Product Requirements Document: Learnille Server

1. Introduction

1.1. Purpose of this Document
    This document outlines the product requirements for the Learnille Server, the backend application programming interface (API) and core business logic engine for the Learnille e-learning platform.
1.2. Scope of the Product (Learnille Server)
    The Learnille Server is responsible for managing user accounts, authentication, course content, enrollments, payments, notifications, and other core functionalities of the platform. It serves as the backend for various client applications (web, mobile).
1.3. Target Audience for this Document
    Product managers, project stakeholders, engineering teams (developers, QA), and architects.
1.4. Definitions, Acronyms, and Abbreviations
    - API: Application Programming Interface
    - JWT: JSON Web Token
    - CRUD: Create, Read, Update, Delete
    - DTO: Data Transfer Object
    - ORM: Object-Relational Mapper (TypeORM)
    - PRD: Product Requirements Document
    - SAD: Software Architecture Document
    - NFR: Non-Functional Requirement

2. Overall Description

2.1. Product Perspective
    The Learnille Server is the core backend component of the Learnille e-learning ecosystem. It provides the necessary APIs and services for client applications (web, mobile) to deliver a rich learning experience to users (students, instructors) and administrative capabilities for platform managers.
2.2. Product Functions (High-level capabilities)
    - User Account Management: Registration, login, profile management, password recovery.
    - Authentication & Authorization: Secure access to platform resources based on user roles.
    - Course Management: Creation, updating, and organization of course content (sections, lectures, materials).
    - Course Discovery & Access: Enabling users to find and enroll in courses.
    - Payment Processing: Securely process payments for platform services (courses, consultations) via integrated gateways, manage user wallets, and handle payouts/withdrawals.
    - Notification System: Delivering relevant notifications to users.
    - Product Discovery & Browsing: Allow users to search, filter, and browse available courses and consultations through a marketplace interface.
    - Student Enrollment Management: Track student progress and manage access to enrolled content.
    - User Feedback & Reviews: Enable users to provide ratings and reviews for courses and consultations.
    - Communication Features: Facilitate communication between users (details TBD, e.g., chat, notifications for calls).
    - Content Categorization: Organize courses and consultations into a structured system of categories and subcategories.
    - Content Delivery: Providing access to course materials.
    - Analytics & Reporting: Tracking user activity and platform usage (via ClickHouse).
2.3. User Characteristics
    - Students: Individuals seeking to learn by enrolling in and consuming course content.
    - Instructors: Individuals or organizations creating and managing courses.
    - Consultants: Individuals offering specialized advice or services through one-on-one or group consultations.
    - Administrators: Platform managers responsible for overseeing operations, managing users, and content.
    - System (API Consumers): Potential third-party integrations or internal services interacting with the API.
2.4. Operating Environment
    The Learnille Server is a Node.js application designed to run in cloud environments, serving requests over HTTP/S. It relies on external services like databases, caching layers, payment gateways, and notification providers.
2.5. Design and Implementation Constraints
    - Must be scalable to handle a growing number of users and courses.
    - Must be secure, protecting user data and financial transactions.
    - Must integrate with specified third-party services (Paystack, Novu, Sentry, etc.).
    - API design should be RESTful and well-documented (Swagger).
2.6. Assumptions and Dependencies
    - Client applications (web/mobile) will be developed to interact with the server's API.
    - Necessary third-party services (database, cache, payment gateway, etc.) will be available and configured.
    - Users have reliable internet access to interact with client applications.

3. System Features (Expressed as User Stories or High-Level Use Cases)

3.1. Feature: User Authentication & Authorization
    3.1.1. Description: Allow users to securely register, log in, manage their sessions, and access platform resources according to their roles and permissions.
    3.1.2. User Stories:
        - As a new user, I want to register an account using my email and password so I can access the platform.
        - As a new user, I want to optionally register using my Google account for convenience.
        - As a registered user, I want to log in with my email and password to access my account.
        - As a registered user, I want to log in using my Google account.
        - As a user, I want my session to be managed securely (e.g., via JWT).
        - As a user, if I forget my password, I want to be able to request a password reset link/code via email.
        - As a user, I want to be able to reset my password using the provided link/code.
        - As a user, I want to receive an email to verify my email address upon registration.
        - As a user, I want to be able to verify my email address using a code/link.
        - As an authenticated user, I want to be able to change my current password.
        - As a system, I want to ensure that only authorized users can access specific features or data based on their roles (e.g., student, instructor, admin).

3.2. Feature: User Profile Management
    3.2.1. Description: Allow authenticated users to view and update their personal information and preferences.
    3.2.2. User Stories:
        - As an authenticated user, I want to view my profile details (name, email, photo, etc.).
        - As an authenticated user, I want to update my profile information, including my name, contact details, and profile picture.
        - As an instructor/consultant, I want to manage my role-specific profile details.
        3.2.3. Instructor-Specific Profile Management:
            - As an instructor, I want to create and manage my instructor profile, including details like overview, description, expertise, languages, professional experiences, achievements, and social media links.
            - As an instructor, I want to be able to upload and manage my resume.

3.3. Feature: Course Creation & Management (Primarily for Instructors/Admins)
    3.3.1. Description: Enable authorized users (instructors, admins) to create, structure, and manage e-learning courses.
    3.3.2. User Stories:
        - As an instructor, I want to create a new course, providing details like title, subtitle, description, category, level, language, and pricing.
        - As an instructor, I want to upload a thumbnail image and an introductory video for my course.
        - As an instructor, I want to define course sections, subsections, and individual course items (lectures, quizzes, assignments, downloadable files).
        - As an instructor, I want to set course requirements, target audience, and what students will learn (inclusions).
        - As an instructor, I want to manage the publish status of my course (draft, published, archived).
        - As an instructor, I want to update existing course details and content.
        - As an instructor, I want to manage co-instructors or managers for my courses.
        - As an instructor, I want to view summaries and statistics for my courses.

3.4. Feature: Course Discovery & Consumption (Primarily for Students/Public)
    3.4.1. Description: Enable users to find, view details of, and enroll in courses. Allow enrolled students to access and consume course content.
    3.4.2. User Stories:
        - As a user (guest or logged in), I want to browse and search for courses based on keywords, categories, levels, etc.
        - As a user, I want to view detailed information about a course, including its content, instructor, price, reviews, and requirements, before enrolling.
        - (Further stories on enrollment and consumption will be added as those modules are analyzed)

3.5. Feature: Consultation Services
    3.5.1. Description: Enable qualified consultants to offer and manage one-on-one or recurring consultation services, and allow users to discover, book, and attend these consultations.
    3.5.2. User Stories:
        - As a consultant, I want to create and define my consultation offerings (e.g., one-off, recurring packages), including details like title, description, duration, price, category, and availability.
        - As a consultant, I want to manage my availability for consultations through a calendar or timeslot system.
        - As a consultant, I want to specify requirements, benefits, and frequently asked questions for my consultation services.
        - As a user, I want to browse and search for available consultation services based on consultant, topic, or category.
        - As a user, I want to view detailed information about a consultation service, including consultant profile, service description, pricing, and available timeslots.
        - As a user, I want to book an available consultation slot.
        - As a user, I want to receive notifications about my upcoming consultations.
        - As a user (consultant or client), I want to be able to reschedule or cancel a booked consultation (subject to defined rules and potential fees).
        - As a user, I want to be able to leave a review for a completed consultation.

3.6. Feature: Payment Processing & Wallet Management
    3.6.1. Description: Enable users to make payments for services using integrated payment gateways, and provide wallet functionality for managing funds and processing withdrawals.
    3.6.2. User Stories:
        - As a user, I want to be able to pay for a course or consultation using a supported payment gateway (e.g., Paystack).
        - As a user, I want to receive confirmation of my payment success or failure.
        - As a user, I want to view my history of payments made on the platform.
        - As a user (e.g., instructor, consultant), I want to have a wallet where my earnings are credited.
        - As a wallet owner, I want to be able to view my wallet balance and transaction history.
        - As a wallet owner, I want to be able to request a withdrawal of my available funds.
        - As a system, I want to securely process payments and update relevant records (e.g., order status, enrollment) upon successful payment.
        - As a system, I want to handle payment gateway webhooks to asynchronously confirm transaction statuses.
        - As a user, I want to be able to apply valid coupons to reduce the payable amount.

3.x. Feature: Shopping Cart
    3.x.1. Description: Allow users to temporarily collect multiple items (courses, consultations) they intend to purchase.
    3.x.2. User Stories:
        - As a user, I want to add a course or consultation to my shopping cart.
        - As a user, I want to view the items currently in my shopping cart.
        - As a user, I want to remove items from my shopping cart.
        - As a user, I want my shopping cart to persist if I navigate away and come back (if logged in).
        - As a user, I want to proceed from my cart to a checkout/order creation process.

3.y. Feature: Order Management
    3.y.1. Description: Formalize a user's intent to purchase selected items, apply discounts, calculate totals, and track the order through to payment and fulfillment.
    3.y.2. User Stories:
        - As a user, I want to convert my shopping cart into an order for purchase.
        - As a user, I want to be able to apply a valid coupon code to my order.
        - As a user, I want to see a summary of my order, including all items, discounts, and the final total, before making a payment.
        - As a system, I want to track the status of an order (e.g., PENDING, PAID, FAILED, COMPLETED).
        - As a system, upon successful payment for an order, I want to trigger relevant fulfillment actions (e.g., course enrollment).

3.z. Feature: Product Marketplace & Discovery
    3.z.1. Description: Provide a central marketplace for users to discover, search, and filter courses and consultations. Include recommendation features.
    3.z.2. User Stories:
        - As a user, I want to search for courses and consultations using keywords.
        - As a user, I want to filter marketplace listings by category, price, level, etc.
        - As a user, I want to see recommendations for latest products, similar products, or products in specific collections.

3.aa. Feature: Student Enrollment & Progress
    3.aa.1. Description: Manage student enrollment in courses and track their progress.
    3.aa.2. User Stories:
        - As a student, I want to easily see all the courses I am enrolled in.
        - As a student, I want my progress within a course (e.g., completed sections/lectures) to be tracked.
        - As an instructor, I want to view enrollment statistics for my courses.

3.ab. Feature: Reviews and Ratings
    3.ab.1. Description: Allow users to submit and view reviews and ratings for courses and consultations.
    3.ab.2. User Stories:
        - As a user who has completed/taken a course/consultation, I want to be able to leave a rating and a written review.
        - As a user browsing for products, I want to see average ratings and read reviews from other users.
        - As an instructor/consultant, I want to see reviews and ratings for my offerings.

3.ac. Feature: Communication Services
    3.ac.1. Description: Provide tools for real-time or asynchronous communication (details depend on specific integrations like Stream/CometChat).
    3.ac.2. User Stories:
        - As a user, I want to be able to obtain necessary tokens to participate in chat or call features.
        - (More specific stories depend on the exact communication features implemented).

3.ad. Feature: Content Categorization Management (Admin)
    3.ad.1. Description: Allow administrators to create, manage, and organize the hierarchy of categories and subcategories for courses and consultations.
    3.ad.2. User Stories:
        - As an admin, I want to create new top-level categories.
        - As an admin, I want to create subcategories under existing categories.
        - As an admin, I want to update or delete existing categories.
        - As an instructor/consultant, I want to assign my course/consultation to relevant categories/subcategories.

// (Further features like Notifications, etc., will be added here as module analysis progresses)

4. Non-Functional Requirements

4.1. Performance
    - API endpoints should respond within 500ms for the 95th percentile under expected load.
    - Database queries should be optimized to prevent bottlenecks.
4.2. Scalability
    - The system should be designed to handle a significant increase in users, courses, and concurrent requests without degradation in performance.
    - Architecture should support horizontal scaling of application servers.
4.3. Security
    - All sensitive data (passwords, PII) must be encrypted at rest and in transit.
    - Implement protection against common web vulnerabilities (OWASP Top 10).
    - Secure JWT implementation for stateless authentication.
    - Role-based access control must be enforced consistently.
4.4. Reliability & Availability
    - Aim for high availability (e.g., 99.9% uptime).
    - Implement robust error handling and fault tolerance mechanisms.
    - Ensure data integrity and provide mechanisms for backup and recovery.
4.5. Maintainability
    - Codebase should be well-structured, documented, and follow consistent coding standards.
    - Modular design to facilitate easier updates and bug fixes.
4.6. Usability (API)
    - APIs should be intuitive, consistent, and well-documented (via Swagger).
    - Error messages should be clear and informative.

5. Data Requirements (High-Level)

5.1. Types of data to be managed: User profiles, authentication credentials, course content (text, video, files), course metadata, instructor profiles, student enrollment data, payment transaction records, notification preferences, user activity logs, consultation offerings, consultant availability, booking records, user wallet balances, withdrawal requests, student progress data, product reviews and ratings, communication service tokens, content categories.
5.2. Data privacy and compliance considerations: Adherence to relevant data protection regulations (e.g., GDPR if applicable). Secure handling of Personally Identifiable Information (PII).

Appendix (Optional)

- Glossary
- Related Documents (Link to SAD, Technical Documentation)