// Shinohara Intensity Ratio
//
// shinohara_intensity_ratio
//
// Shinohara Intensity Ratio
//
// 
//
// Inputs:    4
// Outputs:   1
// Constants: 1


#include <stdlib.h>
#include <math.h>
#include "ts.h"

typedef struct {
    uint_t k;
} ts_shinohara_intensity_ratio_params_t;

ts_parameter_t const ts_shinohara_intensity_ratio_p = { .n_inputs = 4, .n_outputs = 1, .n_constants = 1, .params_size = sizeof(ts_shinohara_intensity_ratio_params_t) };

uint_t ts_shinohara_intensity_ratio_offset( ts_constant_t const *c )
{
	( void )c;
	return ( c ? ((ts_shinohara_intensity_ratio_params_t *)c)->k > 0 ? ((ts_shinohara_intensity_ratio_params_t *)c)->k - 1 : 0 : 0 );
}

int ts_shinohara_intensity_ratio(
	fp_t * const *y, uint_t y_n,
	fp_t const * const *x, uint_t x_n,
	uint_t n, ts_constant_t const *c
)
{
	TS_PROLOGUE( ts_shinohara_intensity_ratio_p );
	if ( !c ) return -1;
    uint_t k = ((ts_shinohara_intensity_ratio_params_t *)c)->k;
    if (k == 0 || n < k) return -1;

    fp_t *intensity = calloc( n, sizeof( fp_t ) );
    if ( !intensity ) return -1;

    for( uint_t i = 0; i < n; ++i )
    {
        fp_t h = ts_h(x, i);
        fp_t l = ts_l(x, i);
        fp_t cl = ts_c(x, i);
        fp_t o = ts_o(x, i);
        fp_t range = h - l;

        if( range == 0 )
        {
            intensity[i] = 0;
        }
        else if( cl > o )
        {
            intensity[i] = (h - cl) / range;
        }
        else
        {
            intensity[i] = (cl - l) / range;
        }
    }

    for (uint_t j = 0; j < n && j < k - 1; ++j) y[0][j] = 0;
    for( uint_t i = k - 1; i < n; ++i )
    {
        if( i == k - 1 )
        {
            fp_t sum = 0;
            for( uint_t j = 0; j < k; ++j )
                sum += intensity[j];
            y[0][i] = sum / k;
        }
        else
        {
            y[0][i] = y[0][i-1] + (intensity[i] - intensity[i - k]) / k;
        }
    }

    free( intensity );
	return 0;
}