from sqlalchemy import Column, Integer, String, DateTime, JSON, ForeignKey, Text, Boolean
from sqlalchemy.orm import relationship
from sqlalchemy.sql import func
from database import Base


class ChatConversation(Base):
    __tablename__ = "chat_conversations"

    id = Column(Integer, primary_key=True, index=True)
    user_id = Column(Integer, ForeignKey("users.id"), nullable=False, index=True)
    title = Column(String(200), nullable=False, default="新对话")
    subject = Column(String(50), default="")
    grade = Column(String(50), default="")
    pinned = Column(Boolean, default=False)
    created_at = Column(DateTime, server_default=func.now())
    updated_at = Column(DateTime, server_default=func.now(), onupdate=func.now())

    author = relationship("User", back_populates="chat_conversations")
    messages = relationship(
        "ChatMessage",
        back_populates="conversation",
        order_by="ChatMessage.id",
        lazy="selectin",
        cascade="all, delete-orphan",
    )


class ChatMessage(Base):
    __tablename__ = "chat_messages"

    id = Column(Integer, primary_key=True, index=True)
    conversation_id = Column(Integer, ForeignKey("chat_conversations.id"), nullable=False, index=True)
    role = Column(String(20), nullable=False)  # user / assistant / system
    content = Column(Text, nullable=False)
    tokens = Column(Integer, default=0)
    created_at = Column(DateTime, server_default=func.now())

    conversation = relationship("ChatConversation", back_populates="messages")