"""Shared data access for the polymorphic satellite tables — credits,
artwork, videos, external IDs — that attach to more than one entity type via
an (entity_type, entity_id) pair rather than a typed foreign key.
"""

from __future__ import annotations

import uuid
from collections.abc import Sequence
from typing import Protocol

from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from app.models.artwork import Artwork
from app.models.credit import Credit
from app.models.enums import ArtworkType
from app.models.external_id import ExternalID
from app.models.provider import Provider
from app.models.video import Video

_VALID_ARTWORK_TYPES = {t.value for t in ArtworkType}


class _NormalizedArtworkLike(Protocol):
    """Structural type for app.services.metadata.normalizer.NormalizedArtwork
    — a repository shouldn't import from the services layer, so this
    describes the shape `sync_artwork` needs instead of the concrete class.
    """

    artwork_type: str
    url: str
    provider_asset_id: str | None
    width: int | None
    height: int | None
    aspect_ratio: float | None
    vote_average: float | None
    is_primary: bool


async def get_external_ids(
    session: AsyncSession, entity_type: str, entity_id: uuid.UUID
) -> dict[str, str]:
    stmt = (
        select(Provider.slug, ExternalID.external_id)
        .join(Provider, Provider.id == ExternalID.provider_id)
        .where(ExternalID.entity_type == entity_type, ExternalID.entity_id == entity_id)
    )
    result = await session.execute(stmt)
    return {slug: external_id for slug, external_id in result.all()}


async def get_external_ids_bulk(
    session: AsyncSession, entity_type: str, entity_ids: list[uuid.UUID]
) -> dict[uuid.UUID, dict[str, str]]:
    if not entity_ids:
        return {}
    stmt = (
        select(ExternalID.entity_id, Provider.slug, ExternalID.external_id)
        .join(Provider, Provider.id == ExternalID.provider_id)
        .where(ExternalID.entity_type == entity_type, ExternalID.entity_id.in_(entity_ids))
    )
    result = await session.execute(stmt)
    out: dict[uuid.UUID, dict[str, str]] = {eid: {} for eid in entity_ids}
    for entity_id, slug, external_id in result.all():
        out.setdefault(entity_id, {})[slug] = external_id
    return out


async def get_primary_artwork_ids(
    session: AsyncSession, entity_type: str, entity_ids: list[uuid.UUID]
) -> list[uuid.UUID]:
    """IDs of artwork rows marked `is_primary` for any of `entity_ids` — the
    small subset of a title's images (TMDb's own selected poster/backdrop/
    profile) that get auto-downloaded for local hosting, out of the dozens
    of alternates ingestion also stores. See app/services/artwork/."""

    if not entity_ids:
        return []
    stmt = select(Artwork.id).where(
        Artwork.entity_type == entity_type,
        Artwork.entity_id.in_(entity_ids),
        Artwork.is_primary.is_(True),
    )
    result = await session.execute(stmt)
    return list(result.scalars().all())


async def sync_artwork(
    session: AsyncSession,
    *,
    entity_type: str,
    entity_id: uuid.UUID,
    provider_id: uuid.UUID,
    artwork_list: Sequence[_NormalizedArtworkLike],
) -> None:
    """Upsert an entity's artwork rows keyed by `provider_asset_id` (TMDb's
    stable per-image file path), instead of deleting and recreating them on
    every re-sync.

    This matters specifically because of `app/services/artwork/` (section
    10's self-hosting): a delete-then-recreate replace would generate a
    fresh Artwork.id with `local_path=None` every time a title gets
    re-ingested, silently throwing away every previously-downloaded local
    copy and forcing a full re-download on each sync — defeating the point
    of caching them locally at all. Rows for images no longer present in
    `artwork_list` (dropped from the provider's alternates) are still
    deleted, same as before.
    """

    existing = (
        (
            await session.execute(
                select(Artwork).where(
                    Artwork.entity_type == entity_type, Artwork.entity_id == entity_id
                )
            )
        )
        .scalars()
        .all()
    )
    existing_by_asset_id = {
        row.provider_asset_id: row for row in existing if row.provider_asset_id is not None
    }

    seen_asset_ids: set[str] = set()
    for art in artwork_list:
        art_type = art.artwork_type if art.artwork_type in _VALID_ARTWORK_TYPES else "poster"
        matched = (
            existing_by_asset_id.get(art.provider_asset_id) if art.provider_asset_id else None
        )
        if matched is not None:
            seen_asset_ids.add(art.provider_asset_id)  # type: ignore[arg-type]
            matched.artwork_type = ArtworkType(art_type)
            matched.width = art.width
            matched.height = art.height
            matched.aspect_ratio = art.aspect_ratio
            matched.vote_average = art.vote_average
            matched.is_primary = art.is_primary
            matched.original_url = art.url
            # local_path/checksum deliberately untouched — see docstring.
        else:
            session.add(
                Artwork(
                    entity_type=entity_type,
                    entity_id=entity_id,
                    artwork_type=ArtworkType(art_type),
                    width=art.width,
                    height=art.height,
                    aspect_ratio=art.aspect_ratio,
                    provider_id=provider_id,
                    provider_asset_id=art.provider_asset_id,
                    original_url=art.url,
                    vote_average=art.vote_average,
                    is_primary=art.is_primary,
                )
            )
            if art.provider_asset_id:
                seen_asset_ids.add(art.provider_asset_id)

    for row in existing:
        if row.provider_asset_id not in seen_asset_ids:
            await session.delete(row)

    await session.flush()


async def get_artwork(
    session: AsyncSession,
    entity_type: str,
    entity_id: uuid.UUID,
    artwork_type: ArtworkType | None = None,
) -> list[Artwork]:
    stmt = (
        select(Artwork)
        .options(selectinload(Artwork.provider))
        .where(Artwork.entity_type == entity_type, Artwork.entity_id == entity_id)
        .order_by(Artwork.is_primary.desc(), Artwork.vote_average.desc().nulls_last())
    )
    if artwork_type is not None:
        stmt = stmt.where(Artwork.artwork_type == artwork_type)
    result = await session.execute(stmt)
    return list(result.scalars().all())


async def get_videos(session: AsyncSession, entity_type: str, entity_id: uuid.UUID) -> list[Video]:
    stmt = (
        select(Video)
        .options(selectinload(Video.provider))
        .where(Video.entity_type == entity_type, Video.entity_id == entity_id)
        .order_by(Video.is_official.desc(), Video.published_at.desc().nulls_last())
    )
    result = await session.execute(stmt)
    return list(result.scalars().all())


async def get_credits(
    session: AsyncSession, entity_type: str, entity_id: uuid.UUID
) -> list[Credit]:
    stmt = (
        select(Credit)
        .options(selectinload(Credit.person))
        .where(Credit.entity_type == entity_type, Credit.entity_id == entity_id)
        .order_by(Credit.billing_order.asc().nulls_last())
    )
    result = await session.execute(stmt)
    return list(result.scalars().all())