Task Scheduler

This assignment is a PHP-based task management system where users can add tasks to a common list and subscribe to receive hourly email reminders for pending tasks.

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📌 Features to Implemented

1️⃣ Task Management

• Add new tasks to the common list
• Duplicate tasks should not be added.
• Mark tasks as complete/incomplete
• Delete tasks
• Store tasks in tasks.txt

2️⃣ Email Subscription System

• Users can subscribe with their email
• Email verification process:
  • System generates a unique 6-digit verification code
  • Sends verification email with activation link
  • Link contains email and verification code
  • User clicks link to verify subscription
  • System moves email from pending to verified subscribers
• Store subscribers in subscribers.txt
• Store pending verifications in pending_subscriptions.txt

3️⃣ Reminder System

• CRON job runs every hour
• Sends emails to verified subscribers
• Only includes pending tasks in reminders
• Includes unsubscribe link in emails
• Unsubscribe process:
  • Every email includes an unsubscribe link
  • Link contains encoded email address
  • One-click unsubscribe removes email from subscribers

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📜 File Details & Function Stubs

Implemented the following functions in functions.php:

function addTask($task_name) {
    // Add a new task to the list
}

function getAllTasks() {
    // Get all tasks from tasks.txt
}

function markTaskAsCompleted($task_id, $is_completed) {
    // Mark/unmark a task as complete
}

function deleteTask($task_id) {
    // Delete a task from the list
}

function generateVerificationCode() {
    // Generate a 6-digit verification code
}

function subscribeEmail($email) {
    // Add email to pending subscriptions and send verification
}

function verifySubscription($email, $code) {
    // Verify email subscription
}

function unsubscribeEmail($email) {
    // Remove email from subscribers list
}

function sendTaskReminders() {
    // Sends task reminders to all subscribers
 	// Internally calls  sendTaskEmail() for each subscriber
}

function sendTaskEmail( $email, $pending_tasks ) {
	// Sends a task reminder email to a subscriber with pending tasks.
}

📁 File Structure

• functions.php (Core functions)
• index.php (Main interface)
• verify.php (Email verification handler)
• unsubscribe.php (Unsubscribe handler)
• cron.php (Reminder sender)
• setup_cron.sh (CRON job setup)
• tasks.txt (Task storage)
• subscribers.txt (Verified subscribers)
• pending_subscriptions.txt (Pending verifications)

🔄 CRON Job Implementation

Iedmplemented a CRON job that runs cron.php every 1 hour.

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📩 Email Handling

✅ The email content is in HTML format
✅ PHP's mail() function is used for sending emails.
✅ Each email includes an unsubscribe link.
✅ Subscribers email is stored in subscribers.txt. ✅ Pending verifications are stored in pending_subscriptions.txt. ✅ Each email included an unsubscribe link.

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