// Starc Bands
//
// starc_bands
//
// STARC Bands
//
// 
//
// Inputs:    4
// Outputs:   3
// Constants: 2


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


typedef struct {
    uint_t k;
    fp_t mult;
} ts_starc_bands_params_t;

ts_parameter_t const ts_starc_bands_p = { .n_inputs = 4, .n_outputs = 3, .n_constants = 2, .params_size = sizeof(ts_starc_bands_params_t) };


uint_t ts_starc_bands_offset( ts_constant_t const *c )
{
	( void )c;
	return ( c ? ((ts_starc_bands_params_t const *)c)->k : 0 );
}

int ts_starc_bands(
	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_starc_bands_p );
	if ( !c ) return -1;
	TS_CHECK_INPUT(x, x_n, n);
	uint_t k = ((ts_starc_bands_params_t const *)c)->k;
	if (k == 0) return -1;
	if (n < k + 1) return -1;

	fp_t mult = ((ts_starc_bands_params_t const *)c)->mult;
	if (mult < 0 || isnan(mult) || isinf(mult)) return -1;

	for( uint_t i = 0; i < k; ++i )
	{
		y[0][i] = NAN;
		y[1][i] = NAN;
		y[2][i] = NAN;
	}

	for( uint_t i = k; i < n; ++i )
	{
		fp_t tr_sum = 0;
		for( uint_t j = 0; j < k; ++j )
		{
			uint_t idx = i - k + 1 + j;
			fp_t tr = fmax( ts_h( x, idx ) - ts_l( x, idx ), fmax( fabs( ts_h( x, idx ) - ts_c( x, idx - 1 ) ), fabs( ts_l( x, idx ) - ts_c( x, idx - 1 ) ) ) );
			tr_sum += tr;
		}
		fp_t atr = tr_sum / (fp_t)k;

		fp_t sum = 0;
		for( uint_t j = 0; j < k; ++j )
		{
			sum += ts_c( x, i - k + 1 + j );
		}
		fp_t mean = sum / k;

		y[0][i] = mean + mult * atr;
		y[1][i] = mean;
		y[2][i] = mean - mult * atr;
	}
	return 0;
}