// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_FORMATS_MP4_TRACK_RUN_ITERATOR_H_
#define MEDIA_FORMATS_MP4_TRACK_RUN_ITERATOR_H_

#include <stddef.h>
#include <stdint.h>

#include <memory>
#include <vector>

#include "base/containers/span.h"
#include "base/memory/raw_ptr.h"
#include "base/time/time.h"
#include "media/base/media_export.h"
#include "media/base/media_log.h"
#include "media/base/stream_parser_buffer.h"
#include "media/formats/mp4/box_definitions.h"
#include "media/media_buildflags.h"

namespace media {

class DecryptConfig;

namespace mp4 {

base::TimeDelta MEDIA_EXPORT TimeDeltaFromRational(int64_t numer,
                                                   int64_t denom);
DecodeTimestamp MEDIA_EXPORT DecodeTimestampFromRational(int64_t numer,
                                                         int64_t denom);

struct SampleInfo;
struct TrackRunInfo;

class MEDIA_EXPORT TrackRunIterator {
 public:
  // Create a new TrackRunIterator. A reference to |moov| will be retained for
  // the lifetime of this object.
  TrackRunIterator(const Movie* moov, MediaLog* media_log);

  TrackRunIterator(const TrackRunIterator&) = delete;
  TrackRunIterator& operator=(const TrackRunIterator&) = delete;

  ~TrackRunIterator();

  // Sets up the iterator to handle all the runs from the current fragment.
  bool Init(const MovieFragment& moof);

  // Returns true if the properties of the current run or sample are valid.
  bool IsRunValid() const;
  bool IsSampleValid() const;

  // Advance the properties to refer to the next run or sample. These return
  // |false| on failure, but note that advancing to the end (IsRunValid() or
  // IsSampleValid() return false) is not a failure, and the properties are not
  // guaranteed to be consistent in that case.
  bool AdvanceRun();
  bool AdvanceSample();

  // Returns true if this track run has auxiliary information and has not yet
  // been cached. Only valid if IsRunValid().
  bool AuxInfoNeedsToBeCached();

  // Caches the CENC data from the given buffer. |buf| must be a buffer starting
  // at the offset given by cenc_offset(), with a |size| of at least
  // cenc_size(). Returns true on success, false on error.
  bool CacheAuxInfo(base::span<const uint8_t> buf);

  // Returns the maximum buffer location at which no data earlier in the stream
  // will be required in order to read the current or any subsequent sample. You
  // may clear all data up to this offset before reading the current sample
  // safely. Result is in the same units as offset() (for Media Source this is
  // in bytes past the the head of the MOOF box).
  int64_t GetMaxClearOffset();

  // Property of the current run. Only valid if IsRunValid().
  uint32_t track_id() const;
  int64_t aux_info_offset() const;
  int aux_info_size() const;
  bool is_encrypted() const;
  // This will CHECK if the current track is not audio.
  const AudioSampleEntry& audio_description() const;
  // This will CHECK if the current track is not video.
  const VideoSampleEntry& video_description() const;

  // Properties of the current sample. Only valid if IsSampleValid().
  int64_t sample_offset() const;
  uint32_t sample_size() const;
  DecodeTimestamp dts() const;
  base::TimeDelta cts() const;
  base::TimeDelta duration() const;
  bool is_keyframe() const;

  // Only call when is_encrypted() is true and AuxInfoNeedsToBeCached() is
  // false. Result is owned by caller.
  std::unique_ptr<DecryptConfig> GetDecryptConfig();

 private:
  bool UpdateCts();
  bool ResetRun();
  const ProtectionSchemeInfo& protection_scheme_info() const;
  const TrackEncryption& track_encryption() const;

  uint32_t GetGroupDescriptionIndex(uint32_t sample_index) const;

  // Sample encryption information.
  bool IsSampleEncrypted(size_t sample_index) const;
  uint8_t GetIvSize(size_t sample_index) const;
  const std::vector<uint8_t>& GetKeyId(size_t sample_index) const;
  bool ApplyConstantIv(size_t sample_index, SampleEncryptionEntry* entry) const;

  raw_ptr<const Movie, DanglingUntriaged> moov_;
  const std::unique_ptr<MediaLog> media_log_;

  std::vector<TrackRunInfo> runs_;
  std::vector<TrackRunInfo>::const_iterator run_itr_;
  std::vector<SampleInfo>::const_iterator sample_itr_;

  int64_t sample_dts_ = 0;
  int64_t sample_cts_ = 0;
  int64_t sample_offset_ = 0;
};

}  // namespace mp4
}  // namespace media

#endif  // MEDIA_FORMATS_MP4_TRACK_RUN_ITERATOR_H_