feat: Add automatic assignment deadline reminder system

web/asgi.py

@@ -22,7 +22,7 @@
 from django.core.asgi import get_asgi_application
 from sentry_sdk.integrations.asgi import SentryAsgiMiddleware
 
-# Initialize Django settings
+# Initialize Django settings to ensure models and routing can be imported without issues
 os.environ.setdefault("DJANGO_SETTINGS_MODULE", "web.settings")
 django.setup()
 

web/assignment_reminders.py

@@ -0,0 +1,193 @@
+"""
+Assignment deadline reminder system for Alpha One Labs.
+
+Handles automatic sending of reminder emails to students when assignments
+are due soon. Uses Django signals to automatically create and manage reminders.
+"""
+
+import logging
+from datetime import timedelta
+
+from django.conf import settings
+from django.core.mail import send_mail
+from django.db.models.signals import post_save
+from django.dispatch import receiver
+from django.template.loader import render_to_string
+from django.utils import timezone
+
+from .models import CourseMaterial, Enrollment
+
+logger = logging.getLogger(__name__)
+
+
+class ReminderScheduler:
+    """Manages scheduling and sending of assignment deadline reminders."""
+
+    @staticmethod
+    def should_send_early_reminder(course_material):
+        """
+        Check if early reminder (24 hours before) should be sent.
+
+        Returns True if:
+        - Material has a due_date
+        - Reminder hasn't been sent yet
+        - Deadline is within 24-48 hours from now
+        """
+        if not course_material.due_date or course_material.reminder_sent:
+            return False
+
+        now = timezone.now()
+        time_until_due = course_material.due_date - now
+
+
+        return timedelta(hours=24) <= time_until_due <= timedelta(hours=48)
+
+    @staticmethod
+    def should_send_final_reminder(course_material):
+        """
+        Check if final reminder (on deadline day) should be sent.
+
+        Returns True if:
+        - Material has a due_date
+        - Final reminder hasn't been sent yet
+        - Deadline is within next 24 hours
+        """
+        if not course_material.due_date or course_material.final_reminder_sent:
+            return False
+
+        now = timezone.now()
+        time_until_due = course_material.due_date - now
+
+        # Send final reminder if deadline is within 24 hours
+        return timedelta(0) <= time_until_due <= timedelta(hours=24)
+
+    @staticmethod
+    def send_early_reminder(course_material):
+        """Send 24-hour before deadline reminder to all enrolled students."""
+        try:
+            course = course_material.course
+            enrollments = Enrollment.objects.filter(
+                course=course,
+                status="approved"
+            ).select_related("student", "student__profile")
+
+            for enrollment in enrollments:
+                student = enrollment.student
+                context = {
+                    "student_name": student.first_name or student.username,
+                    "assignment_title": course_material.title,
+                    "course_title": course.title,
+                    "due_date": course_material.due_date,
+                    "description": course_material.description,
+                    "hours_remaining": 24,
+                }
+
+                subject = f"Reminder: '{course_material.title}' is due in 24 hours"
+                html_message = render_to_string(
+                    "emails/assignment_reminder_24h.html",
+                    context
+                )
+
+                send_mail(
+                    subject=subject,
+                    message=strip_tags(html_message),
+                    from_email=settings.DEFAULT_FROM_EMAIL,
+                    recipient_list=[student.email],
+                    html_message=html_message,
+                    fail_silently=False,
+                )
+
+                logger.info(
+                    f"24-hour reminder sent to {student.username} for "
+                    f"assignment '{course_material.title}'"
+                )
+
+            # Mark reminder as sent
+            course_material.reminder_sent = True
+            course_material.save(update_fields=["reminder_sent"])
+            logger.info(f"Early reminder sent for {course_material.title}")
+
+        except Exception as e:
+            logger.error(
+                f"Error sending early reminder for {course_material.title}: {str(e)}"
+            )
+
+    @staticmethod
+    def send_final_reminder(course_material):
+        """Send final reminder on deadline day to all enrolled students."""
+        try:
+            course = course_material.course
+            enrollments = Enrollment.objects.filter(
+                course=course,
+                status="approved"
+            ).select_related("student", "student__profile")
+
+            for enrollment in enrollments:
+                student = enrollment.student
+                context = {
+                    "student_name": student.first_name or student.username,
+                    "assignment_title": course_material.title,
+                    "course_title": course.title,
+                    "due_date": course_material.due_date,
+                    "description": course_material.description,
+                    "is_final": True,
+                }
+
+                subject = f"FINAL REMINDER: '{course_material.title}' is due today!"
+                html_message = render_to_string(
+                    "emails/assignment_reminder_final.html",
+                    context
+                )
+
+                send_mail(
+                    subject=subject,
+                    message=strip_tags(html_message),
+                    from_email=settings.DEFAULT_FROM_EMAIL,
+                    recipient_list=[student.email],
+                    html_message=html_message,
+                    fail_silently=False,
+                )
+
+                logger.info(
+                    f"Final reminder sent to {student.username} for "
+                    f"assignment '{course_material.title}'"
+                )
+
+            # Mark final reminder as sent
+            course_material.final_reminder_sent = True
+            course_material.save(update_fields=["final_reminder_sent"])
+            logger.info(f"Final reminder sent for {course_material.title}")
+
+        except Exception as e:
+            logger.error(
+                f"Error sending final reminder for {course_material.title}: {str(e)}"
+            )
+
+
+@receiver(post_save, sender=CourseMaterial)
+def check_and_send_assignment_reminders(sender, instance, created, **kwargs):
+    """
+    Signal handler to check and send assignment reminders when CourseMaterial is saved.
+
+    This runs after every save of a CourseMaterial object and:
+    1. Sends 24-hour early reminder if deadline is 24-48 hours away
+    2. Sends final reminder if deadline is within 24 hours
+    """
+    # Only process if material is an assignment with a due date
+    if instance.material_type != "assignment" or not instance.due_date:
+        return
+
+    # Check and send early reminder
+    if ReminderScheduler.should_send_early_reminder(instance):
+        ReminderScheduler.send_early_reminder(instance)
+
+    # Check and send final reminder
+    if ReminderScheduler.should_send_final_reminder(instance):
+        ReminderScheduler.send_final_reminder(instance)
+
+
+def strip_tags(html):
+    """Utility function to strip HTML tags for plain text emails."""
+    import re
+    clean = re.compile('<.*?>')
+    return re.sub(clean, '', html)

web/signals.py

@@ -67,3 +67,7 @@ def invalidate_session_cache(sender, instance, **kwargs):
     enrollments = Enrollment.objects.filter(course=instance.course)
     for enrollment in enrollments:
         invalidate_progress_cache(enrollment.student)
+
+
+# Import assignment reminder signal handlers
+from .assignment_reminders import check_and_send_assignment_reminders  # noqa

web/templates/emails/assignment_reminder_24h.html

@@ -0,0 +1,89 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <style>
+        body {
+            font-family: Arial, sans-serif;
+            line-height: 1.6;
+            color: #333;
+            max-width: 600px;
+            margin: 0 auto;
+            padding: 20px;
+        }
+        .container {
+            background-color: #f8f9fa;
+            border-radius: 8px;
+            padding: 30px;
+            border-left: 4px solid #FFA500;
+        }
+        .header {
+            color: #FFA500;
+            font-size: 24px;
+            font-weight: bold;
+            margin-bottom: 20px;
+        }
+        .course-name {
+            background-color: #fff3cd;
+            border-left: 4px solid #FFA500;
+            padding: 15px;
+            margin: 20px 0;
+            border-radius: 4px;
+        }
+        .due-date {
+            font-size: 18px;
+            color: #d9534f;
+            font-weight: bold;
+            margin: 10px 0;
+        }
+        .footer {
+            margin-top: 30px;
+            padding-top: 20px;
+            border-top: 1px solid #ddd;
+            font-size: 12px;
+            color: #666;
+        }
+        .button {
+            display: inline-block;
+            background-color: #FFA500;
+            color: white;
+            padding: 12px 24px;
+            text-decoration: none;
+            border-radius: 4px;
+            margin: 20px 0;
+            font-weight: bold;
+        }
+    </style>
+</head>
+<body>
+    <div class="container">
+        <div class="header">⏰ Assignment Due in 24 Hours</div>
+
+        <p>Hi {{ student_name }},</p>
+
+        <p>This is a reminder that you have an assignment due soon in <strong>{{ course_title }}</strong>.</p>
+
+        <div class="course-name">
+            <strong>Assignment:</strong> {{ assignment_title }}<br>
+            <div class="due-date">Due: {{ due_date|date:"F j, Y \a\t g:i A" }}</div>
+        </div>
+
+        {% if description %}
+        <p><strong>Details:</strong></p>
+        <p>{{ description }}</p>
+        {% endif %}
+
+        <p>Make sure to submit your work before the deadline to avoid any late submissions.</p>
+
+        <p>Need help? Visit the course materials or reach out to your instructor.</p>
+
+        <p>
+            <a href="{{ site_url }}" class="button">View Assignment</a>
+        </p>
+
+        <div class="footer">
+            <p>Alpha One Labs Education Platform<br>
+            This is an automated reminder. Please do not reply to this email.</p>
+        </div>
+    </div>
+</body>
+</html>