import json
from datetime import datetime
from typing import Optional

from fastapi import APIRouter, BackgroundTasks, Depends, HTTPException, status
from pydantic import BaseModel
from sqlalchemy.orm import Session
from sqlalchemy import text

from ..auth_utils import get_current_user
from ..database import get_db
from ..models import Channel, Playlist, Video, User
from ..services import ytdlp

router = APIRouter()


class PlaylistOut(BaseModel):
    id: int
    youtube_playlist_id: str
    channel_id: Optional[int]
    title: str
    description: Optional[str]
    thumbnail_url: Optional[str]
    video_count: int
    indexed_at: Optional[datetime]

    model_config = {"from_attributes": True}


class PlaylistVideoOut(BaseModel):
    id: int
    youtube_video_id: str
    title: str
    thumbnail_url: Optional[str]
    duration_seconds: Optional[int]
    published_at: Optional[datetime]
    view_count: Optional[int]
    is_downloaded: bool = False
    is_watched: bool = False
    channel_id: Optional[int] = None
    channel_name: Optional[str] = None

    model_config = {"from_attributes": True}


@router.get("/channel/{channel_id}", response_model=list[PlaylistOut])
def get_channel_playlists(
    channel_id: int,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    rows = db.query(Playlist).filter_by(channel_id=channel_id).order_by(Playlist.video_count.desc()).all()
    return rows


@router.post("/channel/{channel_id}/fetch", status_code=status.HTTP_202_ACCEPTED)
def fetch_channel_playlists(
    channel_id: int,
    background_tasks: BackgroundTasks,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    channel = db.query(Channel).filter_by(id=channel_id).first()
    if not channel:
        raise HTTPException(status_code=404, detail="Channel not found")
    background_tasks.add_task(_fetch_playlists_task, channel_id, channel.youtube_channel_id)
    return {"detail": "Fetching playlists"}


def _fetch_playlists_task(channel_id: int, youtube_channel_id: str):
    from ..database import SessionLocal
    db = SessionLocal()
    try:
        playlists = ytdlp.fetch_channel_playlists(youtube_channel_id)
        for pl in playlists:
            pl_id = pl["youtube_playlist_id"]
            existing = db.query(Playlist).filter_by(youtube_playlist_id=pl_id).first()
            if existing:
                existing.title = pl["title"] or existing.title
                if pl.get("video_count"):
                    existing.video_count = pl["video_count"]
                if pl.get("thumbnail_url") and not existing.thumbnail_url:
                    existing.thumbnail_url = pl["thumbnail_url"]
            else:
                db.add(Playlist(
                    youtube_playlist_id=pl_id,
                    channel_id=channel_id,
                    title=pl["title"],
                    description=pl.get("description"),
                    thumbnail_url=pl.get("thumbnail_url"),
                    video_count=pl.get("video_count") or 0,
                ))
        db.commit()
    except Exception:
        db.rollback()
    finally:
        db.close()


@router.get("/{playlist_id}/videos", response_model=list[PlaylistVideoOut])
def get_playlist_videos(
    playlist_id: int,
    offset: int = 0,
    limit: int = 60,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    playlist = db.query(Playlist).filter_by(id=playlist_id).first()
    if not playlist:
        raise HTTPException(status_code=404, detail="Playlist not found")
    if not playlist.indexed_at:
        return []
    rows = db.execute(
        text("""
            SELECT v.id, v.youtube_video_id, v.title, v.thumbnail_url,
                   v.duration_seconds, v.published_at, v.view_count,
                   c.id AS channel_id, c.name AS channel_name,
                   COALESCE(uv.downloaded, 0) AS is_downloaded,
                   COALESCE(uv.watched, 0) AS is_watched
            FROM videos v
            LEFT JOIN channels c ON v.channel_id = c.id
            LEFT JOIN user_videos uv ON v.id = uv.video_id AND uv.user_id = :user_id
            WHERE v.youtube_video_id IN (
                SELECT value FROM json_each((
                    SELECT video_ids FROM playlists WHERE id = :playlist_id
                ))
            )
            ORDER BY v.published_at DESC NULLS LAST
            LIMIT :limit OFFSET :offset
        """),
        {"user_id": current_user.id, "playlist_id": playlist_id, "limit": limit, "offset": offset},
    ).mappings().all()
    return [PlaylistVideoOut(**dict(r)) for r in rows]


@router.post("/{playlist_id}/index", status_code=status.HTTP_202_ACCEPTED)
def index_playlist(
    playlist_id: int,
    background_tasks: BackgroundTasks,
    db: Session = Depends(get_db),
    current_user: User = Depends(get_current_user),
):
    playlist = db.query(Playlist).filter_by(id=playlist_id).first()
    if not playlist:
        raise HTTPException(status_code=404, detail="Playlist not found")
    background_tasks.add_task(_index_playlist_task, playlist_id, playlist.youtube_playlist_id, playlist.channel_id)
    return {"detail": "Indexing playlist"}


def _index_playlist_task(playlist_id: int, youtube_playlist_id: str, channel_id: Optional[int]):
    from ..database import SessionLocal
    db = SessionLocal()
    try:
        videos = ytdlp.fetch_playlist_videos(youtube_playlist_id)
        playlist = db.query(Playlist).filter_by(id=playlist_id).first()
        if not playlist:
            return

        video_yt_ids = []
        for vdata in videos:
            yt_id = vdata.get("youtube_video_id")
            if not yt_id:
                continue
            video_yt_ids.append(yt_id)
            existing = db.query(Video).filter_by(youtube_video_id=yt_id).first()
            if existing:
                if vdata.get("view_count") is not None:
                    existing.view_count = vdata["view_count"]
            else:
                ch_id = channel_id
                if not ch_id and vdata.get("channel", {}).get("youtube_channel_id"):
                    ch = db.query(Channel).filter_by(
                        youtube_channel_id=vdata["channel"]["youtube_channel_id"]
                    ).first()
                    if ch:
                        ch_id = ch.id
                db.add(Video(
                    youtube_video_id=yt_id,
                    channel_id=ch_id,
                    title=vdata.get("title", ""),
                    thumbnail_url=vdata.get("thumbnail_url"),
                    duration_seconds=vdata.get("duration_seconds"),
                    published_at=vdata.get("published_at"),
                    view_count=vdata.get("view_count"),
                    tags="[]",
                ))

        playlist.video_count = len(video_yt_ids)
        playlist.indexed_at = datetime.utcnow()
        playlist.video_ids = json.dumps(video_yt_ids)
        db.commit()
    except Exception:
        db.rollback()
    finally:
        db.close()