#include <stdlib.h>
#include <stdio.h>

#include <EGL/egl.h>
#include <GLES/gl.h>
#include <GLES/glext.h>


int main(int argc, char** argv)
{
    EGLint s_configAttribs[] = {
         EGL_SURFACE_TYPE, EGL_PBUFFER_BIT,//|EGL_WINDOW_BIT,
         EGL_RED_SIZE,       5,
         EGL_GREEN_SIZE,     6,
         EGL_BLUE_SIZE,      5,
         EGL_NONE
     };

     EGLint numConfigs = -1;
     EGLint majorVersion;
     EGLint minorVersion;
     EGLConfig config;
     EGLContext context;
     EGLSurface surface;
     EGLint w = 2, h = 2;

     int texSize = w;
     char* data = (char*)malloc(4*texSize*texSize*sizeof(char));
     char* result = (char*)malloc(4*texSize*texSize*sizeof(char));

     for (int i=0; i<texSize*texSize*4; i++)
        data[i] = i*10;

     EGLDisplay dpy;


     dpy = eglGetDisplay(EGL_DEFAULT_DISPLAY);
     eglInitialize(dpy, &majorVersion, &minorVersion);

         printf("creating pbuffer\n");
         eglChooseConfig(dpy, s_configAttribs, &config, 1, &numConfigs);
         EGLint attribs[] = { EGL_WIDTH, w, EGL_HEIGHT, h, EGL_NONE };
         surface = eglCreatePbufferSurface(dpy, config, attribs);
         if (surface == EGL_NO_SURFACE) {
             printf("eglCreatePbufferSurface error %x\n", eglGetError());
         }

//         printf("FBO 0x%02X\n", glCheckFramebufferStatus​(GL_FRAMEBUFFER));

     context = eglCreateContext(dpy, config, NULL, NULL);
     eglMakeCurrent(dpy, surface, surface, context);
     eglQuerySurface(dpy, surface, EGL_WIDTH, &w);
     eglQuerySurface(dpy, surface, EGL_HEIGHT, &h);

    printf("Surface %dx%d\n", w, h);

     glViewport(0, 0, w, h);
     glMatrixMode(GL_PROJECTION);
     glLoadIdentity();
     glOrthof(0, w, 0, h, 0, 1); // FIXME: What's that?!?

     //~ glClearColor(0,0,0,0);
     //~ glClear(GL_COLOR_BUFFER_BIT);


//     GLint crop[4] = { 0, 4, 4, -4 };
     glBindTexture(GL_TEXTURE_2D, 0);
//     glTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_CROP_RECT_OES, crop);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
     glTexParameterx(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
//     glTexEnvx(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
//     glEnable(GL_TEXTURE_2D);
//     glColor4f(1,1,1,1);

     printf("%d: 0x%02X\n", __LINE__, glGetError());

     glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA,
         texSize, texSize, 0, GL_RGBA, GL_UNSIGNED_BYTE, data);

    printf("%d: 0x%02X\n", __LINE__, glGetError());


    //glPixelStorei(GL_PACK_ALIGNMENT, 1);
    glReadPixels(0, 0, texSize, texSize, GL_RGBA,
             GL_UNSIGNED_BYTE, result);

    printf("%d: 0x%02X\n", __LINE__, glGetError());



    for (int i=0; i<texSize*texSize*4; i++)
        printf("%d\n",data[i]);
    printf("Data after roundtrip:\n");
    for (int i=0; i<texSize*texSize*4; i++)
        printf("%d\n",result[i]);

     eglTerminate(dpy);
     return 0;
}