Add OpenApi support (formerly Swagger)

[RobThree]

It would be really cool if the json api also served a (static) swagger.json file which would make 'discovering' and more importantly implementing the API a lot simpler (automatic client generation on most plaforms and languages). It also serves as (machine readable) documentation. Adding a (also static) swagger-UI would be extra bonuspoints.

Basic steps:

• Write the swagger.json
• handle the /json/swagger.json request by serving the static file (I guess here somehwere)
• (Optional) Also serve the required (static) swagger-ui files

Ofcourse, this would mean that when changes are made to the api this document needs to be kept in sync. But I do really think it would be worth the effort.

This would require some storage, naturally, but the files can be saved pre-gzipped (or brotli or whatever is hot nowadays) and served as-is (with the correct headers).

I could (help with) write the swagger.json file, but I'm not sure on the other two steps. If anyone is interested in helping or teaming up I would love to prepare a PR. But if there's no interest then I won't make all these efforts in the first place. So: is there interest?

[rodericj]

I would also love this. I've not really done cpp development but I'm happy to take a stab at it

[rodericj]

Googling around suggests that there isn't quite a way to make an automatic generation of the swagger document from the code. I played around a bit and at an embedded level I just don't think we are going to get the type of compiler/interpreter support to auto generate such a file.

So then it comes down to just creating a swagger.json manually. I think that is how this is going to move forward. Again, I'm down to give it a shot. I do get the sense that these devices are so memory constrained that hosting random json/yaml files is going to push us past the limits. This is way out of my wheelhouse.

Anyway, I still think I'm down to try to manually create the swagger doc.

[netmindz]

Yeah you won't be able to use any automatic generation due to the lack of reflection in C++

There is no need to include the swagger-ui as you can just include a link to open https;//editor.swagger.io/ which will help save space

If it's being build manually then perhaps we host the spec file from WLED-Docs, if we can pass the server URL to the editor as well as the spec