validator/asset_validator.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_VALIDATOR_ASSET_VALIDATOR_H_
#define THIRD_PARTY_CREDENTIO_VALIDATOR_ASSET_VALIDATOR_H_

#include <memory>
#include <optional>

#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"
#include "riegeli/bytes/reader.h"
#include "validator/result.h"

namespace credentio {

// A validator of C2PA metadata embedded in media files (assets).
class AssetValidator {
 public:
  virtual ~AssetValidator() = default;

  // Extracts and verifies content credentials from an asset of a supported
  // type. Returns an error if validation could not be performed (e.g., due to
  // internal error) or no C2PA metadata is present.
  //
  // The `input` is a riegeli::Reader over the asset. It must support backwards
  // seeks (e.g., riegeli::FileReader, riegeli::StringReader).
  // The `media_type` is the IANA media type of the asset (e.g. "image/jpeg").
  // If not provided, the media type will be determined from the input.
  //
  // Example:
  // File input:
  //   ABSL_ASSIGN_OR_RETURN(std::string media_type,
  //                         credentio::MediaType(file_path));
  //   riegeli::FileReader reader(file_path);
  //   ABSL_RETURN_IF_ERROR(reader.status());
  //   absl::StatusOr<std::unique_ptr<ValidationResult>> result =
  //       validator->Validate(reader, *media_type);
  //
  // String input:
  //   std::string contents = "contents";
  //   riegeli::StringReader reader(contents);
  //   absl::StatusOr<std::unique_ptr<ValidationResult>> result =
  //       validator->Validate(reader, "image/jpeg");
  virtual absl::StatusOr<std::unique_ptr<ValidationResult>> Validate(
      riegeli::Reader& input,
      std::optional<absl::string_view> media_type) const = 0;
};

}  // namespace credentio

#endif  // THIRD_PARTY_CREDENTIO_VALIDATOR_ASSET_VALIDATOR_H_