"""
数据库模型定义
"""
from datetime import datetime
from sqlalchemy import Column, Integer, String, Text, DateTime, ForeignKey, JSON
from sqlalchemy.ext.declarative import declarative_base
from sqlalchemy.orm import relationship

Base = declarative_base()


class Conversation(Base):
    """对话记录表"""
    __tablename__ = "conversations"

    id = Column(Integer, primary_key=True, index=True)
    session_id = Column(String(64), nullable=False, index=True)
    user_id = Column(String(64), nullable=True)
    created_at = Column(DateTime, default=datetime.utcnow)

    # 关联消息
    messages = relationship("Message", back_populates="conversation", cascade="all, delete-orphan")


class Message(Base):
    """消息记录表"""
    __tablename__ = "messages"

    id = Column(Integer, primary_key=True, index=True)
    conversation_id = Column(Integer, ForeignKey("conversations.id"), nullable=False)
    role = Column(String(20), nullable=False)  # 'user' or 'assistant'
    content = Column(Text, nullable=False)
    msg_metadata = Column(JSON, nullable=True)  # 改名避免与SQLAlchemy保留字冲突
    created_at = Column(DateTime, default=datetime.utcnow)

    # 关联对话
    conversation = relationship("Conversation", back_populates="messages")


class UserPreference(Base):
    """用户偏好表"""
    __tablename__ = "user_preferences"

    id = Column(Integer, primary_key=True, index=True)
    user_id = Column(String(64), unique=True, nullable=False, index=True)
    preferences = Column(JSON, nullable=True)
    updated_at = Column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)