Add comments in composer, add TODOs, refactor the signatures

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

@@ -30,6 +30,10 @@
 import java.util.stream.Stream;
 
 class ServiceClientCommentComposer {
+  // Name Pattern.
+  private static final String SETTINGS_NAME_PATTERN = "%sSettings";
+  private static final String CLASS_NAME_PATTERN = "%sClient";
+
   // Tokens.
   private static final String COLON = ":";
   private static final String EMPTY_STRING = "";
@@ -106,6 +110,10 @@ class ServiceClientCommentComposer {
 
   static List<CommentStatement> createClassHeaderComments(
       Service service, Map<String, TypeNode> types) {
+    String settingsName = JavaStyle.toLowerCamelCase(getSettingsName(service.name()));
+    String clientName = JavaStyle.toLowerCamelCase(getClientClassName(service.name()));
+    TypeNode settingsType = types.get(getSettingsName(service.name()));
+    TypeNode clientType = types.get(getClientClassName(service.name()));
     JavaDocComment.Builder classHeaderJavadocBuilder = JavaDocComment.builder();
     if (service.hasDescription()) {
       classHeaderJavadocBuilder =
@@ -137,7 +145,8 @@ static List<CommentStatement> createClassHeaderComments(
             String.format("%sSettings", JavaStyle.toUpperCamelCase(service.name()))));
     classHeaderJavadocBuilder.addParagraph(SERVICE_DESCRIPTION_CREDENTIALS_SUMMARY_STRING);
     classHeaderJavadocBuilder.addSampleCode(
-        ServiceClientSampleCodeComposer.composeClassHeaderCredentialsSampleCode(service, types));
+        ServiceClientSampleCodeComposer.composeClassHeaderCredentialsSampleCode(
+            clientName, clientType, settingsName, settingsType));
     classHeaderJavadocBuilder.addParagraph(SERVICE_DESCRIPTION_ENDPOINT_SUMMARY_STRING);
     classHeaderJavadocBuilder.addSampleCode(
         ServiceClientSampleCodeComposer.composeClassHeaderEndpointSampleCode(service, types));
@@ -258,4 +267,12 @@ private static JavaDocComment.Builder processProtobufComment(
 
     return commentBuilder;
   }
+
+  private static String getSettingsName(String serviceName) {
+    return String.format(SETTINGS_NAME_PATTERN, serviceName);
+  }
+
+  private static String getClientClassName(String serviceName) {
+    return String.format(CLASS_NAME_PATTERN, serviceName);
+  }
 }

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

@@ -28,25 +28,22 @@
 import com.google.api.generator.engine.ast.VariableExpr;
 import com.google.api.generator.engine.writer.JavaWriterVisitor;
 import com.google.api.generator.gapic.composer.samplecode.SampleCodeJavaFormatter;
-import com.google.api.generator.gapic.model.Service;
-import com.google.api.generator.gapic.utils.JavaStyle;
 import java.util.Arrays;
 import java.util.List;
-import java.util.Map;
 import java.util.stream.Collectors;
 
 public class ServiceClientSampleCodeComposer {
-  private static final String SETTINGS_NAME_PATTERN = "%sSettings";
-  private static final String CLASS_NAME_PATTERN = "%sClient";
+  //TODO(summerji): Add unit tests for ServiceClientSampleCodeComposer.
 
   public static String composeClassHeaderCredentialsSampleCode(
-      Service service, Map<String, TypeNode> types) {
-    String settingsVarName = JavaStyle.toLowerCamelCase(getSettingsName(service.name()));
-    TypeNode settingsVarType = types.get(getSettingsName(service.name()));
-    VariableExpr settingsVarExpr = createVariableExpr(settingsVarName, settingsVarType);
+      String clientName, TypeNode clientType, String settingsName, TypeNode settingsType) {
+    // Initialize clientSettings with builder() method.
+    // e.g. EchoSettings echoSettings =
+    // EchoSettings.newBuilder().setCredentialsProvider(FixedCredentialsProvider.create("myCredentials")).build();
+    VariableExpr settingsVarExpr = createVariableExpr(settingsName, settingsType);
     MethodInvocationExpr newBuilderMethodExpr =
         MethodInvocationExpr.builder()
-            .setStaticReferenceType(settingsVarType)
+            .setStaticReferenceType(settingsType)
             .setMethodName("newBuilder")
             .build();
     TypeNode fixedCredentialProvideType =
@@ -66,7 +63,7 @@ public static String composeClassHeaderCredentialsSampleCode(
     MethodInvocationExpr buildMethodExpr =
         MethodInvocationExpr.builder()
             .setExprReferenceExpr(credentialsMethodExpr)
-            .setReturnType(settingsVarType)
+            .setReturnType(settingsType)
             .setMethodName("build")
             .build();
     Expr initSettingsVarExpr =
@@ -75,8 +72,8 @@ public static String composeClassHeaderCredentialsSampleCode(
             .setValueExpr(buildMethodExpr)
             .build();
 
-    String clientName = JavaStyle.toLowerCamelCase(getClientClassName(service.name()));
-    TypeNode clientType = types.get(getClientClassName(service.name()));
+    // Initialized client with create() method.
+    // e.g. EchoClient echoClient = EchoClient.create(echoSettings);
     VariableExpr clientVarExpr = createVariableExpr(clientName, clientType);
     MethodInvocationExpr createMethodExpr =
         MethodInvocationExpr.builder()
@@ -143,15 +140,7 @@ public static String composeClassHeaderEndpointSampleCode(
   }
 
   // ======================================== Helpers ==========================================//
-
-  private static String getClientClassName(String serviceName) {
-    return String.format(CLASS_NAME_PATTERN, serviceName);
-  }
-
-  private static String getSettingsName(String serviceName) {
-    return String.format(SETTINGS_NAME_PATTERN, serviceName);
-  }
-
+  // TODO(summerji): Use writeSampleCode method in new class once PR#499 merged.
   private static String writeSampleCode(List<Expr> exprs) {
     List<Statement> statements =
         exprs.stream().map(e -> ExprStatement.withExpr(e)).collect(Collectors.toList());