#include "frei0r.h"
#include "frei0r/math.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>

static uint32_t average(const uint32_t* start,
                        int bxsize,
                        int bysize, int xsize);

static void fill_block(uint32_t* start,
                       int bxsize,
                       int bysize,
                       int xsize, uint32_t col);


typedef struct pixelizer_instance
{
    unsigned int width;
    unsigned int height;
    unsigned int block_size_x;
    unsigned int block_size_y;
    unsigned char pass_alpha;
} pixelizer_instance_t;

int f0r_init()
{
    return 1;
}

void f0r_deinit()
{ /* no initialization required */ }

void f0r_get_plugin_info(f0r_plugin_info_t* pixelizerInfo)
{
    pixelizerInfo->name = "pixeliz0r";
    pixelizerInfo->author = "Gephex crew";
    pixelizerInfo->plugin_type = F0R_PLUGIN_TYPE_FILTER;
    pixelizerInfo->color_model = F0R_COLOR_MODEL_PACKED32;
    pixelizerInfo->frei0r_version = FREI0R_MAJOR_VERSION;
    pixelizerInfo->major_version = 2;
    pixelizerInfo->minor_version = 0;
    pixelizerInfo->num_params =  3;
    pixelizerInfo->explanation = "Pixelize input image.";
}

void f0r_get_param_info(f0r_param_info_t* info, int param_index)
{
    switch(param_index)
    {
    case 0:
        info->name = "Block width";
        info->type = F0R_PARAM_DOUBLE;
        info->explanation = "Horizontal size of one 'pixel'";
        break;
    case 1:
        info->name = "Block height";
        info->type = F0R_PARAM_DOUBLE;
        info->explanation = "Vertical size of one 'pixel'";
        break;
    case 2:
        info->name = "Pass-through alpha";
        info->type = F0R_PARAM_BOOL;
        info->explanation = "Do not average the alpha channel over each block";
        break;
    }
}

f0r_instance_t f0r_construct(unsigned int width, unsigned int height)
{
    pixelizer_instance_t* inst = (pixelizer_instance_t*)calloc(1, sizeof(*inst));
    inst->width = width; inst->height = height;
    inst->block_size_x = 8; inst->block_size_y = 8;
    return (f0r_instance_t)inst;
}

void f0r_destruct(f0r_instance_t instance)
{
    free(instance);
}

void f0r_set_param_value(f0r_instance_t instance, 
                         f0r_param_t param, int param_index)
{ 
    assert(instance);
    pixelizer_instance_t* inst = (pixelizer_instance_t*)instance;

    switch(param_index)
    {
    case 0:
        // scale to [1..width]
        inst->block_size_x =  MAX(1 + ( *((double*)param) * (inst->width/2)), 1);
        break;
    case 1:
        // scale to [1..height]
        inst->block_size_y =  MAX(1 + ( *((double*)param) * (inst->height/2)), 1);
        break;
    case 2:
        inst->pass_alpha = *((double*)param) >= 0.5;
        break;
    }
}

void f0r_get_param_value(f0r_instance_t instance,
                         f0r_param_t param, int param_index)
{ 
    assert(instance);
    pixelizer_instance_t* inst = (pixelizer_instance_t*)instance;

    switch(param_index)
    {
    case 0:
        // scale back to [0..1]
        *((double*)param) = (double)(inst->block_size_x-1)/(inst->width/2);
        break;
    case 1:
        // scale back to [0..1]
        *((double*)param) = (double)(inst->block_size_y-1)/(inst->height/2);
        break;
    case 2:
        *((double*)param) = inst->pass_alpha ? 1.0 : 0.0;
        break;
    }
}

void f0r_update(f0r_instance_t instance, double time,
                const uint32_t* inframe, uint32_t* outframe)
{
    assert(instance);
    pixelizer_instance_t* inst = (pixelizer_instance_t*)instance;
    unsigned int xsize = inst->width;
    unsigned int ysize = inst->height;
    unsigned int bsizex = inst->block_size_x;
    unsigned int bsizey = inst->block_size_y;
    unsigned int offset = 0;
    unsigned int blocks_x, blocks_y, xrest, yrest, xi, yi;

    blocks_x = xsize / bsizex;
    blocks_y = ysize / bsizey;
    xrest = xsize - blocks_x*bsizex;
    yrest = ysize - blocks_y*bsizey;

    uint32_t* dst = outframe;
    const uint32_t* src = inframe;


    if (bsizex == 1 && bsizey == 1)
    {
        memcpy(dst, src, xsize*ysize*sizeof(uint32_t));
    }


    // now get average for every block and write the average color to the output
    for (yi = 0; yi < blocks_y; ++yi)
    {	  
        offset = yi*bsizey*xsize;
        for (xi = 0; xi < blocks_x; ++xi)
        {
            uint32_t col = average(src + offset, bsizex, bsizey, xsize);
            fill_block(dst + offset, bsizex, bsizey, xsize, col);
            offset += bsizex;
        }
        if (xrest > 0)
        {
            uint32_t col = average(src + offset, xrest, bsizey, xsize);
            fill_block(dst + offset, xrest, bsizey, xsize, col);
        }
    }
    // check for last line
    if (yrest > 0)
    {
        offset = blocks_y*bsizey*xsize;
        for (xi = 0; xi < blocks_x; ++xi)
        {
            uint32_t col = average(src + offset, bsizex, yrest, xsize);
            fill_block(dst + offset, bsizex, yrest, xsize, col);
            offset += bsizex;
        }
        if (xrest > 0)
        {
            uint32_t col = average(src + offset, xrest, yrest, xsize);
            fill_block(dst + offset, xrest, yrest, xsize, col);
        }
    }
    if (inst->pass_alpha)
    {
        for (xi = 0; xi < inst->width * inst->height; ++xi)
        {
            dst[xi] = (src[xi] & 0xff000000) | (dst[xi] & 0x00ffffff);
        }
    }
}


static uint32_t average(const uint32_t* start, 
                        int bxsize, int bysize, int xsize)
{
    const uint32_t* p = start;
    uint32_t alpha = 0, red = 0, green = 0, blue = 0;
    uint32_t avg_alpha, avg_red, avg_green, avg_blue;
    int x, y;
    const uint32_t* pp;
    uint32_t c;

    for (y = 0; y < bysize; ++y)
    {
        pp = p;
        for (x = 0; x < bxsize; ++x)
        {
            c = *(pp++);
            alpha += (c & 0xff000000) >> 24;
            red   += (c & 0x00ff0000) >> 16;
            green += (c & 0x0000ff00) >> 8;
            blue  += (c & 0x000000ff);
        }
        p += xsize;
    }

    avg_alpha = (alpha / (bxsize*bysize)) & 0xff;
    avg_red   = (red   / (bxsize*bysize)) & 0xff;
    avg_green = (green / (bxsize*bysize)) & 0xff;
    avg_blue  = (blue  / (bxsize*bysize)) & 0xff;

    return (avg_alpha << 24) + (avg_red << 16) + (avg_green << 8) + avg_blue;
}

static void fill_block(uint32_t* start, int bxsize, int bysize,
                       int xsize, uint32_t col)
{
    uint32_t* p = start;
    int x, y;
    uint32_t* pp;

    for (y = 0; y < bysize; ++y)
    {
        pp = p;
        for (x = 0; x < bxsize; ++x)
        {
            *(pp++) = col;
        }
        p += xsize;
    }

}