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#include "google/protobuf/compiler/objectivec/enum_field.h"

#include <string>

#include "absl/container/flat_hash_map.h"
#include "google/protobuf/compiler/objectivec/names.h"
#include "google/protobuf/io/printer.h"

namespace google {
namespace protobuf {
namespace compiler {
namespace objectivec {

namespace {

void SetEnumVariables(
    const FieldDescriptor* descriptor,
    absl::flat_hash_map<absl::string_view, std::string>* variables) {
  const std::string type = EnumName(descriptor->enum_type());
  const std::string enum_desc_func = absl::StrCat(type, "_EnumDescriptor");
  (*variables)["storage_type"] = type;
  // For non repeated fields, if it was defined in a different file, the
  // property decls need to use "enum NAME" rather than just "NAME" to support
  // the forward declaration of the enums.
  if (!descriptor->is_repeated() &&
      (descriptor->file() != descriptor->enum_type()->file())) {
    (*variables)["property_type"] = absl::StrCat("enum ", type);
  }
  (*variables)["enum_verifier"] = absl::StrCat(type, "_IsValidValue");
  (*variables)["enum_desc_func"] = enum_desc_func;

  (*variables)["dataTypeSpecific_name"] = "enumDescFunc";
  (*variables)["dataTypeSpecific_value"] = enum_desc_func;

  const Descriptor* msg_descriptor = descriptor->containing_type();
  (*variables)["owning_message_class"] = ClassName(msg_descriptor);
}
}  // namespace

EnumFieldGenerator::EnumFieldGenerator(const FieldDescriptor* descriptor)
    : SingleFieldGenerator(descriptor) {
  SetEnumVariables(descriptor, &variables_);
}

void EnumFieldGenerator::GenerateCFunctionDeclarations(
    io::Printer* printer) const {
  if (descriptor_->enum_type()->is_closed()) {
    return;
  }

  auto vars = printer->WithVars(variables_);
  printer->Emit(R"objc(
    /**
     * Fetches the raw value of a @c $owning_message_class$'s @c $name$ property, even
     * if the value was not defined by the enum at the time the code was generated.
     **/
    int32_t $owning_message_class$_$capitalized_name$_RawValue($owning_message_class$ *message);
    /**
     * Sets the raw value of an @c $owning_message_class$'s @c $name$ property, allowing
     * it to be set to a value that was not defined by the enum at the time the code
     * was generated.
     **/
    void Set$owning_message_class$_$capitalized_name$_RawValue($owning_message_class$ *message, int32_t value);
  )objc");
  printer->Emit("\n");
}

void EnumFieldGenerator::GenerateCFunctionImplementations(
    io::Printer* printer) const {
  if (descriptor_->enum_type()->is_closed()) {
    return;
  }

  auto vars = printer->WithVars(variables_);
  printer->Emit(R"objc(
    int32_t $owning_message_class$_$capitalized_name$_RawValue($owning_message_class$ *message) {
      GPBDescriptor *descriptor = [$owning_message_class$ descriptor];
      GPBFieldDescriptor *field = [descriptor fieldWithNumber:$field_number_name$];
      return GPBGetMessageRawEnumField(message, field);
    }

    void Set$owning_message_class$_$capitalized_name$_RawValue($owning_message_class$ *message, int32_t value) {
      GPBDescriptor *descriptor = [$owning_message_class$ descriptor];
      GPBFieldDescriptor *field = [descriptor fieldWithNumber:$field_number_name$];
      GPBSetMessageRawEnumField(message, field, value);
    }
  )objc");
  printer->Emit("\n");
}

void EnumFieldGenerator::DetermineForwardDeclarations(
    absl::btree_set<std::string>* fwd_decls,
    bool include_external_types) const {
  SingleFieldGenerator::DetermineForwardDeclarations(fwd_decls,
                                                     include_external_types);
  // If it is an enum defined in a different file (and not a WKT), then we'll
  // need a forward declaration for it.  When it is in our file, all the enums
  // are output before the message, so it will be declared before it is needed.
  if (include_external_types &&
      descriptor_->file() != descriptor_->enum_type()->file() &&
      !IsProtobufLibraryBundledProtoFile(descriptor_->enum_type()->file())) {
    // Enum name is already in "storage_type".
    const std::string& name = variable("storage_type");
    fwd_decls->insert(absl::StrCat("GPB_ENUM_FWD_DECLARE(", name, ");"));
  }
}

RepeatedEnumFieldGenerator::RepeatedEnumFieldGenerator(
    const FieldDescriptor* descriptor)
    : RepeatedFieldGenerator(descriptor) {
  SetEnumVariables(descriptor, &variables_);
  variables_["array_storage_type"] = "GPBEnumArray";
}

void RepeatedEnumFieldGenerator::EmitArrayComment(io::Printer* printer) const {
  auto vars = printer->WithVars(variables_);
  printer->Emit(R"objc(
    // |$name$| contains |$storage_type$|
  )objc");
}

// NOTE: RepeatedEnumFieldGenerator::DetermineForwardDeclarations isn't needed
// because `GPBEnumArray` isn't generic (like `NSArray` would be for messages)
// and thus doesn't reference the type in the header.

}  // namespace objectivec
}  // namespace compiler
}  // namespace protobuf
}  // namespace google