[GdScript] Templates for GdScript (Godot 4) (#19267)

* feat(gdscript): sketch implementation of gdscript target language

This does not really work yet, but it's a start.
Results are not denormalized, no support for enums nor datetimes,
and thousands of other features are missing.

I still don't know how we are going to denormalize JSON+LD
without writing a whole GDScript lib for it…

* feat: add an exhaustive list of keywords reserved in GDScript

I've also provided the small python script I used to generate the list.

* refacto(gdscript): start using partials in templates

Whilst I'm racking my brains trying to figure out integration testing…

* test(gdscript): prepare a demo and integration testing

* fix(gdscript): do not use subclasses, use plain POGO

(plain ol' godot object)

One: I don't know how they work under-the-hood.
Two: I'm very confused over-the-hood.
Tri: We do not need them.

* refacto(gdscript): move demo files to their own directory

I know I'm making a lot of commits for not much,
but now I'm opening the sample files with Godot as well,
and doing unholy things with filesystems,
so I'm not taking any chances.

It's all going to be squashed anyway.  :)

* fix(gdscript): sample as a Godot project

It works !  I can now write integration tests in GDScript.
The real work starts now.

/spend 25h

* feat(gdscript): serialize and send body params

The test suite is now past its first hurdle, the 415 HTTP status code,
and went straight into an unexpected error 500.

I suspect the server does not like me trying to set the pet id at 0,
because that's what we're trying to do right now.

Godot is crashing a lot, mostly because I don't know how to make Callable.NOOP
and my current solution hints at optional on_success and on_failure,
yet if we omit them the engine will ragequit.

* feat(gdscript): check request body for required yet missing properties

Now we'll get a nice error when we forget to set a required property.

The demo is now able to:
- connect
- create a user
- login as that user
- create a pet

* feat(gdscript): namespace core classes as well with apiPrefixName

This makes our usage of `class_name` a little more acceptable.

* feat(gdscript): support prefixes and suffixes for class names

This will crutch namespacing well enough for most uses.

* feat(gdscript): handle enums, naively

* feat(gdscript): support basic API endpoint param constraints

- minLength
- maxLength
- minItems
- maxItems
- minimum
- maximum
- pattern (no flags)

* feat(gdscript): handle header params and header customization

We also support serializing to application/x-www-form-urlencoded now.

Next up: DateTimes !

* feat(gdscript): handle Date and DateTime like Strings

There's no timezone support in Godot for DateTimes.

* feat(gdscript): support plain text responses

* feat(gdscript): support collections of models

Those are Arrays, not custom collection objects.

* feat(gdscript): configure default host from OAS

* feat(gdscript): some documentation and better config

We don't need no factories nor singletons ; config is enough.

* docs(gdscript): document usage a little

* feat(gdscript): add more reserved words, skip jsonld models and configure features

We can now generate a client for an OAS server running ApiPlatform (PHP).

* feat(gdscript): improve logging with a configurable log level

* feat(gdscript): add support for Basic Bearer and Header ApiKey

(but I can't find the `description` template handler)

* fix(gdscript)

Too late to amend >.<

* fix(gdscript)

dangsarnit

* chore(gdscript): clean up a sprint artifact

* fix: don't forget the HTTP error code when relevant

* feat: use Resource as base class for models

* fix. Default string values now with "quotes"

* temporary remove settings as godot api have changed

* kick ci

* docs: review gdscript java class

* feat: support for TLS, some refacto, some review

There's still a lot of holes, TODOs and FIXMEs.

* feat: experimental support of Request inline objects

The inline response objects are still not supported.

* feat(gdscript): support inline request and response objects

* chore(gdscript): review the templates

* fix(gdscript): unexpected nulls in default values

{{#if defaultValue}} evaluates to true for null if we call super here.

* refacto(gdscript): replace "bee" prefix by "bzz", use a constructor

Now we pass the config and the client via the constructor.
This reduces the area of the public surface a bit, for the better I think.
This commit also cleans up the class name shenanigans.

* fix(gdscript): add missing file

* test(gdscript): refactor the test project to use the generated lib as addon

Since there is no singleton in the generated client, the addon need not be enabled in the project configuration to be usable.

The --headless mode is broken for now, as things changed in Godot 4 since the beta.

* docs(gdscript): document petstore server ADR

* test(gdscript): add GUT and an integration test

We used the latest stable GUT, but a feature we're going to need was merged today, so we'll need to update it either to master or to the next release at some point.

* refacto(gdscript, breaking): use an ApiResponse object in success callbacks

/spent 6d since the beginning

* test(gdscript): update integration tests

/spend 2h

* docs(gdscript): explain the new ApiResponse

Also moving core templates to their own subdir, for clarity.

/spend 10m

* chore(gdscript): review, document, clean up

/spend 2h

* test(gdscript): test the delete operation as well

/spend 7m

* feat(gdscript): update GUT and exit with appropriate code

/spend 2h

* docs(gdscript): add Gdscript's PI

Hire me while I'm available !  :D
I'd rather code than make a CV.

* feat(gdscript): support reserved keywords

Also adding some more assertions,
and using our own OAS file now.

/spend 3h

* refacto(gdscript): use "base" instead of "bee"

/spend 1h

* feat(gdscript): improve descriptions

/spend 1h

* fix(gdscript): await before polling

Contributed by @jchu231

* docs(gdscript): review the template files

* docs(gdscript): review and generate docs

---------

Co-authored-by: Bagrat <b.saatsazov@gmail.com>

Author: Goutte

README.md

@@ -998,6 +998,7 @@ Here is a list of template creators:
    * Groovy: @victorgit
    * Go: @wing328 [:heart:](https://www.patreon.com/wing328)
    * Go (rewritten in 2.3.0): @antihax
+   * Godot (GDScript): @Goutte [:heart:](https://liberapay.com/Goutte)
    * Haskell (http-client): @jonschoning
    * Java (Feign): @davidkiss
    * Java (Retrofit): @0legg

bin/configs/gdscript-petstore.yaml

@@ -0,0 +1,35 @@
+# Run this configuration to update the sample project used in integration testing:
+#     bin/generate-samples.sh bin/configs/gdscript-petstore.yaml
+
+generatorName: gdscript
+
+# We output straight into an addon directory. (any addon name will work)
+# The addon need not be enabled in Project Settings to be used, for now,
+# but that may change, so as best practice you should enable it anyway.
+outputDir: samples/client/petstore/gdscript/addons/oas.petstore.client
+
+# We have two test servers available.
+# See https://github.com/OpenAPITools/openapi-generator/wiki/Integration-Tests
+
+# A: Newer, recommended echo server OAS, that we're failing for now:
+# Exception: Could not process model 'Bird'. Please make sure that your schema is correct!
+# Caused by: java.lang.RuntimeException: reserved word color not allowed
+# Perhaps try this again later, using another config file like gdscript-echo.yaml
+# > Later: this has been solved, we should now be able to use echo as well
+#inputSpec: modules/openapi-generator/src/test/resources/3_0/echo_api.yaml
+
+# B: Older (legacy, deprecated) petstore server OAS
+inputSpec: modules/openapi-generator/src/test/resources/3_0/gdscript/petstore.yaml
+
+templateDir: modules/openapi-generator/src/main/resources/gdscript
+
+additionalProperties:
+  # Timestamping the generated sample project would only add noise to git
+  hideGenerationTimestamp: "true"
+  # Since we're polluting the global namespace with class_name (it's really convenient),
+  # we can use these affixes to namespace the generated classes.
+  # Best make sure the words you use here are not part of the domain of Godot.
+  apiNamePrefix: Demo
+  modelNamePrefix: Demo
+  modelNameSuffix: Model
+  coreNamePrefix: Demo