#include <X11/Xlib.h>
#include <X11/extensions/Xinerama.h>

#include "xinerama.h"

#define max_monitors 16

struct monitor {
	int x;
	int y;
	int width;
	int height;
};

static struct monitor monitors[max_monitors];
static int monitor_count;

static int
point_in_monitor(int x, int y, int monitor)
{
	if (x < monitors[monitor].x || y < monitors[monitor].y)
	    return 0;
	if (x >= monitors[monitor].x + monitors[monitor].width)
	    return 0;
	if (y >= monitors[monitor].y + monitors[monitor].height)
	    return 0;
	return 1;
}

int
xinerama_init(Display *display, Window root_window)
{
	XWindowAttributes root_attrs;
	XineramaScreenInfo *screen_info;
	int i, j, major, minor;

	monitor_count = 1;
	if (!XGetWindowAttributes(display, root_window, &root_attrs))
	    return monitor_count;
	monitors[0].x = 0;
	monitors[0].y = 0;
	monitors[0].width = root_attrs.width;
	monitors[0].height = root_attrs.height;
	if (!XineramaQueryExtension(display, &major, &minor) ||
	    !XineramaIsActive(display))
	    return monitor_count;
	screen_info = XineramaQueryScreens(display, &j);
	if (screen_info == None || j < 1)
	    return monitor_count;
	monitor_count = j;
	if (monitor_count > max_monitors)
	    monitor_count = max_monitors;
	for (i = 0; i < monitor_count; i++) {
	    monitors[i].x = screen_info[i].x_org;
	    monitors[i].y = screen_info[i].y_org;
	    monitors[i].width = screen_info[i].width;
	    monitors[i].height = screen_info[i].height;
	}
	XFree(screen_info);
	return monitor_count;
}

int
xinerama_monitor_for_point(int x, int y)
{
	int i;

	for (i = 0; i < monitor_count; i++)
	    if (point_in_monitor(x, y, i))
	        return i;
	return 0;
}

int
xinerama_monitor_for_window(Display *display, Window root_window, Window window)
{
	XWindowAttributes window_attrs;
	int x, y;

	(void)root_window;
	if (!XGetWindowAttributes(display, window, &window_attrs))
	    return 0;
	x = window_attrs.x + (window_attrs.width / 2);
	y = window_attrs.y + (window_attrs.height / 2);
	return xinerama_monitor_for_point(x, y);
}

int
xinerama_monitor_geometry(int monitor, int *x, int *y, int *width, int *height)
{
	if (monitor < 0 || monitor >= monitor_count)
	    return 0;
	if (x != NULL)
	    *x = monitors[monitor].x;
	if (y != NULL)
	    *y = monitors[monitor].y;
	if (width != NULL)
	    *width = monitors[monitor].width;
	if (height != NULL)
	    *height = monitors[monitor].height;
	return 1;
}