formats/pdf/embedder.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_PDF_EMBEDDER_H_
#define THIRD_PARTY_CREDENTIO_FORMATS_PDF_EMBEDDER_H_

#include <cstdint>

#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/cord.h"
#include "absl/strings/string_view.h"
#include "riegeli/bytes/reader.h"
#include "riegeli/bytes/writer.h"

namespace credentio {

// A utility class for embedding a C2PA manifest store as an embedded file
// stream in a non-C2PA PDF file.
class PdfEmbedder {
 public:
  explicit PdfEmbedder() = default;

  // Rewrites a PDF file to be C2PA-embeddable, making necessary updates while
  // preserving the original structure. Returns the offset of the zero-filled
  // manifest store in the output. Fails if the input PDF already contains a
  // C2PA manifest store or if rewriting fails.
  absl::StatusOr<int64_t> RewriteForEmbedding(
      riegeli::Reader& input, int64_t estimated_manifest_store_size,
      riegeli::Writer& output) const;

  // Embeds the C2PA manifest store at the insertion point.
  absl::Status Embed(absl::string_view manifest_store, int64_t insert_at_offset,
                     absl::Cord& embeddable_asset) const;
};

}  // namespace credentio

#endif  // THIRD_PARTY_CREDENTIO_FORMATS_PDF_EMBEDDER_H_