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

#include <X11/Xlib.h>
#include <X11/keysym.h>

#include "jpeg.h"
#include "util.h"

Display *display;
int screen;
Window window;
GC gc;

void usage(){
	printf("USAGE: meh [FILE1 [FILE2 [...]]]");
	exit(1);
}

static int popcount(unsigned long mask){
#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
    return __builtin_popcount(mask);
#else
    int y;

    y = (mask >> 1) &033333333333;
    y = mask - y - ((y >>1) & 033333333333);
    return (((y + (y >> 3)) & 030707070707) % 077);
#endif
}


unsigned int getshift(unsigned int mask){
	return popcount((mask - 1) & ~mask) & 31;
}

XImage *create_image_from_buffer(unsigned char *buf, int width, int height, int bufwidth, int bufheight) {
	int depth;
	XImage *img = NULL;
	Visual *vis;
	unsigned int rshift, gshift, bshift;
	int outIndex = 0;	
	int i;
	int x,y;
	int numBufBytes = (3 * bufwidth * bufheight);
	
	depth = DefaultDepth(display, screen);
	vis = DefaultVisual(display, screen);

	rshift = getshift(vis->red_mask);
	gshift = getshift(vis->green_mask);
	bshift = getshift(vis->blue_mask);

	if (depth >= 24) {
		size_t numNewBufBytes = (4 * (width * height));
		u_int32_t *newBuf = malloc(numNewBufBytes);
	
		//for(outIndex = 0; outIndex < width * height; outIndex++){
		for(y = 0; y < height; y++){
			for(x = 0; x < width; x++){
				unsigned int r, g, b;
				i = (y * bufheight / height * bufwidth + x * bufwidth / width) * 3;
				assert(i < numBufBytes);
				r = (buf[i++] << rshift) & vis->red_mask;
				g = (buf[i++] << gshift) & vis->green_mask;
				b = (buf[i++] << bshift) & vis->blue_mask;
				
				newBuf[y * width + x] = r | g | b;
			}
		}		
		
		img = XCreateImage (display, 
			CopyFromParent, depth, 
			ZPixmap, 0, 
			(char *) newBuf,
			width, height,
			32, 0
		);
		
	} else if (depth >= 15) {
		exit(1);
		size_t numNewBufBytes = (2 * (width * height));
		u_int16_t *newBuf = malloc (numNewBufBytes);
		
		for (i = 0; i < numBufBytes;) {
			unsigned int r, g, b;
			r = (buf[i++] << rshift) & vis->red_mask;
			g = (buf[i++] << gshift) & vis->green_mask;
			b = (buf[i++] << bshift) & vis->blue_mask;
			
			newBuf[outIndex++] = r | g | b;
		}		
		
		img = XCreateImage (display,
			CopyFromParent, depth,
			ZPixmap, 0,
			(char *) newBuf,
			width, height,
			16, 0
		);
	} else {
		fprintf (stderr, "This program does not support displays with a depth less than 15.");
		exit(1);
		return NULL;				
	}

	XInitImage (img);

	return img;
}		


void init(){
	display = XOpenDisplay (NULL);
	assert(display);
	screen = DefaultScreen(display);

	window = XCreateWindow(display, DefaultRootWindow(display), 0, 0, 640, 480, 0, DefaultDepth(display, screen), InputOutput, CopyFromParent, 0, NULL);
	gc = XCreateGC(display, window, 0, NULL);

	XMapRaised(display, window);
	XSelectInput(display, window, StructureNotifyMask | ExposureMask | KeyPressMask);
	XFlush(display);
}

void run(char *images[], int length){
	int i = 0;
	int bufwidth, bufheight;
	int width = 0, height = 0;
	XImage *img = NULL;
	unsigned char *buf = NULL;
	int redraw = 0;

	for(;;){
		XEvent event;
		XNextEvent(display, &event);
		switch(event.type){
			case MapNotify:
				printf("MapNotify\n");
				break;
			case ConfigureNotify:
				printf("ConfigureNotify(%i, %i, %i, %i)\n", event.xconfigure.x, event.xconfigure.y, event.xconfigure.width, event.xconfigure.height);
				if(width != event.xconfigure.width || height != event.xconfigure.height){
					if(img)
						free(img);
					img = NULL;
					width = event.xconfigure.width;
					height = event.xconfigure.height;
				}
				break;
			case Expose:
				printf("Expose(%i)\n", event.xexpose.count);
				redraw = 1;
				break;
			case KeyPress:
				switch(XLookupKeysym(&event.xkey, 0)){
					case XK_Escape:
						exit(0);
						break;
					case XK_q:
						exit(0);
						break;
					case XK_t:
						i = (i + 1) % length;
						if(img)
							free(img);
						if(buf)
							free(buf);
						img = NULL;
						buf = NULL;
						redraw = 1;
						break;
					case XK_n:
						i = i ? i - 1 : length - 1;
						if(img)
							free(img);
						if(buf)
							free(buf);
						img = NULL;
						buf = NULL;
						redraw = 1;
						break;
				}
				break;
		}
		if(redraw){
			if(!buf)
				buf = loadjpeg(images[i], &bufwidth, &bufheight);
			assert(buf);
			if(!img)
				img = create_image_from_buffer(buf, width, height, bufwidth, bufheight);
			assert(img);
			XPutImage(display, window, gc, img, 0, 0, 0, 0, width, height);
			XFlush(display);
			redraw = 0;
		}
	}
}

int main(int argc, char *argv[]){
	if(argc < 2)
		usage();
	init();

	run(&argv[1], argc - 1);

	return 0;
}