#pragma once

#include <twist/ed/stdlike/mutex.hpp>
#include <twist/ed/stdlike/condition_variable.hpp>

#include <cstdlib>

class Semaphore {
 public:
  explicit Semaphore(size_t tokens)
      : tokens_amount_(tokens) {
  }

  void Acquire() {
    std::unique_lock lock(mutex_);

    while (tokens_amount_ == 0) {
      have_tokens_inside_.wait(lock);
    }

    --tokens_amount_;
  }

  void Release() {
    std::lock_guard guard(mutex_);

    ++tokens_amount_;
    have_tokens_inside_.notify_one();
  }

 private:
  twist::ed::stdlike::condition_variable have_tokens_inside_;
  twist::ed::stdlike::mutex mutex_;
  size_t tokens_amount_;  // protected by mutex
};