import { each } from '../../util/common';

function _mod(n, m) {
  return (n % m + m) % m;
}

function _addStop(steps, gradient) {
  each(steps, function (item) {
    item = item.split(':');
    gradient.addColorStop(Number(item[0]), item[1]);
  });
} // the string format: 'l(0) 0:#ffffff 0.5:#7ec2f3 1:#1890ff'


function _parseLineGradient(color, shape, context) {
  var arr = color.split(' ');
  var angle = arr[0].slice(2, arr[0].length - 1);
  angle = _mod(parseFloat(angle) * Math.PI / 180, Math.PI * 2);
  var steps = arr.slice(1);
  var {
    minX,
    minY,
    maxX,
    maxY
  } = shape.getBBox();
  var start;
  var end;

  if (angle >= 0 && angle < 0.5 * Math.PI) {
    start = {
      x: minX,
      y: minY
    };
    end = {
      x: maxX,
      y: maxY
    };
  } else if (0.5 * Math.PI <= angle && angle < Math.PI) {
    start = {
      x: maxX,
      y: minY
    };
    end = {
      x: minX,
      y: maxY
    };
  } else if (Math.PI <= angle && angle < 1.5 * Math.PI) {
    start = {
      x: maxX,
      y: maxY
    };
    end = {
      x: minX,
      y: minY
    };
  } else {
    start = {
      x: minX,
      y: maxY
    };
    end = {
      x: maxX,
      y: minY
    };
  }

  var tanTheta = Math.tan(angle);
  var tanTheta2 = tanTheta * tanTheta;
  var x = (end.x - start.x + tanTheta * (end.y - start.y)) / (tanTheta2 + 1) + start.x;
  var y = tanTheta * (end.x - start.x + tanTheta * (end.y - start.y)) / (tanTheta2 + 1) + start.y;
  var gradient = context.createLinearGradient(start.x, start.y, x, y);

  _addStop(steps, gradient);

  return gradient;
} // the string format: 'r(0.5, 0.5, 0.1) 0:#ffffff 1:#1890ff'


function _parseRadialGradient(color, shape, context) {
  var arr = color.split(' ');
  var circleCfg = arr[0].slice(2, arr[0].length - 1);
  circleCfg = circleCfg.split(',');
  var fx = parseFloat(circleCfg[0]);
  var fy = parseFloat(circleCfg[1]);
  var fr = parseFloat(circleCfg[2]);
  var steps = arr.slice(1); // if radius is 0, no gradient, stroke with the last color

  if (fr === 0) {
    var _color = steps[steps.length - 1];
    return _color.split(':')[1];
  }

  var {
    width,
    height,
    minX,
    minY
  } = shape.getBBox();
  var r = Math.sqrt(width * width + height * height) / 2;
  var gradient = context.createRadialGradient(minX + width * fx, minY + height * fy, fr * r, minX + width / 2, minY + height / 2, r);

  _addStop(steps, gradient);

  return gradient;
}

function parseStyle(color, shape, context) {
  if (color[1] === '(') {
    try {
      var firstCode = color[0];

      if (firstCode === 'l') {
        return _parseLineGradient(color, shape, context);
      } else if (firstCode === 'r') {
        return _parseRadialGradient(color, shape, context);
      }
    } catch (ev) {
      console.error('error in parsing gradient string, please check if there are any extra whitespaces.');
      console.error(ev);
    }
  }

  return color;
}

export { parseStyle };
export default {
  parseStyle
};