timer.js

/**
 * Timer Application Script
 * 
 * This script controls the countdown timer functionality, including start, stop, and restart         actions. It also handles audio playback when the timer reaches zero.
 * 
 * @file timer.js
 * @author Nicky Moreno Gonzalez
 * @description Implementation of a simple countdown timer with audio notification and alert.
 */

let timer;   // Stores the interval ID for the countdown timer
let timeRemaining;   // Stores the remaining time in seconds
let isRunning = false; // Tracks whether the timer is currently running

// Update the countdown display
function updateDisplay() {
    const minutes = Math.floor(timeRemaining / 60); 
    const seconds = timeRemaining % 60; 
    document.getElementById("countdown").textContent = 
        `${minutes.toString().padStart(2, '0')}:${seconds.toString().padStart(2, '0')}`; 
    // Format as "MM:SS" with leading zeros
}

// Wait for the HTML document to fully load before executing this function
document.addEventListener("DOMContentLoaded", function () {
    
    // Get the query parameters from the URL
    const urlParams = new URLSearchParams(window.location.search);
    const name = urlParams.get("name");  // Extract the timer name
    const duration = parseInt(urlParams.get("duration"), 10); // Convert duration to an integer
    const description = urlParams.get("description"); // Extract the timer description

    // Set the extracted values in the HTML page
    document.getElementById("timer-name").textContent = name;
    document.getElementById("timer-description").textContent = description;

    // Store the extracted duration as the initial countdown value
    timeRemaining = duration;
    updateDisplay(); // Update the countdown display with the initial value

    // Preload sound to ensure it can play when needed
    document.getElementById("alarm-sound").play().then(() => {
        document.getElementById("alarm-sound").pause(); // Immediately pause after playing
        document.getElementById("alarm-sound").currentTime = 0; // Reset audio position
    }).catch(error => {
        console.log("Audio play may be blocked until user interaction:", error);
    });
});

// Function to start the countdown timer
function startTimer() {
    if (!isRunning) { // Only start if the timer is not already running
        isRunning = true;
        timer = setInterval(() => {
            if (timeRemaining > 0) {
                timeRemaining--; 
                updateDisplay(); 
            } else {
                clearInterval(timer); // Stop the countdown
                isRunning = false;
                playSound(); // Play the alarm sound
                alert("Time's up!"); // Show an alert to the user
            }
        }, 1000); // Runs every second (1000ms)
    }
}

// Stop the countdown timer
function stopTimer() {
    clearInterval(timer);
    isRunning = false; 
}

// Restart the timer with the original duration
function restartTimer() {
    stopTimer(); 
    timeRemaining = parseInt(new URLSearchParams(window.location.search).get("duration"), 10); // Reset time
    updateDisplay(); // Refresh the countdown display
}

// Function to play an alarm sound when the timer reaches zero
function playSound() {
    const audio = document.getElementById("alarm-sound");

    if (audio) {
        audio.play(); // Attempt to play the sound
    }
}