"""MediaAsset router — /api/media."""
import io
import math
import uuid
import zipfile

from fastapi import APIRouter, Depends, HTTPException, Query
from fastapi.responses import StreamingResponse
from sqlalchemy import select, func
from sqlalchemy.ext.asyncio import AsyncSession

from app.database import get_db
from app.core.render_paths import resolve_result_path
from app.domains.auth.models import User
from app.domains.media.models import MediaAsset, MediaAssetType
from app.domains.media.schemas import MediaAssetOut, MediaAssetBrowseItem, MediaAssetBrowseResponse
from app.domains.media import service
from app.utils.auth import get_current_user

router = APIRouter(prefix="/api/media", tags=["media"], redirect_slashes=False)


def _resolve_asset_candidate(key: str):
    return resolve_result_path(key)


async def _resolve_thumbnails_bulk(db: AsyncSession, assets: list) -> None:
    """Resolve thumbnail_url for assets using the same priority as product pages.

    Priority per asset (applied only when thumbnail_url is not yet set):
      1. Latest 'still' MediaAsset for the same product (rendered preview)
      2. Product's linked CadFile thumbnail (/api/cad/{id}/thumbnail)
    """
    needs = [a for a in assets if not a.thumbnail_url and a.product_id]
    if not needs:
        return

    product_ids = list({a.product_id for a in needs})

    # 1. Latest 'still' asset per product (DISTINCT ON product_id ORDER BY created_at DESC)
    still_rows = await db.execute(
        select(MediaAsset.product_id, MediaAsset.id)
        .where(
            MediaAsset.product_id.in_(product_ids),
            MediaAsset.asset_type == MediaAssetType.still,
            MediaAsset.is_archived == False,  # noqa: E712
        )
        .order_by(MediaAsset.product_id, MediaAsset.created_at.desc())
        .distinct(MediaAsset.product_id)
    )
    best_still: dict[str, str] = {str(pid): str(sid) for pid, sid in still_rows.all()}

    # 2. Fallback: product's cad_file_id → CAD thumbnail endpoint
    from app.domains.products.models import Product
    from sqlalchemy import text
    # products has RLS — bypass for this internal read-only lookup
    await db.execute(text("SET LOCAL app.current_tenant_id = 'bypass'"))
    prod_rows = await db.execute(
        select(Product.id, Product.cad_file_id).where(Product.id.in_(product_ids))
    )
    product_cad: dict[str, str] = {
        str(pid): str(cid) for pid, cid in prod_rows.all() if cid
    }

    for a in needs:
        pid = str(a.product_id)
        if pid in best_still:
            a.thumbnail_url = f"/api/media/{best_still[pid]}/thumbnail"
        elif pid in product_cad:
            a.thumbnail_url = f"/api/cad/{product_cad[pid]}/thumbnail"


@router.get("", response_model=list[MediaAssetOut])
@router.get("/", response_model=list[MediaAssetOut], include_in_schema=False)
async def list_assets(
    product_id: uuid.UUID | None = None,
    order_line_id: uuid.UUID | None = None,
    cad_file_id: uuid.UUID | None = None,
    asset_type: MediaAssetType | None = None,
    asset_types: list[MediaAssetType] = Query(default=[]),
    skip: int = Query(0, ge=0),
    limit: int = Query(50, ge=1, le=500),
    sort_by: str = Query("created_at"),
    sort_dir: str = Query("desc"),
    _user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    assets = await service.list_media_assets(
        db,
        product_id=product_id,
        order_line_id=order_line_id,
        cad_file_id=cad_file_id,
        asset_type=asset_type,
        asset_types=asset_types if asset_types else None,
        skip=skip,
        limit=limit,
        sort_by=sort_by,
        sort_dir=sort_dir,
    )
    for a in assets:
        a.download_url = service.get_download_url(a)
        a.thumbnail_url = service.get_thumbnail_url(a)
    await _resolve_thumbnails_bulk(db, assets)
    return assets


@router.get("/assets", response_model=MediaAssetBrowseResponse)
async def browse_media_assets(
    asset_type: str | None = None,
    category_key: str | None = None,
    render_status: str | None = None,
    q: str | None = None,
    exclude_technical: bool = Query(True, description="Exclude GLB/STL/Blend technical assets"),
    page: int = Query(1, ge=1),
    page_size: int = Query(50, ge=1, le=200),
    _user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
) -> MediaAssetBrowseResponse:
    """Media browser: server-side filtered + paginated asset list with product context."""
    from app.domains.products.models import Product
    from app.domains.orders.models import OrderLine
    from sqlalchemy import desc

    # Build query with LEFT JOINs to get product and order_line context.
    # MediaAsset has direct product_id FK and order_line_id FK.
    # OrderLine has render_status which we also want to surface.
    stmt = (
        select(
            MediaAsset,
            Product.name.label("product_name"),
            Product.pim_id.label("product_pim_id"),
            Product.category_key.label("category_key"),
            OrderLine.render_status.label("render_status"),
            Product.ebene1.label("product_ebene1"),
            Product.ebene2.label("product_ebene2"),
            Product.baureihe.label("product_baureihe"),
            Product.produkt_baureihe.label("product_produkt_baureihe"),
            Product.lagertyp.label("product_lagertyp"),
            Product.name_cad_modell.label("product_name_cad_modell"),
        )
        .outerjoin(Product, MediaAsset.product_id == Product.id)
        .outerjoin(OrderLine, MediaAsset.order_line_id == OrderLine.id)
        .where(MediaAsset.is_archived == False)  # noqa: E712
        .order_by(desc(MediaAsset.created_at))
    )

    # Apply filters
    _TECHNICAL_TYPES = (
        MediaAssetType.gltf_geometry,
        MediaAssetType.blend_production,
        MediaAssetType.stl_low,
        MediaAssetType.stl_high,
    )
    if asset_type:
        try:
            at_enum = MediaAssetType(asset_type)
            stmt = stmt.where(MediaAsset.asset_type == at_enum)
        except ValueError:
            pass  # invalid type → ignore filter
    elif exclude_technical:
        stmt = stmt.where(MediaAsset.asset_type.notin_(_TECHNICAL_TYPES))

    if category_key:
        stmt = stmt.where(Product.category_key == category_key)

    if render_status:
        stmt = stmt.where(OrderLine.render_status == render_status)

    if q:
        pattern = f"%{q}%"
        from sqlalchemy import or_
        stmt = stmt.where(
            or_(
                Product.name.ilike(pattern),
                Product.pim_id.ilike(pattern),
                Product.ebene1.ilike(pattern),
                Product.ebene2.ilike(pattern),
                Product.baureihe.ilike(pattern),
                Product.produkt_baureihe.ilike(pattern),
                Product.lagertyp.ilike(pattern),
                Product.name_cad_modell.ilike(pattern),
            )
        )

    # Count total matching rows
    count_stmt = select(func.count()).select_from(stmt.subquery())
    total_result = await db.execute(count_stmt)
    total = total_result.scalar_one()

    # Paginate
    offset = (page - 1) * page_size
    stmt = stmt.offset(offset).limit(page_size)

    all_rows = (await db.execute(stmt)).all()

    # Pre-assign thumbnail_url so _resolve_thumbnails_bulk can check it
    raw_assets = [row[0] for row in all_rows]
    for a in raw_assets:
        a.thumbnail_url = service.get_thumbnail_url(a)
    # Resolve fallback thumbnails for non-image assets via product→cad lookup
    await _resolve_thumbnails_bulk(db, raw_assets)

    items: list[MediaAssetBrowseItem] = []
    for row in all_rows:
        asset: MediaAsset = row[0]
        product_name: str | None = row[1]
        product_pim_id: str | None = row[2]
        cat_key: str | None = row[3]
        r_status: str | None = row[4]
        ebene1: str | None = row[5]
        ebene2: str | None = row[6]
        baureihe: str | None = row[7]
        produkt_baureihe: str | None = row[8]
        lagertyp: str | None = row[9]
        name_cad_modell: str | None = row[10]

        thumb = asset.thumbnail_url
        item = MediaAssetBrowseItem(
            id=asset.id,
            asset_type=asset.asset_type,
            file_path=asset.storage_key,
            file_size_bytes=asset.file_size_bytes,
            mime_type=asset.mime_type,
            created_at=asset.created_at,
            order_line_id=asset.order_line_id,
            product_id=asset.product_id,
            product_name=product_name,
            product_pim_id=product_pim_id,
            category_key=cat_key,
            render_status=r_status,
            product_ebene1=ebene1,
            product_ebene2=ebene2,
            product_baureihe=baureihe,
            product_produkt_baureihe=produkt_baureihe,
            product_lagertyp=lagertyp,
            product_name_cad_modell=name_cad_modell,
            download_url=f"/api/media/{asset.id}/download",
            thumbnail_url=thumb,
        )
        items.append(item)

    pages = max(1, math.ceil(total / page_size))
    return MediaAssetBrowseResponse(
        items=items,
        total=total,
        page=page,
        page_size=page_size,
        pages=pages,
    )


@router.get("/{asset_id}", response_model=MediaAssetOut)
async def get_asset(asset_id: uuid.UUID, db: AsyncSession = Depends(get_db)):
    asset = await service.get_media_asset(db, asset_id)
    if not asset:
        raise HTTPException(404, "Asset not found")
    asset.download_url = service.get_download_url(asset)
    asset.thumbnail_url = service.get_thumbnail_url(asset)
    await _resolve_thumbnails_bulk(db, [asset])
    return asset


@router.get("/{asset_id}/thumbnail")
async def thumbnail_asset(
    asset_id: uuid.UUID,
    db: AsyncSession = Depends(get_db),
):
    """Serve asset as an inline image — no auth required (UUID is opaque enough).

    Only serves image/video MIME types; returns 404 for binary files.
    """
    from fastapi.responses import FileResponse, Response
    from pathlib import Path
    asset = await service.get_media_asset(db, asset_id)
    if not asset:
        raise HTTPException(404, "Asset not found")

    mime = asset.mime_type or ""
    if not (mime.startswith("image/") or mime.startswith("video/")):
        raise HTTPException(404, "Not a previewable asset")

    key = asset.storage_key
    candidate = _resolve_asset_candidate(key)
    if candidate is not None and candidate.exists():
        return FileResponse(
            str(candidate), media_type=mime,
            headers={"Cache-Control": "max-age=86400, public"},
        )
    try:
        from app.core.storage import get_storage
        data = get_storage().download_bytes(key)
        return Response(content=data, media_type=mime,
                        headers={"Cache-Control": "max-age=86400, public"})
    except Exception:
        raise HTTPException(404, "File not available")


@router.api_route("/{asset_id}/download", methods=["GET", "HEAD"])
async def download_asset(
    asset_id: uuid.UUID,
    _user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    """Proxy file content directly — avoids internal MinIO hostname issues."""
    from fastapi.responses import FileResponse, Response
    from pathlib import Path
    asset = await service.get_media_asset(db, asset_id)
    if not asset:
        raise HTTPException(404, "Asset not found")

    key = asset.storage_key
    mime = asset.mime_type or "application/octet-stream"

    # Local file path (absolute or relative to UPLOAD_DIR)
    candidate = _resolve_asset_candidate(key)
    if candidate is not None and candidate.exists():
        ext = candidate.suffix.lstrip(".")
        fname = f"{asset.asset_type.value}_{asset_id}.{ext or 'bin'}"
        return FileResponse(
            str(candidate), media_type=mime, filename=fname,
            headers={"Cache-Control": "no-cache"},
        )

    # Fall back to MinIO
    try:
        from app.core.storage import get_storage
        data = get_storage().download_bytes(key)
        ext = key.rsplit(".", 1)[-1] if "." in key else "bin"
        fname = f"{asset.asset_type.value}_{asset_id}.{ext}"
        return Response(
            content=data,
            media_type=mime,
            headers={
                "Content-Disposition": f"attachment; filename={fname}",
                "Cache-Control": "no-cache",
            },
        )
    except Exception:
        raise HTTPException(404, "File not available")


@router.post("/zip")
async def zip_download(
    asset_ids: list[uuid.UUID],
    _user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    assets = []
    for aid in asset_ids:
        a = await service.get_media_asset(db, aid)
        if a:
            assets.append(a)
    if not assets:
        raise HTTPException(404, "No assets found")

    def generate():
        import logging
        from pathlib import Path
        from app.core.storage import get_storage
        logger = logging.getLogger(__name__)
        buf = io.BytesIO()
        seen_names: dict[str, int] = {}
        with zipfile.ZipFile(buf, "w", zipfile.ZIP_DEFLATED) as zf:
            storage = get_storage()
            for a in assets:
                key = a.storage_key
                # Use filename from storage_key (always has correct extension)
                original_name = Path(key).name
                ext = Path(key).suffix.lstrip(".") or (a.mime_type or "").split("/")[-1] or "bin"
                base = original_name if original_name else f"{a.asset_type.value}_{a.id}.{ext}"
                # Deduplicate filenames within the ZIP
                if base in seen_names:
                    seen_names[base] += 1
                    stem = Path(base).stem
                    suffix = Path(base).suffix
                    fname = f"{stem}_{seen_names[base]}{suffix}"
                else:
                    seen_names[base] = 0
                    fname = base
                try:
                    # Check absolute path first (local filesystem)
                    candidate = _resolve_asset_candidate(key)
                    if candidate is not None and candidate.exists():
                        data = candidate.read_bytes()
                    else:
                        data = storage.download_bytes(key)
                    zf.writestr(fname, data)
                except Exception as exc:
                    logger.warning("ZIP: skipping asset %s — %s", a.id, exc)
        yield buf.getvalue()

    return StreamingResponse(
        generate(),
        media_type="application/zip",
        headers={"Content-Disposition": "attachment; filename=media-export.zip"},
    )


@router.delete("/{asset_id}")
async def archive_asset(asset_id: uuid.UUID, db: AsyncSession = Depends(get_db)):
    asset = await service.archive_media_asset(db, asset_id)
    if not asset:
        raise HTTPException(404, "Asset not found")
    return {"ok": True}


@router.delete("/{asset_id}/permanent")
async def delete_asset_permanent(asset_id: uuid.UUID, db: AsyncSession = Depends(get_db)):
    """Permanently remove a MediaAsset record from the database."""
    deleted = await service.delete_media_asset(db, asset_id)
    if not deleted:
        raise HTTPException(404, "Asset not found")
    return {"ok": True}


@router.post("/batch-delete")
async def batch_delete_assets(
    asset_ids: list[uuid.UUID],
    _user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    """Permanently delete multiple MediaAsset records."""
    from app.utils.auth import require_global_admin
    await require_global_admin(_user)

    deleted = 0
    for aid in asset_ids:
        ok = await service.delete_media_asset(db, aid)
        if ok:
            deleted += 1
    return {"deleted": deleted, "requested": len(asset_ids)}


@router.post("/cleanup-orphaned")
async def cleanup_orphaned_assets(
    _user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    """Delete all MediaAsset DB records whose backing file doesn't exist on disk or in MinIO.

    Returns counts of checked/deleted records. Admin only.
    """
    import logging
    from pathlib import Path
    from app.core.storage import get_storage

    logger = logging.getLogger(__name__)
    storage = get_storage()

    def _file_exists(key: str) -> bool:
        candidate = _resolve_asset_candidate(key)
        if candidate is not None and candidate.exists():
            return True
        # Check MinIO
        try:
            storage.download_bytes(key)
            return True
        except Exception:
            return False

    result = await db.execute(select(MediaAsset).where(MediaAsset.is_archived == False))  # noqa: E712
    all_assets = result.scalars().all()

    deleted_ids = []
    for asset in all_assets:
        if not _file_exists(asset.storage_key):
            logger.info("Cleanup: deleting orphaned asset %s (%s)", asset.id, asset.storage_key)
            await db.delete(asset)
            deleted_ids.append(str(asset.id))

    if deleted_ids:
        await db.commit()

    return {
        "checked": len(all_assets),
        "deleted": len(deleted_ids),
        "deleted_ids": deleted_ids,
    }