"""
数据库服务
提供数据库操作功能
"""
from sqlalchemy import create_engine
from sqlalchemy.orm import sessionmaker, Session
from typing import Optional, List
from datetime import datetime
import uuid

from app.config import get_settings
from app.models.database import Base, Conversation, Message, UserPreference
from app.utils.logger import logger


class DatabaseService:
    """数据库服务类"""

    def __init__(self):
        """初始化数据库连接"""
        settings = get_settings()
        self.engine = create_engine(
            settings.database_url,
            connect_args={"check_same_thread": False} if "sqlite" in settings.database_url else {}
        )
        self.SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=self.engine)

        # 创建表
        Base.metadata.create_all(bind=self.engine)
        logger.info("数据库初始化成功")

    def get_session(self) -> Session:
        """获取数据库会话"""
        return self.SessionLocal()

    def create_conversation(self, session_id: Optional[str] = None, user_id: Optional[str] = None) -> Conversation:
        """
        创建新对话

        Args:
            session_id: 会话ID（可选，自动生成）
            user_id: 用户ID

        Returns:
            对话对象
        """
        db = self.get_session()
        try:
            if not session_id:
                session_id = str(uuid.uuid4())

            conversation = Conversation(
                session_id=session_id,
                user_id=user_id
            )
            db.add(conversation)
            db.commit()
            db.refresh(conversation)
            return conversation
        finally:
            db.close()

    def get_conversation(self, session_id: str) -> Optional[Conversation]:
        """
        获取对话

        Args:
            session_id: 会话ID

        Returns:
            对话对象或None
        """
        db = self.get_session()
        try:
            return db.query(Conversation).filter(Conversation.session_id == session_id).first()
        finally:
            db.close()

    def add_message(
        self,
        session_id: str,
        role: str,
        content: str,
        metadata: Optional[dict] = None,
        user_id: Optional[int] = None
    ) -> Message:
        """
        添加消息

        Args:
            session_id: 会话ID
            role: 角色（user/assistant）
            content: 消息内容
            metadata: 元数据
            user_id: 用户ID（创建新对话时需要）

        Returns:
            消息对象
        """
        db = self.get_session()
        try:
            # 获取或创建对话
            conversation = db.query(Conversation).filter(
                Conversation.session_id == session_id
            ).first()

            if not conversation:
                if not user_id:
                    raise ValueError("创建新对话时必须提供 user_id")
                conversation = Conversation(session_id=session_id, user_id=user_id)
                db.add(conversation)
                db.commit()
                db.refresh(conversation)

            # 创建消息
            message = Message(
                conversation_id=conversation.id,
                role=role,
                content=content,
                msg_metadata=metadata
            )
            db.add(message)
            db.commit()
            db.refresh(message)
            return message
        finally:
            db.close()

    def get_conversation_history(self, session_id: str, limit: int = 50) -> List[Message]:
        """
        获取对话历史

        Args:
            session_id: 会话ID
            limit: 最大消息数

        Returns:
            消息列表
        """
        db = self.get_session()
        try:
            conversation = db.query(Conversation).filter(
                Conversation.session_id == session_id
            ).first()

            if not conversation:
                return []

            messages = db.query(Message).filter(
                Message.conversation_id == conversation.id
            ).order_by(Message.created_at.desc()).limit(limit).all()

            return list(reversed(messages))
        finally:
            db.close()

    def get_user_preference(self, user_id: str) -> Optional[dict]:
        """
        获取用户偏好

        Args:
            user_id: 用户ID

        Returns:
            偏好字典或None
        """
        db = self.get_session()
        try:
            pref = db.query(UserPreference).filter(
                UserPreference.user_id == user_id
            ).first()
            return pref.preferences if pref else None
        finally:
            db.close()

    def set_user_preference(self, user_id: str, preferences: dict) -> bool:
        """
        设置用户偏好

        Args:
            user_id: 用户ID
            preferences: 偏好字典

        Returns:
            是否成功
        """
        db = self.get_session()
        try:
            pref = db.query(UserPreference).filter(
                UserPreference.user_id == user_id
            ).first()

            if pref:
                pref.preferences = preferences
                pref.updated_at = datetime.utcnow()
            else:
                pref = UserPreference(
                    user_id=user_id,
                    preferences=preferences
                )
                db.add(pref)

            db.commit()
            return True
        except Exception as e:
            logger.error(f"设置用户偏好失败: {e}")
            db.rollback()
            return False
        finally:
            db.close()


# 创建全局实例
db_service = DatabaseService()