"""
Conversation model for AI chatbot.

Represents a chat session between a user and the AI assistant.
"""

from sqlmodel import SQLModel, Field, Relationship
from datetime import datetime
from typing import Optional, List, TYPE_CHECKING

if TYPE_CHECKING:
    from src.models.message import Message
    from src.models.user import User


class Conversation(SQLModel, table=True):
    """
    Conversation model representing a chat session.

    Each user can have multiple conversations over time.
    Currently, the system uses the most recent conversation for each user.
    """
    __tablename__ = "conversations"

    id: Optional[int] = Field(default=None, primary_key=True)
    user_id: int = Field(foreign_key="users.id", index=True, nullable=False)
    created_at: datetime = Field(default_factory=datetime.utcnow, nullable=False)
    updated_at: datetime = Field(
        default_factory=datetime.utcnow,
        nullable=False,
        sa_column_kwargs={"onupdate": datetime.utcnow}
    )

    # Relationships
    messages: List["Message"] = Relationship(back_populates="conversation")
    user: Optional["User"] = Relationship(back_populates="conversations")