// https://www.youtube.com/watch?v=zYPb7oBU5_E

#include "time_interface.h"
#include "output_interface.h"

class alarm_clock {
public:
  alarm_clock(const time_interface&, output_interface&)
  // ...
  private:
  // ...
  const time_interface& time_;
  output_interface& output_;
};

void alarm_clock::check_alarm() {
  if (!is_active_) return;
  if (now_is_approx_alarm_time()) {
    ring_alarm();
  }
}

bool alarm_clock::now_is_approx_alarm_time() const {
  auto diff = abs(time_.now() - alarm_time_);
  return (diff < 1s);
}

void alarm_clock::ring_alarm() {
  output_ << "Alarm\n";
}