/**
* StackBlur - a fast almost Gaussian Blur For Canvas

In case you find this class useful - especially in commercial projects -
I am not totally unhappy for a small donation to my PayPal account
mario@quasimondo.de

Or support me on flattr:
https://flattr.com/thing/72791/StackBlur-a-fast-almost-Gaussian-Blur-Effect-for-CanvasJavascript

* @module StackBlur
* @version 0.5
* @author Mario Klingemann
Contact: mario@quasimondo.com
Website: http://www.quasimondo.com/StackBlurForCanvas/StackBlurDemo.html
Twitter: @quasimondo

* @copyright (c) 2010 Mario Klingemann

Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.
*/

const mulTable = [
  512, 512, 456, 512, 328, 456, 335, 512, 405, 328, 271, 456, 388, 335, 292, 512,
  454, 405, 364, 328, 298, 271, 496, 456, 420, 388, 360, 335, 312, 292, 273, 512,
  482, 454, 428, 405, 383, 364, 345, 328, 312, 298, 284, 271, 259, 496, 475, 456,
  437, 420, 404, 388, 374, 360, 347, 335, 323, 312, 302, 292, 282, 273, 265, 512,
  497, 482, 468, 454, 441, 428, 417, 405, 394, 383, 373, 364, 354, 345, 337, 328,
  320, 312, 305, 298, 291, 284, 278, 271, 265, 259, 507, 496, 485, 475, 465, 456,
  446, 437, 428, 420, 412, 404, 396, 388, 381, 374, 367, 360, 354, 347, 341, 335,
  329, 323, 318, 312, 307, 302, 297, 292, 287, 282, 278, 273, 269, 265, 261, 512,
  505, 497, 489, 482, 475, 468, 461, 454, 447, 441, 435, 428, 422, 417, 411, 405,
  399, 394, 389, 383, 378, 373, 368, 364, 359, 354, 350, 345, 341, 337, 332, 328,
  324, 320, 316, 312, 309, 305, 301, 298, 294, 291, 287, 284, 281, 278, 274, 271,
  268, 265, 262, 259, 257, 507, 501, 496, 491, 485, 480, 475, 470, 465, 460, 456,
  451, 446, 442, 437, 433, 428, 424, 420, 416, 412, 408, 404, 400, 396, 392, 388,
  385, 381, 377, 374, 370, 367, 363, 360, 357, 354, 350, 347, 344, 341, 338, 335,
  332, 329, 326, 323, 320, 318, 315, 312, 310, 307, 304, 302, 299, 297, 294, 292,
  289, 287, 285, 282, 280, 278, 275, 273, 271, 269, 267, 265, 263, 261, 259];

const shgTable = [
  9, 11, 12, 13, 13, 14, 14, 15, 15, 15, 15, 16, 16, 16, 16, 17,
  17, 17, 17, 17, 17, 17, 18, 18, 18, 18, 18, 18, 18, 18, 18, 19,
  19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 19, 20, 20, 20,
  20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 20, 21,
  21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 21,
  21, 21, 21, 21, 21, 21, 21, 21, 21, 21, 22, 22, 22, 22, 22, 22,
  22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22,
  22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 22, 23,
  23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
  23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
  23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23, 23,
  23, 23, 23, 23, 23, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
  24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
  24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
  24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24,
  24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24, 24];

/**
 * @param {string|HTMLImageElement} img
 * @param {string|HTMLCanvasElement} canvas
 * @param {Float} radius
 * @param {boolean} blurAlphaChannel
 * @returns {undefined}
 */
function processImage (img, canvas, radius, blurAlphaChannel) {
  if (typeof img === 'string') {
    img = document.getElementById(img);
  }
  if (!img || !('naturalWidth' in img)) {
    return;
  }
  const w = img.naturalWidth;
  const h = img.naturalHeight;

  if (typeof canvas === 'string') {
    canvas = document.getElementById(canvas);
  }
  if (!canvas || !('getContext' in canvas)) {
    return;
  }

  canvas.style.width = w + 'px';
  canvas.style.height = h + 'px';
  canvas.width = w;
  canvas.height = h;

  const context = canvas.getContext('2d');
  context.clearRect(0, 0, w, h);
  context.drawImage(img, 0, 0);

  if (isNaN(radius) || radius < 1) { return; }

  if (blurAlphaChannel) {
    processCanvasRGBA(canvas, 0, 0, w, h, radius);
  } else {
    processCanvasRGB(canvas, 0, 0, w, h, radius);
  }
}

/**
 * @param {string|HTMLCanvasElement} canvas
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @throws {Error}
 * @returns {ImageData} See {@link https://html.spec.whatwg.org/multipage/canvas.html#imagedata}
 */
function getImageDataFromCanvas (canvas, topX, topY, width, height) {
  if (typeof canvas === 'string') {
    canvas = document.getElementById(canvas);
  }
  if (!canvas || !('getContext' in canvas)) {
    return;
  }

  const context = canvas.getContext('2d');

  try {
    return context.getImageData(topX, topY, width, height);
  } catch (e) {
    throw new Error('unable to access image data: ' + e);
  }
}

/**
 * @param {HTMLCanvasElement} canvas
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @param {Float} radius
 * @returns {undefined}
 */
function processCanvasRGBA (canvas, topX, topY, width, height, radius) {
  if (isNaN(radius) || radius < 1) { return; }
  radius |= 0;

  let imageData = getImageDataFromCanvas(canvas, topX, topY, width, height);

  imageData = processImageDataRGBA(imageData, topX, topY, width, height, radius);

  canvas.getContext('2d').putImageData(imageData, topX, topY);
}

/**
 * @param {ImageData} imageData
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @param {Float} radius
 * @returns {ImageData}
 */
function processImageDataRGBA (imageData, topX, topY, width, height, radius) {
  const pixels = imageData.data;

  let x, y, i, p, yp, yi, yw, rSum, gSum, bSum, aSum,
    rOutSum, gOutSum, bOutSum, aOutSum,
    rInSum, gInSum, bInSum, aInSum,
    pr, pg, pb, pa, rbs;

  const div = radius + radius + 1;
  // const w4 = width << 2;
  const widthMinus1 = width - 1;
  const heightMinus1 = height - 1;
  const radiusPlus1 = radius + 1;
  const sumFactor = radiusPlus1 * (radiusPlus1 + 1) / 2;

  const stackStart = new BlurStack();
  let stack = stackStart;
  let stackEnd;
  for (i = 1; i < div; i++) {
    stack = stack.next = new BlurStack();
    if (i === radiusPlus1) {
      stackEnd = stack;
    }
  }
  stack.next = stackStart;
  let stackIn = null;
  let stackOut = null;

  yw = yi = 0;

  const mulSum = mulTable[radius];
  const shgSum = shgTable[radius];

  for (y = 0; y < height; y++) {
    rInSum = gInSum = bInSum = aInSum = rSum = gSum = bSum = aSum = 0;

    rOutSum = radiusPlus1 * (pr = pixels[yi]);
    gOutSum = radiusPlus1 * (pg = pixels[yi + 1]);
    bOutSum = radiusPlus1 * (pb = pixels[yi + 2]);
    aOutSum = radiusPlus1 * (pa = pixels[yi + 3]);

    rSum += sumFactor * pr;
    gSum += sumFactor * pg;
    bSum += sumFactor * pb;
    aSum += sumFactor * pa;

    stack = stackStart;

    for (i = 0; i < radiusPlus1; i++) {
      stack.r = pr;
      stack.g = pg;
      stack.b = pb;
      stack.a = pa;
      stack = stack.next;
    }

    for (i = 1; i < radiusPlus1; i++) {
      p = yi + ((widthMinus1 < i ? widthMinus1 : i) << 2);
      rSum += (stack.r = (pr = pixels[p])) * (rbs = radiusPlus1 - i);
      gSum += (stack.g = (pg = pixels[p + 1])) * rbs;
      bSum += (stack.b = (pb = pixels[p + 2])) * rbs;
      aSum += (stack.a = (pa = pixels[p + 3])) * rbs;

      rInSum += pr;
      gInSum += pg;
      bInSum += pb;
      aInSum += pa;

      stack = stack.next;
    }

    stackIn = stackStart;
    stackOut = stackEnd;
    for (x = 0; x < width; x++) {
      pixels[yi + 3] = pa = (aSum * mulSum) >> shgSum;
      if (pa !== 0) {
        pa = 255 / pa;
        pixels[yi] = ((rSum * mulSum) >> shgSum) * pa;
        pixels[yi + 1] = ((gSum * mulSum) >> shgSum) * pa;
        pixels[yi + 2] = ((bSum * mulSum) >> shgSum) * pa;
      } else {
        pixels[yi] = pixels[yi + 1] = pixels[yi + 2] = 0;
      }

      rSum -= rOutSum;
      gSum -= gOutSum;
      bSum -= bOutSum;
      aSum -= aOutSum;

      rOutSum -= stackIn.r;
      gOutSum -= stackIn.g;
      bOutSum -= stackIn.b;
      aOutSum -= stackIn.a;

      p = (yw + ((p = x + radius + 1) < widthMinus1 ? p : widthMinus1)) << 2;

      rInSum += (stackIn.r = pixels[p]);
      gInSum += (stackIn.g = pixels[p + 1]);
      bInSum += (stackIn.b = pixels[p + 2]);
      aInSum += (stackIn.a = pixels[p + 3]);

      rSum += rInSum;
      gSum += gInSum;
      bSum += bInSum;
      aSum += aInSum;

      stackIn = stackIn.next;

      rOutSum += (pr = stackOut.r);
      gOutSum += (pg = stackOut.g);
      bOutSum += (pb = stackOut.b);
      aOutSum += (pa = stackOut.a);

      rInSum -= pr;
      gInSum -= pg;
      bInSum -= pb;
      aInSum -= pa;

      stackOut = stackOut.next;

      yi += 4;
    }
    yw += width;
  }

  for (x = 0; x < width; x++) {
    gInSum = bInSum = aInSum = rInSum = gSum = bSum = aSum = rSum = 0;

    yi = x << 2;
    rOutSum = radiusPlus1 * (pr = pixels[yi]);
    gOutSum = radiusPlus1 * (pg = pixels[yi + 1]);
    bOutSum = radiusPlus1 * (pb = pixels[yi + 2]);
    aOutSum = radiusPlus1 * (pa = pixels[yi + 3]);

    rSum += sumFactor * pr;
    gSum += sumFactor * pg;
    bSum += sumFactor * pb;
    aSum += sumFactor * pa;

    stack = stackStart;

    for (i = 0; i < radiusPlus1; i++) {
      stack.r = pr;
      stack.g = pg;
      stack.b = pb;
      stack.a = pa;
      stack = stack.next;
    }

    yp = width;

    for (i = 1; i <= radius; i++) {
      yi = (yp + x) << 2;

      rSum += (stack.r = (pr = pixels[yi])) * (rbs = radiusPlus1 - i);
      gSum += (stack.g = (pg = pixels[yi + 1])) * rbs;
      bSum += (stack.b = (pb = pixels[yi + 2])) * rbs;
      aSum += (stack.a = (pa = pixels[yi + 3])) * rbs;

      rInSum += pr;
      gInSum += pg;
      bInSum += pb;
      aInSum += pa;

      stack = stack.next;

      if (i < heightMinus1) {
        yp += width;
      }
    }

    yi = x;
    stackIn = stackStart;
    stackOut = stackEnd;
    for (y = 0; y < height; y++) {
      p = yi << 2;
      pixels[p + 3] = pa = (aSum * mulSum) >> shgSum;
      if (pa > 0) {
        pa = 255 / pa;
        pixels[p] = ((rSum * mulSum) >> shgSum) * pa;
        pixels[p + 1] = ((gSum * mulSum) >> shgSum) * pa;
        pixels[p + 2] = ((bSum * mulSum) >> shgSum) * pa;
      } else {
        pixels[p] = pixels[p + 1] = pixels[p + 2] = 0;
      }

      rSum -= rOutSum;
      gSum -= gOutSum;
      bSum -= bOutSum;
      aSum -= aOutSum;

      rOutSum -= stackIn.r;
      gOutSum -= stackIn.g;
      bOutSum -= stackIn.b;
      aOutSum -= stackIn.a;

      p = (x + (((p = y + radiusPlus1) < heightMinus1 ? p : heightMinus1) * width)) << 2;

      rSum += (rInSum += (stackIn.r = pixels[p]));
      gSum += (gInSum += (stackIn.g = pixels[p + 1]));
      bSum += (bInSum += (stackIn.b = pixels[p + 2]));
      aSum += (aInSum += (stackIn.a = pixels[p + 3]));

      stackIn = stackIn.next;

      rOutSum += (pr = stackOut.r);
      gOutSum += (pg = stackOut.g);
      bOutSum += (pb = stackOut.b);
      aOutSum += (pa = stackOut.a);

      rInSum -= pr;
      gInSum -= pg;
      bInSum -= pb;
      aInSum -= pa;

      stackOut = stackOut.next;

      yi += width;
    }
  }
  return imageData;
}

/**
 * @param {HTMLCanvasElement} canvas
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @param {Float} radius
 * @returns {undefined}
 */
function processCanvasRGB (canvas, topX, topY, width, height, radius) {
  if (isNaN(radius) || radius < 1) { return; }
  radius |= 0;

  let imageData = getImageDataFromCanvas(canvas, topX, topY, width, height);
  imageData = processImageDataRGB(imageData, topX, topY, width, height, radius);

  canvas.getContext('2d').putImageData(imageData, topX, topY);
}

/**
 * @param {ImageData} imageData
 * @param {Integer} topX
 * @param {Integer} topY
 * @param {Integer} width
 * @param {Integer} height
 * @param {Float} radius
 * @returns {ImageData}
 */
function processImageDataRGB (imageData, topX, topY, width, height, radius) {
  const pixels = imageData.data;

  let x, y, i, p, yp, yi, yw, rSum, gSum, bSum,
    rOutSum, gOutSum, bOutSum,
    rInSum, gInSum, bInSum,
    pr, pg, pb, rbs;

  const div = radius + radius + 1;
  // const w4 = width << 2;
  const widthMinus1 = width - 1;
  const heightMinus1 = height - 1;
  const radiusPlus1 = radius + 1;
  const sumFactor = radiusPlus1 * (radiusPlus1 + 1) / 2;

  const stackStart = new BlurStack();
  let stack = stackStart;
  let stackEnd;
  for (i = 1; i < div; i++) {
    stack = stack.next = new BlurStack();
    if (i === radiusPlus1) {
      stackEnd = stack;
    }
  }
  stack.next = stackStart;
  let stackIn = null;
  let stackOut = null;

  yw = yi = 0;

  const mulSum = mulTable[radius];
  const shgSum = shgTable[radius];

  for (y = 0; y < height; y++) {
    rInSum = gInSum = bInSum = rSum = gSum = bSum = 0;

    rOutSum = radiusPlus1 * (pr = pixels[yi]);
    gOutSum = radiusPlus1 * (pg = pixels[yi + 1]);
    bOutSum = radiusPlus1 * (pb = pixels[yi + 2]);

    rSum += sumFactor * pr;
    gSum += sumFactor * pg;
    bSum += sumFactor * pb;

    stack = stackStart;

    for (i = 0; i < radiusPlus1; i++) {
      stack.r = pr;
      stack.g = pg;
      stack.b = pb;
      stack = stack.next;
    }

    for (i = 1; i < radiusPlus1; i++) {
      p = yi + ((widthMinus1 < i ? widthMinus1 : i) << 2);
      rSum += (stack.r = (pr = pixels[p])) * (rbs = radiusPlus1 - i);
      gSum += (stack.g = (pg = pixels[p + 1])) * rbs;
      bSum += (stack.b = (pb = pixels[p + 2])) * rbs;

      rInSum += pr;
      gInSum += pg;
      bInSum += pb;

      stack = stack.next;
    }

    stackIn = stackStart;
    stackOut = stackEnd;
    for (x = 0; x < width; x++) {
      pixels[yi] = (rSum * mulSum) >> shgSum;
      pixels[yi + 1] = (gSum * mulSum) >> shgSum;
      pixels[yi + 2] = (bSum * mulSum) >> shgSum;

      rSum -= rOutSum;
      gSum -= gOutSum;
      bSum -= bOutSum;

      rOutSum -= stackIn.r;
      gOutSum -= stackIn.g;
      bOutSum -= stackIn.b;

      p = (yw + ((p = x + radius + 1) < widthMinus1 ? p : widthMinus1)) << 2;

      rInSum += (stackIn.r = pixels[p]);
      gInSum += (stackIn.g = pixels[p + 1]);
      bInSum += (stackIn.b = pixels[p + 2]);

      rSum += rInSum;
      gSum += gInSum;
      bSum += bInSum;

      stackIn = stackIn.next;

      rOutSum += (pr = stackOut.r);
      gOutSum += (pg = stackOut.g);
      bOutSum += (pb = stackOut.b);

      rInSum -= pr;
      gInSum -= pg;
      bInSum -= pb;

      stackOut = stackOut.next;

      yi += 4;
    }
    yw += width;
  }

  for (x = 0; x < width; x++) {
    gInSum = bInSum = rInSum = gSum = bSum = rSum = 0;

    yi = x << 2;
    rOutSum = radiusPlus1 * (pr = pixels[yi]);
    gOutSum = radiusPlus1 * (pg = pixels[yi + 1]);
    bOutSum = radiusPlus1 * (pb = pixels[yi + 2]);

    rSum += sumFactor * pr;
    gSum += sumFactor * pg;
    bSum += sumFactor * pb;

    stack = stackStart;

    for (i = 0; i < radiusPlus1; i++) {
      stack.r = pr;
      stack.g = pg;
      stack.b = pb;
      stack = stack.next;
    }

    yp = width;

    for (i = 1; i <= radius; i++) {
      yi = (yp + x) << 2;

      rSum += (stack.r = (pr = pixels[yi])) * (rbs = radiusPlus1 - i);
      gSum += (stack.g = (pg = pixels[yi + 1])) * rbs;
      bSum += (stack.b = (pb = pixels[yi + 2])) * rbs;

      rInSum += pr;
      gInSum += pg;
      bInSum += pb;

      stack = stack.next;

      if (i < heightMinus1) {
        yp += width;
      }
    }

    yi = x;
    stackIn = stackStart;
    stackOut = stackEnd;
    for (y = 0; y < height; y++) {
      p = yi << 2;
      pixels[p] = (rSum * mulSum) >> shgSum;
      pixels[p + 1] = (gSum * mulSum) >> shgSum;
      pixels[p + 2] = (bSum * mulSum) >> shgSum;

      rSum -= rOutSum;
      gSum -= gOutSum;
      bSum -= bOutSum;

      rOutSum -= stackIn.r;
      gOutSum -= stackIn.g;
      bOutSum -= stackIn.b;

      p = (x + (((p = y + radiusPlus1) < heightMinus1 ? p : heightMinus1) * width)) << 2;

      rSum += (rInSum += (stackIn.r = pixels[p]));
      gSum += (gInSum += (stackIn.g = pixels[p + 1]));
      bSum += (bInSum += (stackIn.b = pixels[p + 2]));

      stackIn = stackIn.next;

      rOutSum += (pr = stackOut.r);
      gOutSum += (pg = stackOut.g);
      bOutSum += (pb = stackOut.b);

      rInSum -= pr;
      gInSum -= pg;
      bInSum -= pb;

      stackOut = stackOut.next;

      yi += width;
    }
  }

  return imageData;
}

/**
 *
 */
export class BlurStack {
  constructor () {
    this.r = 0;
    this.g = 0;
    this.b = 0;
    this.a = 0;
    this.next = null;
  }
}

export {
  /**
  * @class module:StackBlur.image
  * @see module:StackBlur~processImage
  */
  processImage as image,
  /**
  * @class module:StackBlur.canvasRGBA
  * @see module:StackBlur~processCanvasRGBA
  */
  processCanvasRGBA as canvasRGBA,
  /**
  * @class module:StackBlur.canvasRGB
  * @see module:StackBlur~processCanvasRGB
  */
  processCanvasRGB as canvasRGB,
  /**
  * @class module:StackBlur.imageDataRGBA
  * @see module:StackBlur~processImageDataRGBA
  */
  processImageDataRGBA as imageDataRGBA,
  /**
  * @class module:StackBlur.imageDataRGB
  * @see module:StackBlur~processImageDataRGB
  */
  processImageDataRGB as imageDataRGB
};