Support proto modules with external references.

Bug: 236055697
Test: Manual testing and adding new unit tests.
Change-Id: I984c0ecb93f0023727a39a3af3921820337bf8c7
diff --git a/android/bazel.go b/android/bazel.go
index eb6aca4..843ec18 100644
--- a/android/bazel.go
+++ b/android/bazel.go
@@ -32,10 +32,13 @@
 	Bp2BuildTopLevel = "."
 )
 
-// Bp2buildAidlLibrary describes a filegroup module that are converted to aidl_library
-type Bp2buildAidlLibrary interface {
+// FileGroupAsLibrary describes a filegroup module that is converted to some library
+// such as aidl_library or proto_library.
+type FileGroupAsLibrary interface {
 	ShouldConvertToAidlLibrary(ctx BazelConversionPathContext) bool
+	ShouldConvertToProtoLibrary(ctx BazelConversionPathContext) bool
 	GetAidlLibraryLabel(ctx BazelConversionPathContext) string
+	GetProtoLibraryLabel(ctx BazelConversionPathContext) string
 }
 
 type BazelConversionStatus struct {
diff --git a/android/filegroup.go b/android/filegroup.go
index e609f63..e5eec87 100644
--- a/android/filegroup.go
+++ b/android/filegroup.go
@@ -33,6 +33,8 @@
 	ctx.RegisterModuleType("filegroup", FileGroupFactory)
 })
 
+var convertedProtoLibrarySuffix = "_bp2build_converted"
+
 // IsFilegroup checks that a module is a filegroup type
 func IsFilegroup(ctx bazel.OtherModuleContext, m blueprint.Module) bool {
 	return ctx.OtherModuleType(m) == "filegroup"
@@ -117,6 +119,20 @@
 
 		ctx.CreateBazelTargetModule(props, CommonAttributes{Name: fg.Name()}, attrs)
 	} else {
+		if fg.ShouldConvertToProtoLibrary(ctx) {
+			attrs := &ProtoAttrs{
+				Srcs:                srcs,
+				Strip_import_prefix: fg.properties.Path,
+			}
+
+			ctx.CreateBazelTargetModule(
+				bazel.BazelTargetModuleProperties{Rule_class: "proto_library"},
+				CommonAttributes{Name: fg.Name() + convertedProtoLibrarySuffix},
+				attrs)
+		}
+
+		// TODO(b/242847534): Still convert to a filegroup because other unconverted
+		// modules may depend on the filegroup
 		attrs := &bazelFilegroupAttributes{
 			Srcs: srcs,
 		}
@@ -150,14 +166,14 @@
 type fileGroup struct {
 	ModuleBase
 	BazelModuleBase
-	Bp2buildAidlLibrary
+	FileGroupAsLibrary
 	properties fileGroupProperties
 	srcs       Paths
 }
 
 var _ MixedBuildBuildable = (*fileGroup)(nil)
 var _ SourceFileProducer = (*fileGroup)(nil)
-var _ Bp2buildAidlLibrary = (*fileGroup)(nil)
+var _ FileGroupAsLibrary = (*fileGroup)(nil)
 
 // filegroup contains a list of files that are referenced by other modules
 // properties (such as "srcs") using the syntax ":<name>". filegroup are
@@ -243,11 +259,19 @@
 }
 
 func (fg *fileGroup) ShouldConvertToAidlLibrary(ctx BazelConversionPathContext) bool {
+	return fg.shouldConvertToLibrary(ctx, ".aidl")
+}
+
+func (fg *fileGroup) ShouldConvertToProtoLibrary(ctx BazelConversionPathContext) bool {
+	return fg.shouldConvertToLibrary(ctx, ".proto")
+}
+
+func (fg *fileGroup) shouldConvertToLibrary(ctx BazelConversionPathContext, suffix string) bool {
 	if len(fg.properties.Srcs) == 0 || !fg.ShouldConvertWithBp2build(ctx) {
 		return false
 	}
 	for _, src := range fg.properties.Srcs {
-		if !strings.HasSuffix(src, ".aidl") {
+		if !strings.HasSuffix(src, suffix) {
 			return false
 		}
 	}
@@ -255,6 +279,14 @@
 }
 
 func (fg *fileGroup) GetAidlLibraryLabel(ctx BazelConversionPathContext) string {
+	return fg.getFileGroupAsLibraryLabel(ctx)
+}
+
+func (fg *fileGroup) GetProtoLibraryLabel(ctx BazelConversionPathContext) string {
+	return fg.getFileGroupAsLibraryLabel(ctx) + convertedProtoLibrarySuffix
+}
+
+func (fg *fileGroup) getFileGroupAsLibraryLabel(ctx BazelConversionPathContext) string {
 	if ctx.OtherModuleDir(fg.module) == ctx.ModuleDir() {
 		return ":" + fg.Name()
 	} else {
@@ -265,12 +297,19 @@
 // Given a name in srcs prop, check to see if the name references a filegroup
 // and the filegroup is converted to aidl_library
 func IsConvertedToAidlLibrary(ctx BazelConversionPathContext, name string) bool {
+	if fg, ok := ToFileGroupAsLibrary(ctx, name); ok {
+		return fg.ShouldConvertToAidlLibrary(ctx)
+	}
+	return false
+}
+
+func ToFileGroupAsLibrary(ctx BazelConversionPathContext, name string) (FileGroupAsLibrary, bool) {
 	if module, ok := ctx.ModuleFromName(name); ok {
 		if IsFilegroup(ctx, module) {
-			if fg, ok := module.(Bp2buildAidlLibrary); ok {
-				return fg.ShouldConvertToAidlLibrary(ctx)
+			if fg, ok := module.(FileGroupAsLibrary); ok {
+				return fg, true
 			}
 		}
 	}
-	return false
+	return nil, false
 }
diff --git a/android/proto.go b/android/proto.go
index 25cecf4..3a5d4da 100644
--- a/android/proto.go
+++ b/android/proto.go
@@ -155,11 +155,12 @@
 
 // Bp2buildProtoInfo contains information necessary to pass on to language specific conversion.
 type Bp2buildProtoInfo struct {
-	Type *string
-	Name string
+	Type       *string
+	Name       string
+	Proto_libs bazel.LabelList
 }
 
-type protoAttrs struct {
+type ProtoAttrs struct {
 	Srcs                bazel.LabelListAttribute
 	Strip_import_prefix *string
 	Deps                bazel.LabelListAttribute
@@ -179,44 +180,70 @@
 		return info, false
 	}
 
-	info.Name = m.Name() + "_proto"
-	attrs := protoAttrs{
-		Srcs: srcs,
-	}
+	var protoLibraries bazel.LabelList
+	var directProtoSrcs bazel.LabelList
 
-	for axis, configToProps := range m.GetArchVariantProperties(ctx, &ProtoProperties{}) {
-		for _, rawProps := range configToProps {
-			var props *ProtoProperties
-			var ok bool
-			if props, ok = rawProps.(*ProtoProperties); !ok {
-				ctx.ModuleErrorf("Could not cast ProtoProperties to expected type")
-			}
-			if axis == bazel.NoConfigAxis {
-				info.Type = props.Proto.Type
-
-				if !proptools.BoolDefault(props.Proto.Canonical_path_from_root, canonicalPathFromRootDefault) {
-					// an empty string indicates to strips the package path
-					path := ""
-					attrs.Strip_import_prefix = &path
-				}
-
-				for _, dir := range props.Proto.Include_dirs {
-					if dep, ok := includeDirsToProtoDeps[dir]; ok {
-						attrs.Deps.Add(bazel.MakeLabelAttribute(dep))
-					} else {
-						ctx.PropertyErrorf("Could not find the proto_library target for include dir", dir)
-					}
-				}
-			} else if props.Proto.Type != info.Type && props.Proto.Type != nil {
-				ctx.ModuleErrorf("Cannot handle arch-variant types for protos at this time.")
-			}
+	// For filegroups that should be converted to proto_library just collect the
+	// labels of converted proto_library targets.
+	for _, protoSrc := range srcs.Value.Includes {
+		src := protoSrc.OriginalModuleName
+		if fg, ok := ToFileGroupAsLibrary(ctx, src); ok &&
+			fg.ShouldConvertToProtoLibrary(ctx) {
+			protoLibraries.Add(&bazel.Label{
+				Label: fg.GetProtoLibraryLabel(ctx),
+			})
+		} else {
+			directProtoSrcs.Add(&protoSrc)
 		}
 	}
 
-	ctx.CreateBazelTargetModule(
-		bazel.BazelTargetModuleProperties{Rule_class: "proto_library"},
-		CommonAttributes{Name: info.Name},
-		&attrs)
+	info.Name = m.Name() + "_proto"
+
+	if len(directProtoSrcs.Includes) > 0 {
+		attrs := ProtoAttrs{
+			Srcs: bazel.MakeLabelListAttribute(directProtoSrcs),
+		}
+
+		for axis, configToProps := range m.GetArchVariantProperties(ctx, &ProtoProperties{}) {
+			for _, rawProps := range configToProps {
+				var props *ProtoProperties
+				var ok bool
+				if props, ok = rawProps.(*ProtoProperties); !ok {
+					ctx.ModuleErrorf("Could not cast ProtoProperties to expected type")
+				}
+				if axis == bazel.NoConfigAxis {
+					info.Type = props.Proto.Type
+
+					if !proptools.BoolDefault(props.Proto.Canonical_path_from_root, canonicalPathFromRootDefault) {
+						// an empty string indicates to strips the package path
+						path := ""
+						attrs.Strip_import_prefix = &path
+					}
+
+					for _, dir := range props.Proto.Include_dirs {
+						if dep, ok := includeDirsToProtoDeps[dir]; ok {
+							attrs.Deps.Add(bazel.MakeLabelAttribute(dep))
+						} else {
+							ctx.PropertyErrorf("Could not find the proto_library target for include dir", dir)
+						}
+					}
+				} else if props.Proto.Type != info.Type && props.Proto.Type != nil {
+					ctx.ModuleErrorf("Cannot handle arch-variant types for protos at this time.")
+				}
+			}
+		}
+
+		ctx.CreateBazelTargetModule(
+			bazel.BazelTargetModuleProperties{Rule_class: "proto_library"},
+			CommonAttributes{Name: info.Name},
+			&attrs)
+
+		protoLibraries.Add(&bazel.Label{
+			Label: ":" + info.Name,
+		})
+	}
+
+	info.Proto_libs = protoLibraries
 
 	return info, true
 }