/* average image bands
 *
 * Author: Simon Goodall
 * Written on: 17/7/07
 * 17/7/07 JC
 * 	- hacked about a bit
 * 18/8/09
 * 	- gtkdoc
 * 	- get rid of the complex case, just double the width
 * 19/11/11
 * 	- redo as a class
 */

/*

    Copyright (C) 1991-2005 The National Gallery

    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

 */

/*

    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk

 */

/*
#define DEBUG
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

#include <vips/vips.h>

#include "bandary.h"

typedef struct _VipsBandmean {
	VipsBandary parent_instance;

	VipsImage *in;

} VipsBandmean;

typedef VipsBandaryClass VipsBandmeanClass;

G_DEFINE_TYPE( VipsBandmean, vips_bandmean, VIPS_TYPE_BANDARY );

/* Unsigned int types. Round, keep sum in a larger variable.
 */
#define UILOOP( TYPE, STYPE ) { \
	TYPE *p = (TYPE *) in[0]; \
	TYPE *q = (TYPE *) out; \
	\
	for( i = 0; i < sz; i++ ) { \
		STYPE sum; \
		\
		sum = 0; \
		for( j = 0; j < bands; j++ ) \
			sum += p[j]; \
		q[i] = (sum + bands / 2) / bands; \
		p += bands; \
	} \
}

/* Signed int types. Round, keep sum in a larger variable.
 */
#define SILOOP( TYPE, STYPE ) { \
	TYPE *p = (TYPE *) in[0]; \
	TYPE *q = (TYPE *) out; \
	\
	for( i = 0; i < sz; i++ ) { \
		STYPE sum; \
		\
		sum = 0; \
		for( j = 0; j < bands; j++ ) \
			sum += p[j]; \
		q[i] = sum > 0 ? \
			(sum + bands / 2) / bands : \
			(sum - bands / 2) / bands; \
		p += bands; \
	} \
}

/* Float loop. No rounding, sum in same container.
 */
#define FLOOP( TYPE ) { \
	TYPE *p = (TYPE *) in[0]; \
	TYPE *q = (TYPE *) out; \
	\
	for( i = 0; i < sz; i++ ) { \
		TYPE sum; \
		\
		sum = 0; \
		for( j = 0; j < bands; j++ ) \
			sum += p[j]; \
		q[i] = sum / bands; \
		p += bands; \
	} \
}

static void
vips_bandmean_buffer( VipsBandary *bandary, 
	VipsPel *out, VipsPel **in, int width )
{
	VipsImage *im = bandary->ready[0];
	const int bands = im->Bands;
	const int sz = width * 
		(vips_band_format_iscomplex( im->BandFmt ) ? 2 : 1);

	int i, j;

	switch( vips_image_get_format( im ) ) {
	case VIPS_FORMAT_CHAR: 	
		SILOOP( signed char, int ); break; 
	case VIPS_FORMAT_UCHAR:	
		UILOOP( unsigned char, unsigned int ); break; 
	case VIPS_FORMAT_SHORT: 	
		SILOOP( signed short, int ); break; 
	case VIPS_FORMAT_USHORT:	
		UILOOP( unsigned short, unsigned int ); break; 
	case VIPS_FORMAT_INT: 	
		SILOOP( signed int, int ); break; 
	case VIPS_FORMAT_UINT: 	
		UILOOP( unsigned int, unsigned int ); break; 
	case VIPS_FORMAT_FLOAT: 	
		FLOOP( float ); break; 
	case VIPS_FORMAT_DOUBLE:	
		FLOOP( double ); break; 
	case VIPS_FORMAT_COMPLEX:
		FLOOP( float ); break;
	case VIPS_FORMAT_DPCOMPLEX:
		FLOOP( double ); break;

	default:
		g_assert_not_reached();
	}
}

static int
vips_bandmean_build( VipsObject *object )
{
	VipsBandary *bandary = (VipsBandary *) object;
	VipsBandmean *bandmean = (VipsBandmean *) object;

	bandary->n = 1;
	bandary->in = &bandmean->in;

	if( bandmean->in &&
		bandmean->in->Bands == 1 ) 
		return( vips_bandary_copy( bandary ) );

	bandary->out_bands = 1;

	if( VIPS_OBJECT_CLASS( vips_bandmean_parent_class )->build( object ) )
		return( -1 );

	return( 0 );
}

static void
vips_bandmean_class_init( VipsBandmeanClass *class )
{
	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsBandaryClass *bandary_class = VIPS_BANDARY_CLASS( class );

	gobject_class->set_property = vips_object_set_property;
	gobject_class->get_property = vips_object_get_property;

	object_class->nickname = "bandmean";
	object_class->description = _( "band-wise average" );
	object_class->build = vips_bandmean_build;

	bandary_class->process_line = vips_bandmean_buffer;

	VIPS_ARG_IMAGE( class, "in", 0, 
		_( "Input" ), 
		_( "Input image argument" ),
		VIPS_ARGUMENT_REQUIRED_INPUT,
		G_STRUCT_OFFSET( VipsBandmean, in ) );
}

static void
vips_bandmean_init( VipsBandmean *bandmean )
{
}

/**
 * vips_bandmean:
 * @in: input image
 * @out: output image
 * @...: %NULL-terminated list of optional named arguments
 *
 * This operation writes a one-band image where each pixel is the average of 
 * the bands for that pixel in the input image. The output band format is 
 * the same as the input band format. Integer types use round-to-nearest
 * averaging.
 *
 * See also: vips_add(), vips_avg(), vips_recomb()
 *
 * Returns: 0 on success, -1 on error
 */
int
vips_bandmean( VipsImage *in, VipsImage **out, ... )
{
	va_list ap;
	int result;

	va_start( ap, out );
	result = vips_call_split( "bandmean", ap, in, out );
	va_end( ap );

	return( result );
}