// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc.  All rights reserved.
// https://developers.google.com/protocol-buffers/
//
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#include <herogoogle/protobuf/util/internal/type_info.h>

#include <map>
#include <set>

#include <herogoogle/protobuf/stubs/common.h>
#include <herogoogle/protobuf/type.pb.h>
#include <herogoogle/protobuf/util/internal/utility.h>
#include <herogoogle/protobuf/stubs/status.h>
#include <herogoogle/protobuf/stubs/statusor.h>
#include <herogoogle/protobuf/stubs/strutil.h>
#include <herogoogle/protobuf/stubs/map_util.h>
#include <herogoogle/protobuf/stubs/status.h>

namespace herogoogle {
namespace protobuf {
namespace util {
namespace converter {

namespace {
// A TypeInfo that looks up information provided by a TypeResolver.
class TypeInfoForTypeResolver : public TypeInfo {
 public:
  explicit TypeInfoForTypeResolver(TypeResolver* type_resolver)
      : type_resolver_(type_resolver) {}

  virtual ~TypeInfoForTypeResolver() {
    DeleteCachedTypes(&cached_types_);
    DeleteCachedTypes(&cached_enums_);
  }

  util::StatusOr<const herogoogle::protobuf::Type*> ResolveTypeUrl(
      StringPiece type_url) const override {
    std::map<StringPiece, StatusOrType>::iterator it =
        cached_types_.find(type_url);
    if (it != cached_types_.end()) {
      return it->second;
    }
    // Stores the string value so it can be referenced using StringPiece in the
    // cached_types_ map.
    const std::string& string_type_url =
        *string_storage_.insert(std::string(type_url)).first;
    std::unique_ptr<herogoogle::protobuf::Type> type(new herogoogle::protobuf::Type());
    util::Status status =
        type_resolver_->ResolveMessageType(string_type_url, type.get());
    StatusOrType result =
        status.ok() ? StatusOrType(type.release()) : StatusOrType(status);
    cached_types_[string_type_url] = result;
    return result;
  }

  const herogoogle::protobuf::Type* GetTypeByTypeUrl(
      StringPiece type_url) const override {
    StatusOrType result = ResolveTypeUrl(type_url);
    return result.ok() ? result.value() : NULL;
  }

  const herogoogle::protobuf::Enum* GetEnumByTypeUrl(
      StringPiece type_url) const override {
    std::map<StringPiece, StatusOrEnum>::iterator it =
        cached_enums_.find(type_url);
    if (it != cached_enums_.end()) {
      return it->second.ok() ? it->second.value() : NULL;
    }
    // Stores the string value so it can be referenced using StringPiece in the
    // cached_enums_ map.
    const std::string& string_type_url =
        *string_storage_.insert(std::string(type_url)).first;
    std::unique_ptr<herogoogle::protobuf::Enum> enum_type(
        new herogoogle::protobuf::Enum());
    util::Status status =
        type_resolver_->ResolveEnumType(string_type_url, enum_type.get());
    StatusOrEnum result =
        status.ok() ? StatusOrEnum(enum_type.release()) : StatusOrEnum(status);
    cached_enums_[string_type_url] = result;
    return result.ok() ? result.value() : NULL;
  }

  const herogoogle::protobuf::Field* FindField(
      const herogoogle::protobuf::Type* type,
      StringPiece camel_case_name) const override {
    std::map<const herogoogle::protobuf::Type*, CamelCaseNameTable>::const_iterator
        it = indexed_types_.find(type);
    const CamelCaseNameTable& camel_case_name_table =
        (it == indexed_types_.end())
            ? PopulateNameLookupTable(type, &indexed_types_[type])
            : it->second;
    StringPiece name = FindWithDefault(
        camel_case_name_table, camel_case_name, StringPiece());
    if (name.empty()) {
      // Didn't find a mapping. Use whatever provided.
      name = camel_case_name;
    }
    return FindFieldInTypeOrNull(type, name);
  }

 private:
  typedef util::StatusOr<const herogoogle::protobuf::Type*> StatusOrType;
  typedef util::StatusOr<const herogoogle::protobuf::Enum*> StatusOrEnum;
  typedef std::map<StringPiece, StringPiece> CamelCaseNameTable;

  template <typename T>
  static void DeleteCachedTypes(std::map<StringPiece, T>* cached_types) {
    for (typename std::map<StringPiece, T>::iterator it =
             cached_types->begin();
         it != cached_types->end(); ++it) {
      if (it->second.ok()) {
        delete it->second.value();
      }
    }
  }

  const CamelCaseNameTable& PopulateNameLookupTable(
      const herogoogle::protobuf::Type* type,
      CamelCaseNameTable* camel_case_name_table) const {
    for (int i = 0; i < type->fields_size(); ++i) {
      const herogoogle::protobuf::Field& field = type->fields(i);
      StringPiece name = field.name();
      StringPiece camel_case_name = field.json_name();
      const StringPiece* existing = InsertOrReturnExisting(
          camel_case_name_table, camel_case_name, name);
      if (existing && *existing != name) {
        GOOGLE_LOG(WARNING) << "Field '" << name << "' and '" << *existing
                     << "' map to the same camel case name '" << camel_case_name
                     << "'.";
      }
    }
    return *camel_case_name_table;
  }

  TypeResolver* type_resolver_;

  // Stores string values that will be referenced by StringPieces in
  // cached_types_, cached_enums_.
  mutable std::set<std::string> string_storage_;

  mutable std::map<StringPiece, StatusOrType> cached_types_;
  mutable std::map<StringPiece, StatusOrEnum> cached_enums_;

  mutable std::map<const herogoogle::protobuf::Type*, CamelCaseNameTable>
      indexed_types_;
};
}  // namespace

TypeInfo* TypeInfo::NewTypeInfo(TypeResolver* type_resolver) {
  return new TypeInfoForTypeResolver(type_resolver);
}

}  // namespace converter
}  // namespace util
}  // namespace protobuf
}  // namespace google
