backend/app/models/chat.py

"""
Chat ORM Models.

Stores HedgeAI chat sessions and messages for conversation persistence.
"""

from __future__ import annotations

from datetime import datetime

from sqlalchemy import DateTime, ForeignKey, Integer, String, Text, func
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.database import Base


class ChatSession(Base):
    __tablename__ = "chat_sessions"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    user_id: Mapped[int] = mapped_column(Integer, ForeignKey("users.id", ondelete="CASCADE"), nullable=False, index=True)
    title: Mapped[str] = mapped_column(String(255), nullable=False, default="New Chat")
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), nullable=False
    )
    updated_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), onupdate=func.now(), nullable=False
    )

    # Relationships
    user = relationship("User", back_populates="chat_sessions")
    messages = relationship("ChatMessage", back_populates="session", cascade="all, delete-orphan", order_by="ChatMessage.created_at")

    def __repr__(self) -> str:
        return f"<ChatSession(id={self.id}, title='{self.title}')>"


class ChatMessage(Base):
    __tablename__ = "chat_messages"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    session_id: Mapped[int] = mapped_column(Integer, ForeignKey("chat_sessions.id", ondelete="CASCADE"), nullable=False, index=True)
    role: Mapped[str] = mapped_column(String(20), nullable=False)  # 'user' or 'assistant'
    content: Mapped[str] = mapped_column(Text, nullable=False)
    intent: Mapped[str] = mapped_column(String(50), nullable=True)
    actions_json: Mapped[str] = mapped_column(Text, nullable=True)  # JSON string of actions
    created_at: Mapped[datetime] = mapped_column(
        DateTime(timezone=True), server_default=func.now(), nullable=False
    )

    # Relationships
    session = relationship("ChatSession", back_populates="messages")

    def __repr__(self) -> str:
        return f"<ChatMessage(id={self.id}, role='{self.role}')>"