utils/media_type.cc

// Copyright 2026 Google LLC
//
// 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
//
//    https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

#include "utils/media_type.h"

#include <string>

#include "absl/base/no_destructor.h"
#include "absl/container/flat_hash_map.h"
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/ascii.h"
#include "absl/strings/str_cat.h"
#include "absl/strings/string_view.h"

namespace credentio {
namespace {

// Returns the part of the filename after the final ".", or an empty string if
// the filename does not have a ".".
absl::string_view GetFileExtension(absl::string_view filename) {
  auto dot_pos = filename.rfind('.');
  if (dot_pos == absl::string_view::npos) return "";
  return filename.substr(dot_pos + 1);
}

}  // namespace

absl::StatusOr<std::string> MediaType(absl::string_view filename) {
  static absl::NoDestructor<absl::flat_hash_map<std::string, std::string>>
      kExtensionToMediaType({
          {"avif", "image/avif"},
          {"heic", "image/heic"},
          {"heif", "image/heif"},
          {"jpeg", "image/jpeg"},
          {"jpg", "image/jpeg"},
          {"m4a", "audio/mp4"},
          {"mp4", "video/mp4"},
          {"pdf", "application/pdf"},
          {"png", "image/png"},
          {"webp", "image/webp"},
          {"mov", "video/quicktime"},
          {"dng", "image/x-adobe-dng"},
          {"tif", "image/tiff"},
          {"tiff", "image/tiff"},
          {"wav", "audio/wav"},  // Not formally registered.
          {"gif", "image/gif"},
          {"mp3", "audio/mpeg"},
          {"flac", "audio/flac"},
          {"pptx",
           "application/"
           "vnd.openxmlformats-officedocument.presentationml.presentation"},
          {"docx",
           "application/"
           "vnd.openxmlformats-officedocument.wordprocessingml.document"},
          {"xlsx",
           "application/"
           "vnd.openxmlformats-officedocument.spreadsheetml.sheet"},
      });
  std::string extension = absl::AsciiStrToLower(GetFileExtension(filename));
  auto it = kExtensionToMediaType->find(extension);
  if (it != kExtensionToMediaType->end()) {
    return it->second;
  }
  return absl::InvalidArgumentError(
      absl::StrCat("Unsupported file extension: \"", extension, "\""));
}

}  // namespace credentio