Documentation: Meta-Issue: EDTF dates

[kspurgin]

This is a meta issue to track developments and issues with regard to EDTF date form widget, validation, display, and indexing.

Please refer to this issue in any subsequent issues to link them.

Spreadsheet documenting EDTF-related behavior here: https://docs.google.com/spreadsheets/d/1cx2KTkELqCDxczIVQw6La_PTSgmqMj_KEr6dIKvszYg/edit#gid=0

[seth-shaw-unlv]

Thanks for documenting all of these @kspurgin. We really need to write a set of tests to cover all these cases. I'm not sure when I'll be able to work through any of these, but I'm happy to review PRs if they come up.

[kspurgin]

I was thinking some of the simpler display things might be easy enough for meet to try fixing.

But at least the behavior is captured/documented now!

[seth-shaw-unlv]

@nigelgbanks recently pointed out some EDTF PHP libraries in Slack:

• https://github.com/ProfessionalWiki/EDTF
• https://github.com/computerminds/php-edtf

The former looks to be currently maintained while the latter hasn't been touched in several years.

That said, we should probably do a head-to-head comparison and see if we can 🔥 much of our code in favor of one of these libraries.

[dannylamb]

[seth-shaw-unlv]

So, ProfessionalWiki/EDTF looks nice. We could burn most of our code and it gives us a bit more functionality than we already have. I'm especially interested in the min and max functions it provides.

However, it requires PHP 7.4. I think this is fine for new installs of the next release. Existing sites that want to upgrade their islandora should be fine, but they wouldn't be able to upgrade their islandora_defaults (which I think we are also saying is okay) if they want to keep PHP 7.3. _(Edit: or maybe they could upgrade defaults if we don't update the version tagged for controlled_access_terms and simply don't use any new controlled_access_terms features in this release)_ Thoughts, @Islandora/8-x-committers?

[DiegoPino]

@seth-shaw-unlv we are using it in Archipelago and its a great choice.

[seth-shaw-unlv]

I mentioned to @kspurgin above that we needed tests for identified issues. Turns out that we already _do_ have tests, we just need to add these to the list. We've had this initial test set since last September. 🤦‍♂️

Not that the test only tests validation... not expected formatter display.