import React, { useCallback, useEffect, useMemo, useRef, useState } from 'react';
import { createPortal } from 'react-dom';

import { ipcChannels } from '../../../shared/ipc/contracts';
import type {
  AppPlaylist,
  PlaylistAudioId,
  PlaylistId,
  PlaylistTrackId,
} from '../../../shared/types/appPlaylists';
import { filterPlaylistsByQuery } from '../../../shared/types/appPlaylists';
import { filterAudioFilePaths, useFileDropZone } from '../../editor/fileDrop';
import editorStyles from '../../editor/EditorApp.module.css';
import { useEditorI18n } from '../../editor/i18n/EditorI18nContext';
import { getDndApi } from '../dndApi';
import { Button, Input } from '../ui/controls';

import { PlaylistPlayerBar } from './PlaylistPlayerBar';
import styles from './PlaylistsPanel.module.css';
import { useAppPlaylists } from './useAppPlaylists';

const TRACK_DND = 'application/x-dnd-playlist-track';
const PLAYLIST_DND = 'application/x-dnd-playlist-id';

export type PlaylistsPanelLabels = {
  searchPlaceholder: string;
  create: string;
  rename: string;
  duplicate: string;
  delete: string;
  addAudio: string;
  emptyPlaylists: string;
  emptyTracks: string;
  untitled: string;
  play: string;
  pause: string;
  prev: string;
  next: string;
  volume: string;
  scrub: string;
  emptyPlayer: string;
  playPlaylist: string;
  removeTrack: string;
  renameAudio: string;
  dropAudioHint: string;
};

export function PlaylistsPanel({
  labels,
  className,
  readOnly = false,
}: {
  labels: PlaylistsPanelLabels;
  className?: string;
  /** Electron player window: browse + play only (no CRUD / DnD). */
  readOnly?: boolean;
}) {
  const { t } = useEditorI18n();
  const api = getDndApi();
  const state = useAppPlaylists();
  const [query, setQuery] = useState('');
  const [selectedId, setSelectedId] = useState<PlaylistId | null>(null);
  const [editingName, setEditingName] = useState('');
  const [editingAudioId, setEditingAudioId] = useState<PlaylistAudioId | null>(null);
  const [editingAudioTitle, setEditingAudioTitle] = useState('');
  const [pendingDelete, setPendingDelete] = useState<AppPlaylist | null>(null);

  const audioById = useMemo(() => new Map(state.audios.map((a) => [a.id, a])), [state.audios]);
  const filtered = useMemo(() => filterPlaylistsByQuery(state, query), [state, query]);
  const selected = useMemo(
    () => state.playlists.find((p) => p.id === selectedId) ?? filtered.playlists[0] ?? null,
    [filtered.playlists, selectedId, state.playlists],
  );

  useEffect(() => {
    if (selected) {
      setSelectedId(selected.id);
      setEditingName(selected.name);
    } else {
      setEditingName('');
    }
  }, [selected]);

  const audioElRef = useRef<HTMLAudioElement | null>(null);
  const [audioEl, setAudioEl] = useState<HTMLAudioElement | null>(null);
  const [playing, setPlaying] = useState(false);
  const [gain, setGain] = useState(1);
  const [queuePlaylistId, setQueuePlaylistId] = useState<PlaylistId | null>(null);
  const [queueIndex, setQueueIndex] = useState(0);
  const queueRef = useRef<{ playlistId: PlaylistId; index: number } | null>(null);

  const queuePlaylist = useMemo(
    () => (queuePlaylistId ? state.playlists.find((p) => p.id === queuePlaylistId) ?? null : null),
    [queuePlaylistId, state.playlists],
  );
  const currentTrack = queuePlaylist?.tracks[queueIndex] ?? null;
  const currentAudio = currentTrack ? audioById.get(currentTrack.audioId) ?? null : null;

  const stopPlayback = useCallback(() => {
    const el = audioElRef.current;
    if (el) {
      el.pause();
      el.removeAttribute('src');
      el.load();
    }
    audioElRef.current = null;
    setAudioEl(null);
    setPlaying(false);
    queueRef.current = null;
    setQueuePlaylistId(null);
    setQueueIndex(0);
  }, []);

  useEffect(() => () => stopPlayback(), [stopPlayback]);

  const playAt = useCallback(
    async (playlist: AppPlaylist, index: number) => {
      const track = playlist.tracks[index];
      if (!track) return;
      const { url } = await api.invoke(ipcChannels.playlists.audioUrl, { id: track.audioId });
      if (!url) return;
      let el = audioElRef.current;
      if (!el) {
        el = new Audio();
        el.preload = 'auto';
        audioElRef.current = el;
        setAudioEl(el);
      }
      el.volume = gain;
      el.src = url;
      queueRef.current = { playlistId: playlist.id, index };
      setQueuePlaylistId(playlist.id);
      setQueueIndex(index);
      try {
        await el.play();
        setPlaying(true);
      } catch {
        setPlaying(false);
      }
    },
    [api, gain],
  );

  useEffect(() => {
    const el = audioElRef.current;
    if (!el) return;
    const onEnded = () => {
      const q = queueRef.current;
      if (!q) return;
      const pl = state.playlists.find((p) => p.id === q.playlistId);
      if (!pl || pl.tracks.length === 0) {
        stopPlayback();
        return;
      }
      const next = (q.index + 1) % pl.tracks.length;
      void playAt(pl, next);
    };
    const onPlay = () => setPlaying(true);
    const onPause = () => setPlaying(false);
    el.addEventListener('ended', onEnded);
    el.addEventListener('play', onPlay);
    el.addEventListener('pause', onPause);
    return () => {
      el.removeEventListener('ended', onEnded);
      el.removeEventListener('play', onPlay);
      el.removeEventListener('pause', onPause);
    };
  }, [audioEl, playAt, state.playlists, stopPlayback]);

  const step = (delta: number) => {
    const q = queueRef.current;
    const pl = q ? state.playlists.find((p) => p.id === q.playlistId) : selected;
    if (!pl || pl.tracks.length === 0) return;
    const base = q?.playlistId === pl.id ? q.index : 0;
    const next = (base + delta + pl.tracks.length) % pl.tracks.length;
    void playAt(pl, next);
  };

  const createPlaylist = async () => {
    const { playlist } = await api.invoke(ipcChannels.playlists.create, {});
    setSelectedId(playlist.id);
  };

  const saveRename = async () => {
    if (!selected) return;
    if (editingName.trim() === selected.name) return;
    await api.invoke(ipcChannels.playlists.rename, { id: selected.id, name: editingName });
  };

  const addAudio = async () => {
    if (!selected) return;
    const { filePaths } = await api.invoke(ipcChannels.playlists.pickAudioFiles, {});
    if (filePaths.length === 0) return;
    await api.invoke(ipcChannels.playlists.addAudioFiles, {
      playlistId: selected.id,
      filePaths,
    });
  };

  const addAudioFromPaths = useCallback(
    (paths: string[]) => {
      if (!selected || paths.length === 0) return;
      void api.invoke(ipcChannels.playlists.addAudioFiles, {
        playlistId: selected.id,
        filePaths: paths,
      });
    },
    [api, selected],
  );

  const audioFileDrop = useFileDropZone({
    disabled: readOnly || !selected,
    filterPaths: filterAudioFilePaths,
    onDropPaths: addAudioFromPaths,
  });

  const deleteSelected = () => {
    if (readOnly || !selected) return;
    setPendingDelete(selected);
  };

  const confirmDelete = async () => {
    if (!pendingDelete) return;
    const id = pendingDelete.id;
    setPendingDelete(null);
    if (queueRef.current?.playlistId === id) stopPlayback();
    await api.invoke(ipcChannels.playlists.delete, { id });
    setSelectedId((cur) => (cur === id ? null : cur));
  };

  return (
    <div className={[styles.root, className].filter(Boolean).join(' ')} data-testid="playlists-panel">
      <div className={styles.sidebar}>
        <div className={styles.toolbar}>
          <Input
            value={query}
            onChange={setQuery}
            placeholder={labels.searchPlaceholder}
            data-testid="playlists-search"
          />
          {!readOnly ? (
            <Button variant="primary" onClick={() => void createPlaylist()} data-testid="playlists-create">
              {labels.create}
            </Button>
          ) : null}
        </div>
        <div className={styles.list}>
          {filtered.playlists.length === 0 ? (
            <div className={styles.empty}>{labels.emptyPlaylists}</div>
          ) : (
            filtered.playlists.map((pl) => (
              <button
                key={pl.id}
                type="button"
                className={[styles.playlistRow, selected?.id === pl.id ? styles.playlistRowSelected : '']
                  .filter(Boolean)
                  .join(' ')}
                data-testid={`playlist-row-${pl.id}`}
                draggable={!readOnly}
                onDragStart={
                  readOnly
                    ? undefined
                    : (e) => {
                        e.dataTransfer.setData(PLAYLIST_DND, pl.id);
                        e.dataTransfer.effectAllowed = 'move';
                      }
                }
                onDragOver={
                  readOnly
                    ? undefined
                    : (e) => {
                        if (e.dataTransfer.types.includes(PLAYLIST_DND)) e.preventDefault();
                      }
                }
                onDrop={
                  readOnly
                    ? undefined
                    : (e) => {
                        e.preventDefault();
                        const dragged = e.dataTransfer.getData(PLAYLIST_DND) as PlaylistId;
                        if (!dragged || dragged === pl.id) return;
                        const ids = state.playlists.map((p) => p.id);
                        const from = ids.indexOf(dragged);
                        const to = ids.indexOf(pl.id);
                        if (from < 0 || to < 0) return;
                        const next = [...ids];
                        next.splice(from, 1);
                        next.splice(to, 0, dragged);
                        void api.invoke(ipcChannels.playlists.setOrder, { playlistIds: next });
                      }
                }
                onClick={() => setSelectedId(pl.id)}
              >
                <span className={styles.playlistName}>{pl.name || labels.untitled}</span>
                <span className={styles.playlistCount}>{pl.tracks.length}</span>
              </button>
            ))
          )}
        </div>
      </div>

      <div
        className={[
          styles.main,
          !readOnly && selected && audioFileDrop.dragOver ? styles.mainDropActive : '',
        ]
          .filter(Boolean)
          .join(' ')}
        onDragEnter={readOnly ? undefined : audioFileDrop.onDragEnter}
        onDragLeave={readOnly ? undefined : audioFileDrop.onDragLeave}
        onDragOver={readOnly ? undefined : audioFileDrop.onDragOver}
        onDrop={readOnly ? undefined : audioFileDrop.onDrop}
      >
        {!readOnly && selected && audioFileDrop.dragOver ? (
          <div className={styles.dropHintOverlay}>{labels.dropAudioHint}</div>
        ) : null}
        {selected ? (
          <>
            <div className={styles.mainHeader}>
              {readOnly ? (
                <div className={styles.playlistNameReadonly}>{selected.name || labels.untitled}</div>
              ) : (
                <Input value={editingName} onChange={setEditingName} onBlur={() => void saveRename()} />
              )}
              <div className={styles.mainActions}>
                <Button
                  variant="ghost"
                  onClick={() => void playAt(selected, 0)}
                  disabled={selected.tracks.length === 0}
                >
                  {labels.playPlaylist}
                </Button>
                {!readOnly ? (
                  <>
                    <Button variant="ghost" onClick={() => void addAudio()}>
                      {labels.addAudio}
                    </Button>
                    <Button
                      variant="ghost"
                      onClick={() => void api.invoke(ipcChannels.playlists.duplicate, { id: selected.id })}
                    >
                      {labels.duplicate}
                    </Button>
                    <Button variant="ghost" onClick={() => void deleteSelected()}>
                      {labels.delete}
                    </Button>
                  </>
                ) : null}
              </div>
            </div>
            <div className={styles.tracks}>
              {selected.tracks.length === 0 ? (
                <div className={styles.empty}>
                  {labels.emptyTracks}
                  {!readOnly ? <div className={styles.dropHintMuted}>{labels.dropAudioHint}</div> : null}
                </div>
              ) : (
                selected.tracks.map((tr, idx) => {
                  const audio = audioById.get(tr.audioId);
                  const title = audio?.title ?? labels.untitled;
                  const highlighted = query.trim() && filtered.matchedAudioIds.has(tr.audioId);
                  const isCurrent =
                    queuePlaylistId === selected.id && queueIndex === idx && Boolean(currentTrack);
                  return (
                    <div
                      key={tr.id}
                      className={[
                        styles.trackRow,
                        isCurrent ? styles.trackRowCurrent : '',
                        highlighted ? styles.trackRowMatch : '',
                      ]
                        .filter(Boolean)
                        .join(' ')}
                      draggable={!readOnly}
                      onDragStart={
                        readOnly
                          ? undefined
                          : (e) => {
                              e.dataTransfer.setData(TRACK_DND, tr.id);
                              e.dataTransfer.effectAllowed = 'move';
                            }
                      }
                      onDragOver={
                        readOnly
                          ? undefined
                          : (e) => {
                              if (e.dataTransfer.types.includes(TRACK_DND)) e.preventDefault();
                            }
                      }
                      onDrop={
                        readOnly
                          ? undefined
                          : (e) => {
                              if (!e.dataTransfer.types.includes(TRACK_DND)) return;
                              e.preventDefault();
                              e.stopPropagation();
                              const dragged = e.dataTransfer.getData(TRACK_DND) as PlaylistTrackId;
                              if (!dragged || dragged === tr.id) return;
                              const ids = selected.tracks.map((t) => t.id);
                              const from = ids.indexOf(dragged);
                              const to = ids.indexOf(tr.id);
                              if (from < 0 || to < 0) return;
                              const next = [...ids];
                              next.splice(from, 1);
                              next.splice(to, 0, dragged);
                              void api.invoke(ipcChannels.playlists.setTracksOrder, {
                                playlistId: selected.id,
                                trackIds: next,
                              });
                            }
                      }
                      onDoubleClick={() => void playAt(selected, idx)}
                    >
                      <button type="button" className={styles.trackPlay} onClick={() => void playAt(selected, idx)}>
                        ▶
                      </button>
                      {readOnly ? (
                        <span className={styles.trackTitleReadonly}>{title}</span>
                      ) : editingAudioId === tr.audioId ? (
                        <Input
                          value={editingAudioTitle}
                          onChange={setEditingAudioTitle}
                          onBlur={() => {
                            void api.invoke(ipcChannels.playlists.renameAudio, {
                              audioId: tr.audioId,
                              title: editingAudioTitle,
                            });
                            setEditingAudioId(null);
                          }}
                        />
                      ) : (
                        <button
                          type="button"
                          className={styles.trackTitle}
                          onClick={() => {
                            setEditingAudioId(tr.audioId);
                            setEditingAudioTitle(title);
                          }}
                          title={labels.renameAudio}
                        >
                          {title}
                        </button>
                      )}
                      {!readOnly ? (
                        <Button
                          variant="ghost"
                          onClick={() =>
                            void api.invoke(ipcChannels.playlists.removeTrack, {
                              playlistId: selected.id,
                              trackId: tr.id,
                            })
                          }
                        >
                          {labels.removeTrack}
                        </Button>
                      ) : null}
                    </div>
                  );
                })
              )}
            </div>
          </>
        ) : (
          <div className={styles.empty}>{labels.emptyPlaylists}</div>
        )}

        <PlaylistPlayerBar
          title={currentAudio?.title ?? ''}
          subtitle={queuePlaylist?.name}
          audioEl={audioEl}
          playing={playing}
          gain={gain}
          onGainChange={setGain}
          onTogglePlay={() => {
            const el = audioElRef.current;
            if (!el) {
              if (selected && selected.tracks.length > 0) void playAt(selected, 0);
              return;
            }
            if (el.paused) void el.play().then(() => setPlaying(true)).catch(() => setPlaying(false));
            else {
              el.pause();
              setPlaying(false);
            }
          }}
          onPrev={() => step(-1)}
          onNext={() => step(1)}
          playLabel={labels.play}
          pauseLabel={labels.pause}
          prevLabel={labels.prev}
          nextLabel={labels.next}
          volumeLabel={labels.volume}
          scrubLabel={labels.scrub}
          emptyLabel={labels.emptyPlayer}
        />
      </div>
      {!readOnly && pendingDelete
        ? createPortal(
            <>
              <button
                type="button"
                aria-label={t('common.close')}
                className={editorStyles.modalBackdrop}
                onClick={() => setPendingDelete(null)}
              />
              <div
                role="dialog"
                aria-modal="true"
                data-testid="playlists-delete-confirm"
                className={editorStyles.modalDialog}
              >
                <div className={editorStyles.modalHeader}>
                  <div className={editorStyles.modalTitle}>{t('playlists.deleteTitle')}</div>
                  <button
                    type="button"
                    aria-label={t('common.close')}
                    className={editorStyles.modalClose}
                    onClick={() => setPendingDelete(null)}
                  >
                    ×
                  </button>
                </div>
                <div className={editorStyles.muted}>
                  {t('playlists.deleteConfirm', { name: pendingDelete.name })}
                </div>
                <div className={editorStyles.modalFooter}>
                  <Button onClick={() => setPendingDelete(null)}>{t('common.cancel')}</Button>
                  <Button variant="primary" onClick={() => void confirmDelete()}>
                    {t('common.delete')}
                  </Button>
                </div>
              </div>
            </>,
            document.body,
          )
        : null}
    </div>
  );
}

export function playlistsPanelLabelsFromT(t: (key: string) => string): PlaylistsPanelLabels {
  return {
    searchPlaceholder: t('playlists.search'),
    create: t('playlists.create'),
    rename: t('playlists.rename'),
    duplicate: t('playlists.duplicate'),
    delete: t('playlists.delete'),
    addAudio: t('playlists.addAudio'),
    emptyPlaylists: t('playlists.empty'),
    emptyTracks: t('playlists.emptyTracks'),
    untitled: t('playlists.untitled'),
    play: t('playlists.play'),
    pause: t('playlists.pause'),
    prev: t('playlists.prev'),
    next: t('playlists.next'),
    volume: t('playlists.volume'),
    scrub: t('playlists.scrub'),
    emptyPlayer: t('playlists.emptyPlayer'),
    playPlaylist: t('playlists.playPlaylist'),
    removeTrack: t('playlists.removeTrack'),
    renameAudio: t('playlists.renameAudio'),
    dropAudioHint: t('playlists.dropAudioHint'),
  };
}