library ribbon;

import 'package:flutter/material.dart';
import 'dart:math' as math;

import 'package:nhance_app_pwa/logger.dart';

const TextStyle _kTextStyle = TextStyle(
    color: Color(0xFFFFFFFF),
    fontSize: 12,
    fontWeight: FontWeight.w900,
    height: 1.0);

enum RibbonLocation {
  topStart,
  topEnd,
  bottomStart,
  bottomEnd,
}

class Ribbon extends StatelessWidget {
  final double nearLength;
  final double farLength;
  final String title;
  final Color color;
  final TextStyle titleStyle;
  final RibbonLocation location;
  final Widget child;

  const Ribbon(
      {Key? key,
        required this.nearLength,
        required this.farLength,
        required this.title,
        this.titleStyle = _kTextStyle,
        this.color = Colors.white,
        this.location = RibbonLocation.topStart,
        required this.child})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return CustomPaint(
        foregroundPainter: _RibbonPainter(
          nearLength: nearLength,
          farLength: farLength,
          title: title,
          titleStyle: titleStyle,
          color: color,
          location: location,
        ),
        child: child);
  }
}

class _RibbonPainter extends CustomPainter {
  double nearLength;
  double farLength;
  final String title;
  final Color color;
  final TextStyle titleStyle;
  final RibbonLocation location;
  bool initialized = false;
  late TextPainter textPainter;
  late Paint paintRibbon;
  late Path pathRibbon;
  late double rotateRibbon;
  late Offset offsetRibbon;
  late Offset offsetTitle;
  late Paint paintShadow;

  static const BoxShadow _shadow = BoxShadow(
    color: Color(0x7F000000),
    blurRadius: 6.0,
  );

  _RibbonPainter(
      {required this.nearLength,
        required this.farLength,
        required this.title,
        required this.titleStyle,
        required this.color,
        required this.location});

  @override
  void paint(Canvas canvas, Size size) {
    if (!initialized) _initializ(size);
    // canvas.drawPath(pathRibbon, paintShadow);
    canvas
      ..drawShadow(pathRibbon, const Color(0x7F000000), 2.0, true)
      ..drawPath(pathRibbon, paintRibbon)
    // canvas
      ..translate(offsetRibbon.dx, offsetRibbon.dy)
      ..rotate(rotateRibbon);
    // ..clipPath(pathRibbon);
    textPainter.paint(canvas, offsetTitle);
  }

  @override
  bool shouldRepaint(_RibbonPainter oldDelegate) {
    return title != oldDelegate.title ||
        nearLength != oldDelegate.nearLength ||
        farLength != oldDelegate.farLength ||
        color != oldDelegate.color ||
        location != oldDelegate.location;
  }

  void _initializ(Size size) {
    initialized = true;
    if (nearLength > farLength) {
      double temp = farLength;
      farLength = nearLength;
      nearLength = temp;
    }
    if (farLength > size.width) farLength = size.width;
    TextSpan span = TextSpan(style: titleStyle, text: title);
    textPainter = TextPainter(
        text: span,
        textAlign: TextAlign.center,
        textDirection: TextDirection.ltr);
    textPainter.layout();
    paintRibbon = Paint()
      ..color = color
      ..style = PaintingStyle.fill;
    offsetTitle = Offset(-textPainter.width / 2, -textPainter.height / 2);
    rotateRibbon = _rotation;
    pathRibbon = _ribbonPath(size);
    paintShadow = _shadow.toPaint();
  }

  Path _ribbonPath(Size size) {
    Path path = Path();
    List<Offset> vec = [];
    if (size.width <= size.height) {
      switch (location) {
        case RibbonLocation.topStart:
          path.moveTo(nearLength, 0);
          vec.add(Offset(nearLength, 0));
          path.lineTo(farLength, 0);
          vec.add(Offset(farLength, 0));
          path.lineTo(0, farLength);
          vec.add(Offset(0, farLength));
          path.lineTo(0, nearLength);
          vec.add(Offset(0, nearLength));
          break;
        case RibbonLocation.topEnd:
          path.moveTo(size.width - nearLength, 0);
          vec.add(Offset(size.width - nearLength, 0));
          path.lineTo(size.width - farLength, 0);
          vec.add(Offset(size.width - farLength, 0));
          path.lineTo(size.width, farLength);
          vec.add(Offset(size.width, farLength));
          path.lineTo(size.width, nearLength);
          vec.add(Offset(size.width, nearLength));
          break;
        case RibbonLocation.bottomStart:
          path.moveTo(0, size.height - nearLength);
          vec.add(Offset(0, size.height - nearLength));
          path.lineTo(0, size.height - farLength);
          vec.add(Offset(0, size.height - farLength));
          path.lineTo(farLength, size.height);
          vec.add(Offset(farLength, size.height));
          path.lineTo(nearLength, size.height);
          vec.add(Offset(nearLength, size.height));
          break;
        case RibbonLocation.bottomEnd:
          path.moveTo(size.width - nearLength, size.height);
          vec.add(Offset(size.width - nearLength, size.height));
          path.lineTo(size.width - farLength, size.height);
          vec.add(Offset(size.width - farLength, size.height));
          path.lineTo(size.width, size.height - farLength);
          vec.add(Offset(size.width, size.height - farLength));
          path.lineTo(size.width, size.height - nearLength);
          vec.add(Offset(size.width, size.height - nearLength));
          break;
      }
    } else {
      switch (location) {
        case RibbonLocation.topStart:
          path.moveTo(nearLength, 0);
          vec.add(Offset(nearLength, 0));
          path.lineTo(farLength, 0);
          vec.add(Offset(farLength, 0));
          if (farLength <= size.height) {
            path.lineTo(0, farLength);
            vec.add(Offset(0, farLength));
            path.lineTo(0, nearLength);
            vec.add(Offset(0, nearLength));
          } else {
            path.lineTo(farLength - size.height, size.height);
            vec.add(Offset(farLength - size.height, size.height));
            if (nearLength <= size.height) {
              path.lineTo(0, size.height);
              vec.add(Offset(0, size.height));
              path.lineTo(0, nearLength);
              vec.add(Offset(0, nearLength));
            } else {
              path.lineTo(nearLength - size.height, size.height);
              vec.add(Offset(nearLength - size.height, size.height));
            }
          }
          break;
        case RibbonLocation.topEnd:
          path.moveTo(size.width - nearLength, 0);
          vec.add(Offset(size.width - nearLength, 0));
          path.lineTo(size.width - farLength, 0);
          vec.add(Offset(size.width - farLength, 0));
          if (farLength <= size.height) {
            path.lineTo(size.width, farLength);
            vec.add(Offset(size.width, farLength));
            path.lineTo(size.width, nearLength);
            vec.add(Offset(size.width, nearLength));
          } else {
            path.lineTo(size.width - (farLength - size.height), size.height);
            vec.add(
                Offset(size.width - (farLength - size.height), size.height));
            if (nearLength <= size.height) {
              path.lineTo(size.width, size.height);
              vec.add(Offset(size.width, size.height));
              path.lineTo(size.width, nearLength);
              vec.add(Offset(size.width, nearLength));
            } else {
              path.lineTo(size.width - (nearLength - size.height), size.height);
              vec.add(
                  Offset(size.width - (nearLength - size.height), size.height));
            }
          }
          break;
        case RibbonLocation.bottomStart:
          path.moveTo(nearLength, size.height);
          vec.add(Offset(nearLength, size.height));
          path.lineTo(farLength, size.height);
          vec.add(Offset(farLength, size.height));
          if (farLength <= size.height) {
            path.lineTo(0, size.height - farLength);
            vec.add(Offset(0, size.height - farLength));
            path.lineTo(0, size.height - nearLength);
            vec.add(Offset(0, size.height - nearLength));
          } else {
            path.lineTo(farLength - size.height, 0);
            vec.add(Offset(farLength - size.height, 0));
            if (nearLength <= size.height) {
              path.lineTo(0, 0);
              vec.add(const Offset(0, 0));
              path.lineTo(0, size.height - nearLength);
              vec.add(Offset(0, size.height - nearLength));
            } else {
              path.lineTo(nearLength - size.height, 0);
              vec.add(Offset(nearLength - size.height, 0));
            }
          }
          break;
        case RibbonLocation.bottomEnd:
          path.moveTo(size.width - nearLength, size.height);
          vec.add(Offset(size.width - nearLength, size.height));
          path.lineTo(size.width - farLength, size.height);
          vec.add(Offset(size.width - farLength, size.height));
          if (farLength <= size.height) {
            path.lineTo(size.width, size.height - farLength);
            vec.add(Offset(size.width, size.height - farLength));
            path.lineTo(size.width, size.height - nearLength);
            vec.add(Offset(size.width, size.height - nearLength));
          } else {
            path.lineTo(size.width - (farLength - size.height), 0);
            vec.add(Offset(size.width - (farLength - size.height), 0));
            if (nearLength <= size.height) {
              path.lineTo(size.width, 0);
              vec.add(Offset(size.width, 0));
              path.lineTo(size.width, size.height - nearLength);
              vec.add(Offset(size.width, size.height - nearLength));
            } else {
              path.lineTo(size.width - (nearLength - size.height), 0);
              vec.add(Offset(size.width - (nearLength - size.height), 0));
            }
          }
          break;
      }
    }
    path.close();
    List<Offset> vec2 = vec.toSet().toList();
    offsetRibbon = _center(vec2);
    // logDebug('cx = ${offsetRibbon.dx},cy = ${offsetRibbon.dy}');
    return path;
  }

  double get _rotation {
    switch (location) {
      case RibbonLocation.topStart:
        return -math.pi / 4;
      case RibbonLocation.topEnd:
        return math.pi / 4;
      case RibbonLocation.bottomStart:
        return math.pi / 4;
      case RibbonLocation.bottomEnd:
        return -math.pi / 4;
    }
  }

  Offset _center(List<Offset> vecs) {
    double sumX = 0, sumY = 0, sumS = 0;
    double x1 = vecs[0].dx;
    double y1 = vecs[0].dy;
    double x2 = vecs[1].dx;
    double y2 = vecs[1].dy;
    double x3, y3;
    for (int i = 2; i < vecs.length; i++) {
      x3 = vecs[i].dx;
      y3 = vecs[i].dy;
      double s = ((x2 - x1) * (y3 - y1) - (x3 - x1) * (y2 - y1)) / 2.0;
      sumX += (x1 + x2 + x3) * s;
      sumY += (y1 + y2 + y3) * s;
      sumS += s;
      x2 = x3;
      y2 = y3;
    }
    double cx = sumX / sumS / 3.0;
    double cy = sumY / sumS / 3.0;
    return Offset(cx, cy);
  }
}