Add rules for OpenAPI (only typescript for now)

third_party/BUILD

@@ -3,3 +3,10 @@ java_binary(
     main_class = "com.google.copybara.Main",
     runtime_deps = [":copybara_deploy.jar"],
 )
+
+java_binary(
+    name = "openapi_generator",
+    main_class = "org.openapitools.codegen.OpenAPIGenerator",
+    visibility = ["//visibility:public"],
+    runtime_deps = [":openapi-generator-cli-6.6.0.jar"],
+)

tools/build_rules/oapi_gen/BUILD

@@ -0,0 +1,3 @@
+exports_files([
+    "oapi.sh",
+])

tools/build_rules/oapi_gen/defs.bzl

@@ -0,0 +1,28 @@
+load("@aspect_rules_js//js:defs.bzl", "js_library")
+load("//third_party/grpc-gateway/protoc-gen-openapiv2:defs.bzl", "protoc_gen_openapiv2")
+load("//tools/build_rules/ui_library:defs.bzl", "ui_library")
+load(":ts.bzl", _oapi_gen_ts_sdk = "oapi_gen_ts_sdk")
+
+oapi_gen_ts_sdk = _oapi_gen_ts_sdk
+
+def oapi_gen_ts(name, proto, visibility = ["//visibility:private"], **kwargs):
+    protoc_gen_openapiv2(
+        name = name + "_openapiv2",
+        proto = proto,
+        simple_operation_ids = True,
+        single_output = True,
+        visibility = ["//visibility:private"],
+    )
+
+    oapi_gen_ts_sdk(
+        name = name + "_gen",
+        openapi = ":" + name + "_openapiv2",
+        visibility = ["//visibility:private"],
+        **kwargs
+    )
+
+    js_library(
+        name = name,
+        srcs = [name + "_gen"],
+        visibility = visibility,
+    )

tools/build_rules/oapi_gen/oapi.sh

@@ -0,0 +1,10 @@
+#!/usr/bin/env bash
+
+set -euo pipefail
+
+cli_bin="{{generator_cli_bin}}"
+generator="{{generator}}"
+openapi_file="{{openapi_file}}"
+output_dir="{{output_dir}}"
+
+$cli_bin generate -i $openapi_file -g $generator -o $output_dir --skip-validate-spec > /dev/null

tools/build_rules/oapi_gen/ts.bzl

@@ -0,0 +1,67 @@
+def _oapi_gen_ts_sdk_impl(ctx):
+    """
+    :param ctx: rule context
+
+    Converts an OpenAPI spec to a TypeScript SDK using openapi-generator.
+    """
+    openapi = ctx.file.openapi
+
+    # java_binary returns the jar and a wrapper binary that runs it.
+    # we need the wrapper binary
+    oapi_cli_outputs = ctx.files._oapi_bin
+    oapi_cli = ""
+    for output in oapi_cli_outputs:
+        if output.path.endswith(".jar"):
+            continue
+        oapi_cli = output.path
+        break
+
+    # Run openapi-generator. With typescript we can just export a directory
+    # containing the generated code.
+    output_dir = ctx.actions.declare_directory(ctx.attr.name)
+    index_ts = ctx.actions.declare_file(ctx.attr.name + "/index.ts")
+    gen = ctx.actions.declare_file(ctx.attr.name + "_gen.sh")
+    ctx.actions.expand_template(
+        template = ctx.file._oapi_converter,
+        output = gen,
+        substitutions = {
+            "{{generator_cli_bin}}": oapi_cli,
+            "{{openapi_file}}": openapi.path,
+            "{{generator}}": "typescript-fetch",
+            "{{output_dir}}": output_dir.path,
+        },
+        is_executable = True,
+    )
+
+    ctx.actions.run(
+        inputs = [openapi] + ctx.files._oapi_bin,
+        outputs = [output_dir, index_ts],
+        executable = gen,
+    )
+
+    return [
+        DefaultInfo(
+            files = depset([output_dir, index_ts]),
+        ),
+    ]
+
+oapi_gen_ts_sdk = rule(
+    implementation = _oapi_gen_ts_sdk_impl,
+    attrs = {
+        "openapi": attr.label(
+            allow_single_file = True,
+            mandatory = True,
+            doc = "The OpenAPI spec for the API, can be generated with protoc_gen_openapiv2",
+        ),
+        "_oapi_bin": attr.label(
+            allow_files = True,
+            default = Label("//third_party:openapi_generator"),
+            doc = "The openapi-generator CLI binary",
+        ),
+        "_oapi_converter": attr.label(
+            allow_single_file = True,
+            default = Label("//tools/build_rules/oapi_gen:oapi.sh"),
+            doc = "The script that converts an OpenAPI spec to a fern generators.yaml file",
+        ),
+    },
+)