#include <GL/glut.h>
#include "ppmImage.h"

#include <iostream>

//global image
ppmImage image;

/**
*Sets up approriate viewport coordinates for 2D
*/
void reshape(int w, int h)
{
   glViewport(0, 0, w, h);
   glMatrixMode(GL_PROJECTION);
   glLoadIdentity();
   glOrtho(0, w, h, 0, -1, 1);
   glMatrixMode(GL_MODELVIEW);
   glLoadIdentity();
}

/**
 * display callback function 
 */
void display(void){
	glClear(GL_COLOR_BUFFER_BIT);

	glDrawPixels(image.GetWidth(), image.GetHeight(), GL_RGB, GL_UNSIGNED_BYTE, image.getPixels());
	glFlush();  /* Single buffered, so needs a flush. */
}


/**
 * Main entry point
 */
int main(int argc, char *argv[]){
   if(argc != 2)
   { // Take path to image as runtime arg
	std::cerr << "Usage: ./a.out <image.ppm>\n";
	exit(1);
   }   

   if( !image.readFile(argv[1]) )
   { // Read the image
	std::cerr << "Failed to read image\n";
  	exit(1);
   }

   image.writeFile("writeTest.ppm"); // Write the image to disk

   // Initialize glut
   glutInit(&argc, argv);
   glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
   glutInitWindowSize(image.GetWidth(), image.GetHeight());
   glutInitWindowPosition(100,100);
   glutCreateWindow("ImageLoading example");
   glutDisplayFunc(display);
   glutReshapeFunc(reshape);

   //for GL speed-ups
   glDisable(GL_DEPTH_TEST);
   glDisable(GL_ALPHA_TEST);

   // For fixing the 4 byte boundary issue (Thanks Thomas Hofler)
   glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

   glutMainLoop(); // Give control to glut

   exit(0);
}