// Ease of Movement
//
// ease_of_movement - EOM
//
// SMA of (midpoint change) / (volume / range), volume-based momentum
//
// Inputs:    5 (OHLCV)
// Outputs:   1 (EOM)
// Constants: 1 (period)

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

typedef struct {
    uint_t k;
} ts_ease_of_movement_params_t;

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

uint_t ts_ease_of_movement_offset( ts_constant_t const *c )
{
	( void )c;
	return ( 3 );
}

int ts_ease_of_movement(
	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_ease_of_movement_p );
	if ( !c ) return -1;
    uint_t k = ((ts_ease_of_movement_params_t *)c)->k;
    if (k == 0 || n <= k) return -1;

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

    for( uint_t i = 1; i < n; ++i )
    {
        fp_t hl = ts_h( x, i ) - ts_l( x, i );
        if( hl == 0 ) continue;
        fp_t br = ts_v( x, i ) / hl;
        if( br == 0 ) continue;
        fp_t cur_mid = ( ts_h( x, i ) + ts_l( x, i ) ) / 2.0;
        fp_t prev_mid = ( ts_h( x, i - 1 ) + ts_l( x, i - 1 ) ) / 2.0;
        eom[i] = ( cur_mid - prev_mid ) / br;
    }

    {
        for (uint_t i = 0; i < k; ++i) y[0][i] = 0;

        fp_t sum = 0;
        for( uint_t i = 1; i <= k; ++i )
        {
            sum += eom[i];
        }
        y[0][k] = sum / (fp_t)k;
        for( uint_t i = k + 1; i < n; ++i )
        {
            sum = sum - eom[i - k] + eom[i];
            y[0][i] = sum / (fp_t)k;
        }
    }

    free( eom );
	return 0;
}