// Mesa Sine Wave
//
// mesa_sine_wave
//
// Mesa Sine Wave
//
// Adaptive sine wave following price trends
//
// Inputs:    1
// Outputs:   2
// Constants: 1


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

typedef struct {
    uint_t k;
} ts_mesa_sine_wave_params_t;

ts_parameter_t const ts_mesa_sine_wave_p = { .n_inputs = 1, .n_outputs = 2, .n_constants = 1, .params_size = sizeof(ts_mesa_sine_wave_params_t) };

uint_t ts_mesa_sine_wave_offset( ts_constant_t const *c )
{
	( void )c;
	return ( c ? ((ts_mesa_sine_wave_params_t const *)c)->k : 0 );
}

int ts_mesa_sine_wave(
	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_mesa_sine_wave_p );
	if ( !c ) return -1;
    uint_t k = ((ts_mesa_sine_wave_params_t const *)c)->k;
    if (k < 2 || n < k) return -1;

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

    for ( uint_t i = 0; i < n; ++i )
    {
        if ( i < k - 1 )
        {
            fp_t sum = 0;
            for ( uint_t j = 0; j <= i; ++j )
                sum += x[0][j];
            sma[i] = sum / (fp_t)( i + 1 );
        }
        else
        {
            fp_t sum = 0;
            for ( uint_t j = i - k + 1; j <= i; ++j )
                sum += x[0][j];
            sma[i] = sum / (fp_t)k;
        }
    }

    fp_t ema_roc = 0;
    uint_t ema_period = 5;
    fp_t ema_a = 2.0 / ( (fp_t)ema_period + 1 );
    fp_t phase = 0;
    int_t first = 1;

    for ( uint_t j = 0; j < n && j < k; ++j ) { y[0][j] = 0; y[1][j] = 0; }
    for ( uint_t i = k; i < n; ++i )
    {
        fp_t roc = sma[i] - sma[i - 2];

        if ( first )
        {
            ema_roc = roc;
            first = 0;
        }
        else
        {
            ema_roc = ema_roc + ema_a * ( roc - ema_roc );
        }

        fp_t smoothed = ema_roc;
        if ( smoothed > 1.0 ) smoothed = 1.0;
        if ( smoothed < 0.01 ) smoothed = 0.01;

        fp_t wperiod = 2 * PI / smoothed;
        if ( wperiod < 5 ) wperiod = 5;
        if ( wperiod > 12 ) wperiod = 12;

        if ( smoothed >= 1.0 )
        {
            phase = 0;
        }
        else if ( smoothed <= 0.01 )
        {
            phase = 2 * PI;
        }
        else
        {
            phase += 2 * PI / wperiod;
        }
        while ( phase > 2 * PI ) phase -= 2 * PI;

        y[0][i] = cos( phase );
        y[1][i] = cos( phase + PI / 2 );
    }

    free( sma );
	return 0;
}