RFC: Stabilize v1 API for vndb query proxy response

[prekel]

Vndb query can return different responses:

1. results {...json...} (https://vndb.org/d11#5)
2. error {...json...} (https://vndb.org/d11#7)
3. ok (https://vndb.org/d11#3) (will not be used by frontend in normal use)

This kinds of responses must be mapped to one API response. But, there 2 another cases:

4. Unknown response - nor 1, 2, 3. Then, we can provide raw unparsed response.
5. Internal error. Then, we provide error message

This 5 cases can be mapped with 2 ways.

First:

1. Status200OK

   {
   "response": "results",
   "data": {...json...}
   }

2. Status400BadRequest

   {
   "response": "error",
   "data": {...json...}
   }

3. Status200OK

   {
   "response": "ok"
   }

4. Status501NotImplemented

   {
   "response": "unknown",
   "raw": "string with raw response"
   }

5. Status500InternalServerError

   {
   "response": "internalerror",
   "error": "error message"
   }

Second:

1. Status200OK

   {
   "response": "results",
   "data": {...json...}
   }

2. Status400BadRequest

   {
   "response": "error",
   "data": {...json...}
   }

3. Status200OK

   {
   "response": "ok",
   "data": null
   }

4. Status501NotImplemented

   {
   "response": "unknown",
   "data": "string with raw response"
   }

5. Status500InternalServerError

   {
   "response": "internalerror",
   "data": "error message"
   }

Which is better: first or second? @Moltenship @NightOfNights @choi-moeta

[moetazaneta]

For ok we should probably use 204 status code without data (https://restfulapi.net/http-status-codes/).

[panov-aleksey-saritasa]

Don't see much difference, but second is more neat to me.

[prekel]

Done.

https://github.com/vndbre/vndbre-proxy/blob/master/VndbReProxy.Api/Requests/api.http

Where host is https://vndbre-proxy.azurewebsites.net/

[prekel]

Ok, second