#include <sys/stat.h>
#include <sys/time.h>
#include <math.h>
#include <cairo-xlib.h>

#include "initcairo.h"

#define ERROR(condition, msg, ...) if(condition){fprintf(stderr, msg, ##__VA_ARGS__); return 0;}

static Bool alwaysTruePredicate(Display *display, XEvent *event, XPointer arg)
{
	return true;
}

int initCairo(int screen, int mask, int width, int height, const char *name, GraphicsInfo *info)
{
	mask |= StructureNotifyMask | ExposureMask | KeyPressMask | ButtonPressMask | PointerMotionMask;

	info->display = XOpenDisplay(NULL);
	ERROR(!info->display, "Failed to open X display\n");

	Visual *visual = XDefaultVisual(info->display, screen);
	int depth = XDefaultDepth(info->display, screen);
	Window root = XRootWindow(info->display, screen);
	XSetWindowAttributes swa;
	info->cmap = XCreateColormap(info->display, root, visual, AllocNone);
	swa.colormap = info->cmap;
	swa.background_pixmap = None;
	swa.border_pixel = 0;
	swa.event_mask = mask;
	info->win = XCreateWindow(info->display, root, 0, 0, width, height, 0, depth, InputOutput, visual, CWBorderPixel|CWColormap|CWEventMask, &swa);
	ERROR(!info->win, "Failed to create window.\n");
	XStoreName(info->display, info->win, name);

	XMapWindow(info->display, info->win);

	info->sfc = cairo_xlib_surface_create(info->display, info->win, visual, width, height);
	cairo_xlib_surface_set_size(info->sfc, width, height);
	info->ctx = cairo_create(info->sfc);
	cairo_matrix_init_identity(&info->matrix);
	info->scalefactor = 1.0;

	info->wm_delete_window = XInternAtom(info->display, "WM_DELETE_WINDOW", 0);
	info->wm_protocols = XInternAtom(info->display, "WM_PROTOCOLS", 0);
	XSetWMProtocols(info->display, info->win, &info->wm_delete_window, 1);

	return 1;
}

void destroyCairo(GraphicsInfo *info)
{
	XDestroyWindow(info->display, info->win);
	XFreeColormap(info->display, info->cmap);
	XCloseDisplay(info->display);
}

void startTimer(GraphicsInfo *info)
{
	gettimeofday(&info->start_time, NULL);
	info->frames = 0;
}

void waitUpdateTimer(GraphicsInfo *info)
{
	struct timeval current_time;
	double new_elapsed;

	gettimeofday(&current_time, NULL);
	new_elapsed = current_time.tv_sec - info->start_time.tv_sec;
	new_elapsed += (current_time.tv_usec - info->start_time.tv_usec) * 1e-6;
	info->frametime = new_elapsed - info->elapsed;
	if(info->frametime < 0.01) {              // frames < 10ms are considered too short; sleep a while and then measure again
		usleep(10000 - info->frametime*1e6);
		gettimeofday(&current_time, NULL);
		new_elapsed = current_time.tv_sec - info->start_time.tv_sec;
		new_elapsed += (current_time.tv_usec - info->start_time.tv_usec) * 1e-6;
		info->frametime = new_elapsed - info->elapsed;
	}
	info->elapsed = new_elapsed;
	info->frames++;
}

int processStandardEvent(GraphicsInfo *info, XEvent *ev, void (*draw)(void*), void *data)
{
	int state;
	static int last_x, last_y;

	switch(ev->type) {

	case Expose:
		draw(data);
		break;

	case ConfigureNotify:
		printf("ConfigureNotify Event, new dimensions: %d %d %d %d\n", ev->xconfigure.x, ev->xconfigure.y, ev->xconfigure.width, ev->xconfigure.height);
		info->width = ev->xconfigure.width;
		info->height = ev->xconfigure.height;
		cairo_xlib_surface_set_size(info->sfc, info->width, info->height);
		break;

	case KeyPress:
		state = ev->xkey.state & (ShiftMask | LockMask | ControlMask);
		if(state == 0 && ev->xkey.keycode == 24)
			return true;
		break;

	case ButtonPress:
		if(ev->xbutton.button == 4) {
			cairo_matrix_t transform;
			cairo_matrix_init_identity(&transform);
			cairo_matrix_translate(&transform, ev->xbutton.x, ev->xbutton.y);
			cairo_matrix_scale(&transform, 5.0/4.0, 5.0/4.0);
			cairo_matrix_translate(&transform, -ev->xbutton.x, -ev->xbutton.y);
			cairo_matrix_multiply(&info->matrix, &info->matrix, &transform);
			info->scalefactor *= 5.0/4.0;
		} else if(ev->xbutton.button == 5) {
			cairo_matrix_t transform;
			cairo_matrix_init_identity(&transform);
			cairo_matrix_translate(&transform, ev->xbutton.x, ev->xbutton.y);
			cairo_matrix_scale(&transform, 4.0/5.0, 4.0/5.0);
			cairo_matrix_translate(&transform, -ev->xbutton.x, -ev->xbutton.y);
			cairo_matrix_multiply(&info->matrix, &info->matrix, &transform);
			info->scalefactor *= 4.0/5.0;
		}
		last_x = ev->xbutton.x;
		last_y = ev->xbutton.y;
		draw(data);
		break;

	case MotionNotify:
		if(ev->xmotion.state & Button1Mask && !(ev->xmotion.state & ShiftMask)) {
			int dx = ev->xmotion.x - last_x;
			int dy = ev->xmotion.y - last_y;

			cairo_matrix_t transform;
			cairo_matrix_init_identity(&transform);
			cairo_matrix_translate(&transform, dx, dy);
			cairo_matrix_multiply(&info->matrix, &info->matrix, &transform);

			printf("Button1Motion Event, dx: %d, dy: %d\n", dx, dy);

			draw(data);
		} else if(ev->xmotion.state & Button1Mask && ev->xmotion.state & ShiftMask) {
			double angle =
				atan2((double)ev->xmotion.y - (double)info->height/2, (double)ev->xmotion.x - (double)info->width/2)-
				atan2((double)last_y        - (double)info->height/2, (double)last_x        - (double)info->width/2);

			cairo_matrix_t transform;
			cairo_matrix_init_identity(&transform);
			cairo_matrix_translate(&transform, (double)info->width/2, (double)info->height/2);
			cairo_matrix_rotate(&transform, angle);
			cairo_matrix_translate(&transform, -(double)info->width/2, -(double)info->height/2);
			cairo_matrix_multiply(&info->matrix, &info->matrix, &transform);

			printf("Button1Motion Event, angle: %f\n", angle);

			draw(data);
		}
		last_x = ev->xmotion.x;
		last_y = ev->xmotion.y;
		break;

	case ClientMessage:
		if((Atom)ev->xclient.message_type == info->wm_protocols && (Atom)ev->xclient.data.l[0] == info->wm_delete_window) {
//			printf("Window closed\n");
			return true;
		}
		break;
	}

	return 0;

}

int checkEvents(GraphicsInfo *info, int (*process)(GraphicsInfo*, XEvent*, void*), void (*draw)(void*), void *data) // get any events from the queue and the server, process them if neccessary, quit if wanted
{
	XEvent ev;

//	while(XCheckIfEvent(info->display, &ev, alwaysTruePredicate, NULL)) {  // we essentially want XCheckWindowEvent, but we want to avoid that events for other windows fill up the queue

	XNextEvent(info->display, &ev);

	if(ev.xany.window != info->win)
		return 0;

/*	if(ev.type == KeyRelease) { // deal with autorepeat
		XEvent nev;
		if(XCheckIfEvent(info->display, &nev, alwaysTruePredicate, NULL)) { // is there another event?
			if (nev.type == KeyPress && nev.xkey.time == ev.xkey.time && nev.xkey.keycode == ev.xkey.keycode) // which is equal, but KeyPress? Then it's just auto-repeat
				return 0; // so we ignore both

			XPutBackEvent(info->display, &nev); // otherwise put the event back, we will consider it in the next round
		}
		} */

	if(processStandardEvent(info, &ev, draw, data))
		return 1;

	if(process(info, &ev, data))
		return 1; // quit event queue and application

	return 0;
}