HeartModel.java

package MVCPattern.DJExample;

import java.util.ArrayList;
import java.util.Timer;
import java.util.TimerTask;

public class HeartModel {
    ArrayList<BeatObserver> beatObservers = new ArrayList<>();
    ArrayList<BPMObserver> bpmObservers = new ArrayList<>();
    private int heartRate = 72;
    private Timer timer;
    private boolean isRunning = false;

    public int getHeartRate() {
        return heartRate;
    }

    public void setHeartRate(int heartRate) {
        this.heartRate = heartRate;
        notifyBPMObservers();
        // If running, restart timer with new heart rate
        if (isRunning) {
            stopTimer();
            startTimer();
        }
    }

    public void increaseHeartRate() {
        setHeartRate(heartRate + 1);
    }

    public void decreaseHeartRate() {
        setHeartRate(heartRate - 1);
    }

    public void on() {
        isRunning = true;
        startTimer();
        notifyBPMObservers();
    }

    public void off() {
        isRunning = false;
        stopTimer();
        notifyBPMObservers();
    }

    public void initialize() {
        heartRate = 72;
        isRunning = false;
    }

    public void registerObserver(BeatObserver o) {
        beatObservers.add(o);
    }

    public void removeObserver(BeatObserver o) {
        beatObservers.remove(o);
    }

    public void registerObserver(BPMObserver o) {
        bpmObservers.add(o);
    }

    public void removeObserver(BPMObserver o) {
        bpmObservers.remove(o);
    }

    private void startTimer() {
        if (heartRate <= 0) return;

        timer = new Timer();
        long interval = 60000 / heartRate; // Convert BPM to milliseconds per beat
        timer.scheduleAtFixedRate(new TimerTask() {
            @Override
            public void run() {
                notifyBeatObservers();
            }
        }, 0, interval);
    }

    private void stopTimer() {
        if (timer != null) {
            timer.cancel();
            timer = null;
        }
    }

    private void notifyBeatObservers() {
        for (BeatObserver observer : beatObservers) {
            observer.updateBeat();
        }
    }

    private void notifyBPMObservers() {
        for (BPMObserver observer : bpmObservers) {
            observer.updateBPM();
        }
    }
}