package com.kabouzeid.gramophone.helper;

import android.graphics.Bitmap;

import java.util.ArrayList;
import java.util.concurrent.Callable;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * Blur using Java code.
 * <p/>
 * This is a compromise between Gaussian Blur and Box blur
 * It creates much better looking blurs than Box Blur, but is
 * 7x faster than my Gaussian Blur implementation.
 * <p/>
 * I called it Stack Blur because this describes best how this
 * filter works internally: it creates a kind of moving stack
 * of colors whilst scanning through the image. Thereby it
 * just has to add one new block of color to the right side
 * of the stack and remove the leftmost color. The remaining
 * colors on the topmost layer of the stack are either added on
 * or reduced by one, depending on if they are on the right or
 * on the left side of the stack.
 *
 * @author Enrique López Mañas <eenriquelopez@gmail.com>
 *         http://www.neo-tech.es
 *         <p/>
 *         Author of the original algorithm: Mario Klingemann <mario.quasimondo.com>
 *         <p/>
 *         Based heavily on http://vitiy.info/Code/stackblur.cpp
 *         See http://vitiy.info/stackblur-algorithm-multi-threaded-blur-for-cpp/
 * @copyright: Enrique López Mañas
 * @license: Apache License 2.0
 */
public class StackBlur {

    static final int EXECUTOR_THREADS = Runtime.getRuntime().availableProcessors();
    static final ExecutorService EXECUTOR = Executors.newFixedThreadPool(EXECUTOR_THREADS);

    private static final short[] stackblur_mul = {
            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
    };

    private static final byte[] stackblur_shr = {
            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
    };

    public static Bitmap blur(Bitmap original, float radius) {
        int w = original.getWidth();
        int h = original.getHeight();
        int[] currentPixels = new int[w * h];
        original.getPixels(currentPixels, 0, w, 0, 0, w, h);
        int cores = EXECUTOR_THREADS;

        ArrayList<BlurTask> horizontal = new ArrayList<BlurTask>(cores);
        ArrayList<BlurTask> vertical = new ArrayList<BlurTask>(cores);
        for (int i = 0; i < cores; i++) {
            horizontal.add(new BlurTask(currentPixels, w, h, (int) radius, cores, i, 1));
            vertical.add(new BlurTask(currentPixels, w, h, (int) radius, cores, i, 2));
        }

        try {
            EXECUTOR.invokeAll(horizontal);
        } catch (InterruptedException e) {
            return null;
        }

        try {
            EXECUTOR.invokeAll(vertical);
        } catch (InterruptedException e) {
            return null;
        }

        return Bitmap.createBitmap(currentPixels, w, h, Bitmap.Config.ARGB_8888);
    }

    private static void blurIteration(int[] src, int w, int h, int radius, int cores, int core, int step) {
        int x, y, xp, yp, i;
        int sp;
        int stack_start;
        int stack_i;

        int src_i;
        int dst_i;

        long sum_r, sum_g, sum_b,
                sum_in_r, sum_in_g, sum_in_b,
                sum_out_r, sum_out_g, sum_out_b;

        int wm = w - 1;
        int hm = h - 1;
        int div = (radius * 2) + 1;
        int mul_sum = stackblur_mul[radius];
        byte shr_sum = stackblur_shr[radius];
        int[] stack = new int[div];

        if (step == 1) {
            int minY = core * h / cores;
            int maxY = (core + 1) * h / cores;

            for (y = minY; y < maxY; y++) {
                sum_r = sum_g = sum_b =
                        sum_in_r = sum_in_g = sum_in_b =
                                sum_out_r = sum_out_g = sum_out_b = 0;

                src_i = w * y; // start of line (0,y)

                for (i = 0; i <= radius; i++) {
                    stack_i = i;
                    stack[stack_i] = src[src_i];
                    sum_r += ((src[src_i] >>> 16) & 0xff) * (i + 1);
                    sum_g += ((src[src_i] >>> 8) & 0xff) * (i + 1);
                    sum_b += (src[src_i] & 0xff) * (i + 1);
                    sum_out_r += ((src[src_i] >>> 16) & 0xff);
                    sum_out_g += ((src[src_i] >>> 8) & 0xff);
                    sum_out_b += (src[src_i] & 0xff);
                }


                for (i = 1; i <= radius; i++) {
                    if (i <= wm) src_i += 1;
                    stack_i = i + radius;
                    stack[stack_i] = src[src_i];
                    sum_r += ((src[src_i] >>> 16) & 0xff) * (radius + 1 - i);
                    sum_g += ((src[src_i] >>> 8) & 0xff) * (radius + 1 - i);
                    sum_b += (src[src_i] & 0xff) * (radius + 1 - i);
                    sum_in_r += ((src[src_i] >>> 16) & 0xff);
                    sum_in_g += ((src[src_i] >>> 8) & 0xff);
                    sum_in_b += (src[src_i] & 0xff);
                }


                sp = radius;
                xp = radius;
                if (xp > wm) xp = wm;
                src_i = xp + y * w; //   img.pix_ptr(xp, y);
                dst_i = y * w; // img.pix_ptr(0, y);
                for (x = 0; x < w; x++) {
                    src[dst_i] = (int)
                            ((src[dst_i] & 0xff000000) |
                                    ((((sum_r * mul_sum) >>> shr_sum) & 0xff) << 16) |
                                    ((((sum_g * mul_sum) >>> shr_sum) & 0xff) << 8) |
                                    ((((sum_b * mul_sum) >>> shr_sum) & 0xff)));
                    dst_i += 1;

                    sum_r -= sum_out_r;
                    sum_g -= sum_out_g;
                    sum_b -= sum_out_b;

                    stack_start = sp + div - radius;
                    if (stack_start >= div) stack_start -= div;
                    stack_i = stack_start;

                    sum_out_r -= ((stack[stack_i] >>> 16) & 0xff);
                    sum_out_g -= ((stack[stack_i] >>> 8) & 0xff);
                    sum_out_b -= (stack[stack_i] & 0xff);

                    if (xp < wm) {
                        src_i += 1;
                        ++xp;
                    }

                    stack[stack_i] = src[src_i];

                    sum_in_r += ((src[src_i] >>> 16) & 0xff);
                    sum_in_g += ((src[src_i] >>> 8) & 0xff);
                    sum_in_b += (src[src_i] & 0xff);
                    sum_r += sum_in_r;
                    sum_g += sum_in_g;
                    sum_b += sum_in_b;

                    ++sp;
                    if (sp >= div) sp = 0;
                    stack_i = sp;

                    sum_out_r += ((stack[stack_i] >>> 16) & 0xff);
                    sum_out_g += ((stack[stack_i] >>> 8) & 0xff);
                    sum_out_b += (stack[stack_i] & 0xff);
                    sum_in_r -= ((stack[stack_i] >>> 16) & 0xff);
                    sum_in_g -= ((stack[stack_i] >>> 8) & 0xff);
                    sum_in_b -= (stack[stack_i] & 0xff);
                }

            }
        }

        // step 2
        else if (step == 2) {
            int minX = core * w / cores;
            int maxX = (core + 1) * w / cores;

            for (x = minX; x < maxX; x++) {
                sum_r = sum_g = sum_b =
                        sum_in_r = sum_in_g = sum_in_b =
                                sum_out_r = sum_out_g = sum_out_b = 0;

                src_i = x; // x,0
                for (i = 0; i <= radius; i++) {
                    stack_i = i;
                    stack[stack_i] = src[src_i];
                    sum_r += ((src[src_i] >>> 16) & 0xff) * (i + 1);
                    sum_g += ((src[src_i] >>> 8) & 0xff) * (i + 1);
                    sum_b += (src[src_i] & 0xff) * (i + 1);
                    sum_out_r += ((src[src_i] >>> 16) & 0xff);
                    sum_out_g += ((src[src_i] >>> 8) & 0xff);
                    sum_out_b += (src[src_i] & 0xff);
                }
                for (i = 1; i <= radius; i++) {
                    if (i <= hm) src_i += w; // +stride

                    stack_i = i + radius;
                    stack[stack_i] = src[src_i];
                    sum_r += ((src[src_i] >>> 16) & 0xff) * (radius + 1 - i);
                    sum_g += ((src[src_i] >>> 8) & 0xff) * (radius + 1 - i);
                    sum_b += (src[src_i] & 0xff) * (radius + 1 - i);
                    sum_in_r += ((src[src_i] >>> 16) & 0xff);
                    sum_in_g += ((src[src_i] >>> 8) & 0xff);
                    sum_in_b += (src[src_i] & 0xff);
                }

                sp = radius;
                yp = radius;
                if (yp > hm) yp = hm;
                src_i = x + yp * w; // img.pix_ptr(x, yp);
                dst_i = x;               // img.pix_ptr(x, 0);
                for (y = 0; y < h; y++) {
                    src[dst_i] = (int)
                            ((src[dst_i] & 0xff000000) |
                                    ((((sum_r * mul_sum) >>> shr_sum) & 0xff) << 16) |
                                    ((((sum_g * mul_sum) >>> shr_sum) & 0xff) << 8) |
                                    ((((sum_b * mul_sum) >>> shr_sum) & 0xff)));
                    dst_i += w;

                    sum_r -= sum_out_r;
                    sum_g -= sum_out_g;
                    sum_b -= sum_out_b;

                    stack_start = sp + div - radius;
                    if (stack_start >= div) stack_start -= div;
                    stack_i = stack_start;

                    sum_out_r -= ((stack[stack_i] >>> 16) & 0xff);
                    sum_out_g -= ((stack[stack_i] >>> 8) & 0xff);
                    sum_out_b -= (stack[stack_i] & 0xff);

                    if (yp < hm) {
                        src_i += w; // stride
                        ++yp;
                    }

                    stack[stack_i] = src[src_i];

                    sum_in_r += ((src[src_i] >>> 16) & 0xff);
                    sum_in_g += ((src[src_i] >>> 8) & 0xff);
                    sum_in_b += (src[src_i] & 0xff);
                    sum_r += sum_in_r;
                    sum_g += sum_in_g;
                    sum_b += sum_in_b;

                    ++sp;
                    if (sp >= div) sp = 0;
                    stack_i = sp;

                    sum_out_r += ((stack[stack_i] >>> 16) & 0xff);
                    sum_out_g += ((stack[stack_i] >>> 8) & 0xff);
                    sum_out_b += (stack[stack_i] & 0xff);
                    sum_in_r -= ((stack[stack_i] >>> 16) & 0xff);
                    sum_in_g -= ((stack[stack_i] >>> 8) & 0xff);
                    sum_in_b -= (stack[stack_i] & 0xff);
                }
            }
        }

    }

    private static class BlurTask implements Callable<Void> {
        private final int[] _src;
        private final int _w;
        private final int _h;
        private final int _radius;
        private final int _totalCores;
        private final int _coreIndex;
        private final int _round;

        public BlurTask(int[] src, int w, int h, int radius, int totalCores, int coreIndex, int round) {
            _src = src;
            _w = w;
            _h = h;
            _radius = radius;
            _totalCores = totalCores;
            _coreIndex = coreIndex;
            _round = round;
        }

        @Override
        public Void call() throws Exception {
            blurIteration(_src, _w, _h, _radius, _totalCores, _coreIndex, _round);
            return null;
        }

    }
}
