import 'dart:math' as math;

import 'package:flutter/material.dart';

/// Creates a shape constituting a transition between a rectangle and a circle.
///
/// ```dart
/// Widget build(BuildContext context) {
///   return Material(
///     shape: SuperellipseShape(
///       borderRadius: BorderRadius.circular(24.0),
///     ),
///   );
/// }
/// ```
class SuperellipseShape extends ShapeBorder {
  /// The arguments must not be null.
  const SuperellipseShape({
    this.side = BorderSide.none,
    this.borderRadius = BorderRadius.zero,
  });

  /// The radii for each corner.
  ///
  /// Each corner [Radius] defines the endpoints for a line segment that
  /// spans the corner. The endpoints are located in the same place as
  /// They would be for [RoundedRectangleBorder].
  ///
  /// Negative radius values are clamped to 0.0 by [getInnerPath] and
  /// [getOuterPath].
  final BorderRadiusGeometry borderRadius;

  /// The style of this border.
  final BorderSide side;

  @override
  EdgeInsetsGeometry get dimensions => EdgeInsets.all(side.width);

  @override
  ShapeBorder scale(double t) {
    return SuperellipseShape(
      side: side.scale(t),
      borderRadius: borderRadius * t,
    );
  }

  double _clampToShortest(RRect rrect, double value) =>
      value > rrect.shortestSide ? rrect.shortestSide : value;

  Path _getPath(RRect rrect) {
    /// Define the different variables of [rrect].
    final double left = rrect.left;
    final double right = rrect.right;
    final double top = rrect.top;
    final double bottom = rrect.bottom;

    /// Radii will be clamped to the value of the shortest side
    /// of [rrect] to avoid strange tie-fighter shapes.
    final double tlRadiusX =
        math.max(0.0, _clampToShortest(rrect, rrect.tlRadiusX));
    final double tlRadiusY =
        math.max(0.0, _clampToShortest(rrect, rrect.tlRadiusY));
    final double trRadiusX =
        math.max(0.0, _clampToShortest(rrect, rrect.trRadiusX));
    final double trRadiusY =
        math.max(0.0, _clampToShortest(rrect, rrect.trRadiusY));
    final double blRadiusX =
        math.max(0.0, _clampToShortest(rrect, rrect.blRadiusX));
    final double blRadiusY =
        math.max(0.0, _clampToShortest(rrect, rrect.blRadiusY));
    final double brRadiusX =
        math.max(0.0, _clampToShortest(rrect, rrect.brRadiusX));
    final double brRadiusY =
        math.max(0.0, _clampToShortest(rrect, rrect.brRadiusY));

    return Path()
      ..moveTo(left, top + tlRadiusX)
      ..cubicTo(left, top, left, top, left + tlRadiusY, top)
      ..lineTo(right - trRadiusX, top)
      ..cubicTo(right, top, right, top, right, top + trRadiusY)
      ..lineTo(right, bottom - blRadiusX)
      ..cubicTo(right, bottom, right, bottom, right - blRadiusY, bottom)
      ..lineTo(left + brRadiusX, bottom)
      ..cubicTo(left, bottom, left, bottom, left, bottom - brRadiusY)
      ..close();
  }

  @override
  Path getInnerPath(Rect rect, {TextDirection? textDirection}) {
    return _getPath(
        borderRadius.resolve(textDirection).toRRect(rect).deflate(side.width));
  }

  @override
  Path getOuterPath(Rect rect, {TextDirection? textDirection}) {
    return _getPath(borderRadius.resolve(textDirection).toRRect(rect));
  }

  @override
  void paint(Canvas canvas, Rect rect, {TextDirection? textDirection}) {
    if (rect.isEmpty) return;
    switch (side.style) {
      case BorderStyle.none:
        break;
      case BorderStyle.solid:
        Path path = getOuterPath(rect, textDirection: textDirection);
        var paint = side.toPaint();
        canvas.drawPath(path, paint);
        break;
    }
  }
}