Technical Assignment: URL Shortening Service Implementation

Description:

You need to implement a REST API service for shortening long URLs. The service should allow the user to submit a long URL and receive its shortened version, as well as redirect to the original URL when accessing the shortened link.

Most likely, you will not be able to complete the entire task in the allotted time — this is normal, prioritize the points as you think is right. Use any tools you are used to during the task — searching for information on the Internet is not prohibited :)

Functional requirements:

1. API functionality:

• POST /shorten — create a short link:

  • Accepts a JSON request with a field for the original URL.
  • Returns the short link in JSON format.
  • If the URL already exists in the system, return the existing short link.

• GET /{shortUrl} — redirect by short link:

  • When accessing the short link, a redirect to the original URL should occur.
  • If the link has expired or is not found, return a 404 error.

• GET /info/{shortUrl} — get information about the shortened link:

  • Returns information about the original URL, creation date, and expiration date.
  • Returns 404 if the link is not found or has expired.

• DELETE /{shortUrl} — delete a short link:

  • Deletes the short link and original URL record from the system.

2. Error handling requirements:

• Return status 400 if the original URL is invalid.
• Return status 404 for non-existent or expired short links.

Technical requirements:

1. Spring Boot:

• Use Spring Boot to create the application.

2. Storage:

• Use any in-memory storage of your choice for storing the URLs.

3. Short link generation:

• For generating the short link, you can use an alphanumeric character set. The link should have a fixed length (e.g., 6-10 characters).
• It is acceptable to use existing libraries for generating unique strings.

4. Controllers, Services, and Repositories:

• Separate business logic from API and data access.

5. Validation:

• Ensure that the original URL is valid and handle possible errors.

6. API Documentation:

• Use Swagger to document the REST API.

7. Testing:

• Write unit tests for the main functions (creating a short link, redirection, fetching information).
• Use JUnit and Mockito for testing.

Additional requirements:

1. Implement support for custom short links where the user can specify a short identifier.
2. Add authorization for managing links (e.g., JWT tokens for creating and deleting).
3. Add the ability to set the expiration date when creating a link.
4. Implement a metrics system to track the number of clicks on the short link.
5. Add stats for link usage

---