"""数据模型：屏幕设备、素材、节目、节目项、屏幕绑定。"""
from datetime import datetime

from sqlalchemy import (
    Boolean,
    DateTime,
    ForeignKey,
    Integer,
    String,
    Text,
    UniqueConstraint,
)
from sqlalchemy.orm import Mapped, mapped_column, relationship

from .database import Base


class Screen(Base):
    """显示屏设备。device_id 由客户端首次启动时生成并注册。"""

    __tablename__ = "screens"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    name: Mapped[str] = mapped_column(String(100), default="未命名屏幕")
    device_id: Mapped[str] = mapped_column(String(64), unique=True, index=True)
    location: Mapped[str] = mapped_column(String(200), default="")
    status: Mapped[str] = mapped_column(String(20), default="offline")  # online/offline
    last_seen: Mapped[datetime | None] = mapped_column(DateTime, nullable=True)
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.now)

    bindings: Mapped[list["ScreenBinding"]] = relationship(
        back_populates="screen", cascade="all, delete-orphan"
    )


class Asset(Base):
    """媒体素材：图片或视频。url 为相对于 /media 的路径。"""

    __tablename__ = "assets"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    name: Mapped[str] = mapped_column(String(200))
    type: Mapped[str] = mapped_column(String(20))  # image / video
    url: Mapped[str] = mapped_column(String(500))
    size: Mapped[int] = mapped_column(Integer, default=0)
    duration: Mapped[int] = mapped_column(Integer, default=0)  # 图片默认展示秒数；视频为0表示按视频时长
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.now)

    items: Mapped[list["PlaylistItem"]] = relationship(back_populates="asset")


class Playlist(Base):
    """节目：一组素材的轮播清单。"""

    __tablename__ = "playlists"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    name: Mapped[str] = mapped_column(String(100))
    description: Mapped[str] = mapped_column(Text, default="")
    created_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.now)

    items: Mapped[list["PlaylistItem"]] = relationship(
        back_populates="playlist", cascade="all, delete-orphan", order_by="PlaylistItem.sort_order"
    )
    bindings: Mapped[list["ScreenBinding"]] = relationship(
        back_populates="playlist", cascade="all, delete-orphan"
    )


class PlaylistItem(Base):
    """节目项：素材 + 排序 + 可选展示时长覆盖。"""

    __tablename__ = "playlist_items"
    __table_args__ = (UniqueConstraint("playlist_id", "sort_order", name="uq_playlist_sort"),)

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    playlist_id: Mapped[int] = mapped_column(ForeignKey("playlists.id", ondelete="CASCADE"), index=True)
    asset_id: Mapped[int] = mapped_column(ForeignKey("assets.id", ondelete="CASCADE"), index=True)
    sort_order: Mapped[int] = mapped_column(Integer, default=0)
    duration: Mapped[int | None] = mapped_column(Integer, nullable=True)  # 覆盖素材默认时长(秒)

    playlist: Mapped[Playlist] = relationship(back_populates="items")
    asset: Mapped[Asset] = relationship(back_populates="items")


class ScreenBinding(Base):
    """屏幕与节目的绑定。一个屏幕同时只有一个 active=True 的绑定。"""

    __tablename__ = "screen_bindings"

    id: Mapped[int] = mapped_column(Integer, primary_key=True, autoincrement=True)
    screen_id: Mapped[int] = mapped_column(ForeignKey("screens.id", ondelete="CASCADE"), index=True)
    playlist_id: Mapped[int] = mapped_column(ForeignKey("playlists.id", ondelete="CASCADE"), index=True)
    active: Mapped[bool] = mapped_column(Boolean, default=True)
    updated_at: Mapped[datetime] = mapped_column(DateTime, default=datetime.now, onupdate=datetime.now)

    screen: Mapped[Screen] = relationship(back_populates="bindings")
    playlist: Mapped[Playlist] = relationship(back_populates="bindings")