"""
AI Agent 服务类 - 支持多模型动态切换
接收外部传入的 checkpointer，不负责管理连接生命周期
"""

import os
from dotenv import load_dotenv
from langchain_community.chat_models import ChatZhipuAI
from langchain_core.messages import HumanMessage
from langchain_openai import ChatOpenAI
from pydantic import SecretStr

# 本地模块
from graph_builder import GraphBuilder
from tools import AVAILABLE_TOOLS, TOOLS_BY_NAME

load_dotenv()


class AIAgentService:
    """异步 AI Agent 服务，支持多模型动态切换，使用外部传入的 checkpointer"""

    def __init__(self, checkpointer):
        """
        初始化服务
        Args:
            checkpointer: 已经初始化的 AsyncPostgresSaver 实例
        """
        self.checkpointer = checkpointer
        self.graphs = {}  # 存储不同模型对应的 graph 实例

    def _create_zhipu_llm(self):
        """创建智谱在线 LLM"""
        api_key = os.getenv("ZHIPUAI_API_KEY")
        if not api_key:
            raise ValueError("ZHIPUAI_API_KEY not set in environment")
        return ChatZhipuAI(
            model="glm-4.7-flash",
            api_key=api_key,
            temperature=0.1,
            max_tokens=4096,
        )

    def _create_local_llm(self):
        """创建本地 vLLM 服务 LLM"""
        return ChatOpenAI(
            base_url="http://localhost:8000/v1",
            api_key=SecretStr(os.getenv("VLLM_LOCAL_KEY", "")),
            model="gemma-4-E2B-it",
        )

    async def initialize(self):
        """预编译所有模型的 graph（使用传入的 checkpointer）"""
        model_configs = {
            "zhipu": self._create_zhipu_llm,
            "local": self._create_local_llm,
        }

        for model_name, llm_creator in model_configs.items():
            try:
                llm = llm_creator()
                builder = GraphBuilder(llm, AVAILABLE_TOOLS, TOOLS_BY_NAME).build()
                graph = builder.compile(checkpointer=self.checkpointer)
                self.graphs[model_name] = graph
                print(f"✅ 模型 '{model_name}' 初始化成功")
            except Exception as e:
                print(f"⚠️ 模型 '{model_name}' 初始化失败: {e}")

        if not self.graphs:
            raise RuntimeError("没有可用的模型，请检查配置")

        return self

    async def process_message(self, message: str, thread_id: str, model: str = "zhipu") -> str:
        """处理用户消息，返回最终答案"""
        if model not in self.graphs:
            fallback_model = next(iter(self.graphs.keys()))
            print(f"警告: 模型 '{model}' 不可用，已切换到 '{fallback_model}'")
            model = fallback_model

        graph = self.graphs[model]
        config = {"configurable": {"thread_id": thread_id}}
        input_state = {"messages": [HumanMessage(content=message)]}
        result = await graph.ainvoke(input_state, config=config)
        return result["messages"][-1].content