// Trend Intensity Index
//
// trend_intensity_index
//
// Trend Intensity Index
//
// 
//
// Inputs:    5
// Outputs:   1
// Constants: 1


#include "ts.h"

typedef struct {
    uint_t k;
} ts_trend_intensity_index_params_t;

ts_parameter_t const ts_trend_intensity_index_p = { .n_inputs = 5, .n_outputs = 1, .n_constants = 1, .params_size = sizeof(ts_trend_intensity_index_params_t) };

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

int ts_trend_intensity_index(
	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_trend_intensity_index_p );
	if ( !c ) return -1;
    uint_t k = ((ts_trend_intensity_index_params_t const *)c)->k;
    if ( k == 0 || n < k ) return -1;

    fp_t signed_sum = 0;
    fp_t vol_sum = 0;

    for ( uint_t i = 1; i <= k; ++i )
    {
        signed_sum += ( ts_c( x, i ) > ts_c( x, i - 1 ) ) ? ts_v( x, i ) : -ts_v( x, i );
        vol_sum += ts_v( x, i );
    }

    y[0][k - 1] = vol_sum != 0 ? signed_sum / vol_sum : 0;

    for ( uint_t i = k + 1; i < n; ++i )
    {
        fp_t cur_signed = ( ts_c( x, i ) > ts_c( x, i - 1 ) ) ? ts_v( x, i ) : -ts_v( x, i );
        fp_t old_signed = ( ts_c( x, i - k ) > ts_c( x, i - k - 1 ) ) ? ts_v( x, i - k ) : -ts_v( x, i - k );

        signed_sum = signed_sum - old_signed + cur_signed;
        vol_sum = vol_sum - ts_v( x, i - k ) + ts_v( x, i );

        y[0][i] = vol_sum != 0 ? signed_sum / vol_sum : 0;
    }
	return 0;
}