/* 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 <glib/gi18n-lib.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(VipsBandarySequence *seq,
	VipsPel *out, VipsPel **in, int width)
{
	VipsBandary *bandary = seq->bandary;
	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: (method)
 * @in: input image
 * @out: (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;
}
