"""
聊天标题相关 API 路由模块

处理会话标题的生成和重命名功能。
"""
from fastapi import APIRouter, Depends, HTTPException, status

from utils.helpers import BaseResponse
from logger.logging import get_logger
from core.dependencies import get_current_user
from models.user import User
from core.database import get_db_pool
from models.chat import (
    GenerateTitleRequest,
    GenerateTitleResponse,
    RenameThreadRequest
)
from core.llm_catalog import build_chat_model

# 获取日志记录器
logger = get_logger(__name__)

# 创建路由实例
chat_title_router = APIRouter(prefix="/api", tags=["聊天标题接口"])


@chat_title_router.put("/chat/thread/{thread_id}/rename", summary="重命名会话", response_model=BaseResponse)
async def rename_thread(
    thread_id: str,
    request: RenameThreadRequest,
    current_user: User = Depends(get_current_user)
):
    """
    重命名聊天会话
    
    Args:
        thread_id: 会话线程 ID（路径参数）
        request: 重命名请求数据（包含新标题）
        current_user: 当前登录用户
        
    Returns:
        BaseResponse: 重命名结果
        
    Raises:
        HTTPException: 会话不存在、无权限或会话已删除
    """
    logger.info(f"用户 {current_user.username} (ID: {current_user.id}) 请求重命名会话: {thread_id}, 新标题: {request.title}")
    
    pool = await get_db_pool()
    async with pool.acquire() as conn:
        # 检查会话是否存在且属于该用户
        thread_info = await conn.fetchrow(
            """
            SELECT id, user_id, is_deleted
            FROM chat_threads
            WHERE thread_id = $1
            """,
            thread_id
        )
        
        if not thread_info:
            raise HTTPException(
                status_code=status.HTTP_404_NOT_FOUND,
                detail="会话不存在"
            )
        
        if thread_info['user_id'] != current_user.id:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="无权限访问该会话"
            )
        
        if thread_info['is_deleted']:
            raise HTTPException(
                status_code=status.HTTP_404_NOT_FOUND,
                detail="会话已被删除"
            )
        
        # 更新标题
        await conn.execute(
            """
            UPDATE chat_threads 
            SET title = $1,
                updated_at = CURRENT_TIMESTAMP
            WHERE thread_id = $2
            """,
            request.title,
            thread_id
        )
        
        logger.info(f"成功重命名会话: thread_id={thread_id}, 新标题='{request.title}'")
        
        return BaseResponse(
            code=200,
            msg="重命名成功",
            data={"thread_id": thread_id, "title": request.title}
        )


@chat_title_router.post("/chat/generate-title", summary="生成会话标题", response_model=GenerateTitleResponse)
async def generate_title(
    request: GenerateTitleRequest,
    current_user: User = Depends(get_current_user)
):
    """
    根据用户的查询内容生成简洁的会话标题
    
    Args:
        request: 生成标题请求数据（包含 thread_id 和用户查询内容）
        current_user: 当前登录用户
        
    Returns:
        GenerateTitleResponse: 生成的标题
        
    Raises:
        HTTPException: 会话不存在、无权限或会话已删除
    """
    logger.info(f"用户 {current_user.username} (ID: {current_user.id}) 请求生成标题，thread_id: {request.thread_id}, query: {request.query[:50]}...")
    
    pool = await get_db_pool()
    async with pool.acquire() as conn:
        # 检查会话是否存在且属于该用户
        thread_info = await conn.fetchrow(
            """
            SELECT id, user_id, is_deleted
            FROM chat_threads
            WHERE thread_id = $1
            """,
            request.thread_id
        )
        
        if not thread_info:
            raise HTTPException(
                status_code=status.HTTP_404_NOT_FOUND,
                detail="会话不存在"
            )
        
        if thread_info['user_id'] != current_user.id:
            raise HTTPException(
                status_code=status.HTTP_403_FORBIDDEN,
                detail="无权限访问该会话"
            )
        
        if thread_info['is_deleted']:
            raise HTTPException(
                status_code=status.HTTP_404_NOT_FOUND,
                detail="会话已被删除"
            )
    
    try:
        # 标题生成默认走 DeepSeek（短文本、低温度）
        from langchain_deepseek import ChatDeepSeek
        import os
        model = ChatDeepSeek(
            model="deepseek-chat",
            api_key=os.getenv("DEEPSEEK_API_KEY"),
            base_url=os.getenv("DEEPSEEK_BASE_URL"),
            streaming=False,
            temperature=0.1,
        )
        
        # 创建专门用于生成标题的 system prompt
        system_message = """你是一个专业的标题生成助手。你的任务是根据用户的问题生成一个简洁的标题。

严格要求：
1. 只返回标题文本，不要有任何其他内容
2. 标题长度：2-10个汉字
3. 不要包含标点符号
4. 不要有引号、冒号等任何符号
5. 直接返回标题，不要解释

示例：
用户："今天苏州天气怎么样啊" -> 苏州天气
用户："请帮我写一个Python爬虫" -> Python爬虫
用户："如何学习机器学习" -> 机器学习入门"""
        
        # 构造消息
        messages = [
            {"role": "system", "content": system_message},
            {"role": "user", "content": f"请为以下问题生成标题：{request.query}"}
        ]
        
        # 调用模型生成标题（非流式）
        response = await model.ainvoke(messages)
        
        # 提取生成的标题
        title = response.content.strip()
        
        # 清理标题：移除可能的引号、标点符号等
        title = title.strip('"\'""''「」『』【】《》：:。，,、！!？?')
        
        # 如果生成失败或标题为空，使用默认逻辑
        if not title or len(title) < 2:
            title = request.query[:10] if len(request.query) <= 10 else request.query[:10]
            logger.warning(f"AI 生成标题失败或过短，使用默认逻辑: {title}")
        
        # 确保标题长度合理（最多 20 个字符）
        if len(title) > 20:
            title = title[:20]
        
        # 更新数据库中的标题
        async with pool.acquire() as conn:
            await conn.execute(
                """
                UPDATE chat_threads 
                SET title = $1,
                    updated_at = CURRENT_TIMESTAMP
                WHERE thread_id = $2
                """,
                title,
                request.thread_id
            )
        
        logger.info(f"成功生成并更新标题: '{title}', thread_id: {request.thread_id}")
        
        return GenerateTitleResponse(
            title=title,
            original_query=request.query
        )
        
    except HTTPException:
        # 重新抛出 HTTP 异常
        raise
    except Exception as e:
        logger.error(f"生成标题失败: {e}")
        # 降级处理：使用简单的截取逻辑
        fallback_title = request.query[:10] if len(request.query) <= 10 else request.query[:10]
        logger.info(f"使用降级标题: {fallback_title}")
        
        # 更新数据库中的标题
        async with pool.acquire() as conn:
            await conn.execute(
                """
                UPDATE chat_threads 
                SET title = $1,
                    updated_at = CURRENT_TIMESTAMP
                WHERE thread_id = $2
                """,
                fallback_title,
                request.thread_id
            )
        
        return GenerateTitleResponse(
            title=fallback_title,
            original_query=request.query
        )