from fastapi import APIRouter, Depends, HTTPException
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy.orm import selectinload

from app.core.config import settings
from app.core.database import get_db
from app.core.security import get_current_user
from app.models.user import User
from app.models.playlist import Playlist
from app.models.track import Track
from app.schemas.playlist import (
    PlaylistResponse,
    PlaylistDetailResponse,
    SpotifyPlaylistItem,
    ImportSpotifyRequest,
)
from app.services.spotify import get_user_playlists, get_playlist_tracks, get_audio_features
from app.services.recommender import build_taste_profile

router = APIRouter(prefix="/playlists", tags=["playlists"])


@router.get("", response_model=list[PlaylistResponse])
async def list_playlists(
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(Playlist).where(Playlist.user_id == user.id).order_by(Playlist.imported_at.desc())
    )
    return result.scalars().all()


@router.get("/{playlist_id}", response_model=PlaylistDetailResponse)
async def get_playlist(
    playlist_id: int,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(Playlist)
        .options(selectinload(Playlist.tracks))
        .where(Playlist.id == playlist_id, Playlist.user_id == user.id)
    )
    playlist = result.scalar_one_or_none()
    if not playlist:
        raise HTTPException(status_code=404, detail="Playlist not found")
    return playlist


@router.delete("/{playlist_id}")
async def delete_playlist(
    playlist_id: int,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    result = await db.execute(
        select(Playlist).where(Playlist.id == playlist_id, Playlist.user_id == user.id)
    )
    playlist = result.scalar_one_or_none()
    if not playlist:
        raise HTTPException(status_code=404, detail="Playlist not found")
    await db.delete(playlist)
    return {"ok": True}


@router.get("/spotify/available", response_model=list[SpotifyPlaylistItem])
async def list_spotify_playlists(user: User = Depends(get_current_user)):
    if not user.spotify_access_token:
        raise HTTPException(status_code=400, detail="Spotify not connected")
    playlists = await get_user_playlists(user.spotify_access_token)
    return playlists


@router.post("/spotify/import", response_model=PlaylistDetailResponse)
async def import_spotify_playlist(
    data: ImportSpotifyRequest,
    user: User = Depends(get_current_user),
    db: AsyncSession = Depends(get_db),
):
    if not user.spotify_access_token:
        raise HTTPException(status_code=400, detail="Spotify not connected")

    # Free tier limit
    if not user.is_pro:
        result = await db.execute(
            select(Playlist).where(Playlist.user_id == user.id)
        )
        existing = list(result.scalars().all())
        if len(existing) >= settings.FREE_MAX_PLAYLISTS:
            raise HTTPException(status_code=403, detail="Free tier limited to 1 playlist. Upgrade to Pro for unlimited.")

    # Fetch tracks from Spotify
    raw_tracks = await get_playlist_tracks(user.spotify_access_token, data.playlist_id)

    # Get playlist name from Spotify playlists
    spotify_playlists = await get_user_playlists(user.spotify_access_token)
    playlist_name = data.playlist_id
    for sp in spotify_playlists:
        if sp["id"] == data.playlist_id:
            playlist_name = sp["name"]
            break

    # Create playlist
    playlist = Playlist(
        user_id=user.id,
        name=playlist_name,
        platform_source="spotify",
        external_id=data.playlist_id,
        track_count=len(raw_tracks),
    )
    db.add(playlist)
    await db.flush()

    # Create tracks
    tracks = []
    for rt in raw_tracks:
        track = Track(
            playlist_id=playlist.id,
            title=rt["title"],
            artist=rt["artist"],
            album=rt.get("album"),
            spotify_id=rt.get("spotify_id"),
            isrc=rt.get("isrc"),
            preview_url=rt.get("preview_url"),
            image_url=rt.get("image_url"),
        )
        db.add(track)
        tracks.append(track)

    await db.flush()

    # Fetch audio features
    spotify_ids = [t.spotify_id for t in tracks if t.spotify_id]
    if spotify_ids:
        features = await get_audio_features(user.spotify_access_token, spotify_ids)
        features_map = {f["id"]: f for f in features if f}
        for track in tracks:
            if track.spotify_id and track.spotify_id in features_map:
                f = features_map[track.spotify_id]
                track.tempo = f.get("tempo")
                track.energy = f.get("energy")
                track.danceability = f.get("danceability")
                track.valence = f.get("valence")
                track.acousticness = f.get("acousticness")
                track.instrumentalness = f.get("instrumentalness")

    # Build taste profile
    playlist.taste_profile = build_taste_profile(tracks)
    playlist.tracks = tracks

    return playlist