formats/jpeg/testing/app_segment_creator.h

// 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.
//

#ifndef THIRD_PARTY_CREDENTIO_FORMATS_JPEG_TESTING_APP_SEGMENT_CREATOR_H_
#define THIRD_PARTY_CREDENTIO_FORMATS_JPEG_TESTING_APP_SEGMENT_CREATOR_H_

#include <cstdint>
#include <optional>
#include <string>
#include <vector>

#include "absl/status/statusor.h"

namespace credentio {

struct AppSegmentParams {
  uint16_t marker = 0xffeb;                   // APP11 Marker
  uint16_t cl = 0x4a50;                       // APP11 JPEG Extension Indicator
  std::optional<uint16_t> en = std::nullopt;  // En: Instance Number

  // Maximum size of the segment in bytes
  uint32_t max_size = 65535;

  // Z is the sequence number of the segment starting at the speficied value and
  // using the z_incrementer function to increment
  uint32_t starting_z = 1;
  uint32_t (*z_incrementer)(uint32_t) = [](uint32_t z) { return z + 1; };

  // The data to be embedded, potentially split into multiple segments
  std::string payload;
};

// Creates Jpeg APP segments they are APP11 segments by default but can be
// overridden by setting the various fields within the AppSegmentParams
// See ISO/IEC 18477-3:2023 for the specification of APP segments
absl::StatusOr<std::vector<std::string>> CreateAppSegments(
    AppSegmentParams params);

}  // namespace credentio

#endif  // THIRD_PARTY_CREDENTIO_FORMATS_JPEG_TESTING_APP_SEGMENT_CREATOR_H_