API design

POST `/v1/users`

Body:

{
   "first_name": string,
   "last_name": string,
   "email": string
}

Response:

201 Created

{
   "first_name": string,
   "last_name": string,
   "email": string,
   "id": string
}

POST `/v1/links`

Accepts a body with url, user_id, and optional custom_short_url to create a new short link.

Body:

{
   "url": string,
   "user_id": string,
   "custom_short_url": string,
   "expiration": UNIX timestamp
}

"url": string, starting with `http://` or `https://`, with max length 512 bytes.

"user_id": alpanumerical user ID

"custom_short_url": custom link ID - 8 chars. If custom_short_url is not provided, ID is generated automatically.

Response:

201 Created

{
   "id": ID,
   "short_url": SHORT_URL,
   "long_url": LONG_URL,
   "user_id": USER_ID
}

400 Bad Request - for invalid URL (invalid scheme, missing domain, exceeding max length, etc).

409 Conflict - if provided `custom_short_url` is already used.

When a user attempts to generate a short URL for an already existing long URL, already existing short URL is returned.

GET `/v1/links/{ID}`

GET /v1/links/{ID}: Takes a short_url ID and returns the corresponding long URL with additional metadata, if applicable.

Response:

200 OK

{
   "id": ID,
   "short_url": SHORT_URL,
   "long_url": LONG_URL
}

404 Not found

GET `/v1/users/<USER_ID>/links?limit=N&cursor=CURSOR`

Allows fetching all links associated with a given user_id, with pagination support (e.g., limit and cursor).

Response:

[
   {
   "id": ID,
   "short_url": SHORT_URL,
   "long_url": LONG_URL
   },
   ...
]