Aconfig rules

Test: m services_device_config (which runs sooong tests too)
Change-Id: I432e914d01d2bff77ba68de65ae5baea527090f5
diff --git a/device_config/device_config_definitions.go b/device_config/device_config_definitions.go
new file mode 100644
index 0000000..c565766
--- /dev/null
+++ b/device_config/device_config_definitions.go
@@ -0,0 +1,150 @@
+// Copyright 2023 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 device_config
+
+import (
+	"android/soong/android"
+	"fmt"
+	"github.com/google/blueprint"
+	"strings"
+)
+
+type DefinitionsModule struct {
+	android.ModuleBase
+	android.DefaultableModuleBase
+
+	// Properties for "device_config_definitions"
+	properties struct {
+		// aconfig files, relative to this Android.bp file
+		Srcs []string `android:"path"`
+
+		// Release config flag namespace
+		Namespace string
+
+		// Values from TARGET_RELEASE / RELEASE_DEVICE_CONFIG_VALUE_SETS
+		Values []string `blueprint:"mutated"`
+	}
+
+	intermediatePath android.WritablePath
+	srcJarPath       android.WritablePath
+}
+
+func DefinitionsFactory() android.Module {
+	module := &DefinitionsModule{}
+
+	android.InitAndroidModule(module)
+	android.InitDefaultableModule(module)
+	module.AddProperties(&module.properties)
+	// TODO: bp2build
+	//android.InitBazelModule(module)
+
+	return module
+}
+
+type implicitValuesTagType struct {
+	blueprint.BaseDependencyTag
+}
+
+var implicitValuesTag = implicitValuesTagType{}
+
+func (module *DefinitionsModule) DepsMutator(ctx android.BottomUpMutatorContext) {
+	// Validate Properties
+	if len(module.properties.Srcs) == 0 {
+		ctx.PropertyErrorf("srcs", "missing source files")
+		return
+	}
+	if len(module.properties.Namespace) == 0 {
+		ctx.PropertyErrorf("namespace", "missing namespace property")
+	}
+
+	// Add a dependency on the device_config_value_sets defined in
+	// RELEASE_DEVICE_CONFIG_VALUE_SETS, and add any device_config_values that
+	// match our namespace.
+	valuesFromConfig := ctx.Config().ReleaseDeviceConfigValueSets()
+	ctx.AddDependency(ctx.Module(), implicitValuesTag, valuesFromConfig...)
+}
+
+func (module *DefinitionsModule) OutputFiles(tag string) (android.Paths, error) {
+	switch tag {
+	case ".srcjar":
+		return []android.Path{module.srcJarPath}, nil
+	case "":
+		// The default output of this module is the intermediates format, which is
+		// not installable and in a private format that no other rules can handle
+		// correctly.
+		return []android.Path{module.intermediatePath}, nil
+	default:
+		return nil, fmt.Errorf("unsupported device_config_definitions module reference tag %q", tag)
+	}
+}
+
+func joinAndPrefix(prefix string, values []string) string {
+	var sb strings.Builder
+	for _, v := range values {
+		sb.WriteString(prefix)
+		sb.WriteString(v)
+	}
+	return sb.String()
+}
+
+func (module *DefinitionsModule) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	// Get the values that came from the global RELEASE_DEVICE_CONFIG_VALUE_SETS flag
+	ctx.VisitDirectDeps(func(dep android.Module) {
+		if !ctx.OtherModuleHasProvider(dep, valueSetProviderKey) {
+			// Other modules get injected as dependencies too, for example the license modules
+			return
+		}
+		depData := ctx.OtherModuleProvider(dep, valueSetProviderKey).(valueSetProviderData)
+		valuesFiles, ok := depData.AvailableNamespaces[module.properties.Namespace]
+		if ok {
+			for _, path := range valuesFiles {
+				module.properties.Values = append(module.properties.Values, path.String())
+			}
+		}
+	})
+
+	// Intermediate format
+	inputFiles := android.PathsForModuleSrc(ctx, module.properties.Srcs)
+	module.intermediatePath = android.PathForModuleOut(ctx, "intermediate.json")
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        aconfigRule,
+		Inputs:      inputFiles,
+		Output:      module.intermediatePath,
+		Description: "device_config_definitions",
+		Args: map[string]string{
+			"release_version": ctx.Config().ReleaseVersion(),
+			"namespace":       module.properties.Namespace,
+			"values":          joinAndPrefix(" --values ", module.properties.Values),
+		},
+	})
+
+	// Generated java inside a srcjar
+	module.srcJarPath = android.PathForModuleGen(ctx, ctx.ModuleName()+".srcjar")
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        srcJarRule,
+		Input:       module.intermediatePath,
+		Output:      module.srcJarPath,
+		Description: "device_config.srcjar",
+	})
+
+	// TODO: C++
+
+	// Phony target for debugging convenience
+	ctx.Build(pctx, android.BuildParams{
+		Rule:   blueprint.Phony,
+		Output: android.PathForPhony(ctx, ctx.ModuleName()),
+		Inputs: []android.Path{module.srcJarPath}, // TODO: C++
+	})
+}