#include <stdint.h>
#include "env.h"
#include "psyn.h"

void env_init(struct envelope_t *env, double attack, double attack_hold, double decay, double sustain, double release)
{
	env->attack      = attack;
	env->attack_hold = attack_hold;
	env->decay       = decay;
	env->sustain     = sustain;
	env->release     = release;

	env->attack_s      = env->attack * _sample_rate;
	env->attack_hold_s = env->attack_s + env->attack_hold * _sample_rate;
	env->decay_s       = env->attack_hold_s + env->decay * _sample_rate;
	env->release_s     = env->release * _sample_rate;
}

double env_getamplitude(const struct envelope_t *env, uint32_t sample, uint32_t released)
{
	double amplitude;

	if (sample < env->attack_s) {
		amplitude = sample / env->attack_s;
	} else if (sample < env->attack_hold_s) {
		amplitude = 1.0;
	} else if (sample < env->decay_s) {
		amplitude = 1.0 - (sample - env->attack_hold_s) / (env->decay_s - env->attack_hold_s) * (1.0 - env->sustain);
	} else {
		amplitude = env->sustain;
	}

	if (released > 0) {
		amplitude *= (1.0 - (sample - released) / env->release_s);
	}

	return amplitude;
}