import os
import pathlib
import sys

from dotenv import load_dotenv
import spotipy
from spotipy.oauth2 import SpotifyOAuth
from spotipy.cache_handler import CacheFileHandler


def _dbg(msg: str) -> None:
    print(f"[spotify-mcp] {msg}", file=sys.stderr, flush=True)

load_dotenv()

_SCOPES = " ".join([
    "playlist-read-private",
    "playlist-read-collaborative",
    "playlist-modify-public",
    "playlist-modify-private",
    "user-library-read",
])

# Cache relative to this file so Claude Code always finds it regardless of cwd
_CACHE_PATH = pathlib.Path(__file__).parent / ".cache"

_client: spotipy.Spotify | None = None


def get_client() -> spotipy.Spotify:
    global _client
    if _client is None:
        client_id = os.environ.get("SPOTIPY_CLIENT_ID")
        client_secret = os.environ.get("SPOTIPY_CLIENT_SECRET")
        redirect_uri = os.environ.get("SPOTIPY_REDIRECT_URI", "http://localhost:8888/callback")
        if not client_id or not client_secret:
            raise RuntimeError(
                "Missing SPOTIPY_CLIENT_ID or SPOTIPY_CLIENT_SECRET. "
                "Copy .env.example to .env and fill in your Spotify app credentials."
            )
        _client = spotipy.Spotify(
            auth_manager=SpotifyOAuth(
                client_id=client_id,
                client_secret=client_secret,
                redirect_uri=redirect_uri,
                scope=_SCOPES,
                cache_handler=CacheFileHandler(cache_path=str(_CACHE_PATH)),
            )
        )
    return _client


def _format_duration(ms: int) -> str:
    if ms is None:
        return "unknown"
    seconds = ms // 1000
    minutes, seconds = divmod(seconds, 60)
    return f"{minutes}:{seconds:02d}"


def list_playlists() -> list[dict]:
    sp = get_client()
    results = []
    response = sp.current_user_playlists(limit=50)
    while response:
        for item in response["items"]:
            results.append({
                "id": item["id"],
                "name": item["name"],
                "description": item.get("description", ""),
                "tracks_total": (item.get("tracks") or {}).get("total", 0),
                "public": item["public"],
                "uri": item["uri"],
            })
        response = sp.next(response) if response["next"] else None
    return results


def get_playlist_tracks(playlist_id: str) -> list[dict]:
    _dbg(f"get_playlist_tracks called with playlist_id={playlist_id!r}")
    sp = get_client()
    results = []
    page = 0
    response = sp.playlist_items(playlist_id, additional_types=["track"])
    while response:
        items = response.get("items") or []
        total = response.get("total")
        _dbg(f"  page {page}: total={total}, items_in_page={len(items)}, next={bool(response.get('next'))}")
        for idx, item in enumerate(items):
            # Spotify API returns the track under "item" key (newer API) or "track" key (older)
            track = item.get("item") or item.get("track")
            if track is None:
                _dbg(f"    item[{idx}]: track=None (local/null track), skipping")
                continue
            track_type = track.get("type")
            track_name = track.get("name", "<no-name>")
            track_uri = track.get("uri", "<no-uri>")
            if track_type != "track":
                _dbg(f"    item[{idx}]: SKIPPED type={track_type!r} name={track_name!r} uri={track_uri!r}")
                continue
            _dbg(f"    item[{idx}]: OK type={track_type!r} name={track_name!r}")
            results.append({
                "name": track["name"],
                "artists": [a["name"] for a in track["artists"]],
                "album": track["album"]["name"],
                "duration_ms": track["duration_ms"],
                "duration": _format_duration(track["duration_ms"]),
                "popularity": track.get("popularity"),
                "uri": track["uri"],
                "added_at": item["added_at"],
            })
        page += 1
        response = sp.next(response) if response["next"] else None
    _dbg(f"get_playlist_tracks returning {len(results)} tracks")
    return results


def list_saved_tracks(limit: int = 50) -> list[dict]:
    sp = get_client()
    results = []
    response = sp.current_user_saved_tracks(limit=min(limit, 50))
    while response and len(results) < limit:
        for item in response["items"]:
            if len(results) >= limit:
                break
            track = item["track"]
            results.append({
                "name": track["name"],
                "artists": [a["name"] for a in track["artists"]],
                "album": track["album"]["name"],
                "duration_ms": track["duration_ms"],
                "duration": _format_duration(track["duration_ms"]),
                "popularity": track["popularity"],
                "uri": track["uri"],
                "added_at": item["added_at"],
            })
        if response["next"] and len(results) < limit:
            response = sp.next(response)
        else:
            break
    return results


def search_tracks(query: str, limit: int = 10) -> list[dict]:
    sp = get_client()
    # Spotify's search endpoint returns at most 50 results per call; no pagination available
    response = sp.search(q=query, type="track", limit=min(limit, 50))
    results = []
    for track in response["tracks"]["items"]:
        results.append({
            "name": track["name"],
            "artists": [a["name"] for a in track["artists"]],
            "album": track["album"]["name"],
            "duration_ms": track["duration_ms"],
            "duration": _format_duration(track["duration_ms"]),
            "popularity": track["popularity"],
            "uri": track["uri"],
        })
    return results


def create_playlist(name: str, description: str = "", public: bool = False) -> dict:
    sp = get_client()
    user_id = sp.current_user()["id"]
    playlist = sp.user_playlist_create(
        user=user_id,
        name=name,
        public=public,
        description=description,
    )
    return {
        "id": playlist["id"],
        "name": playlist["name"],
        "uri": playlist["uri"],
        "public": playlist["public"],
    }


def add_tracks_to_playlist(playlist_id: str, track_uris: list[str]) -> dict:
    if not track_uris:
        raise ValueError("track_uris must not be empty")
    sp = get_client()
    for i in range(0, len(track_uris), 100):
        sp.playlist_add_items(playlist_id, track_uris[i : i + 100])
    # Only reached if all batches succeed — any SpotifyException propagates to the caller
    return {"added": len(track_uris)}