formats/tiff/writer.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_TIFF_WRITER_H_
#define THIRD_PARTY_CREDENTIO_FORMATS_TIFF_WRITER_H_

#include <cstdint>
#include <utility>
#include <vector>

#include "absl/base/nullability.h"
#include "absl/container/flat_hash_set.h"
#include "absl/functional/any_invocable.h"
#include "absl/log/die_if_null.h"
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "formats/byte_range.h"
#include "formats/tiff/reader.h"
#include "generator/generator.h"
#include "proto/generator.pb.h"
#include "riegeli/bytes/reader.h"
#include "riegeli/bytes/writer.h"
#include "utils/byte_instruction.h"

namespace credentio {

// Writer of C2PA manifest stores into TIFF images.
class TiffWriter {
 public:
  struct OutputMetadata {
    bool timestamp_included = false;
  };

  // A function that determines byte ranges associated with a given IFD entry to
  // be excluded from hashing.
  using ExclusionProcessor =
      absl::AnyInvocable<absl::StatusOr<std::vector<ByteRange>>(
          riegeli::Reader&, const TiffImageFileDirectoryEntry&, TiffEndianness,
          absl::flat_hash_set<uint32_t>&, const GenerateManifestStoreRequest&)
                             const>;

  struct Options {
    ExclusionProcessor exclusion_processor = nullptr;
  };

  // Creates a TIFF writer.
  //
  // The generator must outlive the writer.
  explicit TiffWriter(const ManifestStoreGenerator* absl_nonnull generator)
      : TiffWriter(generator, Options{}) {}

  TiffWriter(const ManifestStoreGenerator* absl_nonnull generator,
             Options options)
      : generator_(*ABSL_DIE_IF_NULL(generator)),
        options_(std::move(options)) {}

  // Generates a C2PA manifest store and embeds it into a copy of the given
  // asset. The riegeli::Reader and riegeli::Writer cannot be pointed to the
  // same underlying data. The request must not include `hard_binding`.
  // Fails if C2PA metadata already exists.
  absl::Status Write(
      GenerateManifestStoreRequest request,
      riegeli::Reader* absl_nonnull source,
      riegeli::Writer* absl_nonnull destination,
      OutputMetadata* absl_nullable output_metadata = nullptr) const;

  // Generates and embeds C2PA manifest in place into the given asset.
  absl::Status Write(
      GenerateManifestStoreRequest request, riegeli::Writer* absl_nonnull asset,
      OutputMetadata* absl_nullable output_metadata = nullptr) const;

 private:
  absl::StatusOr<std::vector<ByteInstruction>> WriteInternal(
      GenerateManifestStoreRequest request,
      riegeli::Reader* absl_nonnull source,
      OutputMetadata* absl_nullable output_metadata) const;

  const ManifestStoreGenerator& generator_;
  Options options_;
};

}  // namespace credentio

#endif  // THIRD_PARTY_CREDENTIO_FORMATS_TIFF_WRITER_H_