Currency Exchange Service

This project provides a suite of services to deliver daily currency exchange rates to users. It includes the Gateway and Currency services, each with specific functionalities.

Overview

This system is designed to:

• Provide users with daily currency exchange rates.
• Validate user permissions and convert user requests.
• Fetch and store currency rates from a public API.

Services

Gateway Service

The Gateway service is responsible for the initial handling of user requests, validating user permissions, and converting requests to a format suitable for further processing by the Currency service. This service masks the implementation details of the Currency service from the end user.

Key Features

1. HTTP REST API: Processes user requests via a standard HTTP REST API.
2. Authorization Requests: Interfaces with an authentication service to generate and validate access tokens.
3. Data Request Forwarding: Sends transformed requests to the Currency service using REST/RPC.

Assumptions

• Does not maintain a separate database for user storage; opts for simple in-memory structures like slices or maps.
• User registration is simplified; user data may be hardcoded or configured through files.
• Minimal user data is utilized: only login and password are necessary.

Currency Service

The Currency service is tasked with fetching currency exchange rates from a public API and storing this data in a database. It also processes requests from the Gateway service to retrieve stored rates and historical data.

Key Features

1. Automated Worker: Runs daily to fetch the current RUB exchange rate against one foreign currency.
2. Data Storage: Saves fetched exchange rates in a database.
3. Data Retrieval: Responds to Gateway service requests for specific dates and historical exchange data over time.

Deployment and Setup

The services can be orchestrated using Docker Compose, with dependencies on a PostgreSQL database for data storage.

Prerequisites

• Docker and Docker Compose should be installed on the host machine.

Running the Services

1. Start Services: Use Docker Compose to start the services:

   docker compose up --build
   

2. Generate test data: You can generate some test data using script

   go run ./currency/internal/scripts/generate_test_data.go
   

Testing the API with curl

This guide outlines how to interact with the API using curl for registering a user, logging in, and fetching currency rates.

Step 1: Register User

Register a new user by sending a POST request with the username and password in JSON format.

curl -X POST http://localhost:8080/api/v1/register \
  -H "Content-Type: application/json" \
  -d '{
        "Username": "test",
        "Password": "test"
      }'

Step 2: Login User

Authenticate the user and retrieve a token by sending a POST request with the username and password.

curl -X POST http://localhost:8080/api/v1/login \
  -H "Content-Type: application/json" \
  -d '{
        "Username": "test",
        "Password": "test"
      }'

Note: The response will contain a JSON object with a "token" field. Extract the token value from the response to use it in the next request.

Step 3: Get Currency Rates

Fetch currency rates by sending a GET request. Include the Authorization header with the token obtained from the login step.

curl -X GET "http://localhost:8080/api/v1/rate?currency=USD&date_from=2024-10-01&date_to=2024-10-21" \
  -H "Authorization: Bearer <YOUR_TOKEN>"

Replace <YOUR_TOKEN> with the actual token obtained in step 2.

Notes

• Authorization Token: Ensure that the token from the login step is used in the Authorization header of the third request.
• Content-Type Header: The Content-Type header should be set to application/json for POST requests to specify that the request body contains JSON data.

These steps assume the API is running locally on localhost:8080. Adjust the host and port as necessary if your API is hosted elsewhere.