# File: backend/app/api/v1/endpoints/sessions.py (新建)
# Description: 会话管理的 API 路由

from fastapi import APIRouter, HTTPException, Depends, status
from typing import List
from app.models.pydantic_models import SessionRead, SessionCreateRequest, SessionCreateResponse
from app.services.session_service import session_service_instance, SessionService

router = APIRouter()

def get_session_service() -> SessionService:
    return session_service_instance

@router.post("/", response_model=SessionCreateResponse, status_code=status.HTTP_201_CREATED)
async def create_new_session(
    session_data: SessionCreateRequest,
    service: SessionService = Depends(get_session_service)
):
    """创建新会话并自动生成标题"""
    try:
        return await service.create_session(session_data)
    except ValueError as e:
        raise HTTPException(status_code=status.HTTP_400_BAD_REQUEST, detail=str(e))
    except Exception as e:
        # 处理可能的 LLM 调用错误
        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")

@router.get("/assistant/{assistant_id}", response_model=List[SessionRead])
async def read_sessions_for_assistant(
    assistant_id: str,
    service: SessionService = Depends(get_session_service)
):
    """获取指定助手的所有会话列表"""
    # TODO: 添加检查助手是否存在
    return service.get_sessions_by_assistant(assistant_id)

@router.get("/{session_id}", response_model=SessionRead)
async def read_session_by_id(
    session_id: str,
    service: SessionService = Depends(get_session_service)
):
    """获取单个会话信息"""
    session = service.get_session(session_id)
    if not session:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="找不到指定的会话")
    return session

@router.delete("/{session_id}", status_code=status.HTTP_204_NO_CONTENT)
async def delete_existing_session(
    session_id: str,
    service: SessionService = Depends(get_session_service)
):
    """删除指定 ID 的会话"""
    deleted = service.delete_session(session_id)
    if not deleted:
        raise HTTPException(status_code=status.HTTP_404_NOT_FOUND, detail="找不到指定的会话")