#pragma once

#include <twist/ed/stdlike/atomic.hpp>
#include <twist/ed/wait/sys.hpp>

#include <cstdlib>

namespace stdlike {

class Mutex {
 public:
  Mutex() = default;

  Mutex(Mutex&) = delete;

  void Lock() {
    locked_threads_count_.fetch_add(1);

    while (is_locked_.exchange(LockCond::locked) != LockCond::unlocked) {
      twist::ed::Wait(is_locked_, LockCond::locked);
    }

    locked_threads_count_.fetch_sub(1);
  }

  void Unlock() {
    auto wake_key = twist::ed::PrepareWake(is_locked_);

    is_locked_.store(LockCond::unlocked);

    if (locked_threads_count_.load() > 0) {
      twist::ed::WakeOne(wake_key);
    }
  }

 private:
  enum LockCond { unlocked = 0, locked = 1 };

  twist::ed::stdlike::atomic<uint32_t> locked_threads_count_{0};
  twist::ed::stdlike::atomic<uint32_t> is_locked_ = LockCond::unlocked;
};

}  // namespace stdlike