"""Playlist-Track association model."""
import uuid
from datetime import datetime
from typing import TYPE_CHECKING

from sqlalchemy import Integer, ForeignKey, UniqueConstraint
from sqlalchemy.dialects.postgresql import UUID
from sqlalchemy.orm import Mapped, mapped_column, relationship

from app.core.database import Base

if TYPE_CHECKING:
    from app.models.playlist import Playlist
    from app.models.track import Track
    from app.models.user import User


class PlaylistTrack(Base):
    """Association model for Playlist-Track many-to-many relationship."""

    __tablename__ = "playlist_tracks"
    __table_args__ = (
        UniqueConstraint("playlist_id", "position", name="uq_playlist_position"),
    )

    # Primary key
    id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        primary_key=True,
        default=uuid.uuid4,
        index=True,
    )

    # Foreign keys
    playlist_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("playlists.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )
    track_id: Mapped[uuid.UUID] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("tracks.id", ondelete="CASCADE"),
        nullable=False,
        index=True,
    )

    # Position in playlist (starts at 0)
    position: Mapped[int] = mapped_column(
        Integer,
        nullable=False,
    )

    # User who added this track to playlist
    added_by: Mapped[uuid.UUID | None] = mapped_column(
        UUID(as_uuid=True),
        ForeignKey("users.id", ondelete="SET NULL"),
        nullable=True,
    )

    # Timestamp when track was added
    added_at: Mapped[datetime] = mapped_column(
        default=datetime.utcnow,
        nullable=False,
    )

    # Relationships
    playlist: Mapped["Playlist"] = relationship(
        "Playlist",
        back_populates="playlist_tracks",
        lazy="selectin",
    )
    track: Mapped["Track"] = relationship(
        "Track",
        lazy="selectin",
    )
    added_by_user: Mapped["User"] = relationship(
        "User",
        back_populates="added_playlist_tracks",
        lazy="selectin",
        foreign_keys=[added_by],
    )

    def __repr__(self) -> str:
        return f"<PlaylistTrack playlist={self.playlist_id} track={self.track_id} pos={self.position}>"

    def to_dict(self) -> dict:
        """Convert playlist-track model to dictionary."""
        return {
            "id": str(self.id),
            "playlist_id": str(self.playlist_id),
            "track_id": str(self.track_id),
            "position": self.position,
            "added_by": str(self.added_by) if self.added_by else None,
            "added_at": self.added_at.isoformat(),
        }