/* Turn XYZ to Lab colourspace.
 *
 * Modified:
 * 16/11/94 JC
 *	- uses im_wrapone()
 *	- in-line conversion
 * 27/1/03 JC
 *	- swapped cbrt() for pow(), more portable
 * 12/11/04
 * 	- swapped pow() for cbrt() again, pow() is insanely slow on win32
 * 	- added a configure test for cbrt().
 * 23/11/04
 *	- use a large LUT instead, about 5x faster
 * 23/11/06
 *	- ahem, build the LUT outside the eval thread
 * 2/11/09
 * 	- gtkdoc
 * 3/8/11
 * 	- fix a race in the table build
 * 19/9/12
 * 	- redone as a class
 */

/*

	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 <vips/internal.h>

#include "pcolour.h"

#ifndef HAVE_CBRT
#define cbrt(X) pow((X), 1.0 / 3.0)
#endif /*!HAVE_CBRT*/

/* Lookup table size.
 */
#define QUANT_ELEMENTS (100000)

static float cbrt_table[QUANT_ELEMENTS];

typedef struct _VipsXYZ2Lab {
	VipsColourTransform parent_instance;

	/* The colour temperature -- default to D65.
	 */
	VipsArea *temp;

	/* Broken out as xyz.
	 */
	double X0;
	double Y0;
	double Z0;

} VipsXYZ2Lab;

typedef VipsColourTransformClass VipsXYZ2LabClass;

G_DEFINE_TYPE(VipsXYZ2Lab, vips_XYZ2Lab, VIPS_TYPE_COLOUR_TRANSFORM);

static GOnce table_init_once = G_ONCE_INIT;

static void *
table_init(void *client)
{
	int i;

	for (i = 0; i < QUANT_ELEMENTS; i++) {
		float Y = (double) i / QUANT_ELEMENTS;

		if (Y < 0.008856)
			cbrt_table[i] = 7.787 * Y + (16.0 / 116.0);
		else
			cbrt_table[i] = cbrt(Y);
	}

	return NULL;
}

static void
vips_col_XYZ2Lab_helper(VipsXYZ2Lab *XYZ2Lab,
	float X, float Y, float Z, float *L, float *a, float *b)
{
	float nX, nY, nZ;
	int i;
	float f;
	float cbx, cby, cbz;

	nX = QUANT_ELEMENTS * X / XYZ2Lab->X0;
	nY = QUANT_ELEMENTS * Y / XYZ2Lab->Y0;
	nZ = QUANT_ELEMENTS * Z / XYZ2Lab->Z0;

	/* CLIP is much faster than FCLIP, and we want an int result.
	 */
	i = VIPS_CLIP(0, (int) nX, QUANT_ELEMENTS - 2);
	f = nX - i;
	cbx = cbrt_table[i] + f * (cbrt_table[i + 1] - cbrt_table[i]);

	i = VIPS_CLIP(0, (int) nY, QUANT_ELEMENTS - 2);
	f = nY - i;
	cby = cbrt_table[i] + f * (cbrt_table[i + 1] - cbrt_table[i]);

	i = VIPS_CLIP(0, (int) nZ, QUANT_ELEMENTS - 2);
	f = nZ - i;
	cbz = cbrt_table[i] + f * (cbrt_table[i + 1] - cbrt_table[i]);

	*L = 116.0 * cby - 16.0;
	*a = 500.0 * (cbx - cby);
	*b = 200.0 * (cby - cbz);
}

/* Process a buffer of data.
 */
VIPS_TARGET_CLONES("default,avx")
static void
vips_XYZ2Lab_line(VipsColour *colour, VipsPel *out, VipsPel **in, int width)
{
	VipsXYZ2Lab *XYZ2Lab = (VipsXYZ2Lab *) colour;
	float *p = (float *) in[0];
	float *q = (float *) out;

	int x;

	VIPS_ONCE(&table_init_once, table_init, NULL);

	for (x = 0; x < width; x++) {
		float X, Y, Z;
		float L, a, b;

		X = p[0];
		Y = p[1];
		Z = p[2];
		p += 3;

		vips_col_XYZ2Lab_helper(XYZ2Lab, X, Y, Z, &L, &a, &b);

		q[0] = L;
		q[1] = a;
		q[2] = b;
		q += 3;
	}
}

/**
 * vips_col_XYZ2Lab:
 * @X: Input CIE XYZ colour
 * @Y: Input CIE XYZ colour
 * @Z: Input CIE XYZ colour
 * @L: (out): Return CIE Lab value
 * @a: (out): Return CIE Lab value
 * @b: (out): Return CIE Lab value
 *
 * Calculate XYZ from Lab, D65.
 *
 * See also: vips_XYZ2Lab().
 */
void
vips_col_XYZ2Lab(float X, float Y, float Z, float *L, float *a, float *b)
{
	VipsXYZ2Lab XYZ2Lab;

	VIPS_ONCE(&table_init_once, table_init, NULL);

	XYZ2Lab.X0 = VIPS_D65_X0;
	XYZ2Lab.Y0 = VIPS_D65_Y0;
	XYZ2Lab.Z0 = VIPS_D65_Z0;
	vips_col_XYZ2Lab_helper(&XYZ2Lab, X, Y, Z, L, a, b);
}

static int
vips_XYZ2Lab_build(VipsObject *object)
{
	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS(object);
	VipsXYZ2Lab *XYZ2Lab = (VipsXYZ2Lab *) object;

	if (XYZ2Lab->temp) {
		if (vips_check_vector_length(class->nickname,
				XYZ2Lab->temp->n, 3))
			return -1;
		XYZ2Lab->X0 = ((double *) XYZ2Lab->temp->data)[0];
		XYZ2Lab->Y0 = ((double *) XYZ2Lab->temp->data)[1];
		XYZ2Lab->Z0 = ((double *) XYZ2Lab->temp->data)[2];
	}

	if (VIPS_OBJECT_CLASS(vips_XYZ2Lab_parent_class)->build(object))
		return -1;

	return 0;
}

static void
vips_XYZ2Lab_class_init(VipsXYZ2LabClass *class)
{
	GObjectClass *gobject_class = G_OBJECT_CLASS(class);
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsColourClass *colour_class = VIPS_COLOUR_CLASS(class);

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

	object_class->nickname = "XYZ2Lab";
	object_class->description = _("transform XYZ to Lab");
	object_class->build = vips_XYZ2Lab_build;

	colour_class->process_line = vips_XYZ2Lab_line;

	VIPS_ARG_BOXED(class, "temp", 110,
		_("Temperature"),
		_("Colour temperature"),
		VIPS_ARGUMENT_OPTIONAL_INPUT,
		G_STRUCT_OFFSET(VipsXYZ2Lab, temp),
		VIPS_TYPE_ARRAY_DOUBLE);
}

static void
vips_XYZ2Lab_init(VipsXYZ2Lab *XYZ2Lab)
{
	VipsColour *colour = VIPS_COLOUR(XYZ2Lab);

	XYZ2Lab->X0 = VIPS_D65_X0;
	XYZ2Lab->Y0 = VIPS_D65_Y0;
	XYZ2Lab->Z0 = VIPS_D65_Z0;

	colour->interpretation = VIPS_INTERPRETATION_LAB;
}

/**
 * vips_XYZ2Lab: (method)
 * @in: input image
 * @out: (out): output image
 * @...: %NULL-terminated list of optional named arguments
 *
 * Optional arguments:
 *
 * * @temp: #VipsArrayDouble, colour temperature
 *
 * Turn XYZ to Lab, optionally specifying the colour temperature. @temp
 * defaults to D65.
 *
 * Returns: 0 on success, -1 on error.
 */
int
vips_XYZ2Lab(VipsImage *in, VipsImage **out, ...)
{
	va_list ap;
	int result;

	va_start(ap, out);
	result = vips_call_split("XYZ2Lab", ap, in, out);
	va_end(ap);

	return result;
}
