import 'dart:math';

import 'package:flutter/foundation.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';

/// This is where the current time and total time labels should appear in
/// relation to the progress bar.
enum TimeLabelLocation {
  ///  The time is displayed above the progress bar.
  ///
  ///  | 01:23              05:00 |
  ///  | -------O---------------- |
  above,

  ///  The time is displayed below the progress bar.
  ///
  ///  | -------O---------------- |
  ///  | 01:23              05:00 |
  below,

  ///  The time is displayed on the sides of the progress bar.
  ///
  ///  | 01:23 -------O---------------- 05:00 |
  sides,

  ///  The time is not displayed.
  ///
  ///  | -------O---------------- |
  none,
}

/// The time label on the right hand side can be shown as the [totalTime] or as
/// the [remainingTime]. If the choice is [remainingTime] then this will be
/// shown as a negative number.
///
///
enum TimeLabelType {
  /// The time label on the right shows the total time.
  ///
  /// | -------O---------------- |
  /// | 01:23              05:00 |
  totalTime,

  /// The time label on the right shows the remaining time as a
  /// negative number.
  ///
  /// | -------O---------------- |
  /// | 01:23             -03:37 |
  remainingTime,
}

/// The shape of the progress bar at the left and right ends.
enum BarCapShape {
  /// The left and right ends of the bar are round.
  round,

  /// The left and right ends of the bar are square.
  square,
}

/// A progress bar widget to show or set the location of the currently
/// playing audio or video content.
///
/// This widget does not itself play audio or video content, but you can
/// use it in conjunction with an audio plugin. It is a more convenient
/// replacement for the Flutter Slider widget.
class ProgressBar extends LeafRenderObjectWidget {
  /// You must set the current audio or video duration [progress] and also
  /// the [total] duration. Optionally set the [buffered] content progress
  /// as well.
  ///
  /// When a user drags the thumb to a new location you can be notified
  /// by the [onSeek] callback so that you can update your audio/video player.
  const ProgressBar({
    Key? key,
    required this.progress,
    required this.total,
    this.buffered,
    this.onSeek,
    this.onDragStart,
    this.onDragUpdate,
    this.onDragEnd,
    this.barHeight = 5.0,
    this.baseBarColor,
    this.progressBarColor,
    this.bufferedBarColor,
    this.barCapShape = BarCapShape.round,
    this.thumbRadius = 10.0,
    this.thumbColor,
    this.thumbGlowColor,
    this.thumbGlowRadius = 30.0,
    this.thumbCanPaintOutsideBar = true,
    this.timeLabelLocation,
    this.timeLabelType,
    this.timeLabelTextStyle,
    this.timeLabelPadding = 0.0,
  }) : super(key: key);

  /// The elapsed playing time of the media.
  ///
  /// This should not be greater than the [total] time.
  final Duration progress;

  /// The total duration of the media.
  final Duration total;

  /// The currently buffered content of the media.
  ///
  /// This is useful for streamed content. If you are playing a local file
  /// then you can leave this out.
  final Duration? buffered;

  /// A callback when user moves the thumb.
  ///
  /// When the user moved the thumb on the progress bar this callback will
  /// run. It will not run until after the user has finished the touch event.
  ///
  /// You will get the chosen duration to start playing at which you can pass
  /// on to your media player.
  ///
  /// If you want continuous duration updates as the user moves the thumb,
  /// see [onDragUpdate], where the provided [ThumbDragDetails] has a
  /// `timeStamp` with the seek duration on it.
  final ValueChanged<Duration>? onSeek;

  /// A callback when the user starts to move the thumb.
  ///
  /// This will be called only once when the drag begins. This provides you
  /// with the [ThumbDragDetails].
  ///
  /// This method is useful if you are planning to do something like add a time
  /// label and/or video preview over the thumb and you need to do some
  /// initialization.
  ///
  /// Use [onSeek] if you only want to seek to a new audio position when the
  /// drag event has finished.
  final ThumbDragStartCallback? onDragStart;

  /// A callback when the user is moving the thumb.
  ///
  /// This will be called repeatedly as the thumb position changes. This
  /// provides you with the [ThumbDragDetails], which notify you of the global
  /// and local positions of the drag event as well as the current thumb
  /// duration. The current thumb duration will not go beyond [total] or less
  /// that `Duration.zero` so you can use this information to clamp the drag
  /// position values.
  ///
  /// This method is useful if you are planning to do something like add a time
  /// label and/or video preview over the thumb and need to update the position
  /// to stay in sync with the thumb position.
  ///
  /// Use [onSeek] if you only want to seek to a new audio position when the
  /// drag event has finished.
  final ThumbDragUpdateCallback? onDragUpdate;

  /// A callback when the user is finished moving the thumb.
  ///
  /// This will be called only once when the drag ends.
  ///
  /// This method is useful if you are planning to do something like add a time
  /// label and/or video preview over the thumb and you need to dispose of
  /// something when the drag is finished.
  ///
  /// This method is called directly before [onSeek].
  final VoidCallback? onDragEnd;

  /// The vertical thickness of the progress bar.
  final double barHeight;

  /// The color of the progress bar before playback has started.
  ///
  /// By default it is a transparent version of your theme's primary color.
  final Color? baseBarColor;

  /// The color of the progress bar to the left of the current playing
  /// [progress].
  ///
  /// By default it is your theme's primary color.
  final Color? progressBarColor;

  /// The color of the progress bar between the [progress] location and the
  /// [buffered] location.
  ///
  /// By default it is a transparent version of your theme's primary color,
  /// a shade darker than [baseBarColor].
  final Color? bufferedBarColor;

  /// The shape of the bar at the left and right ends.
  ///
  /// This affects the base bar for the total time, the current progress bar,
  /// and the buffered progress bar. The default is [BarCapShape.round].
  final BarCapShape barCapShape;

  /// The radius of the circle for the moveable progress bar thumb.
  final double thumbRadius;

  /// The color of the circle for the moveable progress bar thumb.
  ///
  /// By default it is your theme's primary color.
  final Color? thumbColor;

  /// The color of the pressed-down effect of the moveable progress bar thumb.
  ///
  /// By default it is [thumbColor] with an alpha value of 80.
  final Color? thumbGlowColor;

  /// The radius of the circle for the pressed-down effect of the moveable
  /// progress bar thumb.
  ///
  /// By default it is 30.
  final double thumbGlowRadius;

  /// Whether the thumb radius will before the start of the bar when at the
  /// beginning or after the end of the bar when at the end.
  ///
  /// The default is `true` and this means that the thumb will be painted
  /// outside of the bounds of the widget if there are no side labels. You can
  /// wrap [ProgressBar] with a `Padding` widget if your layout needs to leave
  /// some extra room for the thumb.
  ///
  /// When set to `false` the thumb will be clamped within the width of the
  /// bar. This is nice for aligning the thumb with vertical labels at the start
  /// and end of playback. However, because of the clamping, the thumb won't
  /// move during audio/video playback when near the ends. Depending on the
  /// size of the thumb and the length of the song, this usually only lasts
  /// a few seconds. The progress label still indicates that playback
  /// is happening during this time, though.
  final bool thumbCanPaintOutsideBar;

  /// The location for the [progress] and [total] duration text labels.
  ///
  /// By default the labels appear under the progress bar but you can also
  /// put them above, on the sides, or remove them altogether.
  final TimeLabelLocation? timeLabelLocation;

  /// What to display for the time label on the right
  ///
  /// The right time label can show the total time or the remaining time as a
  /// negative number. The default is [TimeLabelType.totalTime].
  final TimeLabelType? timeLabelType;

  /// The [TextStyle] used by the time labels.
  ///
  /// By default it is [TextTheme.bodyLarge].
  final TextStyle? timeLabelTextStyle;

  /// The extra space between the time labels and the progress bar.
  ///
  /// The default is 0.0. A positive number will move the labels further from
  /// the progress bar and a negative number will move them closer.
  final double timeLabelPadding;

  @override
  RenderObject createRenderObject(BuildContext context) {
    final theme = Theme.of(context);
    final primaryColor = theme.colorScheme.primary;
    final textStyle = timeLabelTextStyle ?? theme.textTheme.bodyLarge;
    final textScaleFactor = MediaQuery.textScaleFactorOf(context);
    return _RenderProgressBar(
      progress: progress,
      total: total,
      buffered: buffered ?? Duration.zero,
      onSeek: onSeek,
      onDragStart: onDragStart,
      onDragUpdate: onDragUpdate,
      onDragEnd: onDragEnd,
      barHeight: barHeight,
      baseBarColor: baseBarColor ?? primaryColor.withOpacity(0.24),
      progressBarColor: progressBarColor ?? primaryColor,
      bufferedBarColor: bufferedBarColor ?? primaryColor.withOpacity(0.24),
      barCapShape: barCapShape,
      thumbRadius: thumbRadius,
      thumbColor: thumbColor ?? primaryColor,
      thumbGlowColor:
      thumbGlowColor ?? (thumbColor ?? primaryColor).withAlpha(80),
      thumbGlowRadius: thumbGlowRadius,
      thumbCanPaintOutsideBar: thumbCanPaintOutsideBar,
      timeLabelLocation: timeLabelLocation ?? TimeLabelLocation.below,
      timeLabelType: timeLabelType ?? TimeLabelType.totalTime,
      timeLabelTextStyle: textStyle,
      timeLabelPadding: timeLabelPadding,
      textScaleFactor: textScaleFactor,
    );
  }

  @override
  void updateRenderObject(BuildContext context, RenderObject renderObject) {
    final theme = Theme.of(context);
    final primaryColor = theme.colorScheme.primary;
    final textStyle = timeLabelTextStyle ?? theme.textTheme.bodyLarge;
    final textScaleFactor = MediaQuery.textScaleFactorOf(context);
    (renderObject as _RenderProgressBar)
      ..progress = progress
      ..total = total
      ..buffered = buffered ?? Duration.zero
      ..onSeek = onSeek
      ..onDragStart = onDragStart
      ..onDragUpdate = onDragUpdate
      ..onDragEnd = onDragEnd
      ..barHeight = barHeight
      ..baseBarColor = baseBarColor ?? primaryColor.withOpacity(0.24)
      ..progressBarColor = progressBarColor ?? primaryColor
      ..bufferedBarColor = bufferedBarColor ?? primaryColor.withOpacity(0.24)
      ..barCapShape = barCapShape
      ..thumbRadius = thumbRadius
      ..thumbColor = thumbColor ?? primaryColor
      ..thumbGlowColor =
          thumbGlowColor ?? (thumbColor ?? primaryColor).withAlpha(80)
      ..thumbGlowRadius = thumbGlowRadius
      ..thumbCanPaintOutsideBar = thumbCanPaintOutsideBar
      ..timeLabelLocation = timeLabelLocation ?? TimeLabelLocation.below
      ..timeLabelType = timeLabelType ?? TimeLabelType.totalTime
      ..timeLabelTextStyle = textStyle
      ..timeLabelPadding = timeLabelPadding
      ..textScaleFactor = textScaleFactor;
  }

  @override
  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
    super.debugFillProperties(properties);
    properties.add(StringProperty('progress', progress.toString()));
    properties.add(StringProperty('total', total.toString()));
    properties.add(StringProperty('buffered', buffered.toString()));
    properties.add(ObjectFlagProperty<ValueChanged<Duration>>('onSeek', onSeek,
        ifNull: 'unimplemented'));
    properties.add(ObjectFlagProperty<ThumbDragStartCallback>(
        'onDragStart', onDragStart,
        ifNull: 'unimplemented'));
    properties.add(ObjectFlagProperty<ThumbDragUpdateCallback>(
        'onDragUpdate', onDragUpdate,
        ifNull: 'unimplemented'));
    properties.add(ObjectFlagProperty<VoidCallback>('onDragEnd', onDragEnd,
        ifNull: 'unimplemented'));
    properties.add(DoubleProperty('barHeight', barHeight));
    properties.add(ColorProperty('baseBarColor', baseBarColor));
    properties.add(ColorProperty('progressBarColor', progressBarColor));
    properties.add(ColorProperty('bufferedBarColor', bufferedBarColor));
    properties.add(StringProperty('barCapShape', barCapShape.toString()));
    properties.add(DoubleProperty('thumbRadius', thumbRadius));
    properties.add(ColorProperty('thumbColor', thumbColor));
    properties.add(ColorProperty('thumbGlowColor', thumbGlowColor));
    properties.add(DoubleProperty('thumbGlowRadius', thumbGlowRadius));
    properties.add(
      FlagProperty(
        'thumbCanPaintOutsideBar',
        value: thumbCanPaintOutsideBar,
        ifTrue: 'true',
        ifFalse: 'false',
        showName: true,
      ),
    );
    properties
        .add(StringProperty('timeLabelLocation', timeLabelLocation.toString()));
    properties.add(StringProperty('timeLabelType', timeLabelType.toString()));
    properties
        .add(DiagnosticsProperty('timeLabelTextStyle', timeLabelTextStyle));
    properties.add(DoubleProperty('timeLabelPadding', timeLabelPadding));
  }
}

/// The callback signature for when the thumb begins a horizontal drag.
typedef ThumbDragStartCallback = void Function(ThumbDragDetails details);

/// The callback signature for when the thumb is moving on horizontally and has
/// new data.
typedef ThumbDragUpdateCallback = void Function(ThumbDragDetails details);

/// Data to pass back on drag callback events
class ThumbDragDetails {
  const ThumbDragDetails({
    this.timeStamp = Duration.zero,
    this.globalPosition = Offset.zero,
    this.localPosition = Offset.zero,
  });

  /// The duration position of the thumb on the progress bar
  final Duration timeStamp;

  /// The global position of the drag event moving the thumb on the progress bar.
  final Offset globalPosition;

  /// The local position of the drag event moving the thumb on the progress bar.
  final Offset localPosition;

  @override
  String toString() => '${objectRuntimeType(this, 'ThumbDragDetails')}('
      'time: $timeStamp, '
      'global: $globalPosition, '
      'local: $localPosition)';
}

// Handles all gestures so that it will always win a the gesture arena.
// Without doing this, if you used this widget in a swipable tab layout,
// you would cause a swipe rather than a drag when trying to move the thumb.
class _EagerHorizontalDragGestureRecognizer
    extends HorizontalDragGestureRecognizer {
  @override
  void addAllowedPointer(PointerDownEvent event) {
    super.addAllowedPointer(event);
    resolve(GestureDisposition.accepted);
  }

  @override
  String get debugDescription => '_EagerHorizontalDragGestureRecognizer';
}

class _RenderProgressBar extends RenderBox {
  _RenderProgressBar({
    required Duration progress,
    required Duration total,
    required Duration buffered,
    ValueChanged<Duration>? onSeek,
    ThumbDragStartCallback? onDragStart,
    ThumbDragUpdateCallback? onDragUpdate,
    VoidCallback? onDragEnd,
    required double barHeight,
    required Color baseBarColor,
    required Color progressBarColor,
    required Color bufferedBarColor,
    required BarCapShape barCapShape,
    double thumbRadius = 20.0,
    required Color thumbColor,
    required Color thumbGlowColor,
    double thumbGlowRadius = 30.0,
    bool thumbCanPaintOutsideBar = true,
    required TimeLabelLocation timeLabelLocation,
    required TimeLabelType timeLabelType,
    TextStyle? timeLabelTextStyle,
    double timeLabelPadding = 0.0,
    double textScaleFactor = 1.0,
  })  : _total = total,
        _buffered = buffered,
        _onSeek = onSeek,
        _onDragStartUserCallback = onDragStart,
        _onDragUpdateUserCallback = onDragUpdate,
        _onDragEndUserCallback = onDragEnd,
        _barHeight = barHeight,
        _baseBarColor = baseBarColor,
        _progressBarColor = progressBarColor,
        _bufferedBarColor = bufferedBarColor,
        _barCapShape = barCapShape,
        _thumbRadius = thumbRadius,
        _thumbColor = thumbColor,
        _thumbGlowColor = thumbGlowColor,
        _thumbGlowRadius = thumbGlowRadius,
        _thumbCanPaintOutsideBar = thumbCanPaintOutsideBar,
        _timeLabelLocation = timeLabelLocation,
        _timeLabelType = timeLabelType,
        _timeLabelTextStyle = timeLabelTextStyle,
        _timeLabelPadding = timeLabelPadding,
        _textScaleFactor = textScaleFactor {
    _drag = _EagerHorizontalDragGestureRecognizer()
      ..onStart = _onDragStart
      ..onUpdate = _onDragUpdate
      ..onEnd = _onDragEnd
      ..onCancel = _finishDrag;
    if (!_userIsDraggingThumb) {
      _progress = progress;
      _thumbValue = _proportionOfTotal(_progress);
    }
  }

  // This is the gesture recognizer used to move the thumb.
  _EagerHorizontalDragGestureRecognizer? _drag;

  // This is a value between 0.0 and 1.0 used to indicate the position on
  // the bar.
  late double _thumbValue;

  // The thumb can move for two reasons. One is that the [progress] changed.
  // The other is that the user is dragging the thumb. This variable keeps
  // track of that so that while the user is dragging the thumb at the same
  // time as a [progress] update there won't be a conflict.
  bool _userIsDraggingThumb = false;

  // This padding is always used between the time labels and the progress bar
  // when the time labels are on the sides. Any user defined [timeLabelPadding]
  // is in addition to this.
  double get _defaultSidePadding {
    const minPadding = 5.0;
    return (_thumbCanPaintOutsideBar) ? thumbRadius + minPadding : minPadding;
  }

  void _onDragStart(DragStartDetails details) {
    _userIsDraggingThumb = true;
    _updateThumbPosition(details.localPosition);
    onDragStart?.call(ThumbDragDetails(
      timeStamp: _currentThumbDuration(),
      globalPosition: details.globalPosition,
      localPosition: details.localPosition,
    ));
  }

  void _onDragUpdate(DragUpdateDetails details) {
    _updateThumbPosition(details.localPosition);
    onDragUpdate?.call(ThumbDragDetails(
      timeStamp: _currentThumbDuration(),
      globalPosition: details.globalPosition,
      localPosition: details.localPosition,
    ));
  }

  void _onDragEnd(DragEndDetails details) {
    onDragEnd?.call();
    onSeek?.call(_currentThumbDuration());
    _finishDrag();
  }

  void _finishDrag() {
    _userIsDraggingThumb = false;
    markNeedsPaint();
  }

  Duration _currentThumbDuration() {
    final thumbMilliseconds = _thumbValue * total.inMilliseconds;
    return Duration(milliseconds: thumbMilliseconds.round());
  }

  // This needs to stay in sync with the layout. This could be a potential
  // source of bugs if there is a layout change but we forget to update this.
  // It might be a good idea to redesign the architecture so that there is
  // only one place to make changes.
  void _updateThumbPosition(Offset localPosition) {
    final dx = localPosition.dx;
    double lengthBefore = 0.0;
    double lengthAfter = 0.0;
    if (_timeLabelLocation == TimeLabelLocation.sides) {
      lengthBefore =
          _leftLabelSize.width + _defaultSidePadding + _timeLabelPadding;
      lengthAfter =
          _rightLabelSize.width + _defaultSidePadding + _timeLabelPadding;
    }
    // The paint used to draw the bar line draws half of the cap before the
    // start of the line (and after the end of the line). The cap radius is
    // equal to half of the line width, which in this case is the bar height.
    final barCapRadius = _barHeight / 2;
    double barStart = lengthBefore + barCapRadius;
    double barEnd = size.width - lengthAfter - barCapRadius;
    final barWidth = barEnd - barStart;
    final position = (dx - barStart).clamp(0.0, barWidth);
    _thumbValue = (position / barWidth);
    _progress = _currentThumbDuration();
    markNeedsPaint();
  }

  /// The play location of the media.
  ///
  /// This is used to update the thumb value and the left time label.
  Duration get progress => _progress;
  Duration _progress = Duration.zero;
  set progress(Duration value) {
    final clamp = _clampDuration(value);
    if (_progress == clamp) {
      return;
    }
    if (_labelLengthDifferent(_progress, clamp)) {
      _clearLabelCache();
    }
    if (!_userIsDraggingThumb) {
      _progress = clamp;
      _thumbValue = _proportionOfTotal(clamp);
    }
    markNeedsPaint();
  }

  bool _labelLengthDifferent(Duration first, Duration second) {
    return (first.inMinutes < 10 && second.inMinutes >= 10) ||
        (first.inMinutes >= 10 && second.inMinutes < 10) ||
        (first.inHours == 0 && second.inHours != 0) ||
        (first.inHours != 0 && second.inHours == 0) ||
        (first.inHours < 10 && second.inHours >= 10) ||
        (first.inHours >= 10 && second.inHours < 10);
  }

  TextPainter? _cachedLeftLabel;
  Size get _leftLabelSize {
    _cachedLeftLabel ??= _leftTimeLabel();
    return _cachedLeftLabel!.size;
  }

  TextPainter? _cachedRightLabel;
  Size get _rightLabelSize {
    _cachedRightLabel ??= _rightTimeLabel();
    return _cachedRightLabel!.size;
  }

  void _clearLabelCache() {
    _cachedLeftLabel = null;
    _cachedRightLabel = null;
  }

  TextPainter _leftTimeLabel() {
    final text = _getTimeString(progress);
    return _layoutText(text);
  }

  TextPainter _rightTimeLabel() {
    switch (timeLabelType) {
      case TimeLabelType.totalTime:
        final text = _getTimeString(total);
        return _layoutText(text);
      case TimeLabelType.remainingTime:
        final remaining = total - progress;
        final text = '-${_getTimeString(remaining)}';
        return _layoutText(text);
    }
  }

  TextPainter _layoutText(String text) {
    TextPainter textPainter = TextPainter(
      text: TextSpan(text: text, style: _timeLabelTextStyle),
      textDirection: TextDirection.ltr,
      textScaleFactor: textScaleFactor,
    );
    textPainter.layout(minWidth: 0, maxWidth: double.infinity);
    return textPainter;
  }

  /// The total time length of the media.
  Duration get total => _total;
  Duration _total;
  set total(Duration value) {
    final clamp = (value.isNegative) ? Duration.zero : value;
    if (_total == clamp) {
      return;
    }
    if (_labelLengthDifferent(_total, clamp)) {
      _clearLabelCache();
    }
    _total = clamp;
    if (!_userIsDraggingThumb) {
      _thumbValue = _proportionOfTotal(progress);
    }
    markNeedsPaint();
  }

  /// The buffered length of the media when streaming.
  Duration get buffered => _buffered;
  Duration _buffered;
  set buffered(Duration value) {
    final clamp = _clampDuration(value);
    if (_buffered == clamp) {
      return;
    }
    _buffered = clamp;
    markNeedsPaint();
  }

  Duration _clampDuration(Duration value) {
    if (value.isNegative) return Duration.zero;
    if (value.compareTo(_total) > 0) return _total;
    return value;
  }

  /// A callback for the audio duration position to where the thumb was moved.
  ValueChanged<Duration>? get onSeek => _onSeek;
  ValueChanged<Duration>? _onSeek;
  set onSeek(ValueChanged<Duration>? value) {
    if (value == _onSeek) {
      return;
    }
    _onSeek = value;
  }

  /// A callback when the thumb starts being dragged.
  ThumbDragStartCallback? get onDragStart => _onDragStartUserCallback;
  ThumbDragStartCallback? _onDragStartUserCallback;
  set onDragStart(ThumbDragStartCallback? value) {
    if (value == _onDragStartUserCallback) {
      return;
    }
    _onDragStartUserCallback = value;
  }

  /// A callback when the thumb is being dragged.
  ThumbDragUpdateCallback? get onDragUpdate => _onDragUpdateUserCallback;
  ThumbDragUpdateCallback? _onDragUpdateUserCallback;
  set onDragUpdate(ThumbDragUpdateCallback? value) {
    if (value == _onDragUpdateUserCallback) {
      return;
    }
    _onDragUpdateUserCallback = value;
  }

  /// A callback when the thumb drag is finished.
  VoidCallback? get onDragEnd => _onDragEndUserCallback;
  VoidCallback? _onDragEndUserCallback;
  set onDragEnd(VoidCallback? value) {
    if (value == _onDragEndUserCallback) {
      return;
    }
    _onDragEndUserCallback = value;
  }

  /// The vertical thickness of the bar that the thumb moves along.
  double get barHeight => _barHeight;
  double _barHeight;
  set barHeight(double value) {
    if (_barHeight == value) return;
    _barHeight = value;
    markNeedsPaint();
  }

  /// The color of the progress bar before any playing or buffering.
  Color get baseBarColor => _baseBarColor;
  Color _baseBarColor;
  set baseBarColor(Color value) {
    if (_baseBarColor == value) return;
    _baseBarColor = value;
    markNeedsPaint();
  }

  /// The color of the played portion of the progress bar.
  Color get progressBarColor => _progressBarColor;
  Color _progressBarColor;
  set progressBarColor(Color value) {
    if (_progressBarColor == value) return;
    _progressBarColor = value;
    markNeedsPaint();
  }

  /// The color of the visible buffered portion of the progress bar.
  Color get bufferedBarColor => _bufferedBarColor;
  Color _bufferedBarColor;
  set bufferedBarColor(Color value) {
    if (_bufferedBarColor == value) return;
    _bufferedBarColor = value;
    markNeedsPaint();
  }

  BarCapShape get barCapShape => _barCapShape;
  BarCapShape _barCapShape;
  set barCapShape(BarCapShape value) {
    if (_barCapShape == value) return;
    _barCapShape = value;
    markNeedsPaint();
  }

  /// The color of the moveable thumb.
  Color get thumbColor => _thumbColor;
  Color _thumbColor;
  set thumbColor(Color value) {
    if (_thumbColor == value) return;
    _thumbColor = value;
    markNeedsPaint();
  }

  /// The length of the radius for the circular thumb.
  double get thumbRadius => _thumbRadius;
  double _thumbRadius;
  set thumbRadius(double value) {
    if (_thumbRadius == value) return;
    _thumbRadius = value;
    markNeedsLayout();
  }

  /// The color of the pressed-down effect of the moveable thumb.
  Color get thumbGlowColor => _thumbGlowColor;
  Color _thumbGlowColor;
  set thumbGlowColor(Color value) {
    if (_thumbGlowColor == value) return;
    _thumbGlowColor = value;
    if (_userIsDraggingThumb) markNeedsPaint();
  }

  /// The length of the radius of the pressed-down effect of the moveable thumb.
  double get thumbGlowRadius => _thumbGlowRadius;
  double _thumbGlowRadius;
  set thumbGlowRadius(double value) {
    if (_thumbGlowRadius == value) return;
    _thumbGlowRadius = value;
    markNeedsLayout();
  }

  /// Whether the thumb will paint before the start or after the end of the bar.
  bool get thumbCanPaintOutsideBar => _thumbCanPaintOutsideBar;
  bool _thumbCanPaintOutsideBar;
  set thumbCanPaintOutsideBar(bool value) {
    if (_thumbCanPaintOutsideBar == value) return;
    _thumbCanPaintOutsideBar = value;
    markNeedsPaint();
  }

  /// The position of the duration text labels for the progress and total time.
  TimeLabelLocation get timeLabelLocation => _timeLabelLocation;
  TimeLabelLocation _timeLabelLocation;
  set timeLabelLocation(TimeLabelLocation value) {
    if (_timeLabelLocation == value) return;
    _timeLabelLocation = value;
    markNeedsLayout();
  }

  /// What to display for the time label on the right
  ///
  /// The right time label can show the total time or the remaining time as a
  /// negative number. The default is [TimeLabelType.totalTime].
  TimeLabelType get timeLabelType => _timeLabelType;
  TimeLabelType _timeLabelType;
  set timeLabelType(TimeLabelType value) {
    if (_timeLabelType == value) return;
    _timeLabelType = value;
    _clearLabelCache();
    markNeedsLayout();
  }

  /// The text style for the duration text labels. By default this style is
  /// taken from the theme's [textStyle.bodyText1].
  TextStyle? get timeLabelTextStyle => _timeLabelTextStyle;
  TextStyle? _timeLabelTextStyle;
  set timeLabelTextStyle(TextStyle? value) {
    if (_timeLabelTextStyle == value) return;
    _timeLabelTextStyle = value;
    _clearLabelCache();
    markNeedsLayout();
  }

  /// The length of the radius for the circular thumb.
  double get timeLabelPadding => _timeLabelPadding;
  double _timeLabelPadding;
  set timeLabelPadding(double value) {
    if (_timeLabelPadding == value) return;
    _timeLabelPadding = value;
    markNeedsLayout();
  }

  /// The text scale factor for the `progress` and `total` text labels.
  /// By default the value is 1.0.
  double get textScaleFactor => _textScaleFactor;
  double _textScaleFactor;
  set textScaleFactor(double value) {
    if (_textScaleFactor == value) return;
    _textScaleFactor = value;
    _clearLabelCache();
    markNeedsLayout();
  }

  // The smallest that this widget would ever want to be.
  static const _minDesiredWidth = 100.0;

  @override
  double computeMinIntrinsicWidth(double height) => _minDesiredWidth;

  @override
  double computeMaxIntrinsicWidth(double height) => _minDesiredWidth;

  @override
  double computeMinIntrinsicHeight(double width) => _calculateDesiredHeight();

  @override
  double computeMaxIntrinsicHeight(double width) => _calculateDesiredHeight();

  @override
  bool hitTestSelf(Offset position) => true;

  @override
  void handleEvent(PointerEvent event, BoxHitTestEntry entry) {
    assert(debugHandleEvent(event, entry));
    if (event is PointerDownEvent) {
      _drag?.addPointer(event);
    }
  }

  @override
  void performLayout() {
    size = computeDryLayout(constraints);
  }

  @override
  Size computeDryLayout(BoxConstraints constraints) {
    final desiredWidth = constraints.maxWidth;
    final desiredHeight = _calculateDesiredHeight();
    final desiredSize = Size(desiredWidth, desiredHeight);
    return constraints.constrain(desiredSize);
  }

  // When changing these remember to keep the gesture recognizer for the
  // thumb in sync.
  double _calculateDesiredHeight() {
    switch (_timeLabelLocation) {
      case TimeLabelLocation.below:
      case TimeLabelLocation.above:
        return _heightWhenLabelsAboveOrBelow();
      case TimeLabelLocation.sides:
        return _heightWhenLabelsOnSides();
      default:
        return _heightWhenNoLabels();
    }
  }

  double _heightWhenLabelsAboveOrBelow() {
    return _heightWhenNoLabels() + _textHeight() + _timeLabelPadding;
  }

  double _heightWhenLabelsOnSides() {
    return max(_heightWhenNoLabels(), _textHeight());
  }

  double _heightWhenNoLabels() {
    return max(2 * _thumbRadius, _barHeight);
  }

  double _textHeight() {
    return _leftLabelSize.height;
  }

  @override
  bool get isRepaintBoundary => true;

  @override
  void paint(PaintingContext context, Offset offset) {
    final canvas = context.canvas;
    canvas.save();
    canvas.translate(offset.dx, offset.dy);

    switch (_timeLabelLocation) {
      case TimeLabelLocation.above:
      case TimeLabelLocation.below:
        _drawProgressBarWithLabelsAboveOrBelow(canvas);
        break;
      case TimeLabelLocation.sides:
        _drawProgressBarWithLabelsOnSides(canvas);
        break;
      default:
        _drawProgressBarWithoutLabels(canvas);
    }

    canvas.restore();
  }

  ///  Draw the progress bar and labels vertically aligned:
  ///
  ///  | -------O---------------- |
  ///  | 01:23              05:00 |
  ///
  /// Or like this:
  ///
  ///  | 01:23              05:00 |
  ///  | -------O---------------- |
  void _drawProgressBarWithLabelsAboveOrBelow(Canvas canvas) {
    // calculate sizes
    final barWidth = size.width;
    final barHeight = _heightWhenNoLabels();

    // whether to paint the labels below the progress bar or above it
    final isLabelBelow = _timeLabelLocation == TimeLabelLocation.below;

    // current time label
    final labelDy = (isLabelBelow) ? barHeight + _timeLabelPadding : 0.0;
    final leftLabelOffset = Offset(0, labelDy);
    _leftTimeLabel().paint(canvas, leftLabelOffset);

    // total or remaining time label
    final rightLabelDx = size.width - _rightLabelSize.width;
    final rightLabelOffset = Offset(rightLabelDx, labelDy);
    _rightTimeLabel().paint(canvas, rightLabelOffset);

    // progress bar
    final barDy =
    (isLabelBelow) ? 0.0 : _leftLabelSize.height + _timeLabelPadding;
    _drawProgressBar(canvas, Offset(0, barDy), Size(barWidth, barHeight));
  }

  ///  Draw the progress bar and labels horizontally aligned:
  ///
  ///  | 01:23 -------O---------------- 05:00 |
  ///
  void _drawProgressBarWithLabelsOnSides(Canvas canvas) {
    // left time label
    final leftLabelSize = _leftLabelSize;
    final verticalOffset = size.height / 2 - leftLabelSize.height / 2;
    final leftLabelOffset = Offset(0, verticalOffset);
    _leftTimeLabel().paint(canvas, leftLabelOffset);

    // right time label
    final rightLabelSize = _rightLabelSize;
    final rightLabelWidth = rightLabelSize.width;
    final totalLabelDx = size.width - rightLabelWidth;
    final totalLabelOffset = Offset(totalLabelDx, verticalOffset);
    _rightTimeLabel().paint(canvas, totalLabelOffset);

    // progress bar
    final leftLabelWidth = leftLabelSize.width;
    final barHeight = _heightWhenNoLabels();
    final barWidth = size.width -
        2 * _defaultSidePadding -
        2 * _timeLabelPadding -
        leftLabelWidth -
        rightLabelWidth;
    final barDy = size.height / 2 - barHeight / 2;
    final barDx = leftLabelWidth + _defaultSidePadding + _timeLabelPadding;
    _drawProgressBar(canvas, Offset(barDx, barDy), Size(barWidth, barHeight));
  }

  /// Draw the progress bar without labels like this:
  ///
  /// | -------O---------------- |
  ///
  void _drawProgressBarWithoutLabels(Canvas canvas) {
    final barWidth = size.width;
    final barHeight = 2 * _thumbRadius;
    _drawProgressBar(canvas, Offset.zero, Size(barWidth, barHeight));
  }

  void _drawProgressBar(Canvas canvas, Offset offset, Size localSize) {
    canvas.save();
    canvas.translate(offset.dx, offset.dy);
    _drawBaseBar(canvas, localSize);
    _drawBufferedBar(canvas, localSize);
    _drawCurrentProgressBar(canvas, localSize);
    _drawThumb(canvas, localSize);
    canvas.restore();
  }

  void _drawBaseBar(Canvas canvas, Size localSize) {
    _drawBar(
      canvas: canvas,
      availableSize: localSize,
      widthProportion: 1.0,
      color: baseBarColor,
    );
  }

  void _drawBufferedBar(Canvas canvas, Size localSize) {
    _drawBar(
      canvas: canvas,
      availableSize: localSize,
      widthProportion: _proportionOfTotal(_buffered),
      color: bufferedBarColor,
    );
  }

  void _drawCurrentProgressBar(Canvas canvas, Size localSize) {
    _drawBar(
      canvas: canvas,
      availableSize: localSize,
      widthProportion: _proportionOfTotal(_progress),
      color: progressBarColor,
    );
  }

  void _drawBar(
      {required Canvas canvas,
        required Size availableSize,
        required double widthProportion,
        required Color color}) {
    final strokeCap = (_barCapShape == BarCapShape.round)
        ? StrokeCap.round
        : StrokeCap.square;
    final baseBarPaint = Paint()
      ..color = color
      ..strokeCap = strokeCap
      ..strokeWidth = _barHeight;
    final capRadius = _barHeight / 2;
    final adjustedWidth = availableSize.width - barHeight;
    final dx = widthProportion * adjustedWidth + capRadius;
    final startPoint = Offset(capRadius, availableSize.height / 2);
    var endPoint = Offset(dx, availableSize.height / 2);
    canvas.drawLine(startPoint, endPoint, baseBarPaint);
  }

  void _drawThumb(Canvas canvas, Size localSize) {
    final thumbPaint = Paint()..color = thumbColor;
    final barCapRadius = _barHeight / 2;
    final availableWidth = localSize.width - _barHeight;
    var thumbDx = _thumbValue * availableWidth + barCapRadius;
    if (!_thumbCanPaintOutsideBar) {
      thumbDx = thumbDx.clamp(_thumbRadius, localSize.width - _thumbRadius);
    }
    final center = Offset(thumbDx, localSize.height / 2);
    if (_userIsDraggingThumb) {
      final thumbGlowPaint = Paint()..color = thumbGlowColor;
      canvas.drawCircle(center, thumbGlowRadius, thumbGlowPaint);
    }
    canvas.drawCircle(center, thumbRadius, thumbPaint);
  }

  double _proportionOfTotal(Duration duration) {
    if (total.inMilliseconds == 0) {
      return 0.0;
    }
    return duration.inMilliseconds / total.inMilliseconds;
  }

  String _getTimeString(Duration time) {
    final minutes =
    time.inMinutes.remainder(Duration.minutesPerHour).toString();
    final seconds = time.inSeconds
        .remainder(Duration.secondsPerMinute)
        .toString()
        .padLeft(2, '0');
    return time.inHours > 0
        ? "${time.inHours}:${minutes.padLeft(2, "0")}:$seconds"
        : "$minutes:$seconds";
  }

  @override
  void describeSemanticsConfiguration(SemanticsConfiguration config) {
    super.describeSemanticsConfiguration(config);

    // description
    config.textDirection = TextDirection.ltr;
    config.label = '进度条';//'Progress bar';
    config.value = '${(_thumbValue * 100).round()}%';

    // increase action
    config.onIncrease = increaseAction;
    final increased = _thumbValue + _semanticActionUnit;
    config.increasedValue = '${((increased).clamp(0.0, 1.0) * 100).round()}%';

    // decrease action
    config.onDecrease = decreaseAction;
    final decreased = _thumbValue - _semanticActionUnit;
    config.decreasedValue = '${((decreased).clamp(0.0, 1.0) * 100).round()}%';
  }

  // This is how much to move the thumb if the move is triggered by a
  // semantic action rather than a touch event.
  static const double _semanticActionUnit = 0.05;

  void increaseAction() {
    final newValue = _thumbValue + _semanticActionUnit;
    _thumbValue = (newValue).clamp(0.0, 1.0);
    markNeedsPaint();
    markNeedsSemanticsUpdate();
    onSeek?.call(_currentThumbDuration());
  }

  void decreaseAction() {
    final newValue = _thumbValue - _semanticActionUnit;
    _thumbValue = (newValue).clamp(0.0, 1.0);
    markNeedsPaint();
    markNeedsSemanticsUpdate();
    onSeek?.call(_currentThumbDuration());
  }
}