bindings/input_hasher.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_BINDINGS_INPUT_HASHER_H_
#define THIRD_PARTY_CREDENTIO_BINDINGS_INPUT_HASHER_H_

#include <stdint.h>

#include <memory>
#include <string>

#include "absl/base/nullability.h"
#include "absl/status/status.h"
#include "absl/status/statusor.h"
#include "absl/strings/string_view.h"
#include "crypto/algorithms.h"
#include "crypto/hash.h"
#include "riegeli/bytes/reader.h"

namespace credentio {

// A simple hasher for C2PA hash computing.
class InputHasher {
 public:
  virtual ~InputHasher() = default;

  // Reads `length` bytes from `input` starting at `offset` and updates the
  // hash.
  virtual absl::Status Update(riegeli::Reader& input, uint64_t offset,
                              uint64_t length) = 0;

  // Updates the hash with `data`.
  virtual void Update(absl::string_view data) = 0;

  // Returns the hash digest.
  virtual std::string Digest() = 0;

  static absl::StatusOr<std::unique_ptr<InputHasher> absl_nonnull> Create(
      absl::string_view alg);
  static absl::StatusOr<std::unique_ptr<InputHasher> absl_nonnull> Create(
      HashAlgorithm alg);
  static absl::StatusOr<std::unique_ptr<InputHasher>> Create(
      std::unique_ptr<Hasher> absl_nonnull hasher);
};

}  // namespace credentio

#endif  // THIRD_PARTY_CREDENTIO_BINDINGS_INPUT_HASHER_H_