fix: update sample region tag to parse host instead of proto package

src/main/java/com/google/api/generator/gapic/composer/Composer.java

@@ -15,6 +15,7 @@
 package com.google.api.generator.gapic.composer;
 
 import com.google.api.generator.engine.ast.ClassDefinition;
+import com.google.api.generator.engine.ast.CommentStatement;
 import com.google.api.generator.gapic.composer.comment.CommentComposer;
 import com.google.api.generator.gapic.composer.grpc.GrpcServiceCallableFactoryClassComposer;
 import com.google.api.generator.gapic.composer.grpc.GrpcServiceStubClassComposer;
@@ -36,6 +37,8 @@
 import com.google.api.generator.gapic.model.Service;
 import com.google.api.generator.gapic.model.Transport;
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Splitter;
+import com.google.common.collect.Iterables;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -191,36 +194,57 @@ public static List<GapicClass> generateTestClasses(GapicContext context) {
 
   @VisibleForTesting
   static List<GapicClass> prepareExecutableSamples(List<GapicClass> clazzes, String protoPackage) {
-    //  parse protoPackage for apiVersion and apiShortName
+    //  parse protoPackage for apiVersion
     String[] pakkage = protoPackage.split("\\.");
     String apiVersion;
-    String apiShortName;
     //  e.g. v1, v2, v1beta1
     if (pakkage[pakkage.length - 1].matches("v[0-9].*")) {
       apiVersion = pakkage[pakkage.length - 1];
-      apiShortName = pakkage[pakkage.length - 2];
     } else {
       apiVersion = "";
-      apiShortName = pakkage[pakkage.length - 1];
     }
-    //  Include license header, apiShortName, and apiVersion
-    return clazzes.stream()
-        .map(
-            gapicClass -> {
-              List<Sample> samples =
-                  gapicClass.samples().stream()
-                      .map(
-                          sample -> addRegionTagAndHeaderToSample(sample, apiShortName, apiVersion))
-                      .collect(Collectors.toList());
-              return gapicClass.withSamples(samples);
-            })
-        .collect(Collectors.toList());
+    // Include license header, apiShortName, and apiVersion
+    List<GapicClass> clazzesWithSamples = new ArrayList<>();
+    clazzes.forEach(
+        gapicClass -> {
+          List<Sample> samples = new ArrayList<>();
+          gapicClass
+              .samples()
+              .forEach(
+                  sample ->
+                      samples.add(
+                          addRegionTagAndHeaderToSample(
+                              sample, parseDefaultHost(gapicClass.defaultHost()), apiVersion)));
+          clazzesWithSamples.add(gapicClass.withSamples(samples));
+        });
+    return clazzesWithSamples;
   }
 
-  private static Sample addRegionTagAndHeaderToSample(
+  // Parse defaultHost for apiShortName for the RegionTag. Need to account for regional default
+  // endpoints like
+  // "us-east1-pubsub.googleapis.com".
+  @VisibleForTesting
+  protected static String parseDefaultHost(String defaultHost) {
+    // If the defaultHost is of the format "**.googleapis.com", take the name before the first
+    // period.
+    String apiShortName = Iterables.getFirst(Splitter.on(".").split(defaultHost), defaultHost);
+    // If the defaultHost is of the format "**-**-**.googleapis.com", take the section before the
+    // first period and after the last dash to follow CSharp's implementation here:
+    // https://github.com/googleapis/gapic-generator-csharp/blob/main/Google.Api.Generator/Generation/ServiceDetails.cs#L70
+    apiShortName = Iterables.getLast(Splitter.on("-").split(apiShortName), defaultHost);
+    // `iam-meta-api` service is an exceptional case and is handled as a one-off
+    if (defaultHost.contains("iam-meta-api")) {
+      apiShortName = "iam";
+    }
+    return apiShortName;
+  }
+
+  @VisibleForTesting
+  protected static Sample addRegionTagAndHeaderToSample(
       Sample sample, String apiShortName, String apiVersion) {
+    final List<CommentStatement> header = Arrays.asList(CommentComposer.APACHE_LICENSE_COMMENT);
     return sample
-        .withHeader(Arrays.asList(CommentComposer.APACHE_LICENSE_COMMENT))
+        .withHeader(header)
         .withRegionTag(
             sample.regionTag().withApiVersion(apiVersion).withApiShortName(apiShortName));
   }

src/main/java/com/google/api/generator/gapic/composer/common/AbstractServiceClientClassComposer.java

@@ -163,7 +163,8 @@ public GapicClass generate(GapicContext context, Service service) {
             .build();
 
     updateGapicMetadata(context, service, className, grpcRpcsToJavaMethodNames);
-    return GapicClass.create(kind, classDef, SampleComposerUtil.handleDuplicateSamples(samples));
+    return GapicClass.create(kind, classDef, SampleComposerUtil.handleDuplicateSamples(samples))
+        .withDefaultHost(service.defaultHost());
   }
 
   private static List<AnnotationNode> createClassAnnotations(Service service, TypeStore typeStore) {

src/main/java/com/google/api/generator/gapic/composer/common/AbstractServiceSettingsClassComposer.java

@@ -126,7 +126,8 @@ public GapicClass generate(GapicContext context, Service service) {
             .setMethods(createClassMethods(service, typeStore))
             .setNestedClasses(Arrays.asList(createNestedBuilderClass(service, typeStore)))
             .build();
-    return GapicClass.create(kind, classDef, SampleComposerUtil.handleDuplicateSamples(samples));
+    return GapicClass.create(kind, classDef, SampleComposerUtil.handleDuplicateSamples(samples))
+        .withDefaultHost(service.defaultHost());
   }
 
   private static List<CommentStatement> createClassHeaderComments(

src/main/java/com/google/api/generator/gapic/composer/common/AbstractServiceStubSettingsClassComposer.java

@@ -201,7 +201,8 @@ public GapicClass generate(GapicContext context, Service service) {
                 Arrays.asList(createNestedBuilderClass(service, serviceConfig, typeStore)))
             .build();
     return GapicClass.create(
-        GapicClass.Kind.STUB, classDef, SampleComposerUtil.handleDuplicateSamples(samples));
+            GapicClass.Kind.STUB, classDef, SampleComposerUtil.handleDuplicateSamples(samples))
+        .withDefaultHost(service.defaultHost());
   }
 
   protected MethodDefinition createDefaultCredentialsProviderBuilderMethod() {

src/main/java/com/google/api/generator/gapic/composer/samplecode/SettingsSampleComposer.java

@@ -145,6 +145,7 @@ public static Optional<Sample> composeSettingsSample(
             .map(e -> ExprStatement.withExpr(e))
             .collect(Collectors.toList());
 
+    // TODO: alicejli edit RegionTag to match other languages
     RegionTag regionTag =
         RegionTag.builder()
             .setServiceName(classType.reference().name())

src/main/java/com/google/api/generator/gapic/model/GapicClass.java

@@ -35,6 +35,10 @@ public enum Kind {
 
   public abstract List<Sample> samples();
 
+  // Represents the host URL for the service. May or may not contain a regional endpoint. Only used
+  // for generating the region tag for samples; therefore only used in select Composers.
+  public abstract String defaultHost();
+
   public static GapicClass create(Kind kind, ClassDefinition classDefinition) {
     return builder().setKind(kind).setClassDefinition(classDefinition).build();
   }
@@ -45,7 +49,9 @@ public static GapicClass create(
   }
 
   static Builder builder() {
-    return new AutoValue_GapicClass.Builder().setSamples(Collections.emptyList());
+    return new AutoValue_GapicClass.Builder()
+        .setSamples(Collections.emptyList())
+        .setDefaultHost("");
   }
 
   abstract Builder toBuilder();
@@ -54,6 +60,10 @@ public final GapicClass withSamples(List<Sample> samples) {
     return toBuilder().setSamples(samples).build();
   }
 
+  public final GapicClass withDefaultHost(String defaultHost) {
+    return toBuilder().setDefaultHost(defaultHost).build();
+  }
+
   @AutoValue.Builder
   abstract static class Builder {
     abstract Builder setKind(Kind kind);
@@ -62,6 +72,8 @@ abstract static class Builder {
 
     abstract Builder setSamples(List<Sample> samples);
 
+    abstract Builder setDefaultHost(String defaultHost);
+
     abstract GapicClass build();
   }
 }

src/main/java/com/google/api/generator/gapic/model/RegionTag.java

@@ -20,6 +20,7 @@
 import com.google.auto.value.AutoValue;
 import com.google.common.base.Preconditions;
 
+// TODO: alicejli edit RegionTag to match other languages
 /**
  * This model represents a code sample region tag. Matching region start and end region tag comments
  * are used to determine the boundaries of code snippets to be used in documentation.

src/test/java/com/google/api/generator/gapic/composer/ComposerTest.java

@@ -15,6 +15,7 @@
 package com.google.api.generator.gapic.composer;
 
 import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
 
 import com.google.api.generator.engine.ast.ClassDefinition;
 import com.google.api.generator.engine.ast.ScopeNode;
@@ -25,11 +26,11 @@
 import com.google.api.generator.gapic.model.GapicClass;
 import com.google.api.generator.gapic.model.GapicClass.Kind;
 import com.google.api.generator.gapic.model.GapicContext;
+import com.google.api.generator.gapic.model.RegionTag;
 import com.google.api.generator.gapic.model.Sample;
 import com.google.api.generator.gapic.model.Service;
 import com.google.api.generator.test.framework.Assert;
 import com.google.api.generator.test.framework.Utils;
-import com.google.common.collect.ImmutableList;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.util.Arrays;
@@ -42,8 +43,13 @@ public class ComposerTest {
   private final List<GapicClass> clazzes =
       Arrays.asList(
           GrpcServiceCallableFactoryClassComposer.instance().generate(context, echoProtoService));
-  private final String protoPackage = context.gapicMetadata().getProtoPackage();
-  private final List<Sample> samples = clazzes.get(0).samples();
+  private final Sample sample =
+      Sample.builder()
+          .setRegionTag(
+              RegionTag.builder().setServiceName("serviceName").setRpcName("rpcName").build())
+          .build();
+  private List<Sample> ListofSamples = Arrays.asList(new Sample[] {sample});
+  private final String protoPackage = echoProtoService.protoPakkage();
 
   @Test
   public void gapicClass_addApacheLicense() {
@@ -65,58 +71,102 @@ public void gapicClass_addApacheLicense() {
 
   @Test
   public void composeSamples_showcase() {
-    for (Sample sample : samples) {
-      assertEquals(
-          "File header will be empty before composing samples",
-          sample.fileHeader(),
-          ImmutableList.of());
-      assertEquals(
-          "ApiShortName will be empty before composing samples",
-          sample.regionTag().apiShortName(),
-          "");
-      assertEquals(
-          "ApiVersion will be empty before composing samples", sample.regionTag().apiVersion(), "");
-    }
+    GapicClass testClass = clazzes.get(0).withSamples(ListofSamples);
+    List<GapicClass> testClassList = Arrays.asList(new GapicClass[] {testClass});
 
     List<Sample> composedSamples =
-        Composer.prepareExecutableSamples(clazzes, protoPackage).get(0).samples();
+        Composer.prepareExecutableSamples(testClassList, protoPackage).get(0).samples();
 
+    assertFalse(composedSamples.isEmpty());
     for (Sample sample : composedSamples) {
       assertEquals(
-          "File header should be apache",
-          sample.fileHeader(),
-          Arrays.asList(CommentComposer.APACHE_LICENSE_COMMENT));
-      assertEquals(
-          "ApiShortName should be showcase", sample.regionTag().apiShortName(), "showcase");
-      assertEquals("ApiVersion should be v1beta1", sample.regionTag().apiVersion(), "v1beta1");
+          "File header should be APACHE",
+          Arrays.asList(CommentComposer.APACHE_LICENSE_COMMENT),
+          sample.fileHeader());
+      assertEquals("ApiShortName should be empty", "", sample.regionTag().apiShortName());
+      assertEquals("ApiVersion should be V1beta1", "V1Beta1", sample.regionTag().apiVersion());
     }
   }
 
+  @Test
+  public void parseDefaultHost_shouldReturnApiShortNameIfHostContainsRegionalEndpoint() {
+    String defaultHost = "us-east1-pubsub.googleapis.com";
+    String apiShortName = Composer.parseDefaultHost(defaultHost);
+    assertEquals("pubsub", apiShortName);
+  }
+
+  @Test
+  public void parseDefaultHost_shouldReturnApiShortName() {
+    String defaultHost = "logging.googleapis.com";
+    String apiShortName = Composer.parseDefaultHost(defaultHost);
+    assertEquals("logging", apiShortName);
+  }
+
+  @Test
+  public void parseDefaultHost_shouldReturnApiShortNameForIam() {
+    String defaultHost = "iam-meta-api.googleapis.com";
+    String apiShortName = Composer.parseDefaultHost(defaultHost);
+    assertEquals("iam", apiShortName);
+  }
+
+  @Test
+  public void parseDefaultHost_shouldReturnHostIfNoPeriods() {
+    String defaultHost = "logging:7469";
+    String apiShortName = Composer.parseDefaultHost(defaultHost);
+    assertEquals("logging:7469", apiShortName);
+  }
+
+  @Test
+  public void gapicClass_addRegionTagAndHeaderToSample() {
+    Sample testSample;
+    testSample = Composer.addRegionTagAndHeaderToSample(sample, "showcase", "v1");
+    assertEquals("Showcase", testSample.regionTag().apiShortName());
+    assertEquals("V1", testSample.regionTag().apiVersion());
+    assertEquals(Arrays.asList(CommentComposer.APACHE_LICENSE_COMMENT), testSample.fileHeader());
+  }
+
   @Test
   public void composeSamples_parseProtoPackage() {
+
+    String defaultHost = "accessapproval.googleapis.com:443";
+    GapicClass testClass = clazzes.get(0).withSamples(ListofSamples).withDefaultHost(defaultHost);
+    List<GapicClass> testClassList = Arrays.asList(new GapicClass[] {testClass});
     String protoPack = "google.cloud.accessapproval.v1";
+
     List<Sample> composedSamples =
-        Composer.prepareExecutableSamples(clazzes, protoPack).get(0).samples();
+        Composer.prepareExecutableSamples(testClassList, protoPack).get(0).samples();
+
+    // If samples is empty, the test automatically passes without checking.
+    assertFalse(composedSamples.isEmpty());
 
     for (Sample sample : composedSamples) {
       assertEquals(
-          "ApiShortName should be accessapproval",
+          "ApiShortName should be Accessapproval",
           sample.regionTag().apiShortName(),
-          "accessapproval");
-      assertEquals("ApiVersion should be v1", sample.regionTag().apiVersion(), "v1");
+          "Accessapproval");
+      assertEquals("ApiVersion should be V1", sample.regionTag().apiVersion(), "V1");
     }
 
     protoPack = "google.cloud.vision.v1p1beta1";
-    composedSamples = Composer.prepareExecutableSamples(clazzes, protoPack).get(0).samples();
+    defaultHost = "vision.googleapis.com";
+    testClass = clazzes.get(0).withSamples(ListofSamples).withDefaultHost(defaultHost);
+    testClassList = Arrays.asList(new GapicClass[] {testClass});
+    composedSamples = Composer.prepareExecutableSamples(testClassList, protoPack).get(0).samples();
+    // If samples is empty, the test automatically passes without checking.
+    assertFalse(composedSamples.isEmpty());
+
     for (Sample sample : composedSamples) {
-      assertEquals("ApiShortName should be vision", sample.regionTag().apiShortName(), "vision");
-      assertEquals("ApiVersion should be v1p1beta1", sample.regionTag().apiVersion(), "v1p1beta1");
+      assertEquals("ApiShortName should be Vision", sample.regionTag().apiShortName(), "Vision");
+      assertEquals("ApiVersion should be V1P1Beta1", sample.regionTag().apiVersion(), "V1P1Beta1");
     }
 
     protoPack = "google.cloud.vision";
-    composedSamples = Composer.prepareExecutableSamples(clazzes, protoPack).get(0).samples();
+    composedSamples = Composer.prepareExecutableSamples(testClassList, protoPack).get(0).samples();
+    // If samples is empty, the test automatically passes without checking.
+    assertFalse(composedSamples.isEmpty());
+
     for (Sample sample : composedSamples) {
-      assertEquals("ApiShortName should be vision", sample.regionTag().apiShortName(), "vision");
+      assertEquals("ApiShortName should be Vision", sample.regionTag().apiShortName(), "Vision");
       assertEquals("ApiVersion should be empty", sample.regionTag().apiVersion(), "");
     }
   }