// Average Weighted Series
//
// average_weighted_series - aws
//
// SMA of the product of two series: SMA(x0 * x1, k)
//
// Inputs:    1
// Outputs:   1
// Constants: 1 (period)

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


typedef struct {
    uint_t k;
} ts_average_weighted_series_params_t;

ts_parameter_t const ts_average_weighted_series_p = { .n_inputs = 2, .n_outputs = 1, .n_constants = 1, .params_size = sizeof(ts_average_weighted_series_params_t) };


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

int ts_average_weighted_series(
	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_average_weighted_series_p );
	if ( !c ) return -1;
	uint_t k = ((ts_average_weighted_series_params_t *)c)->k;
	if (k == 0 || n < k) return -1;

	uint_t xi = 0;
	uint_t yi = k;

    fp_t *b = malloc(k * sizeof(fp_t));
    if (!b) return -1;
    uint_t bi = 0;

	fp_t sum = 0;

	while( xi < k )
		{
        	b[bi] = x[0][xi] * x[1][xi];
			sum += b[bi];

			++xi;
			bi = _ts_circle_increment( bi, k );
		}

		y[0][k - 1] = sum / k;
	uint_t tmp;

	while( xi < n )
	{
		tmp = b[bi];
		b[bi] = x[0][xi] * x[1][xi];

		y[0][yi] = y[0][yi - 1] + ( b[bi] - tmp ) / k;

		++xi;
		++yi;
		bi = _ts_circle_increment( bi, k );
	}

    free(b);
	return 0;
}