"""ORM model for likes — an append-only event log.

A like/dislike is **never** updated in place. Current state for a ``(user,
track)`` pair is the latest event by ``created_at``. This shape is required for
future sync and as a clean ML signal (plan §4.1). Hence: no ``updated_at``,
no unique constraint on ``(user, track)``.
"""

import datetime as dt
import uuid

from sqlalchemy import DateTime, ForeignKey, Index, String, func
from sqlalchemy.orm import Mapped, mapped_column

from app.infrastructure.db.base import Base
from app.infrastructure.db.models.mixins import UUIDPrimaryKeyMixin


class LikeModel(UUIDPrimaryKeyMixin, Base):
    __tablename__ = "likes"
    __table_args__ = (
        # Latest-event lookups query by (user, track) ordered by time.
        Index("ix_likes_user_id_track_id", "user_id", "track_id"),
    )

    user_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("users.id", ondelete="CASCADE"),
        nullable=False,
    )
    track_id: Mapped[uuid.UUID] = mapped_column(
        ForeignKey("tracks.id", ondelete="CASCADE"),
        nullable=False,
    )
    value: Mapped[str] = mapped_column(String(16), nullable=False)
    created_at: Mapped[dt.datetime] = mapped_column(
        DateTime(timezone=True),
        server_default=func.now(),
        nullable=False,
    )