[composer][2/5]Implement pure RPC method's sample code

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

@@ -22,5 +22,7 @@
 
 public interface ClassComposer {
   GapicClass generate(
+      // TODO(miraleung): clean up the hierarchy to avoid pass another parameter (resourceNames is
+      // only used for composing sample code).
       Service service, Map<String, Message> messageTypes, Map<String, ResourceName> resourceNames);
 }

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

@@ -16,6 +16,8 @@
 
 import com.google.api.generator.engine.ast.AssignmentExpr;
 import com.google.api.generator.engine.ast.CommentStatement;
+import com.google.api.generator.engine.ast.Expr;
+import com.google.api.generator.engine.ast.ExprStatement;
 import com.google.api.generator.engine.ast.LineComment;
 import com.google.api.generator.engine.ast.MethodInvocationExpr;
 import com.google.api.generator.engine.ast.TryCatchStatement;
@@ -26,17 +28,26 @@
 import com.google.api.generator.gapic.model.MethodArgument;
 import com.google.api.generator.gapic.model.ResourceName;
 import com.google.api.generator.gapic.utils.JavaStyle;
+import com.google.common.base.Preconditions;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Map;
+import java.util.stream.Collectors;
 
 public final class SampleCodeHelperComposer {
+  private static String RESPONSE = "response";
 
   public static TryCatchStatement composeRpcMethodSampleCode(
       Method method,
       List<MethodArgument> arguments,
       TypeNode clientType,
       Map<String, ResourceName> resourceNames) {
+    Preconditions.checkState(
+        !arguments.isEmpty(),
+        "If method %s's arguments is none, it should pass %s as argument.",
+        method.name(),
+        method.inputType().reference().name());
     // Paged Unary RPC method.
     if (method.isPaged()) {
       return composePagedUnaryRpcMethodSampleCode(method, arguments, clientType, resourceNames);
@@ -71,14 +82,45 @@ private static TryCatchStatement composeUnaryRpcMethodSampleCode(
       List<MethodArgument> arguments,
       TypeNode clientType,
       Map<String, ResourceName> resourceNames) {
-    // TODO(summerji): compose sample code for unary rpc method.
     VariableExpr clientVarExpr = createVariableExpr(getClientName(clientType), clientType);
+    // Assign each method arguments with its default value.
+    Map<String, VariableExpr> methodArgVarExprMap = mapMethodArgumentsToVariableExprs(arguments);
+    List<Expr> methodArgumentsAssignmentExpr =
+        assignMethodArgumentsWithDefaultValues(arguments, methodArgVarExprMap, resourceNames);
+    List<Expr> methodVarExprs =
+        arguments.stream()
+            .map(arg -> methodArgVarExprMap.get(arg.name()))
+            .collect(Collectors.toList());
+    // Invoke current method based on return type.
+    // e.g. if return void, echoClient.echo(..); or,
+    // e.g. if return other type, EchoResponse response = echoClient.echo(...);
+    boolean returnsVoid = isProtoEmptyType(method.outputType());
+    Expr responseExpr = null;
+    if (returnsVoid) {
+      responseExpr =
+          MethodInvocationExpr.builder()
+              .setExprReferenceExpr(clientVarExpr)
+              .setMethodName(JavaStyle.toLowerCamelCase(method.name()))
+              .setArguments(methodVarExprs)
+              .setReturnType(clientType)
+              .build();
+    } else {
+      responseExpr =
+          createAssignExprForVariableWithClientMethod(
+              createVariableExpr(RESPONSE, method.outputType()),
+              clientVarExpr,
+              JavaStyle.toLowerCamelCase(method.name()),
+              methodVarExprs);
+    }
+
+    List<Expr> bodyExpr = new ArrayList<>();
+    bodyExpr.addAll(methodArgumentsAssignmentExpr);
+    bodyExpr.add(responseExpr);
+
     return TryCatchStatement.builder()
         .setTryResourceExpr(assignClientVariableWithCreateMethodExpr(clientVarExpr))
         .setTryBody(
-            Arrays.asList(
-                createLineCommentStatement(
-                    "Note: Not implemented yet, placeholder for pure unary rpc method sample code.")))
+            bodyExpr.stream().map(e -> ExprStatement.withExpr(e)).collect(Collectors.toList()))
         .setIsSampleCode(true)
         .build();
   }
@@ -89,6 +131,7 @@ private static TryCatchStatement composeLroUnaryRpcMethodSampleCode(
       TypeNode clientType,
       Map<String, ResourceName> resourceNames) {
     // TODO(summerji): compose sample code for unary lro rpc method.
+    // TODO(summerji): Add unit tests.
     VariableExpr clientVarExpr = createVariableExpr(getClientName(clientType), clientType);
     return TryCatchStatement.builder()
         .setTryResourceExpr(assignClientVariableWithCreateMethodExpr(clientVarExpr))
@@ -106,6 +149,7 @@ private static TryCatchStatement composePagedUnaryRpcMethodSampleCode(
       TypeNode clientType,
       Map<String, ResourceName> resourceNames) {
     // TODO(summerji): compose sample code for unary paged rpc method.
+    // TODO(summerji): Add unit tests.
     VariableExpr clientVarExpr = createVariableExpr(getClientName(clientType), clientType);
     return TryCatchStatement.builder()
         .setTryResourceExpr(assignClientVariableWithCreateMethodExpr(clientVarExpr))
@@ -116,7 +160,6 @@ private static TryCatchStatement composePagedUnaryRpcMethodSampleCode(
         .setIsSampleCode(true)
         .build();
   }
-
   // ==================================Helpers===================================================//
 
   // Assign client variable expr with create client.
@@ -134,6 +177,55 @@ private static AssignmentExpr assignClientVariableWithCreateMethodExpr(
         .build();
   }
 
+  private static List<Expr> assignMethodArgumentsWithDefaultValues(
+      List<MethodArgument> arguments,
+      Map<String, VariableExpr> argVarExprs,
+      Map<String, ResourceName> resourceNames) {
+    return arguments.stream()
+        .map(
+            arg ->
+                createAssignmentExpr(
+                    argVarExprs.get(arg.name()),
+                    DefaultValueComposer.createDefaultValue(arg, resourceNames)))
+        .collect(Collectors.toList());
+  }
+
+  private static AssignmentExpr createAssignmentExpr(VariableExpr variableExpr, Expr valueExpr) {
+    return AssignmentExpr.builder()
+        .setVariableExpr(variableExpr.toBuilder().setIsDecl(true).build())
+        .setValueExpr(valueExpr)
+        .build();
+  }
+
+  private static Expr createAssignExprForVariableWithClientMethod(
+      VariableExpr variableExpr,
+      VariableExpr clientVarExpr,
+      String methodName,
+      List<Expr> argumentsVarExprs) {
+    MethodInvocationExpr clientMethodInvocationExpr =
+        MethodInvocationExpr.builder()
+            .setExprReferenceExpr(clientVarExpr)
+            .setMethodName(JavaStyle.toLowerCamelCase(methodName))
+            .setArguments(argumentsVarExprs)
+            .setReturnType(variableExpr.variable().type())
+            .build();
+    return AssignmentExpr.builder()
+        .setVariableExpr(variableExpr.toBuilder().setIsDecl(true).build())
+        .setValueExpr(clientMethodInvocationExpr)
+        .build();
+  }
+
+  private static Map<String, VariableExpr> mapMethodArgumentsToVariableExprs(
+      List<MethodArgument> arguments) {
+    return arguments.stream()
+        .collect(
+            Collectors.toMap(
+                methodArg -> methodArg.name(),
+                methodArg ->
+                    createVariableExpr(
+                        JavaStyle.toLowerCamelCase(methodArg.name()), methodArg.type())));
+  }
+
   private static String getClientName(TypeNode clientType) {
     return JavaStyle.toLowerCamelCase(clientType.reference().name());
   }
@@ -157,4 +249,9 @@ private static VariableExpr createVariableExpr(
         .setIsDecl(isDecl)
         .build();
   }
+
+  private static boolean isProtoEmptyType(TypeNode type) {
+    return type.reference().pakkage().equals("com.google.protobuf")
+        && type.reference().name().equals("Empty");
+  }
 }

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

@@ -1,6 +1,6 @@
 // Copyright 2020 Google LLC
 //
-// Licensed under the Apache License, Version 2.0 (the "License");\
+// 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
 //

src/test/java/com/google/api/generator/gapic/composer/BUILD.bazel

@@ -22,6 +22,7 @@ TESTS = UPDATE_GOLDENS_TESTS + [
     "DefaultValueComposerTest",
     "ResourceNameTokenizerTest",
     "RetrySettingsComposerTest",
+    "SampleCodeHelperComposerTest"
 ]
 
 TEST_DEPS = [
@@ -38,6 +39,7 @@ TEST_DEPS = [
     "//src/main/java/com/google/api/generator/gapic/protoparser",
     "//src/test/java/com/google/api/generator/gapic/testdata:showcase_java_proto",
     "//src/test/java/com/google/api/generator/gapic/testdata:testgapic_java_proto",
+    "@com_google_api_api_common//jar",
     "@com_google_api_gax_java//gax",
     "@com_google_googleapis//google/logging/v2:logging_java_proto",
     "@com_google_googleapis//google/pubsub/v1:pubsub_java_proto",