// https://gist.github.com/mmp/ba384e1f509e2e38d5df#file-exrcat-cpp

// https://gist.github.com/mmp/ba384e1f509e2e38d5df#file-exrcat-cpp

#include "tinyexr/tinyexr.h"
#include "tinyexr/tinyexr.cc"
#include <stdio.h>
#include <assert.h>
#include <vector>
#include <ImfInputFile.h>
#include <ImfRgbaFile.h>
#include <ImfChannelList.h>
#include <ImfFrameBuffer.h>
#include <half.h>
using namespace Imf;
using namespace Imath;

#if 0
void
SaveAsPFM(const char* filename, int width, int height, float* data)
{
FILE* fp = fopen(filename, "wb");
if (!fp) {
fprintf(stderr, "failed to write a PFM file.\n");
return;
}

fprintf(fp, "PF\n");
fprintf(fp, "%d %d\n", width, height);
fprintf(fp, "-1\n"); // -1: little endian, 1: big endian

// RGBA -> RGB
std::vector<float> rgb(width*height*3);

for (size_t i = 0; i < width * height; i++) {
rgb[3*i+0] = data[4*i+0];
rgb[3*i+1] = data[4*i+1];
rgb[3*i+2] = data[4*i+2];
}

fwrite(&rgb.at(0), sizeof(float), width * height * 3, fp);

fclose(fp);
}
#endif

static float *OpenExrLoad(const char *name, int *width, int *height) {
try {
RgbaInputFile file (name);
Box2i dw = file.dataWindow();
*width = dw.max.x - dw.min.x + 1;
*height = dw.max.y - dw.min.y + 1;
std::vector<Rgba> pixels(*width * *height);
file.setFrameBuffer(&pixels[0] - dw.min.x - dw.min.y * *width, 1, *width);
file.readPixels(dw.min.y, dw.max.y);

printf("OpenExr\n datawindow: (%d %d) - (%d %d)\n", dw.min.x, dw.min.y,
dw.max.x, dw.max.y);
printf(" line order %s\n", (file.lineOrder() == INCREASING_Y) ?
"increasing y" : ((file.lineOrder() == DECREASING_Y) ? "decreasing y"
: "random y"));
printf(" compression: ");
switch (file.compression()) {
case NO_COMPRESSION: printf("none"); break;
case RLE_COMPRESSION: printf("RLE"); break;
case ZIPS_COMPRESSION: printf("zip"); break;
case ZIP_COMPRESSION: printf("zips"); break;
case PIZ_COMPRESSION: printf("piz"); break;
case PXR24_COMPRESSION: printf("pxr24"); break;
case B44_COMPRESSION: printf("b44"); break;
case B44A_COMPRESSION: printf("b44a"); break;
default: printf("unknown!");
}
printf("\n");

printf(" channels: ");
RgbaChannels channels = file.channels();
if (channels & WRITE_R) printf("R");
if (channels & WRITE_G) printf("G");
if (channels & WRITE_B) printf("B");
if (channels & WRITE_A) printf("A");
if (channels & WRITE_Y) printf("Y");
if (channels & WRITE_C) printf("C");
printf("\n");

float *ret = new float[4 * *width * *height];
for (int i = 0; i < *width * *height; ++i) {
ret[4*i] = pixels[i].r;
ret[4*i+1] = pixels[i].g;
ret[4*i+2] = pixels[i].b;
ret[4*i+3] = pixels[i].a;
}
return ret;
} catch (const std::exception &e) {
return NULL;
}
}

int main(int argc, char *argv[]) {
if (argc != 2) {
fprintf(stderr, "usage: exrcat <file.exr>\n");
return 1;
}

int ow, oh;
float *orgb = OpenExrLoad(argv[1], &ow, &oh);

//SaveAsPFM("out.pfm", ow, oh, orgb);

int tw, th;
float *trgb;
const char *err;
if (LoadEXR(&trgb, &tw, &th, argv[1], &err) != 0) {
fprintf(stderr, "exrcat: %s %s\n", argv[1], err);
return 1;
}

assert(ow == tw && oh == th);
int o = 0;
for (int y = 0; y < th; ++y) {
for (int x = 0; x < tw; ++x, ++o) {
printf("(%d, %d): %f %f %f %f - %f %f %f %f\n", x, y,
orgb[4*o], orgb[4*o+1], orgb[4*o+2], orgb[4*o+3],
trgb[4*o], trgb[4*o+1], trgb[4*o+2], trgb[4*o+3]);
}
}

return 0;
}