PMOVEScalc

Overview

This project is a comprehensive loan calculator application consisting of a Next.js frontend and a Python FastAPI backend. It allows users to calculate loan amortization schedules, providing detailed information about payments, interest, and principal balances over the life of a loan.

Project Structure

The project is divided into two main parts:

1. Frontend (loan-calculator-next/)

   • Built with Next.js, a React framework
   • Handles user interface and interactions
   • Communicates with the backend API

2. Backend (loan-calculator-backend/)

   • Built with FastAPI, a modern Python web framework
   • Processes loan calculations
   • Provides API endpoints for the frontend

Key Features

• Calculate loan amortization schedules
• Support for various payment frequencies
• Flexible interest calculation methods (Actual days or 30-day month)
• Option for additional principal payments
• Credit insurance inclusion
• Export amortization schedule to Excel
• Adjustable-rate mortgage support
• Real-time interest rate adjustments
• User-friendly PDF export of loan details and amortization schedule

Advanced Features

• Adjustable-Rate Mortgages: Support for loans with adjustable interest rates, including initial fixed-rate periods and periodic adjustments.
• Interest Rate Adjustments: Ability to simulate interest rate changes over time, with options for random or patterned adjustments.
• Credit Insurance: Option to include credit insurance in the loan calculations, with detailed breakdowns of insurance costs.
• Data Visualization: Graphical representation of loan data, including payment breakdowns and interest over time.
• PDF and Excel Export: Export loan details and amortization schedules to PDF and Excel formats for easy sharing and record-keeping.

Technical Details

Frontend (Next.js)

The frontend is built using Next.js, a popular React framework. It provides a user-friendly interface for inputting loan details and displaying the calculated results.

Key components and features:

• React components for form inputs and result displays
• State management for handling user inputs and API responses
• API integration using Axios for communication with the backend
• Responsive design for various screen sizes
• Data visualization for displaying loan information graphically

Backend (FastAPI)

The backend is powered by FastAPI, a high-performance Python web framework. It handles the complex calculations for loan amortization and provides API endpoints for the frontend to consume.

Key features and endpoints:

1. Main application (app.py):

   • Defines the FastAPI application
   • Sets up CORS middleware for cross-origin requests
   • Defines the loan calculation endpoint

2. Loan calculation logic:

   • Handles various loan parameters (loan amount, interest rate, term, etc.)
   • Supports different payment frequencies and interest calculation methods
   • Calculates amortization schedule, including principal, interest, and balance for each payment
   • Handles additional principal payments and credit insurance if applicable

3. API Endpoints:

   • POST /calculate-loan: Accepts loan parameters and returns the amortization schedule
   • GET /export-excel: Generates and returns an Excel file with the amortization schedule

4. Data Models:

   • Uses Pydantic for data validation and serialization
   • Defines LoanRequest model for input validation

Key Dependencies

Frontend:

• React and Next.js for UI and routing
• Axios for API requests
• Recharts for data visualization
• jsPDF and html2canvas for PDF generation

Backend:

• FastAPI for API framework
• Pydantic for data validation
• XlsxWriter for Excel file generation
• python-dateutil for date calculations

How It Works

1. User Input:

   • Users enter loan details on the frontend interface (loan amount, interest rate, term, etc.)

2. API Request:

   • Frontend sends a POST request to the backend's /calculate-loan endpoint with the loan parameters

3. Loan Calculation:

   • Backend processes the request, performing the following steps: a. Validates input data using Pydantic models b. Calculates the payment amount (if not provided) c. Generates the amortization schedule, considering:
     • Payment frequency
     • Interest calculation method (actual days or 30-day month)
     • Additional principal payments
     • Credit insurance (if applicable)

4. Response:

   • Backend sends the calculated amortization schedule back to the frontend

5. Display Results:

   • Frontend displays the amortization schedule and summary information to the user

6. Excel Export (Optional):

   • Users can request an Excel export of the amortization schedule
   • Frontend sends a request to the /export-excel endpoint
   • Backend generates an Excel file and sends it as a downloadable response

Getting Started

To get a local copy up and running, follow these steps:

1. Clone the repository

   git clone https://github.com/yourusername/loan-calculator-project.git
   

2. Follow the installation instructions in INSTRUCTIONS.md for either local setup or Docker setup.

Installation and Running

Regular Installation

Refer to the INSTRUCTIONS.md file for detailed steps on how to install and run the project using traditional methods.

Docker Installation

To run the project using Docker:

1. Ensure you have Docker and Docker Compose installed on your system.

2. Navigate to the root directory of the project (where the docker-compose.yml file is located).

3. Build and start the containers:

   docker-compose up --build
   

   This will build the Docker images for both the frontend and backend, and start the containers.

4. Access the applications:

   • Frontend: http://localhost:3000
   • Backend API: http://localhost:8000

To stop the containers, press Ctrl+C in the terminal where docker-compose is running, or run:

docker-compose down

Future Enhancements

Potential areas for future development:

• Additional loan types (e.g., adjustable-rate mortgages)
• Integration with financial data APIs for real-time interest rates
• User authentication and saved calculations
• Mobile app version

Contributing

Guidelines for contributing to the project, if applicable.

License

Specify the license under which this project is released.