local mbid-based caching

[jreeee]

for songs where lastfm does not provide length or coverart this app sends one or two queries to musicbrainz to get the album mbid which is then used to get a image link from coverartarchive. although this is queried once per song and thus not very resource intensive, it would make sense to store received data in sth. like a json

[jreeee]

This does not take songs without cover and mbid into account. for those it would make sense to also store the cover art link if it can be retrieved. I thought about hashing the titles to improve lookup, but honestly it's prolly enough if you store it in sth. like artist_url-song_url. it'd then prolly look similar to this:

/.cache/showscrobbling/

• mbid-songs.json
• other-songs.json

with a structure like

{
    "song" : "songname",
    "artist" : "artistname",
    "mbid" : "mbid",
    "key" : "artist_url-song_url",
    "length" : "int",
    "cover" : "link",
}

where key and mbid are used based on which file it is in