/* find histograms
 *
 * Copyright: 1990, 1991, N. Dessipris.
 *
 * Author: Nicos Dessipris.
 * Written on: 09/07/1990
 * Modified on : 11/03/1991
 * 19/7/93 JC
 *	- test for Coding type added
 * 26/10/94 JC
 *	- rewritten for ANSI
 *	- now does USHORT too
 *	- 5 x faster!
 * 2/6/95 JC
 *	- rewritten for partials
 * 3/3/01 JC
 *	- tiny speed ups
 * 21/1/07
 * 	- number bands from zero
 * 24/3/10
 * 	- gtkdoc
 * 	- small cleanups
 * 25/1/12
 * 	- cast @in to u8/u16.
 * 12/8/13
 * 	- redo as a class
 * 28/2/16 lovell
 * 	- unroll common cases
 */

/*

    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 <vips/intl.h>

#include <string.h>

#include <vips/vips.h>

#include "statistic.h"

/* Accumulate a histogram in one of these.
 */
typedef struct {
	int bands;		/* Number of bands in output */
	int which;		/* If one band in out, which band of input */
	int size;		/* Number of bins for each band */
	int mx;			/* Maximum value we have seen */
	unsigned int **bins;	/* All the bins! */
} Histogram;

typedef struct _VipsHistFind {
	VipsStatistic parent_instance;

	/* -1 for all bands, or the band we scan.
	 */
	int which;

	/* Main image histogram. Subhists accumulate to this.
	 */
	Histogram *hist;

	/* Write hist to this output image.
	 */
	VipsImage *out; 

} VipsHistFind;

typedef VipsStatisticClass VipsHistFindClass;

G_DEFINE_TYPE( VipsHistFind, vips_hist_find, VIPS_TYPE_STATISTIC );

/* Build a Histogram.
 */
static Histogram *
histogram_new( VipsHistFind *hist_find, int bands, int which, int size )
{
	Histogram *hist;
	int i;

	if( !(hist = VIPS_NEW( hist_find, Histogram )) ||
		!(hist->bins = VIPS_ARRAY( hist_find, bands, unsigned int * )) )
		return( NULL );

	for( i = 0; i < bands; i++ ) {
		if( !(hist->bins[i] = 
			VIPS_ARRAY( hist_find, size, unsigned int )) )
			return( NULL );
		memset( hist->bins[i], 0, size * sizeof( unsigned int ) );
	}

	hist->bands = bands;
	hist->which = which;
	hist->size = size;
	hist->mx = 0;

	return( hist );
}

static int
vips_hist_find_build( VipsObject *object )
{
	VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
	VipsStatistic *statistic = VIPS_STATISTIC( object ); 
	VipsHistFind *hist_find = (VipsHistFind *) object;

	unsigned int *obuffer;
	unsigned int *q;
	int i, j;

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

	if( statistic->in &&
		vips_check_bandno( class->nickname, 
			statistic->in, hist_find->which ) )
		return( -1 ); 

	/* main hist made on first thread start.
	 */

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

	/* Make the output image.
	 */
	if( vips_image_pipelinev( hist_find->out, 
		VIPS_DEMAND_STYLE_ANY, statistic->ready, NULL ) ) 
		return( -1 );
	vips_image_init_fields( hist_find->out,
		hist_find->hist->mx + 1, 1, hist_find->hist->bands, 
		VIPS_FORMAT_UINT, 
		VIPS_CODING_NONE, VIPS_INTERPRETATION_HISTOGRAM, 1.0, 1.0 );

	/* Interleave for output.
	 */
	if( !(obuffer = VIPS_ARRAY( object, 
		VIPS_IMAGE_N_ELEMENTS( hist_find->out ), unsigned int )) )
		return( -1 );
	for( q = obuffer, j = 0; j < hist_find->out->Xsize; j++ )
		for( i = 0; i < hist_find->out->Bands; i++ )
			*q++ = hist_find->hist->bins[i][j];

	if( vips_image_write_line( hist_find->out, 0, (VipsPel *) obuffer ) )
		return( -1 );

	return( 0 );
}

/* Build a sub-hist, based on the main hist.
 */
static void *
vips_hist_find_start( VipsStatistic *statistic )
{
	VipsHistFind *hist_find = (VipsHistFind *) statistic;

	/* Make the main hist, if necessary.
	 */
	if( !hist_find->hist ) 
		hist_find->hist = histogram_new( hist_find, 
			hist_find->which == -1 ?
				statistic->ready->Bands : 1,
			hist_find->which, 
			statistic->ready->BandFmt == VIPS_FORMAT_UCHAR ? 
				256 : 65536 );

	return( (void *) histogram_new( hist_find, 
		hist_find->hist->bands, 
		hist_find->hist->which, 
		hist_find->hist->size ) );
}

/* Join a sub-hist onto the main hist.
 */
static int
vips_hist_find_stop( VipsStatistic *statistic, void *seq )
{
	Histogram *sub_hist = (Histogram *) seq;
	VipsHistFind *hist_find = (VipsHistFind *) statistic;
	Histogram *hist = hist_find->hist; 

	int i, j;

	g_assert( sub_hist->bands == hist->bands && 
		sub_hist->size == hist->size );

	/* Add on sub-data.
	 */
	hist->mx = VIPS_MAX( hist->mx, sub_hist->mx );
	for( i = 0; i < hist->bands; i++ )
		for( j = 0; j < hist->size; j++ )
			hist->bins[i][j] += sub_hist->bins[i][j];

	/* Blank out sub-hist to make sure we can't add it again.
	 */
	sub_hist->mx = 0;
	for( i = 0; i < sub_hist->bands; i++ )
		sub_hist->bins[i] = NULL;

	return( 0 );
}

/* Hist of all bands of uchar.
 */
static int
vips_hist_find_uchar_scan( VipsStatistic *statistic, 
	void *seq, int x, int y, void *in, int n )
{
	Histogram *hist = (Histogram *) seq;
	unsigned int *bins = hist->bins[0];
	int nb = statistic->ready->Bands;
	VipsPel *p = (VipsPel *) in;

	int j;

	/* The inner loop cannot be auto-vectorized by the compiler.
	 * Unroll for common cases. 
	 */
	switch( nb ) {
	case 1:
		for( j = 0; j < n; j++ )
			bins[p[j]] += 1;
		break;

	case 2:
		for( j = 0; j < n; j++ ) {
			hist->bins[0][p[0]] += 1;
			hist->bins[1][p[1]] += 1;

			p += 2;
		}
		break;

	case 3:
		for( j = 0; j < n; j++ ) {
			hist->bins[0][p[0]] += 1;
			hist->bins[1][p[1]] += 1;
			hist->bins[2][p[2]] += 1;

			p += 3;
		}
		break;

	case 4:
		for( j = 0; j < n; j++ ) {
			hist->bins[0][p[0]] += 1;
			hist->bins[1][p[1]] += 1;
			hist->bins[2][p[2]] += 1;
			hist->bins[3][p[3]] += 1;

			p += 4;
		}
		break;

	default:
		/* Loop when >4 bands
		 */
		for( j = 0; j < n; j++ ) {
			int z;

			for( z = 0; z < nb; z++ ) 
				hist->bins[z][p[z]] += 1;

			p += nb;
		}
	}

	/* Note the maximum.
	 */
	hist->mx = 255;

	return( 0 );
}

/* Histogram of a selected band of a uchar image.
 */
static int
vips_hist_find_uchar_extract_scan( VipsStatistic *statistic, 
	void *seq, int x, int y, void *in, int n )
{
	Histogram *hist = (Histogram *) seq;
	int nb = statistic->ready->Bands;
	int max = n * nb;
	unsigned int *bins = hist->bins[0];
	VipsPel *p = (VipsPel *) in;

	int i;

	for( i = hist->which; i < max; i += nb ) 
		bins[p[i]] += 1;

	/* Note the maximum.
	 */
	hist->mx = 255;

	return( 0 );
}

/* Histogram of all bands of a ushort image.
 */
static int
vips_hist_find_ushort_scan( VipsStatistic *statistic, 
	void *seq, int x, int y, void *in, int n )
{
	Histogram *hist = (Histogram *) seq;
	int mx = hist->mx;
	int nb = statistic->ready->Bands;
	unsigned short *p = (unsigned short *) in; 

	int j, z; 

	for( j = 0; j < n; j++ ) {
		for( z = 0; z < nb; z++ ) {
			int v = p[z];

			/* Adjust maximum.
			 */
			if( v > mx )
				mx = v;

			hist->bins[z][v] += 1;
		}

		p += nb;
	}

	/* Note the maximum.
	 */
	hist->mx = mx;

	return( 0 );
}

/* Histogram of one band of a ushort image.
 */
static int
vips_hist_find_ushort_extract_scan( VipsStatistic *statistic, 
	void *seq, int x, int y, void *in, int n )
{
	Histogram *hist = (Histogram *) seq;
	int mx = hist->mx;
	unsigned int *bins = hist->bins[0];
	unsigned short *p = (unsigned short *) in;
	int nb = statistic->ready->Bands;
	int max = nb * n;

	int i; 

	for( i = hist->which; i < max; i += nb ) {
		int v = p[i];

		/* Adjust maximum.
		 */
		if( v > mx )
			mx = v;

		bins[v] += 1;
	}

	/* Note the maximum.
	 */
	hist->mx = mx;

	return( 0 );
}

static int
vips_hist_find_scan( VipsStatistic *statistic, void *seq, 
	int x, int y, void *in, int n )
{
	VipsHistFind *hist_find = (VipsHistFind *) statistic;
	VipsStatisticScanFn scan;

	if( hist_find->which < 0 ) {
		if( statistic->ready->BandFmt == VIPS_FORMAT_UCHAR ) 
			scan = vips_hist_find_uchar_scan;
		else
			scan = vips_hist_find_ushort_scan;
	}
	else {
		if( statistic->ready->BandFmt == VIPS_FORMAT_UCHAR ) 
			scan = vips_hist_find_uchar_extract_scan;
		else
			scan = vips_hist_find_ushort_extract_scan;
	}

	return( scan( statistic, seq, x, y, in, n ) ); 
}

/* Save a bit of typing.
 */
#define UC VIPS_FORMAT_UCHAR
#define US VIPS_FORMAT_USHORT

/* Type mapping: go to uchar or ushort.
 */
static const VipsBandFormat vips_hist_find_format_table[10] = {
/* UC   C  US   S  UI   I   F   X   D  DX */
   UC, UC, US, US, US, US, US, US, US, US
};

static void
vips_hist_find_class_init( VipsHistFindClass *class )
{
	GObjectClass *gobject_class = (GObjectClass *) class;
	VipsObjectClass *object_class = (VipsObjectClass *) class;
	VipsStatisticClass *sclass = VIPS_STATISTIC_CLASS( class );

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

	object_class->nickname = "hist_find";
	object_class->description = _( "find image histogram" );
	object_class->build = vips_hist_find_build;

	sclass->start = vips_hist_find_start;
	sclass->scan = vips_hist_find_scan;
	sclass->stop = vips_hist_find_stop;
	sclass->format_table = vips_hist_find_format_table;

	VIPS_ARG_IMAGE( class, "out", 100, 
		_( "Output" ), 
		_( "Output histogram" ),
		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
		G_STRUCT_OFFSET( VipsHistFind, out ) );

	VIPS_ARG_INT( class, "band", 110, 
		_( "Band" ), 
		_( "Find histogram of band" ),
		VIPS_ARGUMENT_OPTIONAL_INPUT, 
		G_STRUCT_OFFSET( VipsHistFind, which ),
		-1, 100000, -1 );

}

static void
vips_hist_find_init( VipsHistFind *hist_find )
{
	hist_find->which = -1;
}

/**
 * vips_hist_find:
 * @in: input image
 * @out: output image
 * @...: %NULL-terminated list of optional named arguments
 *
 * Optional arguments:
 *
 * * @band: band to equalise
 *
 * Find the histogram of @in. Find the histogram for band @band (producing a
 * one-band histogram), or for all bands (producing an n-band histogram) if 
 * @band is -1. 
 *
 * @in is cast to u8 or u16. @out is always u32.
 *
 * See also: vips_hist_find_ndim(), vips_hist_find_indexed().
 *
 * Returns: 0 on success, -1 on error
 */
int
vips_hist_find( VipsImage *in, VipsImage **out, ... )
{
	va_list ap;
	int result;

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

	return( result );
}