # Preserve error count
        }
    
    # 4. Add nodes to workflow
    workflow.add_node("agent", agent_node)
    workflow.add_node("tools", tool_node)
    
    # 5. Set entry point
    workflow.set_entry_point("agent")
    
    # 6. Define conditional edges
    def should_continue(state: AgentState):
        last_msg = state["messages"][-1]
        
        # Handle timeout or step limit errors
        if "AGENT ERROR (GLOBAL_TIMEOUT)" in last_msg.content or "AGENT ERROR (STEP_LIMIT)" in last_msg.content or "AGENT ERROR (API_LIMIT)" in last_msg.content:
            return "end"
        
        # Handle all other errors
        if "AGENT ERROR" in last_msg.content:
            # For RESOURCE_EXHAUSTED errors, wait longer before retrying
            if "RESOURCE_EXHAUSTED" in last_msg.content:
                time.sleep(10 + random.uniform(0, 10))  # Wait 10-20 seconds
            return "agent"
        
        # Route to tools if tool calls exist
        if hasattr(last_msg, "tool_calls") and last_msg.tool_calls:
            return "tools"
        
        # End if final answer is present
        if "FINAL ANSWER" in last_msg.content:
            return "end"
        
        # Continue to agent otherwise
        return "agent"
    
    workflow.add_conditional_edges(
        "agent",
        should_continue,
        {
            "agent": "agent",
            "tools": "tools",
            "end": END
        }
    )
    
    # 7. Define flow after tool node
    workflow.add_edge("tools", "agent")
    
    # 8. Compile graph
    return workflow.compile()

# Initialize agent graph
agent_graph = build_graph()

# Wrapper function to ensure execution within time limits
def run_agent(question):
    # Create initial state with all required fields
    initial_state = {
        "messages": [
            SystemMessage(content=system_prompt),
            HumanMessage(content=question)
        ],
        "step_count": 0,
        "start_time": time.time(),
        "last_action": "start",
        "api_errors": 0
    }
    
    # Run with overall timeout
    start_time = time.time()
    result = None
    end_state_reached = False
    
    try:
        # Execute with 3-minute overall timeout
        for step in agent_graph.stream(initial_state):
            # Check overall timeout every step
            if time.time() - start_time > 180:  # 3 minutes
                return {"error": "Overall execution timeout (3 minutes)"}
            
            # Capture the final state when the graph completes
            if END in step:
                result = step[END]
                end_state_reached = True
                break
    except Exception as e:
        return {"error": f"Execution failed: {str(e)}"}
    
    # Extract final answer safely
    if end_state_reached and result is not None:
        if "messages" in result and result["messages"]:
            return {"answer": result["messages"][-1].content}
        else:
            return {"error": "Agent finished but produced no messages"}
    else:
        return {"error": "Agent did not complete execution"}

# 示例调用函数（在app.py中使用）
def process_question(question):
    # Add initial delay to avoid burst requests
    time.sleep(1 + random.uniform(0, 2))
    
    response = run_agent(question)
    if "answer" in response:
        return response["answer"]
    elif "error" in response:
        return f"Error: {response['error']}"
    else:
        return "Unexpected response format"