// Donchian Width
//
// donchian_width - DW
//
// Highest high - lowest low over k periods
//
// Inputs:    5 (OHLCV)
// Outputs:   1 (Width)
// Constants: 1 (period)

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

typedef struct {
    uint_t k;
} ts_donchian_width_params_t;

ts_parameter_t const ts_donchian_width_p = { .n_inputs = 4, .n_outputs = 1, .n_constants = 1, .params_size = sizeof(ts_donchian_width_params_t) };

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

int ts_donchian_width(
	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_donchian_width_p );
	if ( !c ) return -1;
    uint_t k = ((ts_donchian_width_params_t *)c)->k;
    if (k == 0 || n < k) return -1;

    for ( uint_t i = k - 1; i < n; ++i )
    {
        fp_t upper = ts_h( x, i - k + 1 );
        fp_t lower = ts_l( x, i - k + 1 );

        for ( uint_t j = i - k + 1; j <= i; ++j )
        {
            if ( ts_h( x, j ) > upper )
                upper = ts_h( x, j );
            if ( ts_l( x, j ) < lower )
                lower = ts_l( x, j );
        }

        y[0][i] = upper - lower;
    }
	return 0;
}