import 'dart:math';

import 'package:flutter/material.dart';
import '../../service/app.dart';
import 'package:get/get.dart';

class Ruler2 extends StatefulWidget {
  const Ruler2({
    super.key,
    required this.isScaleMode,
    this.onReturn,
    this.mapScale,
  });

  final bool isScaleMode;
  final VoidCallback? onReturn;
  final double? mapScale;

  @override
  State<StatefulWidget> createState() {
    return Ruler2State();
  }
}

class Ruler2State extends State<Ruler2> {
  var _iter1Y = 180.0;
  var _iter2Y = 280.0;
  static const _iterHeight = 50.0;
  static const _iterColorNormal = Colors.green;
  static const _iterColorOnTap = Colors.red;
  var _iter1Color = _iterColorNormal;
  var _iter2Color = _iterColorNormal;
  var screenLen = '';
  String? mapLen;

  @override
  void initState() {
    super.initState();
    onIterChanged();
  }

  @override
  Widget build(BuildContext context) {
    final children = <Widget>[
      CustomPaint(
        painter: _RulerPainter(App.to.heightOneMM(), widget.isScaleMode),
        size: Size(context.width, context.height),
      )
    ];

    if (widget.isScaleMode) {
      children.addAll([
        _lenArrow(context),
        _wIter(
          context,
          _iter1Y,
          _iter1Color,
          onIter1Update,
          () {
            _iter1Color = _iterColorOnTap;
          },
          () {
            _iter1Color = _iterColorNormal;
          },
        ),
        _wIter(context, _iter2Y, _iter2Color, onIter2Update, () {
          _iter2Color = _iterColorOnTap;
        }, () {
          _iter2Color = _iterColorNormal;
        }),
      ]);

      _wIterLenText(context, children);
      children.add(Positioned(
          bottom: 20,
          right: 80,
          child: GestureDetector(
              onTap: widget.onReturn,
              child: Image.asset(
                'assets/images/btn_ruler_no_map.png',
                width: 46,
              ))));
    }

    return Stack(children: children);
  }

  onIter1Update(DragUpdateDetails e) {
    var tmp = _iter1Y + e.delta.dy;
    if (tmp > _iter2Y - _iterHeight || tmp < 30 + _iterHeight) {
      return;
    }
    _iter1Y = tmp;
    onIterChanged();
  }

  onIter2Update(DragUpdateDetails e) {
    var tmp = _iter2Y + e.delta.dy;
    if (tmp - _iterHeight < _iter1Y || tmp > context.height) {
      return;
    }
    _iter2Y = tmp;
    onIterChanged();
  }

  onIterChanged() {
    final heightOneMM = App.to.heightOneMM();
    final height = _iter2Y - _iter1Y;
    final mm = height / heightOneMM;
    final cm = mm / 10;
    screenLen = '${cm.toStringAsFixed(1)} cm';
    if (widget.mapScale != null) {
      var mapL = cm * widget.mapScale! / 100;
      var unit = 'm';
      if (mapL > 1000) {
        mapL /= 1000;
        unit = 'km';
      }

      mapLen = '${mapL.toStringAsFixed(1)} $unit';
    }
  }
  _wIterLenText(
      BuildContext context,
      List<Widget> children
      ) {
    var text = screenLen;
    if(mapLen!=null){
      text += ' ($mapLen)';
    }
    const textLen = 200.0;

    final centerX =  context.width / 2 -textLen/2;

    children.addAll([
      Positioned(
          left: centerX - 15,
          top: (_iter1Y + _iter2Y) / 2 - _iterHeight/2,
          child: Transform.rotate(
              angle: pi / 2,
              child: SizedBox(width:textLen, child: Text(text, textAlign: TextAlign.center,))
          )
      ),
      Positioned(
          left: centerX + 15,
          top: (_iter1Y + _iter2Y) / 2 - _iterHeight/2,
          child: Transform.rotate(
              angle: -pi / 2,
              child: SizedBox(width:textLen, child: Text(text, textAlign: TextAlign.center,))
          )
      ),
    ]);
  }

  Widget _wIter(
    BuildContext context,
    double y,
    Color color,
    void Function(DragUpdateDetails e) onUpdate,
    VoidCallback onTapDown,
    VoidCallback onTapUp,
  ) {
    return Positioned(
        top: y - _iterHeight,
        left: 0,
        child: GestureDetector(
          onPanStart: (e) {
            setState(() {
              onTapDown();
            });
          },
          onPanEnd: (e) {
            setState(() {
              onTapUp();
            });
          },
          onPanUpdate: (DragUpdateDetails e) {
            setState(() {
              onUpdate(e);
            });
          },
          child: Container(
            width: context.width,
            height: _iterHeight,
            color: Colors.white.withAlpha(10),
            alignment: Alignment.center,
            child: Container(width: context.width, height: 2, color: color),
          ),
        ));
  }

  Widget _lenArrow(BuildContext context) {
    final height = _iter2Y - _iter1Y;
    return Positioned(
        top: _iter1Y - _iterHeight / 2,
        child: CustomPaint(
          painter: _LenArrowPainter(screenLen: screenLen, mapLen: mapLen),
          size: Size(context.width, height),
        ));
  }
}

class _LenArrowPainter extends CustomPainter {
  _LenArrowPainter({required this.screenLen, this.mapLen});

  final String? mapLen;
  final String screenLen;

  final textPainter = TextPainter(
    textDirection: TextDirection.ltr,
    textAlign: TextAlign.center,
  );
  final style = const TextStyle(
    color: Colors.white,
    fontSize: 11,
    fontWeight: FontWeight.w500,
  );

  @override
  void paint(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = Colors.white
      ..style = PaintingStyle.stroke
      ..strokeWidth = 2;
    var path = Path();
    final centerX = size.width / 2;
    const arrowR = 3;
    path.moveTo(centerX, 2);
    path.lineTo(centerX + arrowR, arrowR * 2 + 2);
    path.lineTo(centerX - arrowR, arrowR * 2 + 2);
    path.close();
    canvas.drawPath(path, paint);

    path.moveTo(centerX, size.height - 2);
    path.lineTo(centerX + arrowR, size.height - 2 - arrowR * 2);
    path.lineTo(centerX - arrowR, size.height - 2 - arrowR * 2);
    path.close();
    canvas.drawPath(path, paint);

    canvas.drawLine(
        Offset(size.width / 2, 0), Offset(size.width / 2, size.height), paint);

  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) {
    return false;
  }
}

class _RulerPainter extends CustomPainter {
  _RulerPainter(this.heightOneMM, this.isScaleMode);

  final bool isScaleMode;

  final double heightOneMM;
  final textPainter = TextPainter(
    textDirection: TextDirection.ltr,
    textAlign: TextAlign.center,
  );
  final style = TextStyle(
    color: Colors.white.withAlpha(120),
    fontSize: 11,
    fontWeight: FontWeight.w500,
  );

  @override
  void paint(Canvas canvas, Size size) {
    if (isScaleMode) {
      final paint = Paint()
        ..color = Colors.black.withAlpha((255 * 0.8).round())
        ..style = PaintingStyle.fill;

      canvas.drawRect(Rect.largest, paint);
    }

    paintScale(canvas, size);
  }

  void paintScale(Canvas canvas, Size size) {
    final paint = Paint()
      ..color = Colors.white
      ..style = PaintingStyle.stroke;

    var width = 20.0;
    const widthSmall = 20.0;

    var h = size.height;
    var i = 0;
    final maxI = size.height ~/ (heightOneMM * 10) * 10;

    for (; i <= maxI; i++) {
      if (i % 5 == 0) {
        width = 33;
      } else {
        width = widthSmall;
      }

      if (i % 10 == 0) {
        if (i != 0) {
          textPainter.text =
              TextSpan(text: '${(i / 10).round()} cm', style: style);
          textPainter.layout();
          textPainter.paint(canvas,
              Offset(size.width - widthSmall - textPainter.width - 2, h));
        }
        if (i != 0) {
          textPainter.text =
              TextSpan(text: '${(i / 10).round()} cm', style: style);

          textPainter.layout();

          final hLeft = size.height - ((maxI- i) * heightOneMM);
          Offset labelOffset =
              Offset(widthSmall + 2, hLeft - textPainter.height);
          textPainter.paint(canvas, labelOffset);

        }
      }

      canvas.drawLine(Offset(0, h), Offset(width, h), paint);
      canvas.drawLine(
          Offset(size.width, h), Offset(size.width - width, h), paint);

      h -= heightOneMM;
    }
  }

  @override
  bool shouldRepaint(covariant CustomPainter oldDelegate) {
    return true;
  }
}