import 'package:flutter/material.dart';

import '../api.dart';
import '../pickers.dart';
import '../theme.dart';
import '../widgets.dart';

typedef _Lookups = (List<AdminArtist>, List<AdminAlbum>);

Future<_Lookups> _lookups() async => (await AdminApi.artists(), await AdminApi.albums());

/// Edits one song. Returns true when something was saved.
Future<bool> editSong(BuildContext context, AdminTrack track) async =>
    await showDialog<bool>(context: context, builder: (_) => _LookupsDialog(builder: (l) => _SongForm(track, l))) ??
    false;

/// Changes chosen fields on many songs at once. Returns true when something was saved.
Future<bool> bulkEditSongs(BuildContext context, List<String> ids) async =>
    await showDialog<bool>(context: context, builder: (_) => _LookupsDialog(builder: (l) => _BulkForm(ids, l))) ??
    false;

class _LookupsDialog extends StatefulWidget {
  const _LookupsDialog({required this.builder});

  final Widget Function(_Lookups lookups) builder;

  @override
  State<_LookupsDialog> createState() => _LookupsDialogState();
}

class _LookupsDialogState extends State<_LookupsDialog> {
  late Future<_Lookups> _data = _lookups();

  @override
  Widget build(BuildContext context) => FutureBuilder(
        future: _data,
        builder: (context, snap) {
          if (snap.hasData) return widget.builder(snap.data!);
          return AlertDialog(
            content: SizedBox(
              width: 320,
              height: 120,
              child: snap.hasError
                  ? Center(child: Text(errorText(snap.error!)))
                  : const Center(child: CircularProgressIndicator()),
            ),
            actions: [
              if (snap.hasError) TextButton(onPressed: () => setState(() => _data = _lookups()), child: const Text('Retry')),
              TextButton(onPressed: () => Navigator.pop(context), child: const Text('Close')),
            ],
          );
        },
      );
}

Widget _occasionField(String? value, ValueChanged<String?> onChanged) => DropdownButtonFormField<String>(
      initialValue: value,
      decoration: const InputDecoration(labelText: 'Occasion'),
      items: [for (final e in occasions.entries) DropdownMenuItem(value: e.key, child: Text(e.value))],
      onChanged: onChanged,
    );

Widget _statusField(SongStatus? value, ValueChanged<SongStatus?> onChanged) => DropdownButtonFormField<SongStatus>(
      initialValue: value,
      decoration: const InputDecoration(labelText: 'Status'),
      items: [for (final s in SongStatus.values) DropdownMenuItem(value: s, child: Text(s.label))],
      onChanged: onChanged,
    );

class _SongForm extends StatefulWidget {
  const _SongForm(this.track, this.lookups);

  final AdminTrack track;
  final _Lookups lookups;

  @override
  State<_SongForm> createState() => _SongFormState();
}

class _SongFormState extends State<_SongForm> {
  late final t = widget.track;
  late final _title = TextEditingController(text: t.title);
  late final _tamil = TextEditingController(text: t.titleTamil ?? '');
  late final _meaning = TextEditingController(text: t.meaning ?? '');
  late final _year = TextEditingController(text: t.year?.toString() ?? '');
  late String? _albumId = t.albumId;
  late String _occasion = t.occasion;
  late List<String> _singers = [...t.singerIds];
  late SongStatus _status = t.status;
  bool _saving = false;

  @override
  void dispose() {
    for (final c in [_title, _tamil, _meaning, _year]) {
      c.dispose();
    }
    super.dispose();
  }

  Future<void> _save() async {
    if (_title.text.trim().isEmpty) {
      showMessage(context, 'The song needs a title.');
      return;
    }
    final year = int.tryParse(_year.text.trim());
    if (_year.text.trim().isNotEmpty && year == null) {
      showMessage(context, 'The year should be a number, like 1998.');
      return;
    }
    setState(() => _saving = true);
    try {
      await AdminApi.saveSong(
        t,
        title: _title.text.trim(),
        titleTamil: trimmedOrNull(_tamil.text),
        meaning: trimmedOrNull(_meaning.text),
        year: year,
        albumId: _albumId,
        occasion: _occasion,
        status: _status,
        singerIds: _singers,
      );
      if (mounted) Navigator.pop(context, true);
    } catch (e) {
      if (mounted) showError(context, e);
    } finally {
      if (mounted) setState(() => _saving = false);
    }
  }

  @override
  Widget build(BuildContext context) {
    final (artists, albums) = widget.lookups;
    return AlertDialog(
      title: const Text('Edit song'),
      content: DialogBody(
        width: 560,
        children: [
          TextField(controller: _title, decoration: const InputDecoration(labelText: 'Title (English letters)')),
          TextField(controller: _tamil, decoration: const InputDecoration(labelText: 'Title in Tamil script')),
          TextField(controller: _meaning, decoration: const InputDecoration(labelText: 'Meaning in English')),
          Row(
            children: [
              Expanded(child: _occasionField(_occasion, (v) => setState(() => _occasion = v ?? _occasion))),
              const SizedBox(width: 12),
              SizedBox(
                width: 120,
                child: TextField(
                  controller: _year,
                  keyboardType: TextInputType.number,
                  decoration: const InputDecoration(labelText: 'Year'),
                ),
              ),
            ],
          ),
          AlbumPicker(albums: albums, albumId: _albumId, onChanged: (v) => setState(() => _albumId = v)),
          Text('Singers', style: Theme.of(context).textTheme.titleMedium),
          SingerPicker(artists: artists, selected: _singers, onChanged: (v) => setState(() => _singers = v)),
          _statusField(_status, (v) => setState(() => _status = v ?? _status)),
          if (t.status == SongStatus.pending && _status == SongStatus.pending)
            const Text('Tip: set the status to "Live" to publish this song in the app.',
                style: TextStyle(color: NkColors.muted)),
          _Facts(t),
        ],
      ),
      actions: [
        TextButton(onPressed: _saving ? null : () => Navigator.pop(context, false), child: const Text('Cancel')),
        FilledButton(onPressed: _saving ? null : _save, child: Text(_saving ? 'Saving…' : 'Save')),
      ],
    );
  }
}

class _Facts extends StatelessWidget {
  const _Facts(this.t);

  final AdminTrack t;

  @override
  Widget build(BuildContext context) {
    final style = Theme.of(context).textTheme.bodySmall;
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        const Divider(),
        const SizedBox(height: 8),
        Text('Added ${formatDate(t.createdAt)} · ${formatDuration(t.duration)}', style: style),
        if (t.sourceNote != null) Text('Source: ${t.sourceNote}', style: style),
        if (t.audioKey != null) SelectableText('File: ${t.audioKey}', style: style),
        if (t.reviewNote != null) Text('Review note: ${t.reviewNote}', style: style),
      ],
    );
  }
}

class _BulkForm extends StatefulWidget {
  const _BulkForm(this.ids, this.lookups);

  final List<String> ids;
  final _Lookups lookups;

  @override
  State<_BulkForm> createState() => _BulkFormState();
}

class _BulkFormState extends State<_BulkForm> {
  bool _setAlbum = false, _setOccasion = false, _setSingers = false, _setStatus = false;
  String? _albumId;
  String? _occasion;
  List<String> _singers = [];
  bool _replaceSingers = false;
  SongStatus? _status;
  bool _saving = false;

  Future<void> _save() async {
    if (_setOccasion && _occasion == null || _setStatus && _status == null) {
      showMessage(context, 'Choose a value for each ticked field.');
      return;
    }
    if (_setSingers && _singers.isEmpty && !_replaceSingers) {
      showMessage(context, 'Choose at least one singer to add.');
      return;
    }
    if (!(_setAlbum || _setOccasion || _setSingers || _setStatus)) {
      showMessage(context, 'Tick at least one field to change.');
      return;
    }
    setState(() => _saving = true);
    try {
      await AdminApi.updateSongs(
        widget.ids,
        SongChanges(
          albumId: _setAlbum ? _albumId : null,
          clearAlbum: _setAlbum && _albumId == null,
          occasion: _setOccasion ? _occasion : null,
          status: _setStatus ? _status : null,
          singerIds: _setSingers ? _singers : null,
          replaceSingers: _replaceSingers,
        ),
      );
      if (mounted) Navigator.pop(context, true);
    } catch (e) {
      if (mounted) showError(context, e);
    } finally {
      if (mounted) setState(() => _saving = false);
    }
  }

  Widget _toggle(String label, bool value, ValueChanged<bool> onChanged, Widget child) => Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          CheckboxListTile(
            contentPadding: EdgeInsets.zero,
            controlAffinity: ListTileControlAffinity.leading,
            title: Text(label, style: const TextStyle(fontWeight: FontWeight.w700)),
            value: value,
            onChanged: (v) => setState(() => onChanged(v ?? false)),
          ),
          if (value) Padding(padding: const EdgeInsets.only(left: 40), child: child),
        ],
      );

  @override
  Widget build(BuildContext context) {
    final (artists, albums) = widget.lookups;
    return AlertDialog(
      title: Text('Edit ${widget.ids.length} songs'),
      content: DialogBody(
        width: 560,
        children: [
          const Text('Tick what to change. Everything else stays as it is.', style: TextStyle(color: NkColors.muted)),
          _toggle('Album', _setAlbum, (v) => _setAlbum = v, Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              AlbumPicker(albums: albums, albumId: _albumId, onChanged: (v) => setState(() => _albumId = v)),
              if (_albumId == null)
                const Padding(
                  padding: EdgeInsets.only(top: 6),
                  child: Text('No album chosen: the songs will be removed from their album.',
                      style: TextStyle(color: NkColors.muted)),
                ),
            ],
          )),
          _toggle('Occasion', _setOccasion, (v) => _setOccasion = v,
              _occasionField(_occasion, (v) => setState(() => _occasion = v))),
          _toggle('Singers', _setSingers, (v) => _setSingers = v, Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              SegmentedButton<bool>(
                segments: const [
                  ButtonSegment(value: false, label: Text('Add to existing')),
                  ButtonSegment(value: true, label: Text('Replace all')),
                ],
                selected: {_replaceSingers},
                onSelectionChanged: (s) => setState(() => _replaceSingers = s.first),
              ),
              const SizedBox(height: 10),
              SingerPicker(artists: artists, selected: _singers, onChanged: (v) => setState(() => _singers = v)),
            ],
          )),
          _toggle('Status', _setStatus, (v) => _setStatus = v,
              _statusField(_status, (v) => setState(() => _status = v))),
        ],
      ),
      actions: [
        TextButton(onPressed: _saving ? null : () => Navigator.pop(context, false), child: const Text('Cancel')),
        FilledButton(
          onPressed: _saving ? null : _save,
          child: Text(_saving ? 'Saving…' : 'Apply to ${widget.ids.length} songs'),
        ),
      ],
    );
  }
}