Soong AAR prebuilt support

Add support for android_library_import modules that take an
aar file.

Bug: 73724997
Test: m checkbuild
Change-Id: I670b56f0a3b7501d9478a6064a04d0cb9c1bb611
diff --git a/java/aar.go b/java/aar.go
new file mode 100644
index 0000000..0df3632
--- /dev/null
+++ b/java/aar.go
@@ -0,0 +1,170 @@
+// Copyright 2018 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 java
+
+import (
+	"android/soong/android"
+
+	"github.com/google/blueprint"
+)
+
+//
+// AAR (android library) prebuilts
+//
+func init() {
+	android.RegisterModuleType("android_library_import", AARImportFactory)
+}
+
+type AARImportProperties struct {
+	Aars []string
+
+	Sdk_version *string
+}
+
+type AARImport struct {
+	android.ModuleBase
+	prebuilt android.Prebuilt
+
+	properties AARImportProperties
+
+	classpathFile android.WritablePath
+	proguardFlags android.WritablePath
+	exportPackage android.WritablePath
+}
+
+func (a *AARImport) Prebuilt() *android.Prebuilt {
+	return &a.prebuilt
+}
+
+func (a *AARImport) Name() string {
+	return a.prebuilt.Name(a.ModuleBase.Name())
+}
+
+func (a *AARImport) DepsMutator(ctx android.BottomUpMutatorContext) {
+	// TODO: this should use decodeSdkDep once that knows about current
+	if !ctx.Config().UnbundledBuild() {
+		switch String(a.properties.Sdk_version) { // TODO: Res_sdk_version?
+		case "current", "system_current", "test_current", "":
+			ctx.AddDependency(ctx.Module(), frameworkResTag, "framework-res")
+		}
+	}
+}
+
+// Unzip an AAR into its constituent files and directories.  Any files in Outputs that don't exist in the AAR will be
+// touched to create an empty file, and any directories in $expectedDirs will be created.
+var unzipAAR = pctx.AndroidStaticRule("unzipAAR",
+	blueprint.RuleParams{
+		Command: `rm -rf $outDir && mkdir -p $outDir $expectedDirs && ` +
+			`unzip -qo -d $outDir $in && touch $out`,
+	},
+	"expectedDirs", "outDir")
+
+func (a *AARImport) GenerateAndroidBuildActions(ctx android.ModuleContext) {
+	if len(a.properties.Aars) != 1 {
+		ctx.PropertyErrorf("aars", "exactly one aar is required")
+		return
+	}
+
+	aar := android.PathForModuleSrc(ctx, a.properties.Aars[0])
+
+	extractedAARDir := android.PathForModuleOut(ctx, "aar")
+	extractedResDir := extractedAARDir.Join(ctx, "res")
+	a.classpathFile = extractedAARDir.Join(ctx, "classes.jar")
+	a.proguardFlags = extractedAARDir.Join(ctx, "proguard.txt")
+	manifest := extractedAARDir.Join(ctx, "AndroidManifest.xml")
+
+	ctx.Build(pctx, android.BuildParams{
+		Rule:        unzipAAR,
+		Input:       aar,
+		Outputs:     android.WritablePaths{a.classpathFile, a.proguardFlags, manifest},
+		Description: "unzip AAR",
+		Args: map[string]string{
+			"expectedDirs": extractedResDir.String(),
+			"outDir":       extractedAARDir.String(),
+		},
+	})
+
+	compiledResDir := android.PathForModuleOut(ctx, "flat-res")
+	aaptCompileDeps := android.Paths{a.classpathFile}
+	aaptCompileDirs := android.Paths{extractedResDir}
+	flata := compiledResDir.Join(ctx, "gen_res.flata")
+	aapt2CompileDirs(ctx, flata, aaptCompileDirs, aaptCompileDeps)
+
+	a.exportPackage = android.PathForModuleOut(ctx, "package-res.apk")
+	srcJar := android.PathForModuleGen(ctx, "R.jar")
+	proguardOptionsFile := android.PathForModuleGen(ctx, "proguard.options")
+
+	var linkDeps android.Paths
+
+	linkFlags := []string{
+		"--static-lib",
+		"--no-static-lib-packages",
+		"--auto-add-overlay",
+	}
+
+	linkFlags = append(linkFlags, "--manifest "+manifest.String())
+	linkDeps = append(linkDeps, manifest)
+
+	// Include dirs
+	ctx.VisitDirectDeps(func(module android.Module) {
+		var depFiles android.Paths
+		if javaDep, ok := module.(Dependency); ok {
+			// TODO: shared android libraries
+			if ctx.OtherModuleName(module) == "framework-res" {
+				depFiles = android.Paths{javaDep.(*AndroidApp).exportPackage}
+			}
+		}
+
+		for _, dep := range depFiles {
+			linkFlags = append(linkFlags, "-I "+dep.String())
+		}
+		linkDeps = append(linkDeps, depFiles...)
+	})
+
+	sdkDep := decodeSdkDep(ctx, String(a.properties.Sdk_version))
+	if sdkDep.useFiles {
+		linkFlags = append(linkFlags, "-I "+sdkDep.jar.String())
+		linkDeps = append(linkDeps, sdkDep.jar)
+	}
+
+	aapt2Link(ctx, a.exportPackage, srcJar, proguardOptionsFile,
+		linkFlags, linkDeps, nil, android.Paths{flata})
+}
+
+var _ Dependency = (*AARImport)(nil)
+
+func (a *AARImport) HeaderJars() android.Paths {
+	return android.Paths{a.classpathFile}
+}
+
+func (a *AARImport) ImplementationJars() android.Paths {
+	return android.Paths{a.classpathFile}
+}
+
+func (a *AARImport) AidlIncludeDirs() android.Paths {
+	return nil
+}
+
+var _ android.PrebuiltInterface = (*Import)(nil)
+
+func AARImportFactory() android.Module {
+	module := &AARImport{}
+
+	module.AddProperties(&module.properties)
+
+	android.InitPrebuiltModule(module, &module.properties.Aars)
+	android.InitAndroidArchModule(module, android.DeviceSupported, android.MultilibCommon)
+	return module
+}