/* Turn displayable rgb files to scRGB.
 *
 * Modified:
 * 15/11/94 JC
 *	- memory leak fixed
 *	- error message added
 * 16/11/94 JC
 *	- partialed
 * 21/9/12
 * 	- redone as a class
 * 	- sRGB only, support for other RGBs is now via lcms
 * 6/11/12
 * 	- add 16-bit sRGB import
 * 11/12/12
 * 	- cut about to make sRGB2scRGB.c
 * 12/2/15
 * 	- add 16-bit alpha handling
 * 26/2/16
 * 	- look for RGB16 tag, not just ushort, for the 16-bit path
 * 24/11/17 lovell
 * 	- special path for 3 and 4 band images
 */

/*

	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 <math.h>

#include <vips/vips.h>

#include "pcolour.h"

/* We can't use VipsColourCode as our parent class. We want to handle
 * alpha ourselves so we can get 16 -> 8 bit conversion right.
 */

typedef struct _VipssRGB2scRGB {
	VipsOperation parent_instance;

	VipsImage *in;
	VipsImage *out;
} VipssRGB2scRGB;

typedef VipsOperationClass VipssRGB2scRGBClass;

G_DEFINE_TYPE(VipssRGB2scRGB, vips_sRGB2scRGB, VIPS_TYPE_OPERATION);

/* Convert a buffer of 8-bit pixels.
 */
static void
vips_sRGB2scRGB_line_8(float *restrict q, VipsPel *restrict p,
	int extra_bands, int width)
{
	int i, j;

	if (extra_bands == 0) {
		for (i = 0; i < width; i++) {
			q[0] = vips_v2Y_8[p[0]];
			q[1] = vips_v2Y_8[p[1]];
			q[2] = vips_v2Y_8[p[2]];

			p += 3;
			q += 3;
		}
	}
	else if (extra_bands == 1) {
		for (i = 0; i < width; i++) {
			q[0] = vips_v2Y_8[p[0]];
			q[1] = vips_v2Y_8[p[1]];
			q[2] = vips_v2Y_8[p[2]];
			q[3] = p[3] / 255.0;

			p += 4;
			q += 4;
		}
	}
	else {
		for (i = 0; i < width; i++) {
			q[0] = vips_v2Y_8[p[0]];
			q[1] = vips_v2Y_8[p[1]];
			q[2] = vips_v2Y_8[p[2]];

			p += 3;
			q += 3;

			for (j = 0; j < extra_bands; j++)
				q[j] = p[j] / 255.0;
			p += extra_bands;
			q += extra_bands;
		}
	}
}

/* Convert a buffer of 16-bit pixels.
 */
static void
vips_sRGB2scRGB_line_16(float *restrict q, unsigned short *restrict p,
	int extra_bands, int width)
{
	int i, j;

	if (extra_bands == 0) {
		for (i = 0; i < width; i++) {
			q[0] = vips_v2Y_16[p[0]];
			q[1] = vips_v2Y_16[p[1]];
			q[2] = vips_v2Y_16[p[2]];

			p += 3;
			q += 3;
		}
	}
	else if (extra_bands == 1) {
		for (i = 0; i < width; i++) {
			q[0] = vips_v2Y_16[p[0]];
			q[1] = vips_v2Y_16[p[1]];
			q[2] = vips_v2Y_16[p[2]];
			q[3] = p[3] / 65535.0;

			p += 4;
			q += 4;
		}
	}
	else {
		for (i = 0; i < width; i++) {
			q[0] = vips_v2Y_16[p[0]];
			q[1] = vips_v2Y_16[p[1]];
			q[2] = vips_v2Y_16[p[2]];

			p += 3;
			q += 3;

			for (j = 0; j < extra_bands; j++)
				q[j] = p[j] / 65535.0;
			p += extra_bands;
			q += extra_bands;
		}
	}
}

static int
vips_sRGB2scRGB_gen(VipsRegion *out_region,
	void *seq, void *a, void *b, gboolean *stop)
{
	VipsRegion *ir = (VipsRegion *) seq;
	VipsRect *r = &out_region->valid;
	VipsImage *in = ir->im;

	int y;

	if (vips_region_prepare(ir, r))
		return -1;

	VIPS_GATE_START("vips_sRGB2scRGB_gen: work");

	if (in->BandFmt == VIPS_FORMAT_UCHAR) {
		vips_col_make_tables_RGB_8();

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

			vips_sRGB2scRGB_line_8(q, p, in->Bands - 3, r->width);
		}
	}
	else {
		vips_col_make_tables_RGB_16();

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

			vips_sRGB2scRGB_line_16(q, (unsigned short *) p,
				in->Bands - 3, r->width);
		}
	}

	VIPS_GATE_STOP("vips_sRGB2scRGB_gen: work");

	return 0;
}

static int
vips_sRGB2scRGB_build(VipsObject *object)
{
	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS(object);
	VipssRGB2scRGB *sRGB2scRGB = (VipssRGB2scRGB *) object;

	VipsImage **t = (VipsImage **) vips_object_local_array(object, 2);

	VipsImage *in;
	VipsImage *out;
	VipsBandFormat format;

	if (VIPS_OBJECT_CLASS(vips_sRGB2scRGB_parent_class)->build(object))
		return -1;

	in = sRGB2scRGB->in;
	if (vips_check_bands_atleast(class->nickname, in, 3))
		return -1;

	// we are changing the gamma, so any profile on the image can no longer
	// work (and will cause horrible problems in any downstream colour
	// handling)
	if (vips_copy(in, &t[0], NULL))
		return -1;
	in = t[0];
	vips_image_remove(in, VIPS_META_ICC_NAME);

	format = in->Type == VIPS_INTERPRETATION_RGB16
		? VIPS_FORMAT_USHORT
		: VIPS_FORMAT_UCHAR;
	if (in->BandFmt != format) {
		if (vips_cast(in, &t[1], format, NULL))
			return -1;
		in = t[1];
	}

	out = vips_image_new();
	if (vips_image_pipelinev(out,
			VIPS_DEMAND_STYLE_THINSTRIP, in, NULL)) {
		g_object_unref(out);
		return -1;
	}
	out->Type = VIPS_INTERPRETATION_scRGB;
	out->BandFmt = VIPS_FORMAT_FLOAT;

	if (vips_image_generate(out,
			vips_start_one, vips_sRGB2scRGB_gen, vips_stop_one,
			in, sRGB2scRGB)) {
		g_object_unref(out);
		return -1;
	}

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

	return 0;
}

static void
vips_sRGB2scRGB_class_init(VipssRGB2scRGBClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *object_class = (VipsObjectClass *) 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 = "sRGB2scRGB";
	object_class->description = _("convert an sRGB image to scRGB");
	object_class->build = vips_sRGB2scRGB_build;

	operation_class->flags = VIPS_OPERATION_SEQUENTIAL;

	VIPS_ARG_IMAGE(class, "in", 1,
		_("Input"),
		_("Input image"),
		VIPS_ARGUMENT_REQUIRED_INPUT,
		G_STRUCT_OFFSET(VipssRGB2scRGB, in));

	VIPS_ARG_IMAGE(class, "out", 100,
		_("Output"),
		_("Output image"),
		VIPS_ARGUMENT_REQUIRED_OUTPUT,
		G_STRUCT_OFFSET(VipssRGB2scRGB, out));
}

static void
vips_sRGB2scRGB_init(VipssRGB2scRGB *sRGB2scRGB)
{
}

/**
 * vips_sRGB2scRGB: (method)
 * @in: input image
 * @out: (out): output image
 * @...: %NULL-terminated list of optional named arguments
 *
 * Convert an sRGB image to scRGB. The input image can be 8 or 16-bit.
 *
 * If the input image is tagged as #VIPS_INTERPRETATION_RGB16, any extra
 * channels after RGB are divided by 256. Thus, scRGB alpha is
 * always 0 - 255.99.
 *
 * See also: vips_scRGB2XYZ(), vips_scRGB2sRGB(), vips_rad2float().
 *
 * Returns: 0 on success, -1 on error.
 */
int
vips_sRGB2scRGB(VipsImage *in, VipsImage **out, ...)
{
	va_list ap;
	int result;

	va_start(ap, out);
	result = vips_call_split("sRGB2scRGB", ap, in, out);
	va_end(ap);

	return result;
}
