It seems that Spotify has gone https-only. Right now we accept both http and https, we should make it change http to https.

There are two subdomains being used now, open.spotify.com and play.spotify.com. Actually open.spotify.com is preferred over play.spotify.com as it is more versatile. Spotify user settings allow to redirect from open.spotify.com to play.spotify.com.

Both URL parameters (e.g. ?play=true&utm_source=open.spotify.com) and fragments (e.g. #top) are unnecessary and should be removed.

Right now, there's no validation done to make sure the URL matches the entity type. There are three main types of URLs, /artist/, /album/ and /track/, which should correspond to artist, release and recording.

Typical URLs:

• https://play.spotify.com/artist/5d9PdhcsOsXj0GIM857nvE
• https://open.spotify.com/album/1zVa1c0rHOnaNJZgK7IOdQ
• http://open.spotify.com/track/1SI5O5cu8AM19cninxf9RZ

URLs which should get cleaned up:

• http://play.spotify.com/album/3rFPzWNUrtoqMd9yNGaFMr?play=true&utm_source=open.spotify.com&utm_medium=open
• https://play.spotify.com/artist/5zS2OG2kKeGYFqX6lcuVOt?play=true&utm_source=google&utm_medium=growth_paid&utm_campaign=pla_US&gclid=CN-m_fOj3cMCFUJk7AodTBsA8g
• https://open.spotify.com/artist/3dXaa6jwM7B52GZpaJEIr5?ref=atw

Other examples from the database:

• https://play.spotify.com/user/scotchbonnetrecords - user page, should be linked using social network relationships
• https://play.spotify.com/user/1254688529/playlist/0MRy5cv9ZktSjysDEIP72H - user playlist, should be rejected (`album` URL is preferred but cannot be deduced)
• https://open.spotify.com/album/0tabKG66W34Ms0SsovkP6Q/6yVKnHVFGkg4OQ8IrgQVpZ - album, subpath should be removed
• http://open.spotify.com/local/Electrolyze/Single/Belief/265 - user local file, should be rejected (`track` URL is preferred but cannot be deduced)
• https://play.spotify.com/search/The%20Most%20Essential%20Bossa%20Nova - a search, should probably not be accepted since URLs like that can be automatically generated if people want them.

I've made a list at http://reports.mbsandbox.org/report/290/view of URLs which don't match the regex '^https?://(open|play).spotify.com/(artist|album|track)/[A-Za-z0-9]

$' if more examples are needed (I'll wait until this is done before fixing them).