Create api_domain module type and its bp2build converter

This module does not have any build actions in Soong yet. It will be
converted to a Bazel target using bp2build, and API export will be run
on the generated Bazel target

Test: go test ./bp2build
Test: TH
Change-Id: I76df32bd9f23b60e746b2700af07668a2ed74844
diff --git a/android/api_domain.go b/android/api_domain.go
new file mode 100644
index 0000000..a808e32
--- /dev/null
+++ b/android/api_domain.go
@@ -0,0 +1,100 @@
+// Copyright 2022 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package android
+
+import (
+	"github.com/google/blueprint"
+
+	"android/soong/bazel"
+)
+
+func init() {
+	RegisterApiDomainBuildComponents(InitRegistrationContext)
+}
+
+func RegisterApiDomainBuildComponents(ctx RegistrationContext) {
+	ctx.RegisterModuleType("api_domain", ApiDomainFactory)
+}
+
+type apiDomain struct {
+	ModuleBase
+	BazelModuleBase
+
+	properties apiDomainProperties
+}
+
+type apiDomainProperties struct {
+	// cc library contributions (.h files/.map.txt) of this API domain
+	// This dependency is a no-op in Soong, but the corresponding Bazel target in the bp2build workspace will provide a `CcApiContributionInfo` provider
+	Cc_api_contributions []string
+}
+
+func ApiDomainFactory() Module {
+	m := &apiDomain{}
+	m.AddProperties(&m.properties)
+	InitAndroidArchModule(m, DeviceSupported, MultilibBoth)
+	InitBazelModule(m)
+	return m
+}
+
+func (a *apiDomain) DepsMutator(ctx BottomUpMutatorContext) {
+	for _, cc := range a.properties.Cc_api_contributions {
+		// Use FarVariationDependencies since the variants of api_domain is a subset of the variants of the dependency cc module
+		// Creating a dependency on the first variant is ok since this is a no-op in Soong
+		// The primary function of this dependency is to create a connected graph in the corresponding bp2build workspace
+		ctx.AddFarVariationDependencies([]blueprint.Variation{}, nil, cc)
+	}
+}
+
+// API domain does not have any builld actions yet
+func (a *apiDomain) GenerateAndroidBuildActions(ctx ModuleContext) {
+}
+
+const (
+	apiContributionSuffix = ".contribution"
+)
+
+// ApiContributionTargetName returns the name of the bp2build target (e.g. cc_api_contribution)  of contribution modules (e.g. ndk_library)
+// A suffix is necessary to prevent a name collision with the base target in the same bp2build bazel package
+func ApiContributionTargetName(moduleName string) string {
+	return moduleName + apiContributionSuffix
+}
+
+// For each contributing cc_library, format the name to its corresponding contribution bazel target in the bp2build workspace
+func contributionBazelAttributes(ctx TopDownMutatorContext, contributions []string) bazel.LabelListAttribute {
+	addSuffix := func(ctx BazelConversionPathContext, module blueprint.Module) string {
+		baseLabel := BazelModuleLabel(ctx, module)
+		return ApiContributionTargetName(baseLabel)
+	}
+	bazelLabels := BazelLabelForModuleDepsWithFn(ctx, contributions, addSuffix)
+	return bazel.MakeLabelListAttribute(bazelLabels)
+}
+
+type bazelApiDomainAttributes struct {
+	Cc_api_contributions bazel.LabelListAttribute
+}
+
+func (a *apiDomain) ConvertWithBp2build(ctx TopDownMutatorContext) {
+	props := bazel.BazelTargetModuleProperties{
+		Rule_class:        "api_domain",
+		Bzl_load_location: "//build/bazel/rules/apis:api_domain.bzl",
+	}
+	attrs := &bazelApiDomainAttributes{
+		Cc_api_contributions: contributionBazelAttributes(ctx, a.properties.Cc_api_contributions),
+	}
+	ctx.CreateBazelTargetModule(props, CommonAttributes{
+		Name: ctx.ModuleName(),
+	}, attrs)
+}