"""TorrentDownloadPlugin — composes Prowlarr search + torrent client
adapter + archive_pipeline into a uniform download source.

Two flows:

**Per-track flow** (basic search, single-track wishlist) —
1. ``search(query)`` calls ``ProwlarrClient.search`` filtered to
   ``protocol='torrent'`` results, projects releases into
   ``TrackResult`` / ``AlbumResult`` shaped objects the existing
   search UI already understands. Encodes the indexer's
   ``downloadUrl`` (or magnet URI) into the filename so
   ``download()`` can recover it.
2. ``download(username, filename, ...)`` decodes the URL, asks the
   active torrent adapter (qBittorrent, Transmission, or Deluge per
   user's settings) to add it, spawns a background thread that
   polls the adapter for completion.
3. On completion the thread walks the adapter-reported save path
   via ``archive_pipeline.collect_audio_after_extraction`` and
   exposes the full audio-file list. Post-processing can then pick
   the requested track from a completed release instead of importing
   the first file blindly.

**Album-bundle flow** (album-context batch downloads — wired in
``core/downloads/master.py``) —
4. ``download_album_to_staging(album, artist, staging_dir)`` does
   ONE Prowlarr search for the whole release, picks the best
   torrent (prefers FLAC, decent seeders, reasonable size),
   downloads it, extracts archives if needed, copies every audio
   file into the staging directory. The existing per-track
   ``try_staging_match`` flow then finds + imports each track by
   fuzzy title match against the staged files. Per-track Prowlarr
   queries never fire — track titles like "Luther (with SZA)"
   would match album torrents like "GNX (2024) [FLAC]" at near-
   zero confidence and break the per-track dispatch.

Limitations:
- ``save_path`` is the torrent client's view of the disk. If
  SoulSync runs on a different host than qBit / Trans / Deluge,
  the post-processing pipeline can't see those files. The plugin
  works fine for the all-on-one-box case (most users); remote
  setups will need a future sync step (rclone / SMB / Docker
  bind mount).
- Track-level metadata isn't available until after download.
  Search results carry only the release title + indexer metadata;
  individual track names are populated when the matching pipeline
  walks the extracted audio files.
"""

from __future__ import annotations

import asyncio
import re
import threading
import time
import uuid
from pathlib import Path
from typing import Any, Dict, List, Optional, Tuple

from config.settings import config_manager
from core.archive_pipeline import collect_audio_after_extraction
from core.download_plugins.album_bundle import (
    copy_audio_files_atomically,
    get_poll_interval,
    get_poll_timeout,
    pick_best_album_release,
)
from core.download_plugins.base import DownloadSourcePlugin
from core.download_plugins.types import AlbumResult, DownloadStatus, TrackResult
from core.prowlarr_client import (
    DEFAULT_MUSIC_CATEGORIES,
    ProwlarrClient,
    ProwlarrSearchResult,
)
from core.torrent_clients import get_active_adapter as get_active_torrent_adapter
from utils.async_helpers import run_async
from utils.logging_config import get_logger

logger = get_logger("download_plugins.torrent")


# Separator used to encode the download URL inside the filename
# field. Same convention Lidarr / YouTube use for embedding their
# own opaque identifiers — ``<download_url>||<display>``.
_FILENAME_SEP = '||'

# Adapter states that count as the download being on-disk and
# safe to walk. ``seeding`` and ``completed`` both mean the
# bits are there; the user can pause seeding manually if they
# don't want to keep sharing.
_COMPLETE_STATES = frozenset(['seeding', 'completed'])

# Poll cadence / timeout — both pull from config via the shared
# album_bundle helpers so users can extend the deadline for slow
# trackers without editing source. Kept as module aliases so the
# per-track flow at the bottom of this file can still import them
# under the legacy names without re-reading config every loop.
_POLL_TIMEOUT_SECONDS = get_poll_timeout()
_POLL_INTERVAL_SECONDS = get_poll_interval()


class TorrentDownloadPlugin(DownloadSourcePlugin):
    """Torrent download source backed by Prowlarr + an active
    torrent client adapter."""

    def __init__(self) -> None:
        self._prowlarr = ProwlarrClient()
        # Track every download we've kicked off. Keyed by our own
        # uuid — NOT the adapter's hash — because the orchestrator
        # owns the lifecycle and we need a stable id even before
        # the adapter has assigned one.
        self.active_downloads: Dict[str, Dict[str, Any]] = {}
        self._lock = threading.Lock()
        self.shutdown_check = None

    def set_shutdown_check(self, check_callable):
        self.shutdown_check = check_callable

    def reload_settings(self) -> None:
        self._prowlarr.reload_settings()

    # ------------------------------------------------------------------
    # Lifecycle
    # ------------------------------------------------------------------

    def is_configured(self) -> bool:
        if not self._prowlarr.is_configured():
            return False
        adapter = get_active_torrent_adapter()
        return bool(adapter and adapter.is_configured())

    async def check_connection(self) -> bool:
        if not self._prowlarr.is_configured():
            return False
        adapter = get_active_torrent_adapter()
        if not adapter or not adapter.is_configured():
            return False
        # Probe both sides. A torrent download is useless if either
        # the indexer or the downloader is unreachable.
        prowlarr_ok = await self._prowlarr.check_connection()
        if not prowlarr_ok:
            return False
        return await adapter.check_connection()

    # ------------------------------------------------------------------
    # Search
    # ------------------------------------------------------------------

    async def search(
        self,
        query: str,
        timeout: Optional[int] = None,
        progress_callback=None,
    ) -> Tuple[List[TrackResult], List[AlbumResult]]:
        if not self._prowlarr.is_configured():
            return ([], [])
        try:
            indexer_ids = _parse_indexer_id_filter()
            results = await self._prowlarr.search(
                query,
                categories=DEFAULT_MUSIC_CATEGORIES,
                indexer_ids=indexer_ids,
            )
        except Exception as e:
            logger.error("Torrent plugin search failed: %s", e)
            return ([], [])
        return self._project_results(results)

    def _project_results(
        self, results: List[ProwlarrSearchResult]
    ) -> Tuple[List[TrackResult], List[AlbumResult]]:
        """Turn Prowlarr releases into TrackResult / AlbumResult
        shaped objects. One TrackResult + one AlbumResult per
        release — Prowlarr search hits are at the release level,
        not the track level, so we can't synthesise track listings
        without downloading the actual torrent."""
        tracks: List[TrackResult] = []
        albums: List[AlbumResult] = []
        for result in results:
            if result.protocol != 'torrent':
                continue
            download_url = result.magnet_uri or result.download_url
            if not download_url:
                continue
            filename = f"{download_url}{_FILENAME_SEP}{result.title}"
            quality = _guess_quality_from_title(result.title)
            parsed_artist, parsed_title = _parse_release_title(result.title)
            tr = TrackResult(
                username='torrent',
                filename=filename,
                size=result.size,
                bitrate=None,
                duration=None,
                quality=quality,
                # Torrent results don't have per-uploader slot / queue
                # data the way Soulseek does. Fill with neutral values
                # so the quality_score doesn't punish them artificially.
                free_upload_slots=max(1, result.seeders or 0),
                upload_speed=0,
                queue_length=0,
                # Pre-fill artist + title so TrackResult.__post_init__
                # doesn't auto-parse the filename — our filename starts
                # with the indexer download URL, which would otherwise
                # show up as "by download?apikey=..." in the UI.
                artist=parsed_artist or result.indexer_name or 'Torrent',
                title=parsed_title or result.title,
                album=parsed_title or None,
                track_number=None,
                _source_metadata={
                    'indexer': result.indexer_name,
                    'indexer_id': result.indexer_id,
                    'seeders': result.seeders,
                    'leechers': result.leechers,
                    'grabs': result.grabs,
                    'protocol': 'torrent',
                },
            )
            tracks.append(tr)
            albums.append(AlbumResult(
                username='torrent',
                album_path=f"torrent/{result.guid}",
                album_title=parsed_title or result.title,
                artist=parsed_artist or None,
                track_count=1,    # unknown until download finishes
                total_size=result.size,
                tracks=[tr],
                dominant_quality=quality,
                year=None,
            ))
        return tracks, albums

    # ------------------------------------------------------------------
    # Download
    # ------------------------------------------------------------------

    async def download(
        self,
        username: str,
        filename: str,
        file_size: int = 0,
    ) -> Optional[str]:
        if not self.is_configured():
            return None
        download_url, display_name = _decode_filename(filename)
        if not download_url:
            logger.error("Torrent download missing URL in filename: %r", filename)
            return None

        download_id = str(uuid.uuid4())
        with self._lock:
            self.active_downloads[download_id] = {
                'id': download_id,
                'filename': filename,
                'username': 'torrent',
                'display_name': display_name,
                'state': 'Initializing',
                'progress': 0.0,
                'size': file_size,
                'transferred': 0,
                'speed': 0,
                'file_path': None,
                'audio_files': [],
                'torrent_hash': None,
                'error': None,
            }

        thread = threading.Thread(
            target=self._download_thread,
            args=(download_id, download_url, display_name),
            daemon=True,
            name=f'torrent-dl-{download_id[:8]}',
        )
        thread.start()
        return download_id

    def _download_thread(self, download_id: str, download_url: str, display_name: str) -> None:
        """Background worker: hand the URL to the active adapter,
        poll until done, then walk the resulting directory."""
        adapter = get_active_torrent_adapter()
        if adapter is None or not adapter.is_configured():
            self._mark_error(download_id, "No torrent client configured")
            return

        try:
            torrent_hash = run_async(adapter.add_torrent(download_url))
        except Exception as e:
            self._mark_error(download_id, f"add_torrent failed: {e}")
            return
        if not torrent_hash:
            self._mark_error(download_id, "Torrent client refused the URL")
            return

        with self._lock:
            row = self.active_downloads.get(download_id)
            if row is not None:
                row['torrent_hash'] = torrent_hash
                row['state'] = 'InProgress, Downloading'

        deadline = time.monotonic() + _POLL_TIMEOUT_SECONDS
        last_save_path: Optional[str] = None
        while time.monotonic() < deadline:
            if self.shutdown_check and self.shutdown_check():
                return
            try:
                status = run_async(adapter.get_status(torrent_hash))
            except Exception as e:
                logger.warning("Torrent poll error for %s: %s", torrent_hash, e)
                status = None

            if status is None:
                # Adapter forgot about the torrent — probably user-removed.
                self._mark_error(download_id, "Torrent disappeared from client")
                return

            with self._lock:
                row = self.active_downloads.get(download_id)
                if row is not None:
                    row['progress'] = status.progress * 100.0
                    row['transferred'] = status.downloaded
                    row['speed'] = status.download_speed
                    row['size'] = status.size or row.get('size', 0)
                    row['state'] = _adapter_state_to_display(status.state)
                    row['error'] = status.error
            if status.save_path:
                last_save_path = status.save_path

            if status.state in _COMPLETE_STATES:
                self._finalize_download(download_id, last_save_path)
                return
            if status.state == 'error':
                self._mark_error(download_id, status.error or "Torrent client reported error")
                return

            time.sleep(_POLL_INTERVAL_SECONDS)

        self._mark_error(download_id, "Torrent download timed out")

    def _finalize_download(self, download_id: str, save_path: Optional[str]) -> None:
        """Adapter said complete. Walk the directory + pick the
        first audio file as the canonical ``file_path``."""
        if not save_path:
            self._mark_error(download_id, "Torrent completed but no save_path reported")
            return
        try:
            audio_files = collect_audio_after_extraction(Path(save_path))
        except Exception as e:
            self._mark_error(download_id, f"Post-extract walk failed: {e}")
            return
        if not audio_files:
            self._mark_error(download_id, f"No audio files found in {save_path}")
            return
        primary = audio_files[0]
        with self._lock:
            row = self.active_downloads.get(download_id)
            if row is not None:
                row['state'] = 'Completed, Succeeded'
                row['progress'] = 100.0
                row['file_path'] = str(primary)
                row['audio_files'] = [str(path) for path in audio_files]
        logger.info("Torrent download complete: %s -> %s (%d audio files)",
                    download_id[:8], primary.name, len(audio_files))

    def _mark_error(self, download_id: str, message: str) -> None:
        logger.error("Torrent download %s failed: %s", download_id[:8], message)
        with self._lock:
            row = self.active_downloads.get(download_id)
            if row is not None:
                row['state'] = 'Completed, Errored'
                row['error'] = message

    # ------------------------------------------------------------------
    # Status / lifecycle
    # ------------------------------------------------------------------

    async def get_all_downloads(self) -> List[DownloadStatus]:
        with self._lock:
            rows = list(self.active_downloads.values())
        return [_row_to_status(r) for r in rows]

    async def get_download_status(self, download_id: str) -> Optional[DownloadStatus]:
        with self._lock:
            row = self.active_downloads.get(download_id)
            if row is None:
                return None
            return _row_to_status(row)

    async def cancel_download(
        self,
        download_id: str,
        username: Optional[str] = None,
        remove: bool = False,
    ) -> bool:
        adapter = get_active_torrent_adapter()
        with self._lock:
            row = self.active_downloads.get(download_id)
            torrent_hash = row.get('torrent_hash') if row else None
        if adapter and torrent_hash:
            try:
                await adapter.remove(torrent_hash, delete_files=remove)
            except Exception as e:
                logger.warning("Torrent cancel via adapter failed: %s", e)
        with self._lock:
            if remove:
                self.active_downloads.pop(download_id, None)
            else:
                row = self.active_downloads.get(download_id)
                if row is not None:
                    row['state'] = 'Cancelled'
        return True

    async def clear_all_completed_downloads(self) -> bool:
        with self._lock:
            for did in list(self.active_downloads.keys()):
                state = self.active_downloads[did].get('state', '')
                if state.startswith('Completed') or state == 'Cancelled':
                    self.active_downloads.pop(did, None)
        return True

    # ------------------------------------------------------------------
    # Album-bundle flow
    # ------------------------------------------------------------------

    def download_album_to_staging(
        self,
        album_name: str,
        artist_name: str,
        staging_dir: str,
        progress_callback=None,
    ) -> Dict[str, Any]:
        """One-shot album download: search Prowlarr for the whole
        release, pick the best torrent, fetch it, extract if needed,
        copy every audio file into ``staging_dir`` so the existing
        ``try_staging_match`` flow can hand each track off to the
        post-processing pipeline.

        ``progress_callback`` is called with a dict on each state
        change so the batch UI can show download progress without
        waiting for the whole thing.

        Returns ``{'success': bool, 'files': [paths], 'error': str|None}``.
        """
        result: Dict[str, Any] = {'success': False, 'files': [], 'error': None}
        if not self.is_configured():
            result['error'] = 'Torrent source not configured'
            return result

        adapter = get_active_torrent_adapter()
        if adapter is None or not adapter.is_configured():
            result['error'] = 'No active torrent client'
            return result

        def _emit(state: str, **extra) -> None:
            if progress_callback:
                payload = {'state': state, **extra}
                try:
                    progress_callback(payload)
                except Exception as cb_exc:
                    logger.debug("[Torrent album] progress callback failed: %s", cb_exc)

        # Phase 1: search Prowlarr for the album.
        query = f"{artist_name} {album_name}".strip()
        _emit('searching', query=query)
        try:
            search_results = run_async(self._prowlarr.search(
                query, categories=DEFAULT_MUSIC_CATEGORIES,
                indexer_ids=_parse_indexer_id_filter(),
            ))
        except Exception as e:
            result['error'] = f'Prowlarr search failed: {e}'
            return result

        candidates = [r for r in search_results
                      if r.protocol == 'torrent' and (r.magnet_uri or r.download_url)]
        if not candidates:
            result['error'] = f'No torrent results found for "{query}"'
            return result

        picked = pick_best_album_release(candidates, _guess_quality_from_title)
        if picked is None:
            result['error'] = 'No suitable torrent candidate after filtering'
            return result

        download_url = picked.magnet_uri or picked.download_url
        logger.info("[Torrent album] Picked '%s' (size=%.1fMB seeders=%s indexer=%s)",
                    picked.title, picked.size / 1_048_576, picked.seeders, picked.indexer_name)
        _emit('queued', release=picked.title, size=picked.size, seeders=picked.seeders)

        # Phase 2: hand to adapter.
        try:
            torrent_id = run_async(adapter.add_torrent(download_url))
        except Exception as e:
            result['error'] = f'Torrent client refused the release: {e}'
            return result
        if not torrent_id:
            result['error'] = 'Torrent client refused the release'
            return result

        # Phase 3: poll until complete.
        _emit('downloading', release=picked.title)
        save_path = self._poll_album_download(adapter, torrent_id, picked.title, _emit)
        if save_path is None:
            result['error'] = 'Torrent download failed or timed out'
            return result

        # Phase 4: extract + walk + copy to staging.
        _emit('staging', release=picked.title)
        try:
            audio_files = collect_audio_after_extraction(Path(save_path))
        except Exception as e:
            result['error'] = f'Failed to walk audio files: {e}'
            return result
        if not audio_files:
            result['error'] = f'No audio files found in {save_path}'
            return result

        copied = copy_audio_files_atomically(audio_files, Path(staging_dir))
        if not copied:
            result['error'] = 'No audio files copied to staging'
            return result
        logger.info("[Torrent album] Staged %d audio files for '%s'", len(copied), album_name)
        _emit('staged', count=len(copied))
        result['success'] = True
        result['files'] = copied
        return result

    def _poll_album_download(self, adapter, torrent_id, title, emit) -> Optional[str]:
        """Poll the adapter until the torrent is complete. Returns
        the save path or ``None`` on timeout / failure."""
        deadline = time.monotonic() + _POLL_TIMEOUT_SECONDS
        last_save_path: Optional[str] = None
        while time.monotonic() < deadline:
            if self.shutdown_check and self.shutdown_check():
                return None
            try:
                status = run_async(adapter.get_status(torrent_id))
            except Exception as e:
                logger.warning("[Torrent album] Poll error: %s", e)
                status = None
            if status is None:
                logger.error("[Torrent album] '%s' disappeared from client", title)
                return None
            emit('downloading', progress=status.progress, downloaded=status.downloaded,
                 speed=status.download_speed)
            if status.save_path:
                last_save_path = status.save_path
            if status.state in _COMPLETE_STATES:
                return last_save_path
            if status.state == 'error':
                logger.error("[Torrent album] '%s' errored: %s", title, status.error)
                return None
            time.sleep(_POLL_INTERVAL_SECONDS)
        logger.error("[Torrent album] '%s' timed out", title)
        return None


# ---------------------------------------------------------------------------
# Module-level helpers (pure functions — easy to unit-test)
# ---------------------------------------------------------------------------


def _decode_filename(filename: str) -> Tuple[Optional[str], str]:
    """Pull the encoded download URL out of the ``filename`` string.
    Returns ``(url, display_name)``. ``url`` is None when the string
    has no separator."""
    if not filename or _FILENAME_SEP not in filename:
        return (None, filename or '')
    url, display = filename.split(_FILENAME_SEP, 1)
    return (url, display)


def _parse_release_title(title: str) -> Tuple[str, str]:
    """Split a release title into ``(artist, title)`` using the
    ``Artist - Title`` / ``Artist - Album`` convention almost every
    indexer follows. Returns ``('', title)`` when no dash is found.

    Without this, ``TrackResult.__post_init__`` runs the bare
    filename through ``parse_filename_metadata`` — and our filename
    starts with the indexer's download URL, so the auto-parser
    extracts garbage like ``download?apikey=...`` as the artist
    and shows it in the search-result UI's "by" line. Pre-filling
    the artist field short-circuits the auto-parse.
    """
    if not title:
        return ('', '')
    # Strip common quality / format tags so the dash split doesn't
    # eat them — "Artist - Album [FLAC] (2020)" → "Artist", "Album".
    cleaned = re.sub(r'\s*[\[\(][^\]\)]*[\]\)]\s*$', '', title.strip())
    # Look for the FIRST " - " (or "-" surrounded by content). Some
    # release titles have multiple dashes (subtitle dashes); the
    # first split is the artist/work boundary.
    parts = re.split(r'\s+-\s+|\s+-(?=\S)|(?<=\S)-\s+', cleaned, maxsplit=1)
    if len(parts) == 2:
        artist = parts[0].strip()
        rest = parts[1].strip()
        # Reject obvious non-artist prefixes (URLs, hashes, single
        # punctuation) so we don't propagate garbage.
        if artist and not re.match(r'^https?:|^[a-f0-9]{32,}$', artist):
            return (artist, rest or cleaned)
    return ('', cleaned)


def _guess_quality_from_title(title: str) -> str:
    """Read the quality hint from a release title — most music
    torrents put the encoding right in the name (FLAC, MP3 320,
    etc.). Falls back to ``'mp3'`` so quality_score doesn't crash."""
    if not title:
        return 'mp3'
    lower = title.lower()
    if 'flac' in lower:
        return 'flac'
    if re.search(r'\b24[\s-]?bit\b', lower) or 'hi-?res' in lower:
        return 'flac'
    if 'aac' in lower:
        return 'aac'
    if 'ogg' in lower:
        return 'ogg'
    return 'mp3'


def _parse_indexer_id_filter() -> List[int]:
    """Read the comma-separated indexer-ID allowlist from config.
    Empty list = search every enabled indexer."""
    raw = (config_manager.get('prowlarr.indexer_ids', '') or '').strip()
    if not raw:
        return []
    out: List[int] = []
    for chunk in raw.split(','):
        chunk = chunk.strip()
        if not chunk:
            continue
        try:
            out.append(int(chunk))
        except ValueError:
            continue
    return out


def _adapter_state_to_display(state: str) -> str:
    """Translate the adapter-uniform state strings into the
    ``'InProgress, Downloading'`` / ``'Completed, Succeeded'``
    style the existing UI expects (matches Soulseek + Lidarr)."""
    mapping = {
        'queued':      'Queued',
        'downloading': 'InProgress, Downloading',
        'stalled':     'InProgress, Stalled',
        'seeding':     'Completed, Succeeded',
        'completed':   'Completed, Succeeded',
        'paused':      'Paused',
        'error':       'Completed, Errored',
    }
    return mapping.get(state, state.title())


def _row_to_status(row: Dict[str, Any]) -> DownloadStatus:
    return DownloadStatus(
        id=row['id'],
        filename=row['filename'],
        username=row['username'],
        state=row.get('state', 'Unknown'),
        progress=float(row.get('progress', 0.0)),
        size=int(row.get('size', 0)),
        transferred=int(row.get('transferred', 0)),
        speed=int(row.get('speed', 0)),
        time_remaining=None,
        file_path=row.get('file_path'),
        audio_files=row.get('audio_files') or None,
    )
