/*
 * Copyright 2013 Stephen Fryatt <stevef@netsurf-browser.org>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * NetSurf is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/** \file mouse.c
 * Mouse dragging and tracking support (implementation).
 *
 * Two different functions are provided:-
 *
 * 1. Wimp_DragBox support, allowing clients to start a drag and specify
 *    callbacks to be used
 *
 *    - on Null Polls while the drag is active,
 *    - when the drag terminates with Event_DragEnd, and
 *    - when the drag terminates with Escape being pressed.
 */

#include "oslib/wimp.h"

#include "riscos/mouse.h"
#include "utils/log.h"
#include "utils/utils.h"

/* Data for the wimp drag handler. */

static void (*ro_mouse_drag_end_callback)(wimp_dragged *dragged, void *data)
		= NULL;
static void (*ro_mouse_drag_track_callback)(wimp_pointer *pointer, void *data)
		= NULL;
static void (*ro_mouse_drag_cancel_callback)(void *data) = NULL;
static void *ro_mouse_drag_data = NULL;

/**
 * Process Null polls for any drags and mouse trackers that are currently
 * active.
 */

void ro_mouse_poll(void)
{
	wimp_pointer	pointer;
	os_error	*error;

	/* If no trackers are active, just exit. */

	if (ro_mouse_drag_track_callback == NULL /* && no trackers */)
		return;

	error = xwimp_get_pointer_info(&pointer);
	if (error) {
		LOG(("xwimp_get_pointer_info: 0x%x: %s",
			error->errnum, error->errmess));
		warn_user("WimpError", error->errmess);
		return;
	}

	/* Process the drag tracker, if one is active. */

	if (ro_mouse_drag_track_callback != NULL)
		ro_mouse_drag_track_callback(&pointer, ro_mouse_drag_data);
}


/**
 * Start a drag, providing a function to be called when the Wimp_DragEnd event
 * is received and optionally a tracking function to be called on null polls
 * in between times.
 *
 * \param *drag_end	Callback for when the drag terminates, or NULL for none.
 * \param *drag_track	Callback for mouse tracking during the drag, or NULL for
 *			none.
 * \param *drag_cancel	Callback for cancelling the drag, or NULL if the drag
 *			can't be cancelled.
 * \param *data		Data to be passed to the callback functions, or NULL.
 */
 
void ro_mouse_drag_start(void (*drag_end)(wimp_dragged *dragged, void *data),
		void (*drag_track)(wimp_pointer *pointer, void *data),
		void (*drag_cancel)(void *data), void *data)
{
	/* A drag should never be started when one is already in progress. */

	assert(ro_mouse_drag_end_callback == NULL &&
			ro_mouse_drag_track_callback == NULL &&
			ro_mouse_drag_cancel_callback == NULL &&
			ro_mouse_drag_data == NULL);

	ro_mouse_drag_end_callback = drag_end;
	ro_mouse_drag_track_callback = drag_track;
	ro_mouse_drag_cancel_callback = drag_cancel;
	ro_mouse_drag_data = data;
}


/**
 * Process Wimp_DragEnd events by passing the details on to any registered
 * event handler.
 *
 * \param *dragged	The Wimp_DragEnd data block.
 */

void ro_mouse_drag_end(wimp_dragged *dragged)
{
	if (ro_mouse_drag_end_callback != NULL)
		ro_mouse_drag_end_callback(dragged, ro_mouse_drag_data);
	else
		warn_user("WimpError", "No callback");

	/* Wimp_DragEnd is a one-shot event, so clear the data ready for
	 * another claimant.
	 */

	ro_mouse_drag_end_callback = NULL;
	ro_mouse_drag_track_callback = NULL;
	ro_mouse_drag_cancel_callback = NULL;
	ro_mouse_drag_data = NULL;
}