📚 Go Backend User Authentication API

This project is a robust RESTful API for user authentication, built with Go. It features a clean architecture with clear separation of concerns, structured logging, and graceful server management. The API handles user signup, login, and provides a protected endpoint to access user profile information.

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✨ Features

• User Authentication: Secure signup and login functionality.
• JWT Authentication: Uses JSON Web Tokens for secure, stateless authentication.
• Secure Password Storage: Passwords are hashed using bcrypt for enhanced security.
• SQLite Database: Utilizes a file-based SQLite database for simple and efficient data storage.
• Request Validation: Ensures data integrity by validating incoming JSON requests for signup and login.
• CORS Middleware: Configured to handle Cross-Origin Resource Sharing.
• Structured Logging: Employs the slog package for clear and informative logging.
• Graceful Shutdown: The server shuts down gracefully on interrupt signals (SIGINT, SIGTERM) to prevent data loss during termination.

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🛠️ Prerequisites

• Go 1.25.0 or later

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🚀 Getting Started

To get the API up and running, follow these simple steps.

1. Clone the repository:

   git clone [https://github.com/ageniouscoder/backend](https://github.com/ageniouscoder/backend)
   cd backend/Backend-535981ce3b9f5080f6e85e580ebea75cc010705b

2. Install dependencies: The project uses Go modules. The required dependencies will be downloaded automatically.

   go mod tidy

3. Create a .env file: The application uses environment variables for configuration. Create a .env file in the root directory and add the following line:

   JWT_SECRET=your_secret_key_here
   

   You can optionally specify the database address and port in this file:

   DB_ADDR=./storage/app.db
   PORT=8080
   

4. Run the application: Start the server. The SQLite database file will be created in the storage directory if it doesn't already exist.

   go run ./cmd/myapp/main.go

   The server will start on localhost:8080 (or the port specified in your .env file).

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📝 API Endpoints

The API interacts with a User data model.

POST /signup

Creates a new user account.

Request Body:

{
  "username": "your_username",
  "email": "your.email@example.com",
  "password": "your_password"
}
Success Response (200 OK):

JSON

{
  "id": 123,
  "username": "your_username"
}
Error Response (400 Bad Request):

JSON

{
  "error": "This field is required."
}
POST /login
Authenticates a user and returns a JWT token.

Request Body:

JSON

{
  "identifier": "your_username_or_email",
  "password": "your_password"
}
Success Response (200 OK):

JSON

{
  "login": "succes",
  "token": "your_jwt_token_here"
}
Error Response (401 Unauthorized):

JSON

{
  "error": "Password is Incorrect. Try Again"
}
GET /api/profile
Retrieves the profile of the authenticated user. This is a protected endpoint that requires a valid JWT in the Authorization header.

Request Header:

Authorization: Bearer <your_jwt_token>
Success Response (200 OK):

JSON

{
  "username": "your_username",
  "email": "your.email@example.com",
  "isAdmin": false
}
Error Response (401 Unauthorized):

JSON

{
  "error": "Invalid or expired token"
}
📂 File Structure
.
├── .gitignore
├── cmd/
│   └── myapp/
│       └── main.go               # Main application entry point.
├── go.mod                        # Go module dependencies.
├── go.sum                        # Go module checksums.
└── internal/
    ├── database/
    │   ├── sqlite/
    │   │   └── sqlite.go         # SQLite database implementation.
    │   └── storage.go            # Database interface definition.
    ├── handlers/
    │   ├── auth.go               # Handlers for signup and login.
    │   └── profile.go            # Handler for user profile retrieval.
    ├── jwt/
    │   └── jwt.go                # JWT token generation logic.
    ├── middleware.go/
    │   ├── auth_middleware.go    # Authentication middleware for protected routes.
    │   └── cors_middleware.go    # CORS middleware.
    ├── models/
    │   └── models.go             # Data structures for the application.
    └── utils/
        └── utils.go              # Utility functions for hashing passwords and handling validation errors.