/*
 * Copyright 2010 Johan Veenhuizen
 */

#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>

#include "wind.h"

struct dragger {
	struct listener listener;
	void (*dragnotify)(void *, int, int, unsigned long, Time);
	void *arg;
	unsigned long counter;
	Window window;
	int x0;
	int y0;
	int x;
	int y;
};

static void event(void *, XEvent *);
static void buttonpress(struct dragger *, XButtonEvent *);
static void motionnotify(struct dragger *, XMotionEvent *);

struct dragger *dcreate(Window parent, int x, int y,
		int width, int height, int gravity, Cursor cursor,
		void (*dragnotify)(void *, int, int, unsigned long, Time),
		void *arg)
{
	struct dragger *d = xmalloc(sizeof *d);
	d->window = XCreateWindow(dpy, parent, x, y, width, height, 0,
			CopyFromParent, InputOnly, CopyFromParent,
			CWWinGravity | CWCursor,
			&(XSetWindowAttributes){
				.win_gravity = gravity,
				.cursor = cursor });
	d->listener.function = event;
	d->listener.pointer = d;
	setlistener(d->window, &d->listener);
	d->counter = 0;

	switch (gravity) {
	case NorthWestGravity:
	case WestGravity:
	case SouthWestGravity:
		d->x0 = 0;
		break;
	case NorthGravity:
	case CenterGravity:
	case SouthGravity:
		d->x0 = width / 2;
		break;
	case NorthEastGravity:
	case EastGravity:
	case SouthEastGravity:
		d->x0 = width - 1;
		break;
	default:
		d->x0 = 0;
		break;
	}

	switch (gravity) {
	case NorthWestGravity:
	case NorthGravity:
	case NorthEastGravity:
		d->y0 = 0;
		break;
	case WestGravity:
	case CenterGravity:
	case EastGravity:
		d->y0 = height / 2;
		break;
	case SouthWestGravity:
	case SouthGravity:
	case SouthEastGravity:
		d->y0 = height - 1;
		break;
	default:
		d->y0 = 0;
		break;
	}

	d->x = 0;
	d->y = 0;
	d->dragnotify = dragnotify;
	d->arg = arg;
	XGrabButton(dpy, Button1, AnyModifier, d->window, False,
			Button1MotionMask, GrabModeAsync, GrabModeAsync,
			None, cursor);
	XMapWindow(dpy, d->window);
	return d;
}

void ddestroy(struct dragger *d)
{
	setlistener(d->window, NULL);
	XDestroyWindow(dpy, d->window);
	free(d);
}

static void event(void *self, XEvent *e)
{
	switch (e->type) {
	case MotionNotify:
		motionnotify(self, &e->xmotion);
		break;
	case ButtonPress:
		buttonpress(self, &e->xbutton);
		break;
	}
}

static void buttonpress(struct dragger *d, XButtonEvent *e)
{
	d->counter = 0;
	d->x = e->x - d->x0;
	d->y = e->y - d->y0;
	if (d->dragnotify != NULL)
		d->dragnotify(d->arg,
				e->x_root - d->x,
				e->y_root - d->y,
				d->counter++, e->time);
}

static void motionnotify(struct dragger *d, XMotionEvent *e)
{
	if (d->dragnotify != NULL)
		d->dragnotify(d->arg,
				e->x_root - d->x, e->y_root - d->y,
				d->counter++, e->time);
}