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

class User(Base):
    __tablename__ = "users"
    id = Column(Integer, primary_key=True, index=True)
    telegram_id = Column(String, unique=True, index=True)
    username = Column(String, nullable=True)

    chats = relationship("Chat", back_populates="owner")


class Chat(Base):
    __tablename__ = "chats"
    id = Column(Integer, primary_key=True, index=True)
    title = Column(String, default="Новый чат")

    owner_id = Column(Integer, ForeignKey("users.id"))
    owner = relationship("User", back_populates="chats")

    messages = relationship("Message", back_populates="chat", cascade="all, delete-orphan")


class Message(Base):
    __tablename__ = "messages"
    id = Column(Integer, primary_key=True, index=True)
    role = Column(String)  # 'user' | 'assistant' | 'system'
    content = Column(Text)
    created_at = Column(DateTime(timezone=True), server_default=func.now())

    chat_id = Column(Integer, ForeignKey("chats.id"))
    chat = relationship("Chat", back_populates="messages")