from datetime import datetime
from sqlalchemy import (
    Boolean, DateTime, ForeignKey, Integer, String, Table, Column, UniqueConstraint
)
from sqlalchemy.orm import Mapped, mapped_column, relationship
from app.database import Base


media_item_tags = Table(
    "media_item_tags",
    Base.metadata,
    Column("media_item_id", Integer, ForeignKey("media_items.id", ondelete="CASCADE"), primary_key=True),
    Column("tag_id", Integer, ForeignKey("tags.id", ondelete="CASCADE"), primary_key=True),
)


class Library(Base):
    __tablename__ = "libraries"

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    name: Mapped[str] = mapped_column(String, nullable=False)
    path: Mapped[str] = mapped_column(String, nullable=False, unique=True)

    items: Mapped[list["MediaItem"]] = relationship(
        "MediaItem", back_populates="library", cascade="all, delete-orphan"
    )


class MediaItem(Base):
    __tablename__ = "media_items"
    __table_args__ = (UniqueConstraint("library_id", "rel_path"),)

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    library_id: Mapped[int] = mapped_column(Integer, ForeignKey("libraries.id", ondelete="CASCADE"), nullable=False)
    rel_path: Mapped[str] = mapped_column(String, nullable=False)
    filename: Mapped[str] = mapped_column(String, nullable=False)
    file_hash: Mapped[str | None] = mapped_column(String)
    media_type: Mapped[str] = mapped_column(String, nullable=False)  # 'image' | 'video'
    size_bytes: Mapped[int | None] = mapped_column(Integer)
    missing: Mapped[bool] = mapped_column(Boolean, default=False)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow)
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.utcnow, onupdate=datetime.utcnow)

    library: Mapped["Library"] = relationship("Library", back_populates="items")
    tags: Mapped[list["Tag"]] = relationship("Tag", secondary=media_item_tags, back_populates="items")


class Tag(Base):
    __tablename__ = "tags"
    __table_args__ = (UniqueConstraint("name", "category"),)

    id: Mapped[int] = mapped_column(Integer, primary_key=True)
    name: Mapped[str] = mapped_column(String, nullable=False)
    category: Mapped[str] = mapped_column(String, nullable=False)

    items: Mapped[list["MediaItem"]] = relationship("MediaItem", secondary=media_item_tags, back_populates="tags")