import 'dart:async';

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:spotiflac_android/l10n/l10n.dart';
import 'package:spotiflac_android/widgets/mornye_player_slider.dart';
import 'package:spotiflac_android/utils/logger.dart';
import 'package:volume_controller/volume_controller.dart';
import 'package:spotiflac_android/services/music_playback_deck.dart';

final usbVolumeProvider = StreamProvider.autoDispose<UsbVolumeState?>((ref) {
  final events = StreamController<UsbVolumeState?>();
  void changed() => events.add(usbHardwareVolume.value);
  usbHardwareVolume.addListener(changed);
  changed();
  ref.onDispose(() {
    usbHardwareVolume.removeListener(changed);
    unawaited(events.close());
  });
  return events.stream;
});

/// A single shared subscription for the visible player, including hardware
/// volume-button changes. This controls system volume, not ReplayGain gain.
final systemVolumeProvider = StreamProvider.autoDispose<double>((ref) {
  final events = StreamController<double>();
  final volume = VolumeController.instance;
  final subscription = volume.addListener(events.add);
  subscription.onError((Object error, StackTrace stack) {
    events.addError(error, stack);
  });
  ref.onDispose(() {
    unawaited(subscription.cancel());
    volume.removeListener();
    unawaited(events.close());
  });
  return events.stream;
});

final systemVolumeWriterProvider = Provider<Future<void> Function(double)>((
  ref,
) {
  return (value) {
    if (usbHardwareVolume.value != null) return setUsbHardwareVolume(value);
    final volume = VolumeController.instance;
    volume.showSystemUI = false;
    return volume.setVolume(value.clamp(0, 1));
  };
});

class MornyeVolumeControl extends ConsumerStatefulWidget {
  const MornyeVolumeControl({super.key, this.foreground = Colors.white});

  final Color foreground;

  @override
  ConsumerState<MornyeVolumeControl> createState() =>
      _MornyeVolumeControlState();
}

class _MornyeVolumeControlState extends ConsumerState<MornyeVolumeControl> {
  double? _preview;
  double? _pendingVolume;
  bool _dragging = false;
  bool _writing = false;

  void _setVolume(double value) {
    setState(() => _preview = value);
    _pendingVolume = value;
    if (!_writing) unawaited(_flushVolume());
  }

  Future<void> _flushVolume() async {
    _writing = true;
    final write = ref.read(systemVolumeWriterProvider);
    final usbToken = usbHardwareVolume.value?.token;
    try {
      // Send changes during the gesture. If the platform is still processing
      // a write, keep only the newest value instead of queuing stale positions.
      while (mounted && _pendingVolume != null) {
        if (usbHardwareVolume.value?.token != usbToken) {
          _pendingVolume = null;
          break;
        }
        final value = _pendingVolume!;
        _pendingVolume = null;
        try {
          await write(value);
        } catch (error) {
          AppLogger('PlayerVolume').w('Could not set system volume: $error');
        }
      }
    } finally {
      _writing = false;
      if (mounted && !_dragging) setState(() => _preview = null);
    }
  }

  @override
  Widget build(BuildContext context) {
    final usb = ref.watch(usbVolumeProvider).value ?? usbHardwareVolume.value;
    final volume = usb == null
        ? ref.watch(systemVolumeProvider).value
        : usb.available
        ? usb.fraction
        : null;
    final value = (_preview ?? volume ?? 0).clamp(0.0, 1.0);
    String percentage(double volume) => '${(volume * 100).round()}%';
    return Semantics(
      label: usb == null
          ? context.l10n.nowPlayingVolume
          : context.l10n.usbHardwareVolume,
      slider: true,
      enabled: volume != null,
      excludeSemantics: true,
      value: volume == null ? null : percentage(value),
      increasedValue: volume == null
          ? null
          : percentage((value + 0.05).clamp(0, 1)),
      decreasedValue: volume == null
          ? null
          : percentage((value - 0.05).clamp(0, 1)),
      onIncrease: volume == null
          ? null
          : () => _setVolume((value + 0.05).clamp(0, 1)),
      onDecrease: volume == null
          ? null
          : () => _setVolume((value - 0.05).clamp(0, 1)),
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 28),
        child: Row(
          children: [
            Icon(
              CupertinoIcons.speaker_fill,
              size: 16,
              color: widget.foreground.withValues(alpha: 0.54),
            ),
            const SizedBox(width: 10),
            Expanded(
              child: LayoutBuilder(
                builder: (context, constraints) => IgnorePointer(
                  ignoring: volume == null,
                  child: Opacity(
                    opacity: volume == null ? 0.4 : 1,
                    child: MornyePlayerSlider(
                      value: value,
                      activeColor: widget.foreground.withValues(alpha: 0.70),
                      inactiveColor: widget.foreground.withValues(alpha: 0.12),
                      onChangeStart: (_) => _dragging = true,
                      onChanged: _setVolume,
                      onChangeEnd: (value) {
                        _dragging = false;
                        _setVolume(value);
                      },
                    ),
                  ),
                ),
              ),
            ),
            const SizedBox(width: 10),
            Icon(
              CupertinoIcons.speaker_3_fill,
              size: 16,
              color: widget.foreground.withValues(alpha: 0.54),
            ),
          ],
        ),
      ),
    );
  }
}