/*
 * filter_strobe.c -- simple strobing filter
 * Copyright (C) 2020 Martin Sandsmark <martin.sandsmark@kde.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 */

#include <framework/mlt_filter.h>
#include <framework/mlt_frame.h>
#include <framework/mlt_producer.h>
#include <framework/mlt_service.h>
#include <framework/mlt_factory.h>
#include <framework/mlt_property.h>

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

static int filter_get_image( mlt_frame frame, uint8_t **image, mlt_image_format *format, int *width, int *height, int writable )
{
	mlt_filter filter = mlt_frame_pop_service( frame );
	mlt_properties properties = MLT_FILTER_PROPERTIES( filter );

	int error = mlt_frame_get_image( frame, image, format, width, height, 1 );
	if ( error )
	{
		return error;
	}

	mlt_position position = mlt_filter_get_position( filter, frame );
	mlt_position length = mlt_filter_get_length2( filter, frame );

	int invert = mlt_properties_anim_get_int( properties, "strobe_invert", position, length );
	int interval = mlt_properties_anim_get_int( properties, "interval", position, length );

	int do_strobe = ( position % ( interval + 1 ) ) > interval / 2;

	if ( invert )
	{
		do_strobe = !do_strobe;
	}

	if ( do_strobe != 1 )
	{
		return 0;
	}

	assert( *width >= 0 );
	assert( *height >= 0 );
	size_t pixelCount = *width * *height;

	if ( *format == mlt_image_rgba )
	{
		uint8_t *bytes = *image;
		for ( size_t i=3; i<pixelCount * 4; i+=4 )
		{
			bytes[i] = 0;
		}
		// Clear any alpha buffer that may be attached to the frame
		mlt_frame_set_alpha( frame, NULL, 0, NULL );
	}
	else
	{
		uint8_t* alpha = mlt_pool_alloc( pixelCount );
		memset( alpha, 0, pixelCount );
		mlt_frame_set_alpha( frame, alpha, pixelCount, mlt_pool_release );
	}

	return 0;

}

/** Filter processing.
*/

static mlt_frame filter_process( mlt_filter filter, mlt_frame frame )
{

	// Push the filter on to the stack
	mlt_frame_push_service( frame, filter );

	// Push the frame filter
	mlt_frame_push_get_image( frame, filter_get_image );

	return frame;
}

/** Constructor for the filter.
*/

mlt_filter filter_strobe_init( mlt_profile profile, mlt_service_type type, const char *id, char *arg )
{
	mlt_filter filter = mlt_filter_new( );
	if ( filter != NULL )
	{
		filter->process = filter_process;
		// If strobe_invert == 1, the odd number of frames will be filtered out
		mlt_properties_set( MLT_FILTER_PROPERTIES( filter ), "strobe_invert", "0" );
		mlt_properties_set( MLT_FILTER_PROPERTIES( filter ), "interval", "1" );
	}
	return filter;
}



