/* Fold up x into bands.
 *
 * 5/6/15
 * 	- from copy.c
 * 10/6/15
 * 	- add @factor option
 */

/*

	This file is part of VIPS.

	VIPS 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 of the License, or
	(at your option) any later version.

	This program 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 program; 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 VIPS_DEBUG
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <glib/gi18n-lib.h>

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

#include <vips/vips.h>
#include <vips/internal.h>
#include <vips/debug.h>

#include "pconversion.h"

typedef struct _VipsBandfold {
	VipsConversion parent_instance;

	/* The input image.
	 */
	VipsImage *in;

	int factor;

} VipsBandfold;

typedef VipsConversionClass VipsBandfoldClass;

G_DEFINE_TYPE(VipsBandfold, vips_bandfold, VIPS_TYPE_CONVERSION);

static int
vips_bandfold_gen(VipsRegion *out_region,
	void *seq, void *a, void *b, gboolean *stop)
{
	VipsBandfold *bandfold = (VipsBandfold *) b;
	VipsRegion *ir = (VipsRegion *) seq;
	VipsImage *out = out_region->im;
	VipsRect *r = &out_region->valid;
	int psize = VIPS_IMAGE_SIZEOF_PEL(out);

	VipsRect need;
	int y;

	need.left = r->left * bandfold->factor;
	need.top = r->top;
	need.width = r->width * bandfold->factor;
	need.height = r->height;
	if (vips_region_prepare(ir, &need))
		return -1;

	for (y = 0; y < r->height; y++) {
		VipsPel *p = VIPS_REGION_ADDR(ir,
			r->left * bandfold->factor, r->top + y);
		VipsPel *q = VIPS_REGION_ADDR(out_region, r->left, r->top + y);

		/* We can't use vips_region_region() since we change pixel
		 * coordinates.
		 */
		memcpy(q, p, (size_t) psize * r->width);
	}

	return 0;
}

static int
vips_bandfold_build(VipsObject *object)
{
	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS(object);
	VipsConversion *conversion = VIPS_CONVERSION(object);
	VipsBandfold *bandfold = (VipsBandfold *) object;
	VipsImage **t = (VipsImage **) vips_object_local_array(object, 1);

	VipsImage *in;

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

	in = bandfold->in;

	if (vips_image_decode(in, &t[0]))
		return -1;
	in = t[0];

	if (bandfold->factor == 0)
		bandfold->factor = in->Xsize; // FIXME: Invalidates operation cache

	if (in->Xsize % bandfold->factor != 0) {
		vips_error(class->nickname,
			"%s", _("@factor must be a factor of image width"));
		return -1;
	}

	if (vips_image_pipelinev(conversion->out,
			VIPS_DEMAND_STYLE_THINSTRIP, in, NULL))
		return -1;

	conversion->out->Xsize /= bandfold->factor;
	conversion->out->Bands *= bandfold->factor;

	if (vips_image_generate(conversion->out,
			vips_start_one, vips_bandfold_gen, vips_stop_one,
			in, bandfold))
		return -1;

	return 0;
}

static void
vips_bandfold_class_init(VipsBandfoldClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS(class);
	VipsOperationClass *operation_class = VIPS_OPERATION_CLASS(class);

	VIPS_DEBUG_MSG("vips_bandfold_class_init\n");

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

	vobject_class->nickname = "bandfold";
	vobject_class->description = _("fold up x axis into bands");
	vobject_class->build = vips_bandfold_build;

	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;

	VIPS_ARG_IMAGE(class, "in", 1,
		_("Input"),
		_("Input image"),
		VIPS_ARGUMENT_REQUIRED_INPUT,
		G_STRUCT_OFFSET(VipsBandfold, in));

	VIPS_ARG_INT(class, "factor", 11,
		_("Factor"),
		_("Fold by this factor"),
		VIPS_ARGUMENT_OPTIONAL_INPUT,
		G_STRUCT_OFFSET(VipsBandfold, factor),
		0, 10000000, 0);
}

static void
vips_bandfold_init(VipsBandfold *bandfold)
{
	/* 0 means fold by width, see above.
	 */
	bandfold->factor = 0;
}

/**
 * vips_bandfold: (method)
 * @in: input image
 * @out: (out): output image
 * @...: `NULL`-terminated list of optional named arguments
 *
 * Fold up an image horizontally: width is collapsed into bands.
 * Use @factor to set how much to fold by: @factor 3, for example, will make
 * the output image three times narrower than the input, and with three times
 * as many bands. By default the whole of the input width is folded up.
 *
 * ::: tip "Optional arguments"
 *     * @factor: `gint`, fold by this factor
 *
 * ::: seealso
 *     [ctor@Image.csvload], [method@Image.bandunfold].
 *
 * Returns: 0 on success, -1 on error.
 */
int
vips_bandfold(VipsImage *in, VipsImage **out, ...)
{
	va_list ap;
	int result;

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

	return result;
}
