# File: backend/app/api/v1/endpoints/chat.py (更新)
# Description: 聊天功能的 API 路由 (使用更新后的 ChatService)

from fastapi import APIRouter, HTTPException, Depends, status
from app.models.pydantic_models import ChatRequest, ChatResponse, SessionCreateRequest
from app.services.chat_service import chat_service_instance, ChatService
from app.services.session_service import session_service_instance, SessionService # 导入 SessionService

router = APIRouter()

# --- 依赖注入 ---
def get_chat_service() -> ChatService:
    return chat_service_instance

def get_session_service() -> SessionService:
    return session_service_instance

@router.post("/", response_model=ChatResponse)
async def handle_chat_message(
    request: ChatRequest,
    chat_service: ChatService = Depends(get_chat_service),
    session_service: SessionService = Depends(get_session_service) # 注入 SessionService
):
    """处理用户发送的聊天消息 (包含 assistantId 和 sessionId)"""
    user_message = request.message
    session_id = request.session_id
    assistant_id = request.assistant_id

    print(f"接收到消息: User='{user_message}', Session='{session_id}', Assistant='{assistant_id}'")

    response_session_id = None
    response_session_title = None

    # --- 处理临时新会话 ---
    if session_id == 'temp-new-chat':
        print("检测到临时新会话，正在创建...")
        try:
            # 调用 SessionService 创建会话
            create_req = SessionCreateRequest(assistant_id=assistant_id, first_message=user_message)
            created_session = await session_service.create_session(create_req)
            session_id = created_session.id # 使用新创建的会话 ID
            response_session_id = created_session.id # 准备在响应中返回新 ID
            response_session_title = created_session.title # 准备在响应中返回新标题
            print(f"新会话已创建: ID={session_id}, Title='{created_session.title}'")
        except ValueError as e: # 助手不存在等错误
            raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(e))
        except Exception as e: # LLM 调用或其他错误
            print(f"创建会话时出错: {e}")
            raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail="创建会话失败")

    # --- 调用聊天服务获取回复 ---
    try:
        ai_reply = await chat_service.get_ai_reply(
            user_message=user_message,
            session_id=session_id, # 使用真实的或新创建的 session_id
            assistant_id=assistant_id
        )
        print(f"发送 AI 回复: '{ai_reply}'")
        return ChatResponse(
            reply=ai_reply,
            session_id=response_session_id, # 返回新 ID (如果创建了)
            session_title=response_session_title # 返回新标题 (如果创建了)
        )
    except ValueError as e: # 助手不存在等错误
         raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(e))
    except Exception as e: # LLM 调用或其他错误
        print(f"处理聊天消息时发生错误: {e}")
        raise HTTPException(status_code=status.HTTP_500_INTERNAL_SERVER_ERROR, detail=str(e))