🧮 Spring MVC Calculator

A modern, responsive calculator web application built with Spring Boot and Spring MVC architecture. This multi-user calculator supports basic arithmetic operations and features a beautiful, intuitive user interface.

🌟 Features

✨ Calculator Operations

• ➕ Addition: Add two numbers with precision
• ➖ Subtraction: Subtract numbers accurately
• ✖️ Multiplication: Multiply numbers with decimal support
• ➗ Division: Divide numbers with zero-division protection
• 🔄 All Clear (AC): Reset calculator to initial state
• ⌫ Backspace: Delete last entered character

🎨 User Experience

• 🎯 Modern UI: Beautiful gradient design with glassmorphism effects
• 📱 Responsive: Works perfectly on desktop, tablet, and mobile devices
• ⌨️ Keyboard Support: Full keyboard navigation and shortcuts
• ⚡ Real-time Calculations: Instant feedback and calculations
• 🚨 Error Handling: User-friendly error messages and validations

🏢 Enterprise Features

• 👥 Multi-User Support: Designed for concurrent user access
• 🔗 REST API: Clean, documented API endpoints
• ✅ Comprehensive Testing: Full unit and integration test coverage
• 📊 Health Monitoring: Application health check endpoints
• 🛡️ CORS Support: Cross-origin resource sharing enabled

🏗️ Architecture

This application implements the Spring MVC (Model-View-Controller) architectural pattern:

📋 Layer Structure

┌─────────────────────┐
│   Presentation      │  ← Static HTML/CSS/JS (View)
├─────────────────────┤
│   Controller        │  ← REST API Endpoints 
├─────────────────────┤
│   Service           │  ← Business Logic (Model)
├─────────────────────┤
│   Data Transfer     │  ← DTOs for API Communication
└─────────────────────┘

🎯 Components

• 🎮 Controller Layer: CalculatorController - Handles HTTP requests and responses
• ⚙️ Service Layer: CalculatorService - Contains business logic for calculations
• 📦 DTO Layer: CalculatorRequest/CalculatorResponse - Data transfer objects
• 🖼️ View Layer: Static HTML/CSS/JavaScript for user interface

🚀 Quick Start

Prerequisites

• ☕ Java 17+ (JDK 17 or higher)
• 📦 Maven 3.6+
• 🖥️ IDE (IntelliJ IDEA, Eclipse, or VS Code recommended)

🔧 Installation & Setup

1. Clone the repository

   git clone https://github.com/AnderssonProgramming/calculator-mvc.git
   cd calculator-mvc

2. Build the project

   mvn clean compile

3. Run tests (optional but recommended)

   mvn test

4. Start the application

   mvn spring-boot:run

5. Access the calculator

   • Open your browser and navigate to: http://localhost:8081
   • Start calculating! 🎉

🔌 Alternative Ways to Run

Using Java directly:

mvn clean package
java -jar target/calculator-mvc-0.0.1-SNAPSHOT.jar

Using your IDE:

• Import the project as a Maven project
• Run CalculatorMvcApplication.java as a Java application

📡 API Documentation

Base URL: http://localhost:8081/api/calculator

🔍 Endpoints

1. Calculate Operation

• URL: POST /calculate
• Description: Performs arithmetic calculations
• Content-Type: application/json

Request Body:

{
  "operand1": 10.5,
  "operand2": 5.2,
  "operation": "add"
}

Supported Operations:

• add or + - Addition
• subtract or - - Subtraction
• multiply or * - Multiplication
• divide or / - Division
• clear or ac - All Clear

Success Response:

{
  "result": 15.7,
  "operation": "add",
  "success": true,
  "errorMessage": null
}

Error Response:

{
  "result": 0,
  "operation": null,
  "success": false,
  "errorMessage": "Cannot divide by zero"
}

2. Health Check

• URL: GET /health
• Description: Check if the calculator service is running
• Response: "Calculator service is running"

🧪 API Testing Examples

Using cURL:

# Addition
curl -X POST http://localhost:8081/api/calculator/calculate \
  -H "Content-Type: application/json" \
  -d '{"operand1": 15, "operand2": 25, "operation": "add"}'

# Division with error handling
curl -X POST http://localhost:8081/api/calculator/calculate \
  -H "Content-Type: application/json" \
  -d '{"operand1": 10, "operand2": 0, "operation": "divide"}'

# Health check
curl http://localhost:8081/api/calculator/health

🧪 Testing

Running Tests

# Run all tests
mvn test

# Run specific test class
mvn test -Dtest=CalculatorServiceTest

# Run tests with coverage report
mvn clean test jacoco:report

📊 Test Coverage

• Service Layer: 100% method coverage
• Controller Layer: Complete API endpoint testing
• Integration Tests: Full application context testing

🎯 Test Categories

• Unit Tests: Individual component testing
• Integration Tests: Spring context and HTTP request testing
• Error Handling: Edge cases and exception scenarios

📁 Project Structure

calculator-mvc/
├── 📄 pom.xml                           # Maven configuration
├── 📄 README.md                         # This file
├── 📁 src/
│   ├── 📁 main/
│   │   ├── 📁 java/edu/eci/arsw/calculator_mvc/
│   │   │   ├── 📄 CalculatorMvcApplication.java    # Main application class
│   │   │   ├── 📁 controller/
│   │   │   │   └── 📄 CalculatorController.java    # REST API controller
│   │   │   ├── 📁 dto/
│   │   │   │   ├── 📄 CalculatorRequest.java       # Request DTO
│   │   │   │   └── 📄 CalculatorResponse.java      # Response DTO
│   │   │   └── 📁 service/
│   │   │       └── 📄 CalculatorService.java       # Business logic
│   │   └── 📁 resources/
│   │       ├── 📄 application.properties           # App configuration
│   │       └── 📁 static/
│   │           ├── 📄 index.html                   # Main UI
│   │           └── 📁 js/
│   │               └── 📄 calculator.js            # Frontend logic
│   └── 📁 test/
│       └── 📁 java/edu/eci/arsw/calculator_mvc/
│           ├── 📄 CalculatorMvcApplicationTests.java
│           ├── 📁 controller/
│           │   └── 📄 CalculatorControllerTest.java
│           └── 📁 service/
│               └── 📄 CalculatorServiceTest.java

⚙️ Configuration

Application Properties

# Application settings
spring.application.name=calculator-mvc
server.port=8081

# Error handling
server.error.include-message=always
server.error.include-binding-errors=always

# Logging
logging.level.edu.eci.arsw.calculator_mvc=DEBUG
logging.level.org.springframework.web=INFO

🔧 Customization Options

• Port: Modify server.port in application.properties
• Logging: Adjust logging levels for different packages
• CORS: Configure allowed origins in CalculatorController

🎨 User Interface

💡 Features

• Glassmorphism Design: Modern frosted glass effect
• Responsive Layout: Adapts to different screen sizes
• Smooth Animations: Button hover effects and transitions
• Color-Coded Buttons: Different colors for numbers, operators, and functions
• Real-time Display: Shows both expression and result

⌨️ Keyboard Shortcuts

• Numbers: 0-9 keys
• Operations: +, -, *, /
• Calculate: Enter or =
• Clear: Escape key
• Delete: Backspace key
• Decimal: . key

🐛 Troubleshooting

Common Issues

1. Port Already in Use

Error: Web server failed to start. Port 8081 was already in use.

Solution: Change the port in application.properties or stop the process using port 8081.

2. Maven Build Issues

Error: Could not find or load main class

Solution: Run mvn clean compile and ensure Java 17+ is installed.

3. Application Won't Start

Error: APPLICATION FAILED TO START

Solution: Check logs for specific errors, verify Java version and dependencies.

🔧 Debug Mode

Run with debug logging:

mvn spring-boot:run -Dspring-boot.run.profiles=debug

🤝 Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/AmazingFeature)
3. Commit your changes (git commit -m 'Add some AmazingFeature')
4. Push to the branch (git push origin feature/AmazingFeature)
5. Open a Pull Request

📝 Development Guidelines

• Follow Spring Boot best practices
• Maintain test coverage above 90%
• Use meaningful commit messages
• Update documentation for new features

📄 License

This project is licensed under the MIT License - see the LICENSE file for details.

🙏 Acknowledgments

• Spring Framework Team - For the excellent Spring Boot framework
• Font Awesome - For the beautiful icons
• Stack Overflow Community - For countless solutions and inspiration

🔮 Future Enhancements

• Scientific Calculator: Add trigonometric and logarithmic functions
• History Feature: Store and display calculation history
• Memory Functions: M+, M-, MR, MC operations
• Themes: Multiple UI themes and dark mode
• Keyboard Layout: Virtual keyboard display
• Unit Converter: Length, weight, temperature conversions
• Export Results: Save calculations to file
• User Profiles: Personal calculation preferences

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⭐ If you found this project helpful, please give it a star! ⭐

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Happy Calculating! 🧮✨