Key generation with conditions?

Is there a way to use conditions for the key generation patterns?

e.g. for “Online” or "WWW"
IF “author” and “year” is given: [author][year]
IF “author” and NOT “year”: [author]
IF NOT “author”: [veryshorttitle]

EDIT: Please move this to FeatureRequest section if this is not possible. This is very relevant for Website (WWW, Online, Unpublished) entries. The meta-data for that has often very low quality and is far away from being complete. So there are a lot of “cases” need to be consired when generating a key of such entries. This are kind of entries I don’t want to edit manualy.