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

#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysym.h>
#include <X11/extensions/XShm.h>
#include <sys/ipc.h>
#include <sys/shm.h>

#include "meh.h"

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

int xshm = 0;

XShmSegmentInfo *shminfo;
XImage *ximage(struct image *img, unsigned int width, unsigned int height, int fast){
	int depth;
	XImage *ximg = NULL;
	Visual *vis;

	depth = DefaultDepth(display, screen);
	vis = DefaultVisual(display, screen);

	if(depth >= 24){
		if(xshm){
			shminfo = malloc(sizeof(XShmSegmentInfo));
			if(!(ximg = XShmCreateImage(display,
				CopyFromParent, depth,
				ZPixmap,
				NULL,
				shminfo,
				width, height
			))){
				fprintf(stderr, "XShm problems\n");
				exit(1);
			}
			if((shminfo->shmid = shmget(IPC_PRIVATE, ximg->bytes_per_line * ximg->height, IPC_CREAT|0777)) == -1){
				fprintf(stderr, "XShm problems\n");
				exit(1);
			}
			if((shminfo->shmaddr = ximg->data = shmat(shminfo->shmid, 0, 0)) == (void *)-1){
				fprintf(stderr, "XShm problems\n");
				exit(1);
			}
			shminfo->readOnly = False;
			if(!XShmAttach(display, shminfo)){
				fprintf(stderr, "XShm problems, falling back to to XImage\n");
				xshm = 0;
			}
		}
		if(!xshm){
			ximg = XCreateImage(display, 
				CopyFromParent, depth, 
				ZPixmap, 0, 
				NULL,
				width, height,
				32, 0
			);
			ximg->data  = malloc(ximg->bytes_per_line * ximg->height);
			XInitImage(ximg);
		}
		(fast ? nearestscale : scale)(img, ximg->width, ximg->height, ximg->bytes_per_line, ximg->data);
	}else{
		/* TODO other depths */
		fprintf(stderr, "This program does not yet support display depths <24.\n");
		exit(1);
		return NULL;				
	}

	return ximg;
}

XImage *getimage(struct image *img, unsigned int width, unsigned int height, int fast){
	if(width * img->bufheight > height * img->bufwidth){
		return ximage(img, img->bufwidth * height / img->bufheight, height, fast);
	}else{
		return ximage(img, width, img->bufheight * width / img->bufwidth, fast);
	}
}

void drawimage(XImage *ximg, unsigned int width, unsigned int height){
	XRectangle rects[2];
	int yoffset, xoffset;
	xoffset = (width - ximg->width) / 2;
	yoffset = (height - ximg->height) / 2;
	if(xoffset || yoffset){
		rects[0].x = rects[0].y = 0;
		if(xoffset){
			rects[0].width = rects[1].width = xoffset;
			rects[0].height = rects[1].height = height;
			rects[1].x = xoffset + ximg->width;
			rects[1].y = 0;
			rects[1].width = width - rects[1].x;
		}else if(yoffset){
			rects[0].width = rects[1].width = width;
			rects[0].height = yoffset;
			rects[1].x = 0;
			rects[1].y = yoffset + ximg->height;
			rects[1].height = height - rects[1].y;
		}
		XFillRectangles(display, window, gc, rects, 2);
	}
	if(xshm){
		XShmPutImage(display, window, gc, ximg, 0, 0, xoffset, yoffset, ximg->width, ximg->height, False);
	}else{
		XPutImage(display, window, gc, ximg, 0, 0, xoffset, yoffset, ximg->width, ximg->height);
	}
	XFlush(display);
}

void freeXImg(XImage *ximg){
	if(xshm){
		XShmDetach(display, shminfo);
		XDestroyImage(ximg);
		shmdt(shminfo->shmaddr);
		shmctl(shminfo->shmid, IPC_RMID, 0);
		free(shminfo);
	}else{
		XDestroyImage(ximg);
	}
}


void setaspect(unsigned int w, unsigned int h){
	XSizeHints *hints = XAllocSizeHints();
	//hints->flags = PAspect;
	hints->flags = 0;
	hints->min_aspect.x = hints->max_aspect.x = w;
	hints->min_aspect.y = hints->max_aspect.y = h;
	XSetWMNormalHints(display, window, hints);
	XFlush(display);
	XFree(hints);
}

/* Alt-F4 silent. Keeps people happy */
int xquit(Display *d){
	(void)d;
	exit(EXIT_SUCCESS);
	return 0;
}

void xinit(){
	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);
	setaspect(1, 1);
	gc = XCreateGC(display, window, 0, NULL);

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