// Lowest Low
//
// lowest_low
//
// Lowest low over rolling window
//
// LL = min(L[t-k+1..t])
//
// Inputs:    5
// Outputs:   1
// Constants: 1


#include "ts.h"

typedef struct {
    uint_t k;
} ts_lowest_low_params_t;

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

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

int ts_lowest_low(
	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_lowest_low_p );
	if ( !c ) return -1;
	uint_t k = ((ts_lowest_low_params_t const *)c)->k;
	if (k == 0 || n < k) return -1;

	fp_t min_val = ts_l( x, 0 );
	for( uint_t j = 1; j < k; ++j )
	{
		fp_t val = ts_l( x, j );
		if( val < min_val )
			min_val = val;
	}
	y[0][k - 1] = min_val;

	for( uint_t i = k; i < n; ++i )
	{
		fp_t new_val = ts_l( x, i );
		fp_t old_val = ts_l( x, i - k );
		if ( new_val < min_val ) min_val = new_val;
		if ( old_val == min_val )
		{
			min_val = ts_l( x, i - k + 1 );
			for( uint_t j = i - k + 2; j <= i; ++j )
			{
				fp_t val = ts_l( x, j );
				if( val < min_val ) min_val = val;
			}
		}
		y[0][i] = min_val;
	}
	return 0;
}