import 'dart:async';
import 'dart:io' show Platform;
import 'dart:ui' show window;

import 'package:flutter/widgets.dart';
import 'package:screen_brightness/screen_brightness.dart';
import 'package:screen_state/screen_state.dart';
import 'package:volume_controller/volume_controller.dart';

/// Native runtime observation fields backed by platform plugins.
class RuntimeObservationMonitor {
  final List<StreamSubscription<dynamic>> _subscriptions;
  final WidgetsBindingObserver? _metricsObserver;

  const RuntimeObservationMonitor(
    this._subscriptions, {
    WidgetsBindingObserver? metricsObserver,
  }) : _metricsObserver = metricsObserver;

  Future<void> dispose() async {
    for (final subscription in _subscriptions) {
      await subscription.cancel();
    }
    final metricsObserver = _metricsObserver;
    if (metricsObserver != null) {
      try {
        WidgetsBinding.instance.removeObserver(metricsObserver);
      } catch (_) {}
    }
    try {
      VolumeController().removeListener();
    } catch (_) {}
  }
}

Future<Map<String, dynamic>> collectRuntimeObservationFields() async {
  return {
    ..._screenObservationFields(),
    'screen_brightness': await _readScreenBrightness(),
    'volume': await _readVolume(),
    'is_screen_on': _initialScreenOn(),
  };
}

RuntimeObservationMonitor startRuntimeObservationMonitoring(
  void Function(Map<String, dynamic> fields) onFields,
) {
  final subscriptions = <StreamSubscription<dynamic>>[];
  WidgetsBindingObserver? metricsObserver;

  try {
    metricsObserver = _MetricsObserver(
      onMetricsChanged: () => onFields(_screenObservationFields()),
    );
    WidgetsBinding.instance.addObserver(metricsObserver);
  } catch (_) {}

  try {
    subscriptions.add(ScreenBrightness().onCurrentBrightnessChanged.listen(
        (value) => onFields({
              'screen_brightness': _normalizedPercent(value),
            }), onError: (_) {
      onFields({'screen_brightness': -1});
    }));
  } catch (_) {}

  try {
    subscriptions.add(VolumeController().listener((value) {
      onFields({'volume': _normalizedPercent(value)});
    }));
  } catch (_) {}

  try {
    if (Platform.isAndroid || Platform.isIOS) {
      subscriptions.add(Screen().screenStateStream.listen((event) {
        onFields({'is_screen_on': _screenStateValue(event)});
      }, onError: (_) {
        onFields({'is_screen_on': -1});
      }));
    }
  } catch (_) {}

  return RuntimeObservationMonitor(
    subscriptions,
    metricsObserver: metricsObserver,
  );
}

Map<String, dynamic> _screenObservationFields() {
  try {
    final size = window.physicalSize;
    final width = size.width.round();
    final height = size.height.round();
    final pixelRatio = (window.devicePixelRatio * 100).round();
    final dpi = (window.devicePixelRatio * 160).round();
    return {
      'screen_width': width,
      'screen_height': height,
      'screen_dpi': dpi,
      'device_pixel_ratio': pixelRatio,
      'orientation': width >= height ? 'landscape' : 'portrait',
    };
  } catch (_) {
    return const {
      'screen_width': -1,
      'screen_height': -1,
      'screen_dpi': -1,
      'device_pixel_ratio': -1,
      'orientation': '',
    };
  }
}

Future<int> _readScreenBrightness() async {
  try {
    return _normalizedPercent(await ScreenBrightness().current);
  } catch (_) {
    return -1;
  }
}

Future<int> _readVolume() async {
  try {
    return _normalizedPercent(await VolumeController().getVolume());
  } catch (_) {
    return -1;
  }
}

int _initialScreenOn() {
  try {
    return Platform.isAndroid || Platform.isIOS ? 1 : -1;
  } catch (_) {
    return -1;
  }
}

int _screenStateValue(ScreenStateEvent event) {
  switch (event) {
    case ScreenStateEvent.SCREEN_ON:
    case ScreenStateEvent.SCREEN_UNLOCKED:
      return 1;
    case ScreenStateEvent.SCREEN_OFF:
      return 0;
  }
}

int _normalizedPercent(num value) {
  final numeric = value.toDouble();
  if (!numeric.isFinite) return -1;
  final scaled = numeric <= 1 ? numeric * 100 : numeric;
  return scaled.clamp(0, 100).round();
}

class _MetricsObserver with WidgetsBindingObserver {
  final void Function() onMetricsChanged;

  const _MetricsObserver({required this.onMetricsChanged});

  @override
  void didChangeMetrics() {
    onMetricsChanged();
  }
}