💳 Digital Wallet API

A secure and extensible digital wallet API built with Java and Spring Boot.

Customers can manage their own wallets, deposits, and withdrawals. Employees can perform operations on behalf of any customer.

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🚀 Features

• ✅ Create wallets with different currencies (TRY, USD, EUR)
• ✅ Deposit and withdraw money with business rules
• ✅ Approve or deny large transactions
• ✅ Role-based access control (CUSTOMER vs EMPLOYEE)
• ✅ Integrated Swagger documentation for API testing
• ✅ H2 in-memory database
• ✅ Unit and integration test coverage
• ✅ Secure endpoints with Spring Security

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🧰 Tech Stack

• Java 21
• Spring Boot 3.x
• Spring Security
• Spring Data JPA (H2)
• Lombok
• Swagger (SpringDoc OpenAPI)
• JUnit 5 & Mockito
• Maven

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📦 Getting Started

1. Clone the repository

git clone <repo-url>
cd digital-wallet
./mvnw clean install

2. Run the application

./mvnw spring-boot:run

3. Access the H2 database console

http://localhost:8080/h2-console

• JDBC URL: jdbc:h2:mem:digitalwallet
• Username: digitalwallet
• Password: (leave empty)

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🔐 Default Users

Role	Username	Password
CUSTOMER	12345678901	12345678901
EMPLOYEE	employee1	employee1

• CUSTOMERS can only manage their own wallets and transactions
• EMPLOYEES can access and manage all customer data

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📘 Business Rules

Deposits

• Amount ≤ 1000 → Automatically APPROVED
• Amount > 1000 → Saved as PENDING
  • APPROVED → added to both balance and usableBalance
  • PENDING → added only to balance

Withdrawals

• Amount ≤ 1000 → Automatically APPROVED
• Amount > 1000 → Saved as PENDING
  • APPROVED → deducted from both balance and usableBalance
  • PENDING → deducted only from usableBalance

Approvals

• APPROVED → Applies the transaction effect to wallet
• DENIED → Cancels the transaction, reverts balances if necessary

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📂 API Documentation (Swagger)

Accessible at:

http://localhost:8080/swagger-ui/index.html

🧪 Sample API Calls

Create Wallet

POST /api/wallets/create/{customerId}
Content-Type: application/json

{
  "walletName": "My Wallet",
  "currency": "TRY",
  "activeForShopping": true,
  "activeForWithdraw": true
}

Deposit

POST /api/transactions/deposit
{
  "walletId": 1,
  "amount": 1500,
  "oppositePartyType": "IBAN",
  "oppositeParty": "TR123..."
}

Withdraw

POST /api/transactions/withdraw
{
  "walletId": 1,
  "amount": 500,
  "oppositePartyType": "PAYMENT",
  "oppositeParty": "PAY_ABC_001"
}

Approve/Deny

POST /api/transactions/approve
{
  "transactionId": 10,
  "status": "APPROVED"
}

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🧪 Running Tests

./mvnw test

Includes:

• ✅ Unit tests for services
• ✅ Integration tests for controllers and repositories

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🧱 Project Structure

com.digitalwallet
├── controller         # REST endpoints
├── dto                # Data Transfer Objects
├── service            # Business logic
├── repository         # JPA repositories
├── entity             # Domain models
├── security           # Spring Security config
├── config             # Swagger, database configs
└── util               # Common utility classes

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🛡 Security Overview

• Basic Authentication
• Dynamic login:
  • CUSTOMERS are authenticated via TCKN (used as both username & password)
  • EMPLOYEES are authenticated via in-memory credentials
• Method-level access control with role checks

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⚠️ Notes

• Passwords are not encoded – this is for development only.
• Production usage should replace this with BCryptPasswordEncoder or JWT-based auth.
• Database is in-memory; use PostgreSQL or MySQL for persistence.

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📄 License

This project is licensed under the MIT License.

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👨‍💻 Contributing

Feel free to fork and submit pull requests. Feedback is always welcome!