Invoice Generator API

This Spring Boot application provides an API for generating PDF invoices based on user data. It uses Apache PDFBox to convert HTML templates into downloadable PDF files.

Features

• Web UI for invoice generation with live form validation
• Generate PDF invoices from HTML templates
• Store invoice data in a database
• Configurable invoice limit per user (default: 10)
• Download generated PDFs locally
• REST API for programmatic access

Technologies Used

• Java 17
• Spring Boot 3.2.0
• Apache PDFBox 2.0.33
• H2 Database (for development)
• Maven
• Thymeleaf (for HTML templates)

Project Structure

invoice-generator/
├── src/
│   ├── main/
│   │   ├── java/com/invoice/generator/
│   │   │   ├── controller/
│   │   │   ├── model/
│   │   │   ├── repository/
│   │   │   ├── service/
│   │   │   ├── dto/
│   │   │   ├── exception/
│   │   │   └── InvoiceGeneratorApplication.java
│   │   └── resources/
│   │       ├── templates/
│   │       │   └── invoice-template.html
│   │       ├── static/
│   │       │   └── css/
│   │       │       └── invoice-styles.css
│   │       └── application.properties
│   └── test/
│       └── java/com/invoice/generator/
├── pom.xml
└── README.md

Setup Instructions

Development Environment

1. Clone the repository
2. Make sure you have JDK 17 and Maven installed
3. Configure application.properties for your environment
4. Run the application using Maven:

mvn spring-boot:run

Production Environment

1. Build the application JAR:

mvn clean package

2. Configure production settings in application-prod.properties
3. Run the application with production profile:

java -jar target/invoice-generator-0.0.1-SNAPSHOT.jar --spring.profiles.active=prod

Usage

Web Interface

Access the web UI at http://localhost:8080/ after starting the application. The interface provides:

• User-friendly form with all invoice fields
• Dynamic invoice item rows (add/remove items)
• Automatic calculation of item amounts and totals
• Real-time validation
• Automatic PDF download on success

REST API

Generate Invoice

Endpoint: POST /api/invoices

Request Body Example:

{
  "userId": "12345",
  "billerDetails": {
    "name": "Company ABC",
    "address": "123 Business St, Suite 100, City, Country - 12345",
    "pan": "ABCDE1234F",
    "gst": "22AAAAA0000A1Z5"
  },
  "clientDetails": {
    "name": "XYZ Corporation",
    "address": "456 Corporate Ave, City, Country - 54321",
    "pan": "PQRST5678G",
    "gst": "27BBBBB1111B1Z4"
  },
  "invoiceDetails": {
    "invoiceNumber": "INV-2023-001",
    "invoiceDate": "2023-11-20",
    "dueDate": "2023-12-20"
  },
  "items": [
    {
      "description": "Web Development Services",
      "days": 15,
      "unitCost": 5000.00,
      "amount": 75000.00
    },
    {
      "description": "UI/UX Design",
      "days": 5,
      "unitCost": 6000.00,
      "amount": 30000.00
    }
  ],
  "taxes": 18900.00,
  "adjustments": {
    "discount": 5000.00,
    "coupon": 1000.00
  },
  "tds": 2500.00,
  "totalAmount": 115400.00,
  "bankDetails": {
    "accountName": "Company ABC",
    "accountNumber": "1234567890",
    "bankName": "National Bank",
    "ifscCode": "NATL0001234",
    "branchName": "Main Branch"
  }
}

Response:

• HTTP 201: Invoice generated successfully with download link
• HTTP 400: Invalid request
• HTTP 409: Invoice already exists for the user

Configuration

application.properties

# Server configuration
server.port=8080

# Database configuration (H2 for development)
spring.datasource.url=jdbc:h2:mem:invoicedb
spring.datasource.driverClassName=org.h2.Driver
spring.datasource.username=sa
spring.datasource.password=
spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.h2.console.enabled=true

# Invoice PDF storage path
invoice.pdf.storage.path=./invoices

Testing

Run the tests using Maven:

mvn test

Docker Deployment

Build and Run with Docker

# Build the Docker image
docker build -t pdf-invoice-gen:latest .

# Run the container
docker run -d \
  --name pdf-invoice-gen \
  -p 8080:8080 \
  -v $(pwd)/invoices:/app/invoices \
  pdf-invoice-gen:latest

Using Docker Compose (Recommended)

# Start the application
docker-compose up -d

# View logs
docker-compose logs -f

# Stop the application
docker-compose down

Environment Variables

Override default configuration using environment variables:

• SPRING_PROFILES_ACTIVE: Active Spring profile (default: docker)
• SERVER_PORT: Application port (default: 8080)
• INVOICE_PDF_STORAGE_PATH: PDF storage directory (default: /app/invoices)
• INVOICE_MAX_PER_USER: Maximum invoices per user (default: 10)
• SPRING_DATASOURCE_URL: Database connection URL
• SPRING_H2_CONSOLE_ENABLED: Enable H2 console (default: true)

Health Check

The application includes a health check endpoint for monitoring:

curl http://localhost:8080/actuator/health