ailine/backend/app/agent/service.py

"""
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 json

# 本地模块
from ..graph.graph_builder import GraphBuilder, GraphContext
from ..graph.graph_tools import AVAILABLE_TOOLS, TOOLS_BY_NAME
from .llm_factory import LLMFactory
from .rag_initializer import init_rag_tool
from ..logger import info, warning

class AIAgentService:
    def __init__(self, checkpointer):
        self.checkpointer = checkpointer
        self.graphs = {}
        self.tools = AVAILABLE_TOOLS.copy()
        self.tools_by_name = TOOLS_BY_NAME.copy()

    async def initialize(self):
        # 1. 初始化 RAG 工具（如果需要）
        rag_tool = await init_rag_tool(LLMFactory.create_local)
        if rag_tool:
            self.tools.append(rag_tool)
            self.tools_by_name[rag_tool.name] = rag_tool

        # 2. 构建各模型的 Graph
        for name, creator in LLMFactory.CREATORS.items():
            try:
                info(f"🔄 初始化模型 '{name}'...")
                llm = creator()
                builder = GraphBuilder(llm, self.tools, self.tools_by_name).build()
                graph = builder.compile(checkpointer=self.checkpointer)
                self.graphs[name] = graph
                info(f"✅ 模型 '{name}' 初始化成功")
            except Exception as e:
                warning(f"⚠️ 模型 '{name}' 初始化失败: {e}")

        if not self.graphs:
            raise RuntimeError("没有可用的模型")
        return self

    async def process_message(self, message: str, thread_id: str, model: str = "local", user_id: str = "default_user") -> dict:
        """处理用户消息，返回包含回复、token统计和耗时的字典"""
        if model not in self.graphs:
            # 回退到第一个可用模型
            available = list(self.graphs.keys())
            if not available:
                raise RuntimeError("没有可用的模型")
            model = available[0]
            warning(f"模型 '{model}' 不可用，已回退到 '{model}'")

        graph = self.graphs[model]
        config = {
            "configurable": {"thread_id": thread_id},
            "metadata": {"user_id": user_id}
        }
        input_state = {"messages": [{"role": "user", "content": message}]}
        context = GraphContext(user_id=user_id)

        result = await graph.ainvoke(input_state, config=config, context=context)

        reply = result["messages"][-1].content
        token_usage = result.get("last_token_usage", {})
        elapsed_time = result.get("last_elapsed_time", 0.0)

        return {
            "reply": reply,
            "token_usage": token_usage,
            "elapsed_time": elapsed_time
        }

    def _serialize_value(self, value):
        """递归将 LangChain 对象转换为可 JSON 序列化的格式"""
        if hasattr(value, 'content'):
            msg_type = getattr(value, 'type', 'message')
            return {
                "role": msg_type,
                "content": getattr(value, 'content', ''),
                "additional_kwargs": getattr(value, 'additional_kwargs', {}),
                "tool_calls": getattr(value, 'tool_calls', [])
            }
        elif isinstance(value, dict):
            return {k: self._serialize_value(v) for k, v in value.items()}
        elif isinstance(value, (list, tuple)):
            return [self._serialize_value(item) for item in value]
        else:
            try:
                json.dumps(value)
                return value
            except (TypeError, ValueError):
                return str(value)

    async def process_message_stream(self, message: str, thread_id: str, model_name: str, user_id: str = "default_user"):
        """流式处理消息，返回异步生成器"""
        graph = self.graphs.get(model_name)
        if not graph:
            raise ValueError(f"模型 '{model_name}' 未找到或未初始化")

        config = {
            "configurable": {"thread_id": thread_id},
            "metadata": {"user_id": user_id}
        }
        input_state = {"messages": [{"role": "user", "content": message}]}
        context = GraphContext(user_id=user_id)

        async for chunk in graph.astream(
            input_state,
            config=config,
            context=context,
            stream_mode=["messages", "updates", "custom"],
            version="v2",
            subgraphs=True
        ):
            chunk_type = chunk["type"]
            processed_event = {}

            if chunk_type == "messages":
                message_chunk, metadata = chunk["data"]
                node_name = metadata.get("langgraph_node", "unknown")
                token_content = getattr(message_chunk, 'content', str(message_chunk))
                reasoning_token = ""
                if hasattr(message_chunk, 'additional_kwargs'):
                    reasoning_token = message_chunk.additional_kwargs.get("reasoning_content", "")

                processed_event = {
                    "type": "llm_token",
                    "node": node_name,
                    "token": token_content,
                    "reasoning_token": reasoning_token,
                    "metadata": metadata
                }
            elif chunk_type == "updates":
                updates_data = chunk["data"]
                serialized_data = self._serialize_value(updates_data)
                processed_event = {
                    "type": "state_update",
                    "data": serialized_data
                }
                if "messages" in serialized_data:
                    processed_event["messages"] = serialized_data["messages"]
            elif chunk_type == "custom":
                serialized_data = self._serialize_value(chunk["data"])
                processed_event = {
                    "type": "custom",
                    "data": serialized_data
                }
            else:
                continue

            if processed_event:
                yield processed_event