Blog System: Full-Stack Social Blogging Platform

This project is a modern, full-stack application designed to be a scalable social blogging platform. It features RESTful API communication, robust security using JWT, and a smooth user experience with infinite scrolling and robust error handling.

🚀 Technologies Used

This project is split into two distinct parts: a Java Spring Boot backend for API and security, and an Angular frontend for the user interface.

Backend (API Server)

Category	Technology	Description
Framework	Spring Boot 3	Used for rapid application development and building a microservice architecture.
Security	Spring Security	Handles authentication (login/registration) and authorization (role-based access control).
Authentication	JWT (JSON Web Tokens)	Stateless, token-based authentication for secure API access.
Persistence	Spring Data JPA / Hibernate	Object-Relational Mapping (ORM) for efficient database interaction.
Database	PostgreSQL	Robust, open-source relational database used for data storage.
Utility	Lombok	Reduces boilerplate code (getters, setters, constructors).

Frontend (Client Application)

Category	Technology	Description
Framework	Angular	A platform for building efficient and scalable single-page applications (SPAs).
Communication	HttpClient & Interceptors	Manages HTTP requests and automatically attaches JWT tokens.
Routing	Angular Router	Handles client-side navigation and route guarding.
UI/UX	Custom CSS	Styling the application, including the infinite scroll user experience.

⚙️ Setup and Installation

Follow these steps to get the project running locally.

Prerequisites

• Java Development Kit (JDK) 17+
• Node.js (LTS version)
• Angular CLI (npm install -g @angular/cli)
• PostgreSQL Database
• An IDE (IntelliJ IDEA or VS Code recommended)

Step 1: Database Setup

1. Ensure your PostgreSQL server is running.
2. Create a new database for the project (e.g., blog_db).

Step 2: Backend Configuration

1. Navigate to the /backend directory.

2. Open the application.properties (or application.yml) file.

3. Configure the database connection details:

   # application.properties
   spring.datasource.url=jdbc:postgresql://localhost:5432/blog_db
   spring.datasource.username=<YOUR_DB_USERNAME>
   spring.datasource.password=<YOUR_DB_PASSWORD>
   
   # Hibernate will automatically create tables (set to update after first run)
   spring.jpa.hibernate.ddl-auto=update 
   
   # Configure your JWT secret key
   application.security.jwt.secret-key=<YOUR_VERY_LONG_SECRET_KEY>

4. Run the Spring Boot application:

   ./mvnw spring-boot:run

   (Or run the main class from your IDE). The backend will start on http://localhost:8080.

Step 3: Frontend Configuration

1. Navigate to the /frontend directory.

2. Open the environment file (src/environments/environment.ts).

3. Ensure the apiUrl points to your running backend:

   // src/environments/environment.ts
   export const environment = {
     production: false,
     apiUrl: 'http://localhost:8080/api' // Base API path
   };

4. Install the required dependencies:

   npm install

5. Start the Angular development server:

   ng serve -o

   The frontend will automatically open in your browser on http://localhost:4200.

💻 Key Architectural Features

• Custom JWT Authentication Filter: Handles token validation, manages the SecurityContext, and implements advanced error handling for banned/deleted users to ensure proper client-side logout/redirection.
• Role-Based Access Control (RBAC): Utilizes Spring Security's @EnableMethodSecurity and hasAuthority("ADMIN") for endpoint protection.
• Infinite Scroll: Implemented in the Angular component using the @HostListener('window:scroll') to efficiently load posts page-by-page. Special care is taken to prevent scroll jumping by reserving image space with CSS aspect ratios and carefully restoring the scroll position.
• Data Integrity (ON DELETE CASCADE): JPA/Hibernate is configured using @OnDelete(action = OnDeleteAction.CASCADE) on foreign keys to automatically clean up related data (posts, comments) when a user is deleted by an administrator.