/** Returns a code block that directly injects the instance's field or method. */
 private CodeBlock directInjectMemberCodeBlock(
     MembersInjectionBinding binding,
     ImmutableMap<BindingKey, FieldSpec> dependencyFields,
     InjectionSite injectionSite) {
   return CodeBlocks.format(
       injectionSite.element().getKind().isField() ? "$L.$L = $L;" : "$L.$L($L);",
       getInstanceCodeBlockWithPotentialCast(
           injectionSite.element().getEnclosingElement(), binding.bindingElement()),
       injectionSite.element().getSimpleName(),
       makeParametersCodeBlock(
           parameterCodeBlocks(dependencyFields, injectionSite.dependencies(), true)));
 }
 /**
  * Returns a code block that injects the instance's field or method by calling a static method on
  * the parent MembersInjector class.
  */
 private CodeBlock delegateInjectMemberCodeBlock(
     ImmutableMap<BindingKey, FieldSpec> dependencyFields, InjectionSite injectionSite) {
   return CodeBlocks.format(
       "$L.$L($L);",
       javapoetMembersInjectorNameForType(
           MoreElements.asType(injectionSite.element().getEnclosingElement())),
       injectionSiteDelegateMethodName(injectionSite.element()),
       makeParametersCodeBlock(
           new ImmutableList.Builder<CodeBlock>()
               .add(CodeBlocks.format("instance"))
               .addAll(parameterCodeBlocks(dependencyFields, injectionSite.dependencies(), false))
               .build()));
 }
  @Override
  Optional<TypeSpec.Builder> write(ClassName generatedTypeName, MembersInjectionBinding binding) {
    // Empty members injection bindings are special and don't need source files.
    if (binding.injectionSites().isEmpty()) {
      return Optional.absent();
    }
    // We don't want to write out resolved bindings -- we want to write out the generic version.
    checkState(!binding.unresolved().isPresent());

    ImmutableList<TypeVariableName> typeParameters = bindingTypeElementTypeVariableNames(binding);
    TypeSpec.Builder injectorTypeBuilder =
        TypeSpec.classBuilder(generatedTypeName.simpleName())
            .addModifiers(PUBLIC, FINAL)
            .addTypeVariables(typeParameters);

    TypeName injectedTypeName = TypeName.get(binding.key().type());
    TypeName implementedType = membersInjectorOf(injectedTypeName);
    injectorTypeBuilder.addSuperinterface(implementedType);

    MethodSpec.Builder injectMembersBuilder =
        MethodSpec.methodBuilder("injectMembers")
            .returns(TypeName.VOID)
            .addModifiers(PUBLIC)
            .addAnnotation(Override.class)
            .addParameter(injectedTypeName, "instance")
            .addCode("if (instance == null) {")
            .addStatement(
                "throw new $T($S)",
                NullPointerException.class,
                "Cannot inject members into a null reference")
            .addCode("}");

    ImmutableMap<BindingKey, FrameworkField> fields =
        SourceFiles.generateBindingFieldsForDependencies(dependencyRequestMapper, binding);

    ImmutableMap.Builder<BindingKey, FieldSpec> dependencyFieldsBuilder = ImmutableMap.builder();

    MethodSpec.Builder constructorBuilder = MethodSpec.constructorBuilder().addModifiers(PUBLIC);

    // We use a static create method so that generated components can avoid having
    // to refer to the generic types of the factory.
    // (Otherwise they may have visibility problems referring to the types.)
    MethodSpec.Builder createMethodBuilder =
        MethodSpec.methodBuilder("create")
            .returns(implementedType)
            .addModifiers(Modifier.PUBLIC, Modifier.STATIC)
            .addTypeVariables(typeParameters);

    createMethodBuilder.addCode(
        "return new $T(", javapoetParameterizedGeneratedTypeNameForBinding(binding));
    ImmutableList.Builder<CodeBlock> constructorInvocationParameters = ImmutableList.builder();

    boolean usesRawFrameworkTypes = false;
    UniqueNames fieldNames = new UniqueNames();
    for (Entry<BindingKey, FrameworkField> fieldEntry : fields.entrySet()) {
      BindingKey bindingKey = fieldEntry.getKey();
      FrameworkField bindingField = fieldEntry.getValue();

      // If the dependency type is not visible to this members injector, then use the raw framework
      // type for the field.
      boolean useRawFrameworkType =
          !VISIBLE_TO_MEMBERS_INJECTOR.visit(bindingKey.key().type(), binding);

      String fieldName = fieldNames.getUniqueName(bindingField.name());
      TypeName fieldType =
          useRawFrameworkType
              ? bindingField.javapoetFrameworkType().rawType
              : bindingField.javapoetFrameworkType();
      FieldSpec.Builder fieldBuilder = FieldSpec.builder(fieldType, fieldName, PRIVATE, FINAL);
      ParameterSpec.Builder parameterBuilder = ParameterSpec.builder(fieldType, fieldName);

      // If we're using the raw type for the field, then suppress the injectMembers method's
      // unchecked-type warning and the field's and the constructor and create-method's
      // parameters' raw-type warnings.
      if (useRawFrameworkType) {
        usesRawFrameworkTypes = true;
        fieldBuilder.addAnnotation(SUPPRESS_WARNINGS_RAWTYPES);
        parameterBuilder.addAnnotation(SUPPRESS_WARNINGS_RAWTYPES);
      }
      constructorBuilder.addParameter(parameterBuilder.build());
      createMethodBuilder.addParameter(parameterBuilder.build());

      FieldSpec field = fieldBuilder.build();
      injectorTypeBuilder.addField(field);
      constructorBuilder.addStatement("assert $N != null", field);
      constructorBuilder.addStatement("this.$N = $N", field, field);
      dependencyFieldsBuilder.put(bindingKey, field);
      constructorInvocationParameters.add(CodeBlocks.format("$N", field));
    }
    createMethodBuilder.addCode(CodeBlocks.join(constructorInvocationParameters.build(), ", "));
    createMethodBuilder.addCode(");");

    injectorTypeBuilder.addMethod(constructorBuilder.build());
    injectorTypeBuilder.addMethod(createMethodBuilder.build());

    Set<String> delegateMethods = new HashSet<>();
    ImmutableMap<BindingKey, FieldSpec> dependencyFields = dependencyFieldsBuilder.build();
    List<MethodSpec> injectMethodsForSubclasses = new ArrayList<>();
    for (InjectionSite injectionSite : binding.injectionSites()) {
      injectMembersBuilder.addCode(
          visibleToMembersInjector(binding, injectionSite.element())
              ? directInjectMemberCodeBlock(binding, dependencyFields, injectionSite)
              : delegateInjectMemberCodeBlock(dependencyFields, injectionSite));
      if (!injectionSite.element().getModifiers().contains(PUBLIC)
          && injectionSite.element().getEnclosingElement().equals(binding.bindingElement())
          && delegateMethods.add(injectionSiteDelegateMethodName(injectionSite.element()))) {
        injectMethodsForSubclasses.add(
            injectorMethodForSubclasses(
                dependencyFields,
                typeParameters,
                injectedTypeName,
                injectionSite.element(),
                injectionSite.dependencies()));
      }
    }

    if (usesRawFrameworkTypes) {
      injectMembersBuilder.addAnnotation(SUPPRESS_WARNINGS_UNCHECKED);
    }

    injectorTypeBuilder.addMethod(injectMembersBuilder.build());
    for (MethodSpec methodSpec : injectMethodsForSubclasses) {
      injectorTypeBuilder.addMethod(methodSpec);
    }

    return Optional.of(injectorTypeBuilder);
  }