// Acceleration Bands
//
// acceleration_bands - acc_bands
//
// Upper: SMA of highest high over period k
// Middle: SMA of typical price over period k
// Lower: SMA of lowest low over period k
//
// Inputs:    4 (OHLCV)
// Outputs:   3 (Upper, Middle, Lower)
// Constants: 1 (period)

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

typedef struct {
    uint_t k;
} ts_acceleration_bands_params_t;

ts_parameter_t const ts_acceleration_bands_p = { .n_inputs = 4, .n_outputs = 3, .n_constants = 1, .params_size = sizeof(ts_acceleration_bands_params_t) };

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

int ts_acceleration_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_acceleration_bands_p );
	if ( !c ) return -1;
	TS_CHECK_INPUT(x, x_n, n);
    uint_t k = ((ts_acceleration_bands_params_t const *)c)->k;
    if (k == 0 || n < k) return -1;

    if (n > SIZE_MAX / sizeof( fp_t )) return -1;
    fp_t *hh_r = malloc( n * sizeof( fp_t ) );
    fp_t *ll_r = malloc( n * sizeof( fp_t ) );
    fp_t *tp = malloc( n * sizeof( fp_t ) );
    if ( !hh_r || !ll_r || !tp ) {
        free( hh_r ); free( ll_r ); free( tp );
	return -1;
    }

    for ( uint_t i = 0; i < n; ++i )
    {
        tp[i] = ( ts_h( x, i ) + ts_l( x, i ) + ts_c( x, i ) ) / 3.0;
        fp_t hh = ts_h( x, i );
        fp_t ll = ts_l( x, i );
        for ( uint_t j = 1; j < k && i >= j; ++j )
        {
            if ( ts_h( x, i - j ) > hh ) hh = ts_h( x, i - j );
            if ( ts_l( x, i - j ) < ll ) ll = ts_l( x, i - j );
        }
        hh_r[i] = hh;
        ll_r[i] = ll;
    }

    for ( uint_t j = 0; j < n && j < k - 1; ++j ) { y[0][j] = 0; y[1][j] = 0; y[2][j] = 0; }
    for ( uint_t i = k - 1; i < n; ++i )
    {
        fp_t sum_hh = 0, sum_ll = 0, sum_tp = 0;
        for ( uint_t j = 0; j < k; ++j )
        {
            sum_hh += hh_r[i - j];
            sum_ll += ll_r[i - j];
            sum_tp += tp[i - j];
        }
        y[0][i] = sum_hh / (fp_t)k;
        y[1][i] = sum_tp / (fp_t)k;
        y[2][i] = sum_ll / (fp_t)k;
    }

    free( hh_r ); free( ll_r ); free( tp );
	return 0;
}