fix(podcastindex): expose guid as href attribute on podcast:person tag

[saerdnaer]

Additionally, the PR improves UX of the contributor form:

• by reordering fields according to the optimized workflow
• automatically adding missing URL protocol to URI=guid field value
• automatically filling other fields (publicname, realname, identifier, guid, avatar) via lookup by email address or guid value
  • lookup of email or mastodon address in form [email protected] via WebFinger protocol/Mastodon e.g. in my case a request to https://saerdnaer.de/.well-known/webfinger?resource=acct%3Aandi%40saerdnaer.de
  • if that fails: fallback to a request to gravatar.com (managed by wordpress.com) using md5 hash e.g. in my case https://gravatar.com/074e3576cdd125ae31520d9b66dc4f7c.json

And last but not least – the change actually described by the PR title:

• setting the href attribute on the exiting <podcast:person>-Tag in the podcast feed to the value of the URI=guid field

initial PR description

I would propose do automatically fill the guid field in the wp_podlove_modules_contributors_contributor table with the first social media URL, once it is added in the Wordpress backend. Maybe even just in the UI via JavaScript – so for example when I add the users twitter handle in the social table and the URI Field above is empty (looks like URI is the form's label for the guid database field) then it should be automatically filled with the full URL as it is behind the arrow button in the table.

Maybe also add an database migration which automatically does this for all existing entries c.f. #939 (comment)

UPDATE wp_podlove_modules_contributors_contributor c 
  LEFT JOIN wp_podlove_modules_social_contributorservice cs ON c.id = cs.contributor_id
  LEFT JOIN wp_podlove_modules_social_service s ON s.id = cs.service_id 
SET c.guid = CONCAT('https://twitter.com/', cs.value) 
WHERE c.guid IS NULL AND s.type = 'twitter'

Related to #939 & podlove/podlove-specifications#23

[douglaskastle]

If this is to be the case, is it possible to add an "other" as a service to allow any URL to used? Right now podchaser (for example) is not supported, so currently I would like that. However the bigger picture is, I don't know what i might want down the road, and it might not be supported (IMDB is one I have looked at)

Ultimately the href on the person is meant to be more of a central identifier, like linkedIn, IMDB, podchaser than a social service like twitter, deviantart. Facebook is werid here, it is kinda used for both.

[saerdnaer]

Related: Podcastindex-org/podcast-namespace#201

[saerdnaer]

If this is to be the case, is it possible to add an "other" as a service to allow any URL to used? Right now Podchaser (for example) is not supported, so currently I would like that.

Actually, this PR supports any service implementing WebFinger. But yes, as Podchaser now has a proper API, we could also add a feature to lookup persons by name there – but we would somehow mange the api keys problem. But thats a different discussion and PR. :-)

[eteubert]

@saerdnaer Are you still planning to continue working on this? Not sure about the state of the implementation but I vaguely remember it wasn't finished.