import 'dart:math';
import 'dart:ui';

import 'package:fis_measure/interfaces/date_types/point.dart';
import 'package:fis_measure/interfaces/enums/items.dart';
import 'package:fis_measure/interfaces/process/items/item.dart';
import 'package:fis_measure/interfaces/process/items/item_metas.dart';
import 'package:fis_measure/interfaces/process/items/terms.dart';
import 'package:fis_measure/interfaces/process/workspace/point_info.dart';
import 'package:fis_measure/process/calcuators/curve.dart';
import 'package:fis_measure/process/calcuators/calculator.dart';
import 'package:fis_measure/process/primitives/utils/auto_snap.dart';
import 'package:fis_measure/utils/canvas.dart';

import 'area_abstract.dart';

/// 曲线连线
class Spline extends AreaItemAbstract with AutoSnapMixin {
  Spline(ItemMeta meta, [IMeasureItem? parent]) : super(meta, parent);

  static Spline createAreaPerimeter(ItemMeta meta, [IMeasureItem? parent]) {
    Spline spline = Spline(meta, parent);
    spline.calculator = _AreaPerimeterCalc(spline);
    spline.isClosed = false;
    spline.splineTension = 0.5;
    return spline;
  }

  static Spline createCurveLength(
    ItemMeta meta, [
    IMeasureItem? parent,
  ]) {
    Spline spline = Spline(meta, parent);
    spline.calculator = CurveLengthCal(spline);
    spline.isClosed = false;
    spline.splineTension = 0.5;
    return spline;
  }

  @override
  bool onExecuteMouse(PointInfo args) {
    if (state == ItemStates.finished) {
      if (args.pointType == PointInfoType.mouseDown) {
        state = ItemStates.waiting;
      }
    }

    if (state == ItemStates.waiting) {
      if (args.pointType == PointInfoType.mouseDown) {
        handleMouseDownWhileWaiting(args);
      }
    } else if (state == ItemStates.running) {
      if (feature == null) return false;
      if (args.pointType == PointInfoType.mouseUp) return false;

      final f = feature!;

      if (args.pointType == PointInfoType.mouseDown) {
        f.innerPoints.add(args);
      } else {
        f.innerPoints.last = args;
      }
      doCalculate();
      if (checkAutoSnap(args)) {
        f.innerPoints.removeLast();
      }
    }
    return true;
  }

  DPoint lastStartPoint = DPoint(0, 0); // 上一个起点
  bool isFirstPointNeedOffset = false; // 第一个点是否需要施加偏移
  DPoint splineTouchStartPoint = DPoint(0, 0); // 轨迹触摸起始点
  bool isOtherPointNeedOffset = false; // 其他点是否需要施加偏移
  @override
  bool onExecuteTouch(PointInfo args) {
    if (state == ItemStates.finished) {
      if (args.pointType == PointInfoType.touchDown) {
        state = ItemStates.waiting;
      }
    }

    if (state == ItemStates.waiting) {
      if (isFirstPointNeedOffset) args.addOffset(0, -0.2);
      switch (args.pointType) {
        case PointInfoType.touchDown:
          handleTouchDownWhileWaiting(args);
          isFirstPointNeedOffset = false;
          break;
        case PointInfoType.touchUp:
          lastStartPoint = args; // 设置线段起点
          state = ItemStates.running;
          feature?.innerPoints.first = args;
          break; // 按下立即抬起无事发生
        case PointInfoType.touchMove:
          if (isMoveTargetOutOfRange(args)) return true;

          isFirstPointNeedOffset = true;
          feature?.innerPoints.first = args;
          break;
        default:
          break;
      }
    } else if (state == ItemStates.running) {
      if (feature == null) return false;
      PointInfo newPoint = PointInfo.fromOffset(
          lastStartPoint
              .clone()
              .addVector(args - splineTouchStartPoint)
              .toOffset(),
          args.pointType);
      newPoint.hostVisualArea = args.hostVisualArea;
      final f = feature!;
      if (args.pointType == PointInfoType.touchUp) {
        if (!isOtherPointNeedOffset) {
          f.innerPoints.last = args;
          lastStartPoint = args;
          doCalculate();
        } else {
          lastStartPoint = newPoint;
        }
      }

      if (args.pointType == PointInfoType.touchDown) {
        isOtherPointNeedOffset = false;
        splineTouchStartPoint = args;
        f.innerPoints.add(lastStartPoint);
      }
      if (args.pointType == PointInfoType.touchMove) {
        if (isMoveTargetOutOfRange(newPoint)) return true;

        isOtherPointNeedOffset = true;
        f.innerPoints.last = newPoint;
      }
      doCalculate();
      PointInfo newPointInfo = isOtherPointNeedOffset
          ? PointInfo.fromOffset(newPoint.toOffset(), args.pointType)
          : args;
      if (checkAutoSnap(newPointInfo)) {
        f.innerPoints.removeLast();
      }
    }
    return true;
  }

  void handleMouseDownWhileWaiting(PointInfo args) {
    // TODO: 判断是否当前area
    final point = args.toAreaLogicPoint();
    feature = SplineFeature(this, point);
    if (args.hostVisualArea != null) {
      feature!.hostVisualArea = args.hostVisualArea;
    }
    state = ItemStates.running;
  }

  void handleTouchDownWhileWaiting(PointInfo args) {
    // TODO: 判断是否当前area
    final point = args.toAreaLogicPoint();
    feature = SplineFeature.withOneStartPoint(this, point);
    if (args.hostVisualArea != null) {
      feature!.hostVisualArea = args.hostVisualArea;
    }
  }
}

class SplineFeature extends AreaItemFeatureAbstract {
  static const double _splineTolerance = 0.05;

  SplineFeature(Spline refItem, DPoint point) : super(refItem) {
    innerPoints.add(point.clone());
    innerPoints.add(point.clone());
  }

  SplineFeature.withOneStartPoint(Spline refItem, DPoint point)
      : super(refItem) {
    innerPoints.add(point.clone());
  }

  @override
  void paint(Canvas canvas, Size size) {
    if (innerPoints.isEmpty) return;
    final paintPoints = innerPoints;

    drawId(canvas, size);

    final startOffset = convert2ViewPoint(size, startPoint).toOffset();

    if (paintPoints.length == 1) {
      drawVertex(canvas, startOffset, true);
      return;
    } else if (paintPoints.length == 2) {
      final endOffset = convert2ViewPoint(size, endPoint).toOffset();
      drawVertex(canvas, startOffset, true);
      drawVertex(canvas, endOffset, true);
      canvas.drawDashLine(startOffset, endOffset, 1, 10, paintLinePan);
      return;
    }

    /// 全部innerPoints点集转为Offset集绘制
    for (var e in innerPoints) {
      drawVertex(canvas, convert2ViewPoint(size, e).toOffset());
    }

    /// 获取拟合点集
    final fittedPoints = getFitPoints(
        innerPoints, isClosed, splineTension, _splineTolerance / 2);

    /// 全部拟合点集转为Offset集
    final fittedOffsets =
        fittedPoints.map((e) => convert2ViewPoint(size, e).toOffset()).toList();

    canvas.drawDashPointsLine(fittedOffsets, 1, 10, paintLinePan, close: true);
  }

  List<DPoint> getFitPoints(
    List<DPoint> points,
    bool isClosed,
    double tension,
    double tolerance,
  ) {
    final List<DPoint> polyLineSegment = [];
    final len = points.length;
    for (var i = 0; i < points.length; i++) {
      if (i == 0) {
        addSegment(
            polyLineSegment, points, [len - 1, 0, 1, 2], tension, tolerance);
      } else if (i == points.length - 2) {
        addSegment(
            polyLineSegment, points, [i - 1, i, i + 1, 0], tension, tolerance);
      } else if (i == points.length - 1) {
        addSegment(
            polyLineSegment, points, [i - 1, i, 0, 1], tension, tolerance);
      } else {
        addSegment(polyLineSegment, points, [i - 1, i, i + 1, i + 2], tension,
            tolerance);
      }
    }
    return polyLineSegment;
  }

  static void addSegment(List<DPoint> polyLineSegment, List<DPoint> points,
      List<int> pointIndex, double tension, double tolerance) {
    if (points.length < 2) return;
    segment(
      polyLineSegment,
      points[pointIndex[0]],
      points[pointIndex[1]],
      points[pointIndex[2]],
      points[pointIndex[3]],
      tension,
      tension,
      tolerance,
    );
  }

  static double segment(List<DPoint> points, DPoint pt0, DPoint pt1, DPoint pt2,
      DPoint pt3, double t1, double t2, double tolerance) {
    double length = 0;
    final sx1 = t1 * (pt2.x - pt0.x);
    final sy1 = t1 * (pt2.y - pt0.y);
    final sx2 = t2 * (pt3.x - pt1.x);
    final sy2 = t2 * (pt3.y - pt1.y);

    final ax = sx1 + sx2 + 2 * pt1.x - 2 * pt2.x;
    final ay = sy1 + sy2 + 2 * pt1.y - 2 * pt2.y;
    final bx = -2 * sx1 - sx2 - 3 * pt1.x + 3 * pt2.x;
    final by = -2 * sy1 - sy2 - 3 * pt1.y + 3 * pt2.y;

    final cx = sx1;
    final cy = sy1;
    final dx = pt1.x;
    final dy = pt1.y;

    var num = (((pt1.x - pt2.x).abs() + (pt1.y - pt2.y).abs()) ~/ tolerance);

    // Set num = 2 to calculate the length. when the distance of pt1,pt2 is very tiny, the num will be 0, the length will be 0
    if (num < 2) num = 2;

    // Notice begins at 1 so excludes the first point (which is just pt1)
    for (var i = 1; i < num; i++) {
      var t = i / (num - 1);
      var pt = DPoint(ax * t * t * t + bx * t * t + cx * t + dx,
          ay * t * t * t + by * t * t + cy * t + dy);
      if (i == 1) {
        length += (pt - pt1).length;
      } else {
        length += (pt - points[points.length - 1]).length;
      }
      points.add(pt);
    }
    return length;
  }
}

class _AreaPerimeterCalc extends Calculator<Spline, double> {
  _AreaPerimeterCalc(Spline ref) : super(ref);
  @override
  void calculate() {
    if (ref.feature == null) return;

    final feature = ref.feature!;
    final viewport = feature.hostVisualArea!.viewport!;
    final points = feature.innerPoints.map((e) => viewport.convert(e)).toList();
    final tension = feature.splineTension;
    feature.values.clear();
    double area;
    double perimeter;
    //计算周长
    final res = calcPerimeterAndArea(points, feature.isClosed, tension, 0.25);
    perimeter = res[0];
    area = res[1];

    for (var output in ref.meta.outputs) {
      if (output.name == MeasureTerms.Perimeter) {
        var value = roundDouble(perimeter, output.fractionalDigits);
        feature.updateFloatValue(output, value, output.unit);
      } else if (output.name == MeasureTerms.Area) {
        var value = roundDouble(area, output.fractionalDigits);
        feature.updateFloatValue(output, value, output.unit);
      }
    }
  }

  static double calcArea(List<DPoint> points) {
    if (points.isEmpty) {
      return 0;
    }

    double sum = 0;
    var ax = points[0].x;
    var ay = points[0].y;
    for (var i = 1; i < points.length - 1; i++) {
      var bx = points[i].x;
      var by = points[i].y;
      var cx = points[i + 1].x;
      var cy = points[i + 1].y;
      sum += ax * by - ay * bx + ay * cx - ax * cy + bx * cy - cx * by;
    }
    return (-sum / 2).abs();
  }

  static List<double> calcPerimeterAndArea(
    List<DPoint> points,
    bool isClosed,
    double tension,
    double tolerance,
  ) {
    final List<DPoint> polyLineSegment = [];
    final len = points.length;
    double perimeter = 0;
    if (len < 2) {
      return [0, 0];
    }
    if (len == 2) {
      final p1 = points[0];
      final p2 = points[1];
      final dx = p1.x - p2.x;
      final dy = p1.y - p2.y;
      perimeter = sqrt(dx * dx + dy * dy);
      return [perimeter, 0];
    }
    for (var i = 0; i < points.length; i++) {
      if (i == 0) {
        perimeter += segment(
            polyLineSegment,
            isClosed ? points[points.length - 1] : points[0],
            points[0],
            points[1],
            points[2],
            tension,
            tension,
            tolerance);
      } else if (i == points.length - 2) {
        perimeter += segment(
            polyLineSegment,
            points[i - 1],
            points[i],
            points[i + 1],
            isClosed ? points[0] : points[i + 1],
            tension,
            tension,
            tolerance);
      } else if (i == points.length - 1) {
        if (isClosed) {
          perimeter += segment(polyLineSegment, points[i - 1], points[i],
              points[0], points[1], tension, tension, tolerance);
        }
      } else {
        perimeter += segment(polyLineSegment, points[i - 1], points[i],
            points[i + 1], points[i + 2], tension, tension, tolerance);
      }
    }
    final area = calcArea(polyLineSegment);
    return [perimeter, area];
  }

  static double segment(List<DPoint> points, DPoint pt0, DPoint pt1, DPoint pt2,
      DPoint pt3, double t1, double t2, double tolerance) {
    double length = 0;
    final sx1 = t1 * (pt2.x - pt0.x);
    final sy1 = t1 * (pt2.y - pt0.y);
    final sx2 = t2 * (pt3.x - pt1.x);
    final sy2 = t2 * (pt3.y - pt1.y);

    final ax = sx1 + sx2 + 2 * pt1.x - 2 * pt2.x;
    final ay = sy1 + sy2 + 2 * pt1.y - 2 * pt2.y;
    final bx = -2 * sx1 - sx2 - 3 * pt1.x + 3 * pt2.x;
    final by = -2 * sy1 - sy2 - 3 * pt1.y + 3 * pt2.y;

    final cx = sx1;
    final cy = sy1;
    final dx = pt1.x;
    final dy = pt1.y;

    var num = (((pt1.x - pt2.x).abs() + (pt1.y - pt2.y).abs()) ~/ tolerance);

    // Set num = 2 to calculate the length. when the distance of pt1,pt2 is very tiny, the num will be 0, the length will be 0
    if (num < 2) num = 2;

    // Notice begins at 1 so excludes the first point (which is just pt1)
    for (var i = 1; i < num; i++) {
      var t = i / (num - 1);
      var pt = DPoint(ax * t * t * t + bx * t * t + cx * t + dx,
          ay * t * t * t + by * t * t + cy * t + dy);
      if (i == 1) {
        length += (pt - pt1).length;
      } else {
        length += (pt - points[points.length - 1]).length;
      }
      points.add(pt);
    }
    return length;
  }
}