#pragma once

#include <cstddef>
#include <cstdlib>
#include <vector>

using namespace std;

namespace trnr {

enum playback_dir {
	PB_FORWARD,
	PB_BACKWARD,
	PB_PENDULUM,
	PB_RANDOM
};

struct simple_seq {
	size_t current_pos;
	size_t length;
	playback_dir playback_dir;
	vector<int> data;
	bool pendulum_forward;
};

inline void simple_seq_init(simple_seq& s, size_t length)
{
	s.current_pos = 0;
	s.length = length;
	s.playback_dir = PB_FORWARD;
	s.data.resize(s.length);
	s.data.assign(s.length, 0);
	s.pendulum_forward = true;
}

inline int simple_seq_process_step(simple_seq& s)
{
	// play head advancement
	if (s.playback_dir == PB_FORWARD ||
		s.playback_dir == PB_PENDULUM && s.pendulum_forward)
		s.current_pos++;
	else if (s.playback_dir == PB_BACKWARD ||
			 s.playback_dir == PB_PENDULUM && !s.pendulum_forward)
		s.current_pos--;
	else if (s.playback_dir == PB_RANDOM) s.current_pos = rand() % s.length;

	// play head reset
	switch (s.playback_dir) {
	case PB_FORWARD:
		if (s.current_pos > s.length - 1) s.current_pos = 0;
		break;
	case PB_BACKWARD:
		if (s.current_pos < 0) s.current_pos = s.length - 1;
		break;
	case PB_PENDULUM:
		if (s.pendulum_forward && s.current_pos >= s.length - 1)
			s.pendulum_forward = false;
		else if (!s.pendulum_forward && s.current_pos <= 0) s.pendulum_forward = true;
		break;
	case PB_RANDOM:
		break;
	}

	return s.data[s.current_pos];
}
} // namespace trnr