ivanovsdesign/payment_block_api

🚫 Payment Blocking API

This API allows you to manage transaction blocks for payment delivery to businesses, ensuring secure and fraud-free transactions.

payment_block.yaml contains OpenAPI specs for payment blocking feature
database/schema.sql contains script for database schema

Notice: it is just an OpenAPI specification made as an assignment
Acual service isn't developed yet

📜 Table of Contents

• Overview
• API Endpoints
  • Block Transactions
  • Unblock Transactions
  • Check Block Status
  • Distinguish Client Type
• Schemas
• Example Usage
• Database schema

📝 Overview

This API provides functionalities to:

1. Block transactions for a particular client.
2. Unlock transactions for a particular client.
3. Check if a client is blocked.
4. Distinguish fraudsters from ordinary clients.

🔌 API Endpoints

🚫 Block Transactions

POST /clients/{clientId}/block

Block transactions for a specific client due to suspicious activity.

Parameters:

• clientId (string, required): The ID of the client to block.

Responses:

• 200 OK: Client transactions blocked successfully.
• 400 Bad Request: Invalid client ID.
• 404 Not Found: Client not found.

✅ Unblock Transactions

POST /clients/{clientId}/unblock

Unblock transactions for a specific client after verification.

Parameters:

• clientId (string, required): The ID of the client to unblock.

Responses:

• 200 OK: Client transactions unblocked successfully.
• 400 Bad Request: Invalid client ID.
• 404 Not Found: Client not found.

❓ Check Block Status

GET /clients/{clientId}/status

Check the blocking status of a client.

Parameters:

• clientId (string, required): The ID of the client to check.

Responses:

• 200 OK: Blocking status retrieved successfully.
• 400 Bad Request: Invalid client ID.
• 404 Not Found: Client not found.

👤 Get Client Type

GET /clients/{clientId}/type

Check if a client is flagged as a fraudster or an ordinary client.

Parameters:

• clientId (string, required): The ID of the client to check.

Responses:

• 200 OK: Client type retrieved successfully.
• 400 Bad Request: Invalid client ID.
• 404 Not Found: Client not found.

📂 Schemas

Client

type: object
properties:
  clientId:
    type: string
  isBlocked:
    type: boolean
  reason:
    type: string
  clientType:
    type: string
    enum: [fraudster, ordinary]

📘 Example Usage

Block a Client

curl -X POST "https://api.t-bank.com/v1/clients/client123/block"

Unblock a Client

curl -X POST "https://api.t-bank.com/v1/clients/client123/unblock"

Check if a Client is Blocked

curl -X GET "https://api.t-bank.com/v1/clients/client123/status"

Get Client Type

curl -X GET "https://api.t-bank.com/v1/clients/client123/type"

🗄 Database Schema

Overview

This schema supports the functionality required for blocking and unblocking transactions for clients based on various reasons. It consists of tables for managing clients, client types, transaction blocks, and blocking reasons.

Tables

1. ClientTypes

Stores the types of clients.

Column	Type	Description
clientTypeId	INT	Primary key, auto-increment
clientTypeName	VARCHAR(50)	Unique client type name

2. BlockingReasons

Stores the reasons for blocking transactions.

Column	Type	Description
reasonId	INT	Primary key, auto-increment
reasonDescription	VARCHAR(255)	Unique reason description

3. Clients

Stores the client information.

Column	Type	Description
clientId	INT	Primary key, auto-increment
clientTypeId	INT	Foreign key referencing ClientTypes

4. TransactionBlocks

Stores information about transaction blocks.

Column	Type	Description
blockId	INT	Primary key, auto-increment
clientId	INT	Foreign key referencing Clients
isBlocked	BOOLEAN	Indicates if the client is blocked
reasonId	INT	Foreign key referencing BlockingReasons
blockedAt	TIMESTAMP	Timestamp when the block was applied

Relationships

• Clients.clientTypeId → ClientTypes.clientTypeId
• TransactionBlocks.clientId → Clients.clientId
• TransactionBlocks.reasonId → BlockingReasons.reasonId

Example Queries

Block a Client

INSERT INTO transaction_blocking.TransactionBlocks (clientId, isBlocked, reasonId)
VALUES (1, TRUE, (SELECT reasonId FROM transaction_blocking.BlockingReasons WHERE reasonDescription = 'Fraudulent activity detected'));

Unblock a Client

UPDATE transaction_blocking.TransactionBlocks
SET isBlocked = FALSE
WHERE clientId = 1 AND isBlocked = TRUE;

Check if a Client is Blocked

SELECT isBlocked, (SELECT reasonDescription FROM transaction_blocking.BlockingReasons WHERE reasonId = tb.reasonId) AS reason, blockedAt
FROM transaction_blocking.TransactionBlocks tb
WHERE clientId = 1
ORDER BY blockedAt DESC
LIMIT 1;

Distinguish Client Type

SELECT (SELECT clientTypeName FROM transaction_blocking.ClientTypes WHERE clientTypeId = c.clientTypeId) AS clientType
FROM transaction_blocking.Clients c
WHERE clientId = 1;

Example Scenarios

Scenario 1: Transaction Blocked Due to Fraudulent Activity Transaction Attempt: Client with clientId = 1 attempts a transaction. Fraud Detection: System detects suspicious activity and flags it as potentially fraudulent.

Block Transaction:

INSERT INTO transaction_blocking.TransactionBlocks (clientId, isBlocked, reasonId)
VALUES (1, TRUE, (SELECT reasonId FROM transaction_blocking.BlockingReasons WHERE reasonDescription = 'Fraudulent activity detected'));

Scenario 2: Unblocking After Security Check Security Check: After a manual review, the client is cleared of fraudulent activity.

Unblock Client:

UPDATE transaction_blocking.TransactionBlocks
SET isBlocked = FALSE
WHERE clientId = 1 AND isBlocked = TRUE;

Scenario 3: Transaction Blocked Due to Invalid Credentials Transaction Attempt: Client with clientId = 2 attempts a transaction. Credential Check: Client provides invalid credentials, and the transaction is rejected by the bank.

Block Transaction:

INSERT INTO transaction_blocking.TransactionBlocks (clientId, isBlocked, reasonId)
VALUES (2, TRUE, (SELECT reasonId FROM transaction_blocking.BlockingReasons WHERE reasonDescription = 'Invalid credentials'));