import 'dart:ui' show lerpDouble;

import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';

import 'material_state.dart';
import 'theme_data.dart';

/// The visual properties that most selection controls have in common.
///
/// Checkboxes, radio buttons, switches and their themes have a SelectionControlStyle
/// property which defines the visual properties whose default values are to be
/// overridden. The default values are defined by the individual selection control
/// widgets and are typically based on the overall theme's [ThemeData.colorScheme].
///
/// All of the SelectionControlStyle properties are null by default.
///
/// Many of the SelectionControlStyle properties are [MaterialStateProperty] objects
/// which resolve to different values depending on the selection control's state. For
/// example, the [Color] properties are defined with `MaterialStateProperty<Color>`
/// and can resolve to different colors depending on if the control is selected,
/// hovered, focused, disabled, etc.
///
/// These properties can override the default value for just one state or all of
/// them. For example to create a [Checkbox] whose color is the color scheme’s primary
/// color with 50% opacity, but only when the checkbox is indeterminate, one could
/// write:
///
/// ```dart
/// Checkbox(
///   style: SelectionControlStyle(
///     color: MaterialStateProperty.resolveWith<Color>(
///       (Set<MaterialState> states) {
///         if (states.contains(MaterialState.indeterminate))
///           return Theme.of(context).colorScheme.primary.withOpacity(0.5);
///         return null; // Use the component's default.
///       },
///     ),
///   ),
/// )
///```
///
/// In this case the color for all other button states would fallback to the
/// checkbox’s default values. To unconditionally set the checkbox's [color]
/// for all states one could write:
///
/// ```dart
/// Checkbox(
///   style: SelectionControlStyle(
///     color: MaterialStateProperty.all<Color>(Colors.green),
///   ),
/// )
///```
///
/// Configuring a SelectionControlStyle directly makes it possible to very
/// precisely control the selection control’s visual attributes for all states.
/// This level of control is typically required when a custom
/// “branded” look and feel is desirable.  However, in many cases it’s
/// useful to make relatively sweeping changes based on a few initial
/// parameters with simple values. The selection control styleFrom() methods
/// enable such sweeping changes. See:
/// [Checkbox.styleFrom], [Radio.styleFrom], [Switch.styleFrom].
///
/// For example, to override the default color for a [Checkbox] with all
/// of the standard opacity adjustments for the pressed, focused, and
/// hovered states, one could write:
///
/// ```dart
/// Checkbox(
///   style: Checkbox.styleFrom(secondary: Colors.green),
/// )
///```
///
/// To configure all of the application's checkboxes in the same
/// way, specify the overall theme's `checkboxTheme`:
/// ```dart
/// MaterialApp(
///   theme: ThemeData(
///     checkboxTheme: CheckboxThemeData(
///       style: Checkbox.styleFrom(secondary: Colors.green),
///     ),
///   ),
///   home: MyAppHome(),
/// )
///```
/// See also:
///
///  * [CheckboxTheme], the theme for [Checkbox]es.
///  * [RadioTheme], the theme for [Radio] buttons.
///  * [SwitchTheme], the theme for [Switch]es.
@immutable
class SelectionControlStyle with Diagnosticable {
  /// Create a [SelectionControlStyle].
  const SelectionControlStyle({
    this.color,
    this.overlayColor,
    this.padding,
    this.minimumSize,
    this.mouseCursor,
    this.visualDensity,
    this.tapTargetSize,
    this.enableFeedback,
  });

  /// The main color used for the selection control.
  final MaterialStateProperty<Color> color;

  /// The highlight color that's typically used to indicate that
  /// the control is focused, hovered, or pressed.
  final MaterialStateProperty<Color> overlayColor;

  /// The padding between the control's boundary and its child.
  final MaterialStateProperty<EdgeInsetsGeometry> padding;

  /// The minimum size of the control itself.
  ///
  /// The size of the rectangle the control lies within may be larger
  /// per [tapTargetSize].
  final MaterialStateProperty<Size> minimumSize;

  /// The cursor for a mouse pointer when it enters or is hovering over
  /// this control's [InkWell].
  final MaterialStateProperty<MouseCursor> mouseCursor;

  /// Defines how compact the control's layout will be.
  ///
  /// {@macro flutter.material.themeData.visualDensity}
  ///
  /// See also:
  ///
  ///  * [ThemeData.visualDensity], which specifies the [visualDensity] for all widgets
  ///    within a [Theme].
  final VisualDensity visualDensity;

  /// Configures the minimum size of the area within which the control may be pressed.
  ///
  /// If the [tapTargetSize] is larger than [minimumSize], the control will include
  /// a transparent margin that responds to taps.
  ///
  /// Always defaults to [ThemeData.materialTapTargetSize].
  final MaterialTapTargetSize tapTargetSize;

  /// Whether detected gestures should provide acoustic and/or haptic feedback.
  ///
  /// For example, on Android a tap will produce a clicking sound and a
  /// long-press will produce a short vibration, when feedback is enabled.
  ///
  /// Typically the component default value is true.
  ///
  /// See also:
  ///
  ///  * [Feedback] for providing platform-specific feedback to certain actions.
  final bool enableFeedback;

  /// Returns a copy of this SelectionControlStyle with the given fields replaced
  /// with the new values.
  SelectionControlStyle copyWith({
    MaterialStateProperty<Color> color,
    MaterialStateProperty<Color> overlayColor,
    MaterialStateProperty<EdgeInsetsGeometry> padding,
    MaterialStateProperty<Size> minimumSize,
    MaterialStateProperty<MouseCursor> mouseCursor,
    VisualDensity visualDensity,
    MaterialTapTargetSize tapTargetSize,
    bool enableFeedback,
  }) {
    return SelectionControlStyle(
      color: color ?? this.color,
      overlayColor: overlayColor ?? this.overlayColor,
      padding: padding ?? this.padding,
      minimumSize: minimumSize ?? this.minimumSize,
      mouseCursor: mouseCursor ?? this.mouseCursor,
      visualDensity: visualDensity ?? this.visualDensity,
      tapTargetSize: tapTargetSize ?? this.tapTargetSize,
      enableFeedback: enableFeedback ?? this.enableFeedback,
    );
  }

  /// Returns a copy of this SelectionControlStyle where the non-null fields in [style]
  /// have replaced the corresponding null fields in this SelectionControlStyle.
  ///
  /// In other words, [style] is used to fill in unspecified (null) fields in
  /// this SelectionControlStyle.
  SelectionControlStyle merge(SelectionControlStyle style) {
    if (style == null)
      return this;
    return copyWith(
      color: color ?? style.color,
      overlayColor: overlayColor ?? style.overlayColor,
      padding: padding ?? style.padding,
      minimumSize: minimumSize ?? style.minimumSize,
      mouseCursor: mouseCursor ?? style.mouseCursor,
      visualDensity: visualDensity ?? style.visualDensity,
      tapTargetSize: tapTargetSize ?? style.tapTargetSize,
      enableFeedback: enableFeedback ?? style.enableFeedback,
    );
  }

  @override
  int get hashCode {
    return hashValues(
      color,
      overlayColor,
      padding,
      minimumSize,
      mouseCursor,
      visualDensity,
      tapTargetSize,
      enableFeedback,
    );
  }

  @override
  bool operator ==(Object other) {
    if (identical(this, other))
      return true;
    if (other.runtimeType != runtimeType)
      return false;
    return other is SelectionControlStyle
        && other.color == color
        && other.overlayColor == overlayColor
        && other.padding == padding
        && other.minimumSize == minimumSize
        && other.mouseCursor == mouseCursor
        && other.visualDensity == visualDensity
        && other.tapTargetSize == tapTargetSize
        && other.enableFeedback == enableFeedback;
  }

  @override
  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
    super.debugFillProperties(properties);
    properties.add(DiagnosticsProperty<MaterialStateProperty<Color>>('color', color, defaultValue: null));
    properties.add(DiagnosticsProperty<MaterialStateProperty<Color>>('overlayColor', overlayColor, defaultValue: null));
    properties.add(DiagnosticsProperty<MaterialStateProperty<EdgeInsetsGeometry>>('padding', padding, defaultValue: null));
    properties.add(DiagnosticsProperty<MaterialStateProperty<Size>>('minimumSize', minimumSize, defaultValue: null));
    properties.add(DiagnosticsProperty<MaterialStateProperty<MouseCursor>>('mouseCursor', mouseCursor, defaultValue: null));
    properties.add(DiagnosticsProperty<VisualDensity>('visualDensity', visualDensity, defaultValue: null));
    properties.add(EnumProperty<MaterialTapTargetSize>('tapTargetSize', tapTargetSize, defaultValue: null));
    properties.add(DiagnosticsProperty<bool>('enableFeedback', enableFeedback, defaultValue: null));
  }

  /// Linearly interpolate between two [SelectionControlStyle]s.
  static SelectionControlStyle lerp(SelectionControlStyle a, SelectionControlStyle b, double t) {
    assert (t != null);
    if (a == null && b == null)
      return null;
    return SelectionControlStyle(
      color: _lerpProperties<Color>(a?.color, b?.color, t, Color.lerp),
      overlayColor: _lerpProperties<Color>(a?.overlayColor, b?.overlayColor, t, Color.lerp),
      padding:  _lerpProperties<EdgeInsetsGeometry>(a?.padding, b?.padding, t, EdgeInsetsGeometry.lerp),
      minimumSize: _lerpProperties<Size>(a?.minimumSize, b?.minimumSize, t, Size.lerp),
      mouseCursor: t < 0.5 ? a.mouseCursor : b.mouseCursor,
      visualDensity: t < 0.5 ? a.visualDensity : b.visualDensity,
      tapTargetSize: t < 0.5 ? a.tapTargetSize : b.tapTargetSize,
      enableFeedback: t < 0.5 ? a.enableFeedback : b.enableFeedback,
    );
  }

  static MaterialStateProperty<T> _lerpProperties<T>(MaterialStateProperty<T> a, MaterialStateProperty<T> b, double t, T Function(T, T, double) lerpFunction ) {
    // Avoid creating a _LerpProperties object for a common case.
    if (a == null && b == null)
      return null;
    return _LerpProperties<T>(a, b, t, lerpFunction);
  }
}

class _LerpProperties<T> implements MaterialStateProperty<T> {
  const _LerpProperties(this.a, this.b, this.t, this.lerpFunction);

  final MaterialStateProperty<T> a;
  final MaterialStateProperty<T> b;
  final double t;
  final T Function(T, T, double) lerpFunction;

  @override
  T resolve(Set<MaterialState> states) {
    final T resolvedA = a?.resolve(states);
    final T resolvedB = b?.resolve(states);
    return lerpFunction(resolvedA, resolvedB, t);
  }
}