"""SQLAlchemy-Modelle für Quivio.

Zentrale Idee: ein polymorphes ``Media``-Objekt mit ``kind`` (book/series), das
optionale, mediumspezifische Felder als NULL-sparende Spalten mitführt. So
müssen wir keine separaten Tabellen für Bücher vs. Serien pflegen.
"""
# SPDX-License-Identifier: Apache-2.0
from __future__ import annotations

from datetime import date, datetime, timezone
from typing import Optional

from sqlalchemy import (
    CheckConstraint,
    Column,
    Date,
    DateTime,
    Float,
    ForeignKey,
    Index,
    Integer,
    String,
    Table,
    Text,
)
from sqlalchemy.orm import Mapped, mapped_column, relationship

from quivio.database import Base


def _utcnow() -> datetime:
    return datetime.now(timezone.utc)


# ---------- Assoziationstabellen (n:m) ---------------------------------------

media_genres = Table(
    "media_genres",
    Base.metadata,
    Column("media_id", Integer, ForeignKey("media.id", ondelete="CASCADE"), primary_key=True),
    Column("genre_id", Integer, ForeignKey("genres.id", ondelete="CASCADE"), primary_key=True),
)

media_tags = Table(
    "media_tags",
    Base.metadata,
    Column("media_id", Integer, ForeignKey("media.id", ondelete="CASCADE"), primary_key=True),
    Column("tag_id", Integer, ForeignKey("tags.id", ondelete="CASCADE"), primary_key=True),
)


class Genre(Base):
    __tablename__ = "genres"
    id: Mapped[int] = mapped_column(primary_key=True)
    name: Mapped[str] = mapped_column(String(60), unique=True, nullable=False)

    def __repr__(self) -> str:
        return f"<Genre {self.name}>"


class Tag(Base):
    __tablename__ = "tags"
    id: Mapped[int] = mapped_column(primary_key=True)
    name: Mapped[str] = mapped_column(String(40), unique=True, nullable=False)


# ---------- Hauptentität: Media ----------------------------------------------

# Status (an MAL angelehnt, für Bücher + Serien nutzbar):
#   plan     -> auf der Liste / will ich lesen/schauen
#   reading  -> lese ich gerade (Buch) ODER watching (Serie)
#   done     -> fertig (abgeschlossen)
#   hold     -> pausiert
#   dropped  -> abgebrochen
STATUS_VALUES = ("plan", "reading", "done", "hold", "dropped")
KIND_VALUES = ("book", "series")


class Media(Base):
    """Ein Watchlist-Eintrag – Buch ODER Serie."""

    __tablename__ = "media"

    id: Mapped[int] = mapped_column(primary_key=True)

    # Allgemein
    kind: Mapped[str] = mapped_column(String(16), nullable=False)
    title: Mapped[str] = mapped_column(String(200), nullable=False)
    original_title: Mapped[Optional[str]] = mapped_column(String(200))
    description: Mapped[Optional[str]] = mapped_column(Text)
    cover_url: Mapped[Optional[str]] = mapped_column(String(600))
    release_year: Mapped[Optional[int]] = mapped_column(Integer)
    status: Mapped[str] = mapped_column(String(16), nullable=False, default="plan")
    rating: Mapped[Optional[float]] = mapped_column(Float)  # 1-10
    notes: Mapped[Optional[str]] = mapped_column(Text)

    # Buch-spezifisch
    author: Mapped[Optional[str]] = mapped_column(String(200))
    isbn: Mapped[Optional[str]] = mapped_column(String(20))
    total_volumes: Mapped[Optional[int]] = mapped_column(Integer)
    total_chapters: Mapped[Optional[int]] = mapped_column(Integer)
    total_pages: Mapped[Optional[int]] = mapped_column(Integer)
    volumes_read: Mapped[Optional[int]] = mapped_column(Integer, default=0)
    chapters_read: Mapped[Optional[int]] = mapped_column(Integer, default=0)
    pages_read: Mapped[Optional[int]] = mapped_column(Integer, default=0)

    # Serien-spezifisch
    network: Mapped[Optional[str]] = mapped_column(String(120))
    total_seasons: Mapped[Optional[int]] = mapped_column(Integer)
    total_episodes: Mapped[Optional[int]] = mapped_column(Integer)
    episodes_watched: Mapped[Optional[int]] = mapped_column(Integer, default=0)
    season_watching: Mapped[Optional[int]] = mapped_column(Integer)
    start_date: Mapped[Optional[date]] = mapped_column(Date)
    end_date: Mapped[Optional[date]] = mapped_column(Date)

    # Timestamps
    created_at: Mapped[datetime] = mapped_column(DateTime, default=_utcnow, nullable=False)
    updated_at: Mapped[datetime] = mapped_column(
        DateTime, default=_utcnow, onupdate=_utcnow, nullable=False
    )

    genres: Mapped[list[Genre]] = relationship(Genre, secondary=media_genres, lazy="selectin")
    tags: Mapped[list[Tag]] = relationship(Tag, secondary=media_tags, lazy="selectin")

    __table_args__ = (
        Index("ix_media_kind_status", "kind", "status"),
        Index("ix_media_title", "title"),
        CheckConstraint("kind IN ('book','series')", name="ck_media_kind"),
        CheckConstraint("status IN ('plan','reading','done','hold','dropped')", name="ck_media_status"),
    )

    @property
    def progress_percent(self) -> float:
        """Fortschritt in Prozent, je nach Medium."""
        if self.kind == "book":
            total = self.total_chapters or self.total_pages or self.total_volumes or 0
            done = self.chapters_read or self.pages_read or self.volumes_read or 0
        else:  # series
            total = self.total_episodes or 0
            done = self.episodes_watched or 0
        if total <= 0:
            return 0.0
        return round(min(100.0, done * 100.0 / total), 1)

    def __repr__(self) -> str:
        return f"<Media {self.kind}:{self.title!r}>"