Credit Module

This module is responsible for managing the credit of the user. It includes functionalities for creating, listing, and paying loans. The following endpoints are provided:

Endpoints

Create Loan

• Description: Create a new loan for a given customer.

• URL: /loans

• Method: POST

• Request Body:

  {
    "customerId": "string",
    "amount": "number",
    "interestRate": "number",
    "numberOfInstallments": "number"
  }

• Validation:

  • Check if the customer has enough credit limit.
  • Number of installments can only be 6, 9, 12, or 24.
  • Interest rate must be between 0.1 and 0.5.
  • All installments should have the same amount.
  • The due date of installments should be the first day of the month.

• Response:

{
  "loanId": "string",
  "customerId": "string",
  "amount": "number",
  "interestRate": "number",
  "numberOfInstallments": "number",
  "installments": [
    {
      "installmentId": "string",
      "amount": "number",
      "dueDate": "string"
    }
  ]
}

List Loans

• Description: List all loans for a given customer.
• URL: /loans/{customerId}
• Method: GET
• Response:

[
  {
    "loanId": "string",
    "customerId": "string",
    "amount": "number",
    "interestRate": "number",
    "numberOfInstallments": "number",
    "installments": [
      {
        "installmentId": "string",
        "amount": "number",
        "dueDate": "string"
      }
    ]
  }
]

List Installments

• Description: List all installments for a given loan.
• URL: /loans/{loanId}/installments
• Method: GET
• Response:

[
  {
    "installmentId": "string",
    "amount": "number",
    "dueDate": "string",
    "isPaid": "boolean"
  }
]

Pay Loan

• Description: Pay installment for a given loan and amount.ü
• URL: /loans/{loanId}/pay
• Method: POST
• Request Body:

{
  "amount": "number"
}

• Validation:

  • Installments should be paid wholly or not at all.
  • Pay the earliest installment first.
  • Installments due more than 3 months in the future cannot be paid.

• Response:

{
  "installmentsPaid": "number",
  "totalAmountSpent": "number",
  "isLoanPaidCompletely": "boolean"
}

Authorization

All endpoints should be authorized with an admin user and password.

Database Structure

• Customer:

  • id
  • name
  • surname
  • creditLimit
  • usedCreditLimit

• Loan:

  • id
  • customerId
  • loanAmount
  • numberOfInstallments
  • createDate
  • isPaid

• LoanInstallment:

  • id
  • loanId
  • amount
  • paidAmount
  • dueDate
  • paymentDate
  • isPaid

Installation and Running the Project

1. Clone the repository.

git clone https://github.com/FatihBozik/credit-module.git

2. Navigate to the project directory:

cd credit-module

3. Build the project:

./gradlew clean build

4. Run the application:

   ./gradlew bootRun

Unit Tests

Unit tests are provided to ensure the functionality of the application. To run the tests, use the following command:

./gradlew test

Notes

• The application uses Postgres SQL database for simplicity.
• Documentation is important. Ensure to update this README for any changes in the application.

Bonus Features

Authorization Roles

• Admin users can operate for all customers.
• Customer role users can operate for themselves.

Reward and Penalty Logic

• If an installment is paid before the due date, a discount is applied.
• If an installment is paid after the due date, a penalty is added.

Deployment

The application is deployed and can be accessed at:

Host: api.credit-module.fatihbozik.com

Port: 8080

Environment: Test

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This README provides a comprehensive overview of the Credit Module project, its endpoints, and how to use the application.

Feel free to modify the README further based on any additional project-specific details or requirements.