Add model to represent generated snapshot .bp file

Having each module type generate the contents of the snapshot's .bp
file results in lots of duplicated code. This adds an intermediate
model for use by the module types and then generates the .bp file
contents from that.

This not only removes the duplicated formatting code but it also
allows consistent handling of shared properties such as name further
reducing duplication. It also makes it possible to duplicate the
versioned and unversioned prebuilt modules from the same model.

Extracts generatedContents from generatedFile to allow the contents
to be populated without creating an output file, for testing.

Cleans up unused code.

Bug: 143678475
Test: m nothing
Change-Id: If21b84db0ef3fdfb5dc11ea0973ce6cb73603ea3
diff --git a/sdk/update.go b/sdk/update.go
index 000d200..3bd6336 100644
--- a/sdk/update.go
+++ b/sdk/update.go
@@ -17,6 +17,7 @@
 import (
 	"fmt"
 	"path/filepath"
+	"reflect"
 	"strings"
 
 	"github.com/google/blueprint/proptools"
@@ -28,34 +29,37 @@
 
 var pctx = android.NewPackageContext("android/soong/sdk")
 
-// generatedFile abstracts operations for writing contents into a file and emit a build rule
-// for the file.
-type generatedFile struct {
-	path        android.OutputPath
+type generatedContents struct {
 	content     strings.Builder
 	indentLevel int
 }
 
+// generatedFile abstracts operations for writing contents into a file and emit a build rule
+// for the file.
+type generatedFile struct {
+	generatedContents
+	path android.OutputPath
+}
+
 func newGeneratedFile(ctx android.ModuleContext, path ...string) *generatedFile {
 	return &generatedFile{
-		path:        android.PathForModuleOut(ctx, path...).OutputPath,
-		indentLevel: 0,
+		path: android.PathForModuleOut(ctx, path...).OutputPath,
 	}
 }
 
-func (gf *generatedFile) Indent() {
-	gf.indentLevel++
+func (gc *generatedContents) Indent() {
+	gc.indentLevel++
 }
 
-func (gf *generatedFile) Dedent() {
-	gf.indentLevel--
+func (gc *generatedContents) Dedent() {
+	gc.indentLevel--
 }
 
-func (gf *generatedFile) Printfln(format string, args ...interface{}) {
+func (gc *generatedContents) Printfln(format string, args ...interface{}) {
 	// ninja consumes newline characters in rspfile_content. Prevent it by
 	// escaping the backslash in the newline character. The extra backslash
 	// is removed when the rspfile is written to the actual script file
-	fmt.Fprintf(&(gf.content), strings.Repeat("    ", gf.indentLevel)+format+"\\n", args...)
+	fmt.Fprintf(&(gc.content), strings.Repeat("    ", gc.indentLevel)+format+"\\n", args...)
 }
 
 func (gf *generatedFile) build(pctx android.PackageContext, ctx android.BuilderContext, implicits android.Paths) {
@@ -239,15 +243,18 @@
 	snapshotDir := android.PathForModuleOut(ctx, "snapshot")
 
 	bp := newGeneratedFile(ctx, "snapshot", "Android.bp")
-	bp.Printfln("// This is auto-generated. DO NOT EDIT.")
-	bp.Printfln("")
+
+	bpFile := &bpFile{
+		modules: make(map[string]*bpModule),
+	}
 
 	builder := &snapshotBuilder{
-		ctx:           ctx,
-		version:       "current",
-		snapshotDir:   snapshotDir.OutputPath,
-		filesToZip:    []android.Path{bp.path},
-		androidBpFile: bp,
+		ctx:             ctx,
+		version:         "current",
+		snapshotDir:     snapshotDir.OutputPath,
+		filesToZip:      []android.Path{bp.path},
+		bpFile:          bpFile,
+		prebuiltModules: make(map[string]*bpModule),
 	}
 	s.builderForTests = builder
 
@@ -269,41 +276,37 @@
 		buildSharedNativeLibSnapshot(ctx, info, builder)
 	}
 
-	// generate Android.bp
+	for _, unversioned := range builder.prebuiltOrder {
+		// Copy the unversioned module so it can be modified to make it versioned.
+		versioned := unversioned.copy()
+		name := versioned.properties["name"].(string)
+		versioned.setProperty("name", builder.versionedSdkMemberName(name))
+		versioned.insertAfter("name", "sdk_member_name", name)
+		bpFile.AddModule(versioned)
 
-	bp.Printfln("sdk_snapshot {")
-	bp.Indent()
-	bp.Printfln("name: %q,", ctx.ModuleName()+string(android.SdkVersionSeparator)+builder.version)
+		// Set prefer: false - this is not strictly required as that is the default.
+		unversioned.insertAfter("name", "prefer", false)
+		bpFile.AddModule(unversioned)
+	}
+
+	// Create the snapshot module.
+	snapshotName := ctx.ModuleName() + string(android.SdkVersionSeparator) + builder.version
+	snapshotModule := bpFile.newModule("sdk_snapshot")
+	snapshotModule.AddProperty("name", snapshotName)
 	if len(s.properties.Java_libs) > 0 {
-		bp.Printfln("java_libs: [")
-		bp.Indent()
-		for _, m := range s.properties.Java_libs {
-			bp.Printfln("%q,", builder.VersionedSdkMemberName(m))
-		}
-		bp.Dedent()
-		bp.Printfln("],") // java_libs
+		snapshotModule.AddProperty("java_libs", builder.versionedSdkMemberNames(s.properties.Java_libs))
 	}
 	if len(s.properties.Stubs_sources) > 0 {
-		bp.Printfln("stubs_sources: [")
-		bp.Indent()
-		for _, m := range s.properties.Stubs_sources {
-			bp.Printfln("%q,", builder.VersionedSdkMemberName(m))
-		}
-		bp.Dedent()
-		bp.Printfln("],") // stubs_sources
+		snapshotModule.AddProperty("stubs_sources", builder.versionedSdkMemberNames(s.properties.Stubs_sources))
 	}
 	if len(s.properties.Native_shared_libs) > 0 {
-		bp.Printfln("native_shared_libs: [")
-		bp.Indent()
-		for _, m := range s.properties.Native_shared_libs {
-			bp.Printfln("%q,", builder.VersionedSdkMemberName(m))
-		}
-		bp.Dedent()
-		bp.Printfln("],") // native_shared_libs
+		snapshotModule.AddProperty("native_shared_libs", builder.versionedSdkMemberNames(s.properties.Native_shared_libs))
 	}
-	bp.Dedent()
-	bp.Printfln("}") // sdk_snapshot
-	bp.Printfln("")
+	bpFile.AddModule(snapshotModule)
+
+	// generate Android.bp
+	bp = newGeneratedFile(ctx, "snapshot", "Android.bp")
+	generateBpContents(&bp.generatedContents, bpFile)
 
 	bp.build(pctx, ctx, nil)
 
@@ -351,8 +354,61 @@
 	return outputZipFile
 }
 
+func generateBpContents(contents *generatedContents, bpFile *bpFile) {
+	contents.Printfln("// This is auto-generated. DO NOT EDIT.")
+	for _, bpModule := range bpFile.order {
+		contents.Printfln("")
+		contents.Printfln("%s {", bpModule.moduleType)
+		outputPropertySet(contents, &bpModule.bpPropertySet)
+		contents.Printfln("}")
+	}
+	contents.Printfln("")
+}
+
+func outputPropertySet(contents *generatedContents, set *bpPropertySet) {
+	contents.Indent()
+	for _, name := range set.order {
+		value := set.properties[name]
+
+		reflectedValue := reflect.ValueOf(value)
+		t := reflectedValue.Type()
+
+		kind := t.Kind()
+		switch kind {
+		case reflect.Slice:
+			length := reflectedValue.Len()
+			if length > 1 {
+				contents.Printfln("%s: [", name)
+				contents.Indent()
+				for i := 0; i < length; i = i + 1 {
+					contents.Printfln("%q,", reflectedValue.Index(i).Interface())
+				}
+				contents.Dedent()
+				contents.Printfln("],")
+			} else if length == 0 {
+				contents.Printfln("%s: [],", name)
+			} else {
+				contents.Printfln("%s: [%q],", name, reflectedValue.Index(0).Interface())
+			}
+		case reflect.Bool:
+			contents.Printfln("%s: %t,", name, reflectedValue.Bool())
+
+		case reflect.Ptr:
+			contents.Printfln("%s: {", name)
+			outputPropertySet(contents, reflectedValue.Interface().(*bpPropertySet))
+			contents.Printfln("},")
+
+		default:
+			contents.Printfln("%s: %q,", name, value)
+		}
+	}
+	contents.Dedent()
+}
+
 func (s *sdk) GetAndroidBpContentsForTests() string {
-	return s.builderForTests.androidBpFile.content.String()
+	contents := &generatedContents{}
+	generateBpContents(contents, s.builderForTests.bpFile)
+	return contents.content.String()
 }
 
 func buildSharedNativeLibSnapshot(ctx android.ModuleContext, info *nativeLibInfo, builder android.SnapshotBuilder) {
@@ -406,81 +462,57 @@
 		}
 	}
 
-	info.generatePrebuiltLibrary(ctx, builder, true)
-
-	// This module is for the case when the source tree for the unversioned module
-	// doesn't exist (i.e. building in an unbundled tree). "prefer:" is set to false
-	// so that this module does not eclipse the unversioned module if it exists.
-	info.generatePrebuiltLibrary(ctx, builder, false)
+	info.generatePrebuiltLibrary(ctx, builder)
 }
 
-func (info *nativeLibInfo) generatePrebuiltLibrary(ctx android.ModuleContext, builder android.SnapshotBuilder, versioned bool) {
-	bp := builder.AndroidBpFile()
-	bp.Printfln("cc_prebuilt_library_shared {")
-	bp.Indent()
-	name := info.name
-	if versioned {
-		bp.Printfln("name: %q,", builder.VersionedSdkMemberName(name))
-		bp.Printfln("sdk_member_name: %q,", name)
-	} else {
-		bp.Printfln("name: %q,", name)
-		bp.Printfln("prefer: false,")
-	}
+func (info *nativeLibInfo) generatePrebuiltLibrary(ctx android.ModuleContext, builder android.SnapshotBuilder) {
 
 	// a function for emitting include dirs
-	printExportedDirsForNativeLibs := func(lib archSpecificNativeLibInfo, systemInclude bool) {
+	addExportedDirsForNativeLibs := func(lib archSpecificNativeLibInfo, properties android.BpPropertySet, systemInclude bool) {
 		includeDirs := nativeIncludeDirPathsFor(ctx, lib, systemInclude, info.hasArchSpecificFlags)
 		if len(includeDirs) == 0 {
 			return
 		}
+		var propertyName string
 		if !systemInclude {
-			bp.Printfln("export_include_dirs: [")
+			propertyName = "export_include_dirs"
 		} else {
-			bp.Printfln("export_system_include_dirs: [")
+			propertyName = "export_system_include_dirs"
 		}
-		bp.Indent()
-		for _, dir := range includeDirs {
-			bp.Printfln("%q,", dir)
-		}
-		bp.Dedent()
-		bp.Printfln("],")
+		properties.AddProperty(propertyName, includeDirs)
 	}
 
+	pbm := builder.AddPrebuiltModule(info.name, "cc_prebuilt_library_shared")
+
 	if !info.hasArchSpecificFlags {
-		printExportedDirsForNativeLibs(info.archVariants[0], false /*systemInclude*/)
-		printExportedDirsForNativeLibs(info.archVariants[0], true /*systemInclude*/)
+		addExportedDirsForNativeLibs(info.archVariants[0], pbm, false /*systemInclude*/)
+		addExportedDirsForNativeLibs(info.archVariants[0], pbm, true /*systemInclude*/)
 	}
 
-	bp.Printfln("arch: {")
-	bp.Indent()
+	archProperties := pbm.AddPropertySet("arch")
 	for _, av := range info.archVariants {
-		bp.Printfln("%s: {", av.archType)
-		bp.Indent()
-		bp.Printfln("srcs: [%q],", nativeStubFilePathFor(av))
+		archTypeProperties := archProperties.AddPropertySet(av.archType)
+		archTypeProperties.AddProperty("srcs", []string{nativeStubFilePathFor(av)})
 		if info.hasArchSpecificFlags {
 			// export_* properties are added inside the arch: {<arch>: {...}} block
-			printExportedDirsForNativeLibs(av, false /*systemInclude*/)
-			printExportedDirsForNativeLibs(av, true /*systemInclude*/)
+			addExportedDirsForNativeLibs(av, archTypeProperties, false /*systemInclude*/)
+			addExportedDirsForNativeLibs(av, archTypeProperties, true /*systemInclude*/)
 		}
-		bp.Dedent()
-		bp.Printfln("},") // <arch>
 	}
-	bp.Dedent()
-	bp.Printfln("},") // arch
-	bp.Printfln("stl: \"none\",")
-	bp.Printfln("system_shared_libs: [],")
-	bp.Dedent()
-	bp.Printfln("}") // cc_prebuilt_library_shared
-	bp.Printfln("")
+	pbm.AddProperty("stl", "none")
+	pbm.AddProperty("system_shared_libs", []string{})
 }
 
 type snapshotBuilder struct {
-	ctx           android.ModuleContext
-	version       string
-	snapshotDir   android.OutputPath
-	androidBpFile *generatedFile
-	filesToZip    android.Paths
-	zipsToMerge   android.Paths
+	ctx         android.ModuleContext
+	version     string
+	snapshotDir android.OutputPath
+	bpFile      *bpFile
+	filesToZip  android.Paths
+	zipsToMerge android.Paths
+
+	prebuiltModules map[string]*bpModule
+	prebuiltOrder   []*bpModule
 }
 
 func (s *snapshotBuilder) CopyToSnapshot(src android.Path, dest string) {
@@ -512,10 +544,28 @@
 	s.zipsToMerge = append(s.zipsToMerge, tmpZipPath)
 }
 
-func (s *snapshotBuilder) AndroidBpFile() android.GeneratedSnapshotFile {
-	return s.androidBpFile
+func (s *snapshotBuilder) AddPrebuiltModule(name string, moduleType string) android.BpModule {
+	if s.prebuiltModules[name] != nil {
+		panic(fmt.Sprintf("Duplicate module detected, module %s has already been added", name))
+	}
+
+	m := s.bpFile.newModule(moduleType)
+	m.AddProperty("name", name)
+
+	s.prebuiltModules[name] = m
+	s.prebuiltOrder = append(s.prebuiltOrder, m)
+	return m
 }
 
-func (s *snapshotBuilder) VersionedSdkMemberName(unversionedName string) interface{} {
+// Get a versioned name appropriate for the SDK snapshot version being taken.
+func (s *snapshotBuilder) versionedSdkMemberName(unversionedName string) string {
 	return versionedSdkMemberName(s.ctx, unversionedName, s.version)
 }
+
+func (s *snapshotBuilder) versionedSdkMemberNames(members []string) []string {
+	var references []string = nil
+	for _, m := range members {
+		references = append(references, s.versionedSdkMemberName(m))
+	}
+	return references
+}