/*
 * Copyright 2024 The WebRTC project authors. All rights reserved.
 *
 * Use of this source code is governed by a BSD-style license
 * that can be found in the LICENSE file in the root of the source
 * tree. An additional intellectual property rights grant can be found
 * in the file PATENTS.  All contributing project authors may
 * be found in the AUTHORS file in the root of the source tree.
 */

#ifndef COMMON_VIDEO_CORRUPTION_DETECTION_MESSAGE_H_
#define COMMON_VIDEO_CORRUPTION_DETECTION_MESSAGE_H_

#include <cstddef>
#include <optional>

#include "absl/container/inlined_vector.h"
#include "api/array_view.h"

namespace webrtc {

class CorruptionDetectionMessage {
 public:
  class Builder;

  CorruptionDetectionMessage() = default;

  CorruptionDetectionMessage(const CorruptionDetectionMessage&) = default;
  CorruptionDetectionMessage& operator=(const CorruptionDetectionMessage&) =
      default;

  ~CorruptionDetectionMessage() = default;

  int sequence_index() const { return sequence_index_; }
  bool interpret_sequence_index_as_most_significant_bits() const {
    return interpret_sequence_index_as_most_significant_bits_;
  }
  double std_dev() const { return std_dev_; }
  int luma_error_threshold() const { return luma_error_threshold_; }
  int chroma_error_threshold() const { return chroma_error_threshold_; }
  rtc::ArrayView<const double> sample_values() const {
    return rtc::MakeArrayView(sample_values_.data(), sample_values_.size());
  }

 private:
  friend class CorruptionDetectionExtension;

  static const size_t kMaxSampleSize = 13;

  // Sequence index in the Halton sequence.
  // Valid values: [0, 2^7-1]
  int sequence_index_ = 0;

  // Whether to interpret the `sequence_index_` as the most significant bits of
  // the true sequence index.
  bool interpret_sequence_index_as_most_significant_bits_ = false;

  // Standard deviation of the Gaussian filter kernel.
  // Valid values: [0, 40.0]
  double std_dev_ = 0.0;

  // Corruption threshold for the luma layer.
  // Valid values: [0, 2^4 - 1]
  int luma_error_threshold_ = 0;

  // Corruption threshold for the chroma layer.
  // Valid values: [0, 2^4 - 1]
  int chroma_error_threshold_ = 0;

  // An ordered list of samples that are the result of applying the Gaussian
  // filter on the image. The coordinates of the samples and their layer are
  // determined by the Halton sequence.
  // An empty list should be interpreted as a way to keep the `sequence_index`
  // in sync.
  absl::InlinedVector<double, kMaxSampleSize> sample_values_;
};

class CorruptionDetectionMessage::Builder {
 public:
  Builder() = default;

  Builder(const Builder&) = default;
  Builder& operator=(const Builder&) = default;

  ~Builder() = default;

  std::optional<CorruptionDetectionMessage> Build() {
    if (message_.sequence_index_ < 0 ||
        message_.sequence_index_ > 0b0111'1111) {
      return std::nullopt;
    }
    if (message_.std_dev_ < 0.0 || message_.std_dev_ > 40.0) {
      return std::nullopt;
    }
    if (message_.luma_error_threshold_ < 0 ||
        message_.luma_error_threshold_ > 15) {
      return std::nullopt;
    }
    if (message_.chroma_error_threshold_ < 0 ||
        message_.chroma_error_threshold_ > 15) {
      return std::nullopt;
    }
    if (message_.sample_values_.size() > kMaxSampleSize) {
      return std::nullopt;
    }
    for (double sample_value : message_.sample_values_) {
      if (sample_value < 0.0 || sample_value > 255.0) {
        return std::nullopt;
      }
    }
    return message_;
  }

  Builder& WithSequenceIndex(int sequence_index) {
    message_.sequence_index_ = sequence_index;
    return *this;
  }

  Builder& WithInterpretSequenceIndexAsMostSignificantBits(
      bool interpret_sequence_index_as_most_significant_bits) {
    message_.interpret_sequence_index_as_most_significant_bits_ =
        interpret_sequence_index_as_most_significant_bits;
    return *this;
  }

  Builder& WithStdDev(double std_dev) {
    message_.std_dev_ = std_dev;
    return *this;
  }

  Builder& WithLumaErrorThreshold(int luma_error_threshold) {
    message_.luma_error_threshold_ = luma_error_threshold;
    return *this;
  }

  Builder& WithChromaErrorThreshold(int chroma_error_threshold) {
    message_.chroma_error_threshold_ = chroma_error_threshold;
    return *this;
  }

  Builder& WithSampleValues(const rtc::ArrayView<const double>& sample_values) {
    message_.sample_values_.assign(sample_values.cbegin(),
                                   sample_values.cend());
    return *this;
  }

 private:
  CorruptionDetectionMessage message_;
};

}  // namespace webrtc

#endif  // COMMON_VIDEO_CORRUPTION_DETECTION_MESSAGE_H_