formats/riff/chunk_header.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_RIFF_CHUNK_HEADER_H_
#define THIRD_PARTY_CREDENTIO_FORMATS_RIFF_CHUNK_HEADER_H_

#include <cstdint>
#include <string>

#include "absl/status/status.h"
#include "absl/strings/substitute.h"
#include "formats/riff/constants.h"
#include "riegeli/bytes/reader.h"
#include "riegeli/bytes/writer.h"
#include "riegeli/endian/endian_reading.h"
#include "riegeli/endian/endian_writing.h"

namespace credentio {

// Header of a chunk in a RIFF file.
struct ChunkHeader {
  std::string id;      // 4-character chunk ID.
  uint32_t data_size;  // Size of the chunk data, not including the header.

  static uint64_t header_size() { return kRiffIdSize + sizeof(uint32_t); }
  absl::Status Read(riegeli::Reader& input) {
    if (!input.Read(kRiffIdSize, id)) {
      return input.StatusOrAnnotate(
          absl::DataLossError("kUnexpectedEof; chunk_id"));
    }
    if (!riegeli::ReadLittleEndian<uint32_t>(input, data_size)) {
      return input.StatusOrAnnotate(
          absl::DataLossError("kUnexpectedEof; chunk_size"));
    }
    return absl::OkStatus();
  }
  absl::Status Write(riegeli::Writer& output) {
    if (id.size() != kRiffIdSize) {
      return absl::InvalidArgumentError(absl::Substitute(
          "chunk_id size is $0, expected $1", id.size(), kRiffIdSize));
    }
    if (!output.Write(id)) {
      return output.StatusOrAnnotate(
          absl::DataLossError("kDataLoss; chunk_id"));
    }
    if (!riegeli::WriteLittleEndian<uint32_t>(data_size, output)) {
      return output.StatusOrAnnotate(
          absl::DataLossError("kDataLoss; chunk_size"));
    }
    return absl::OkStatus();
  }

  uint64_t pad_size() const { return (data_size % 2 == 1) ? 1 : 0; }
  uint64_t chunk_size() const {
    return static_cast<uint64_t>(data_size) + 8 + pad_size();
  }
};

}  // namespace credentio

#endif  // THIRD_PARTY_CREDENTIO_FORMATS_RIFF_CHUNK_HEADER_H_