URL Shortener API

Build a simple URL shortener API service that handles different path patterns for creating, retrieving, and managing shortened URLs.

Requirements

Create a Koa application with the following routes:

1. Create Short URL: Accept POST requests to create a new shortened URL

   • Path: /shorten
   • Request body contains { "url": "https://example.com" }
   • Response: { "short": "abc123" } with status 201

2. Redirect to Original URL: Accept GET requests with a short code to redirect

   • Path: /r/:code
   • Extracts the short code from the path
   • Response: Redirect (302) to the original URL if found, or 404 if not found

3. Get User URLs: Accept GET requests to list URLs created by a user

   • Path: /user/:username
   • Extracts the username from the path (handles URL-encoded usernames)
   • Response: { "username": "john", "urls": [{"short": "abc123", "url": "..."}] } with status 200
   • Returns empty array if user has no URLs

4. Get URL Details: Accept GET requests with optional code parameter

   • Path: /details/:username/:code?
   • If code is provided, returns detailed info for that URL: { "short": "abc123", "url": "...", "clicks": 5 }
   • If code is not provided, returns summary: { "username": "john", "totalUrls": 3, "totalClicks": 15 }
   • Both username and code should be URL decoded if present

Implementation

@generates

For the purposes of this exercise:

• Store data in memory using simple objects/maps
• Generate short codes as random 6-character strings
• Track click counts each time a redirect occurs
• Associate each shortened URL with the username who created it

API

// Create and configure the Koa application with all routes
function createApp() {
  // Returns configured Koa app instance
}

module.exports = { createApp };

Tests

Create Short URL

• POST to /shorten with {"url": "https://example.com", "username": "john"} returns status 201 with {"short": "..."} @test

Redirect to Original URL

• GET to /r/abc123 (existing code) redirects with status 302 to the original URL and increments click count @test
• GET to /r/missing (non-existent code) returns status 404 @test

Get User URLs

• GET to /user/john returns status 200 with array of URLs created by user "john" @test
• GET to /user/jane%20doe (URL-encoded username with space) correctly decodes to "jane doe" and returns their URLs @test

Get URL Details with Optional Parameter

• GET to /details/john/abc123 returns status 200 with detailed info including click count for that specific URL @test
• GET to /details/john (without code parameter) returns status 200 with summary statistics for user "john" @test
• GET to /details/alice%20smith/xyz789 correctly decodes username "alice smith" and code "xyz789" @test

Dependencies { .dependencies }

koa { .dependency }

Provides the web application framework.

koa-route { .dependency }

Provides routing middleware with path parameter support.

koa-bodyparser { .dependency }

Provides request body parsing for POST requests.