/* switch between an array of images
 *
 * 28/7/19
 * 	- from maplut.c
 */

/*

	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

 */

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

typedef struct _VipsSwitch {
	VipsOperation parent_instance;

	VipsArrayImage *tests;
	VipsImage *out;

	int n;

} VipsSwitch;

typedef VipsOperationClass VipsSwitchClass;

G_DEFINE_TYPE(VipsSwitch, vips_switch, VIPS_TYPE_OPERATION);

static int
vips_switch_gen(VipsRegion *out_region,
	void *seq, void *a, void *b, gboolean *stop)
{
	VipsRegion **ar = (VipsRegion **) seq;
	VipsSwitch *swit = (VipsSwitch *) b;
	VipsRect *r = &out_region->valid;

	int x, y, i;
	VipsPel *restrict q;
	size_t qls;
	VipsPel *restrict p[256];
	size_t ls[256];

	if (vips_reorder_prepare_many(out_region->im, ar, r))
		return -1;

	g_assert(ar[0]->im->BandFmt == VIPS_FORMAT_UCHAR);
	g_assert(ar[0]->im->Bands == 1);

	for (i = 0; i < swit->n; i++) {
		p[i] = VIPS_REGION_ADDR(ar[i], r->left, r->top);
		ls[i] = VIPS_REGION_LSKIP(ar[i]);
	}

	q = VIPS_REGION_ADDR(out_region, r->left, r->top);
	qls = VIPS_REGION_LSKIP(out_region);
	for (y = 0; y < r->height; y++) {
		for (x = 0; x < r->width; x++) {
			for (i = 0; i < swit->n; i++)
				if (p[i][x])
					break;

			q[x] = i;
		}

		q += qls;
		for (i = 0; i < swit->n; i++)
			p[i] += ls[i];
	}

	return 0;
}

static int
vips_switch_build(VipsObject *object)
{
	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS(object);
	VipsSwitch *swit = (VipsSwitch *) object;

	VipsImage **tests;
	VipsImage **decode;
	VipsImage **format;
	VipsImage **band;
	VipsImage **size;
	int i;

	g_object_set(object, "out", vips_image_new(), NULL);

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

	/* 255 rather than 256, since we want to reserve +1 as the no
	 * match value.
	 */
	tests = vips_area_get_data(&swit->tests->area,
		NULL, &swit->n, NULL, NULL);
	if (swit->n > 255 ||
		swit->n < 1) {
		vips_error(class->nickname, "%s", _("bad number of tests"));
		return -1;
	}

	decode = (VipsImage **) vips_object_local_array(object, swit->n);
	format = (VipsImage **) vips_object_local_array(object, swit->n);
	band = (VipsImage **) vips_object_local_array(object, swit->n + 1);
	size = (VipsImage **) vips_object_local_array(object, swit->n + 1);

	/* Decode RAD/LABQ etc.
	 */
	for (i = 0; i < swit->n; i++)
		if (vips_image_decode(tests[i], &decode[i]))
			return -1;
	tests = decode;

	/* Must be uchar.
	 */
	for (i = 0; i < swit->n; i++)
		if (vips_cast_uchar(tests[i], &format[i], NULL))
			return -1;
	tests = format;

	/* Images must match in size and bands.
	 */
	if (vips__bandalike_vec(class->nickname, tests, band, swit->n, 1) ||
		vips__sizealike_vec(band, size, swit->n))
		return -1;
	tests = size;

	if (tests[0]->Bands > 1) {
		vips_error(class->nickname,
			"%s", _("test images not 1-band"));
		return -1;
	}

	if (vips_image_pipeline_array(swit->out,
			VIPS_DEMAND_STYLE_THINSTRIP, tests))
		return -1;

	if (vips_image_generate(swit->out,
			vips_start_many, vips_switch_gen, vips_stop_many,
			tests, swit))
		return -1;

	return 0;
}

static void
vips_switch_class_init(VipsSwitchClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *object_class = VIPS_OBJECT_CLASS(class);
	VipsOperationClass *operation_class = VIPS_OPERATION_CLASS(class);

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

	object_class->nickname = "switch";
	object_class->description =
		_("find the index of the first non-zero pixel in tests");
	object_class->build = vips_switch_build;

	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;

	VIPS_ARG_BOXED(class, "tests", 1,
		_("Tests"),
		_("Table of images to test"),
		VIPS_ARGUMENT_REQUIRED_INPUT,
		G_STRUCT_OFFSET(VipsSwitch, tests),
		VIPS_TYPE_ARRAY_IMAGE);

	VIPS_ARG_IMAGE(class, "out", 2,
		_("Output"),
		_("Output image"),
		VIPS_ARGUMENT_REQUIRED_OUTPUT,
		G_STRUCT_OFFSET(VipsSwitch, out));
}

static void
vips_switch_init(VipsSwitch *swit)
{
}

static int
vips_switchv(VipsImage **tests, VipsImage **out, int n, va_list ap)
{
	VipsArrayImage *tests_array;
	int result;

	tests_array = vips_array_image_new(tests, n);
	result = vips_call_split("switch", ap, tests_array, out);
	vips_area_unref(VIPS_AREA(tests_array));

	return result;
}

/**
 * vips_switch:
 * @tests: (array length=n): test these images
 * @out: (out): output index image
 * @n: number of input images
 * @...: %NULL-terminated list of optional named arguments
 *
 * The @tests images are evaluated and at each point the index of the first
 * non-zero value is written to @out. If all @tests are false, the value
 * (@n + 1) is written.
 *
 * Images in @tests must have one band. They are expanded to the
 * bounding box of the set of images in @tests, and that size is used for
 * @out. @tests can have up to 255 elements.
 *
 * Combine with vips_case() to make an efficient multi-way vips_ifthenelse().
 *
 * See also: vips_maplut(), vips_case(), vips_ifthenelse().
 *
 * Returns: 0 on success, -1 on error
 */
int
vips_switch(VipsImage **tests, VipsImage **out, int n, ...)
{
	va_list ap;
	int result;

	va_start(ap, n);
	result = vips_switchv(tests, out, n, ap);
	va_end(ap);

	return result;
}
