namespace jsfx.filter {
  /**
   * @filter         Blur
   * @description    This is the TriangleBlur from glfx, but for the canvas implementation, we are cheating by
   *                 using StackBlur. The implementations are obviously very different, but the results are very close.
   * @param radius   The radius of the pyramid convolved with the image.
   */
  export class Blur extends jsfx.Filter {
    constructor(radius? : number) {
      super(null, `
            uniform sampler2D texture;
            uniform vec2 delta;
            varying vec2 texCoord;

            void main() {
                vec4 color = vec4(0.0);
                float total = 0.0;

                /* randomize the lookup values to hide the fixed number of samples */
                //float offset = random(vec3(12.9898, 78.233, 151.7182), 0.0);

                vec3 scale = vec3(12.9898, 78.233, 151.7182);
                float offset = fract(sin(dot(gl_FragCoord.xyz + 0.0, scale)) * 43758.5453 + 0.0);

                for (float t = -30.0; t <= 30.0; t++) {
                    float percent = (t + offset - 0.5) / 30.0;
                    float weight = 1.0 - abs(percent);
                    vec4 sample = texture2D(texture, texCoord + delta * percent);

                    /* switch to pre-multiplied alpha to correctly blur transparent images */
                    sample.rgb *= sample.a;

                    color += sample * weight;
                    total += weight;
                }

                gl_FragColor = color / total;

                /* switch back from pre-multiplied alpha */
                gl_FragColor.rgb /= gl_FragColor.a + 0.00001;
            }
        `);

      // set properties
      this.properties.radius = radius;
    }

    public drawWebGL(renderer : jsfx.webgl.Renderer) {
      var shader = renderer.getShader(this);
      var firstPass = {delta: [this.properties.radius / renderer.getSource().width, 0]};
      var secondPass = {delta: [0, this.properties.radius / renderer.getSource().height]};

      renderer.getTexture().use();
      renderer.getNextTexture().drawTo(function () {
        shader.uniforms(firstPass).drawRect();
      });

      renderer.getTexture().use();
      renderer.getNextTexture().drawTo(function () {
        shader.uniforms(secondPass).drawRect();
      });
    }

    public drawCanvas(imageData : ImageData) : ImageData {
      var pixels = imageData.data;
      var radius = this.properties.radius;
      var width = imageData.width;
      var height = imageData.height;

      var x, y, i, p, yp, yi, yw, r_sum, g_sum, b_sum, a_sum,
        r_out_sum, g_out_sum, b_out_sum, a_out_sum,
        r_in_sum, g_in_sum, b_in_sum, a_in_sum,
        pr, pg, pb, pa, rbs;

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

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

      yw = yi = 0;

      var mul_sum = mul_table[radius];
      var shg_sum = shg_table[radius];

      for (y = 0; y < height; y++) {
        r_in_sum = g_in_sum = b_in_sum = a_in_sum = r_sum = g_sum = b_sum = a_sum = 0;

        r_out_sum = radiusPlus1 * ( pr = pixels[yi] );
        g_out_sum = radiusPlus1 * ( pg = pixels[yi + 1] );
        b_out_sum = radiusPlus1 * ( pb = pixels[yi + 2] );
        a_out_sum = radiusPlus1 * ( pa = pixels[yi + 3] );

        r_sum += sumFactor * pr;
        g_sum += sumFactor * pg;
        b_sum += sumFactor * pb;
        a_sum += 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 );
          r_sum += ( stack.r = ( pr = pixels[p])) * ( rbs = radiusPlus1 - i );
          g_sum += ( stack.g = ( pg = pixels[p + 1])) * rbs;
          b_sum += ( stack.b = ( pb = pixels[p + 2])) * rbs;
          a_sum += ( stack.a = ( pa = pixels[p + 3])) * rbs;

          r_in_sum += pr;
          g_in_sum += pg;
          b_in_sum += pb;
          a_in_sum += pa;

          stack = stack.next;
        }

        stackIn = stackStart;
        stackOut = stackEnd;
        for (x = 0; x < width; x++) {
          pixels[yi + 3] = pa = (a_sum * mul_sum) >> shg_sum;
          if (pa != 0) {
            pa = 255 / pa;
            pixels[yi] = ((r_sum * mul_sum) >> shg_sum) * pa;
            pixels[yi + 1] = ((g_sum * mul_sum) >> shg_sum) * pa;
            pixels[yi + 2] = ((b_sum * mul_sum) >> shg_sum) * pa;
          } else {
            pixels[yi] = pixels[yi + 1] = pixels[yi + 2] = 0;
          }

          r_sum -= r_out_sum;
          g_sum -= g_out_sum;
          b_sum -= b_out_sum;
          a_sum -= a_out_sum;

          r_out_sum -= stackIn.r;
          g_out_sum -= stackIn.g;
          b_out_sum -= stackIn.b;
          a_out_sum -= stackIn.a;

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

          r_in_sum += ( stackIn.r = pixels[p]);
          g_in_sum += ( stackIn.g = pixels[p + 1]);
          b_in_sum += ( stackIn.b = pixels[p + 2]);
          a_in_sum += ( stackIn.a = pixels[p + 3]);

          r_sum += r_in_sum;
          g_sum += g_in_sum;
          b_sum += b_in_sum;
          a_sum += a_in_sum;

          stackIn = stackIn.next;

          r_out_sum += ( pr = stackOut.r );
          g_out_sum += ( pg = stackOut.g );
          b_out_sum += ( pb = stackOut.b );
          a_out_sum += ( pa = stackOut.a );

          r_in_sum -= pr;
          g_in_sum -= pg;
          b_in_sum -= pb;
          a_in_sum -= pa;

          stackOut = stackOut.next;

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

      for (x = 0; x < width; x++) {
        g_in_sum = b_in_sum = a_in_sum = r_in_sum = g_sum = b_sum = a_sum = r_sum = 0;

        yi = x << 2;
        r_out_sum = radiusPlus1 * ( pr = pixels[yi]);
        g_out_sum = radiusPlus1 * ( pg = pixels[yi + 1]);
        b_out_sum = radiusPlus1 * ( pb = pixels[yi + 2]);
        a_out_sum = radiusPlus1 * ( pa = pixels[yi + 3]);

        r_sum += sumFactor * pr;
        g_sum += sumFactor * pg;
        b_sum += sumFactor * pb;
        a_sum += 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;

          r_sum += ( stack.r = ( pr = pixels[yi])) * ( rbs = radiusPlus1 - i );
          g_sum += ( stack.g = ( pg = pixels[yi + 1])) * rbs;
          b_sum += ( stack.b = ( pb = pixels[yi + 2])) * rbs;
          a_sum += ( stack.a = ( pa = pixels[yi + 3])) * rbs;

          r_in_sum += pr;
          g_in_sum += pg;
          b_in_sum += pb;
          a_in_sum += 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 = (a_sum * mul_sum) >> shg_sum;
          if (pa > 0) {
            pa = 255 / pa;
            pixels[p] = ((r_sum * mul_sum) >> shg_sum ) * pa;
            pixels[p + 1] = ((g_sum * mul_sum) >> shg_sum ) * pa;
            pixels[p + 2] = ((b_sum * mul_sum) >> shg_sum ) * pa;
          } else {
            pixels[p] = pixels[p + 1] = pixels[p + 2] = 0;
          }

          r_sum -= r_out_sum;
          g_sum -= g_out_sum;
          b_sum -= b_out_sum;
          a_sum -= a_out_sum;

          r_out_sum -= stackIn.r;
          g_out_sum -= stackIn.g;
          b_out_sum -= stackIn.b;
          a_out_sum -= stackIn.a;

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

          r_sum += ( r_in_sum += ( stackIn.r = pixels[p]));
          g_sum += ( g_in_sum += ( stackIn.g = pixels[p + 1]));
          b_sum += ( b_in_sum += ( stackIn.b = pixels[p + 2]));
          a_sum += ( a_in_sum += ( stackIn.a = pixels[p + 3]));

          stackIn = stackIn.next;

          r_out_sum += ( pr = stackOut.r );
          g_out_sum += ( pg = stackOut.g );
          b_out_sum += ( pb = stackOut.b );
          a_out_sum += ( pa = stackOut.a );

          r_in_sum -= pr;
          g_in_sum -= pg;
          b_in_sum -= pb;
          a_in_sum -= pa;

          stackOut = stackOut.next;

          yi += width;
        }
      }

      return imageData;
    }
  }

  var mul_table = [
    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];


  var shg_table = [
    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];

  class BlurStack {
    public r : number = 0;
    public g : number = 0;
    public b : number = 0;
    public a : number = 0;
    public next : BlurStack = null;
  }
}