/*
 *  Copyright (c) 2012 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 MODULES_AUDIO_CODING_NETEQ_AUDIO_VECTOR_H_
#define MODULES_AUDIO_CODING_NETEQ_AUDIO_VECTOR_H_

#include <string.h>
#include <cstdint>
#include <memory>

#include "rtc_base/checks.h"
#include "rtc_base/constructor_magic.h"

namespace webrtc {

class AudioVector {
 public:
  // Creates an empty AudioVector.
  AudioVector();

  // Creates an AudioVector with an initial size.
  explicit AudioVector(size_t initial_size);

  virtual ~AudioVector();

  // Deletes all values and make the vector empty.
  virtual void Clear();

  // Copies all values from this vector to |copy_to|. Any contents in |copy_to|
  // are deleted before the copy operation. After the operation is done,
  // |copy_to| will be an exact replica of this object.
  virtual void CopyTo(AudioVector* copy_to) const;

  // Copies |length| values from |position| in this vector to |copy_to|.
  virtual void CopyTo(size_t length, size_t position, int16_t* copy_to) const;

  // Prepends the contents of AudioVector |prepend_this| to this object. The
  // length of this object is increased with the length of |prepend_this|.
  virtual void PushFront(const AudioVector& prepend_this);

  // Same as above, but with an array |prepend_this| with |length| elements as
  // source.
  virtual void PushFront(const int16_t* prepend_this, size_t length);

  // Same as PushFront but will append to the end of this object.
  virtual void PushBack(const AudioVector& append_this);

  // Appends a segment of |append_this| to the end of this object. The segment
  // starts from |position| and has |length| samples.
  virtual void PushBack(const AudioVector& append_this,
                        size_t length,
                        size_t position);

  // Same as PushFront but will append to the end of this object.
  virtual void PushBack(const int16_t* append_this, size_t length);

  // Removes |length| elements from the beginning of this object.
  virtual void PopFront(size_t length);

  // Removes |length| elements from the end of this object.
  virtual void PopBack(size_t length);

  // Extends this object with |extra_length| elements at the end. The new
  // elements are initialized to zero.
  virtual void Extend(size_t extra_length);

  // Inserts |length| elements taken from the array |insert_this| and insert
  // them at |position|. The length of the AudioVector is increased by |length|.
  // |position| = 0 means that the new values are prepended to the vector.
  // |position| = Size() means that the new values are appended to the vector.
  virtual void InsertAt(const int16_t* insert_this,
                        size_t length,
                        size_t position);

  // Like InsertAt, but inserts |length| zero elements at |position|.
  virtual void InsertZerosAt(size_t length, size_t position);

  // Overwrites |length| elements of this AudioVector starting from |position|
  // with first values in |AudioVector|. The definition of |position|
  // is the same as for InsertAt(). If |length| and |position| are selected
  // such that the new data extends beyond the end of the current AudioVector,
  // the vector is extended to accommodate the new data.
  virtual void OverwriteAt(const AudioVector& insert_this,
                           size_t length,
                           size_t position);

  // Overwrites |length| elements of this AudioVector with values taken from the
  // array |insert_this|, starting at |position|. The definition of |position|
  // is the same as for InsertAt(). If |length| and |position| are selected
  // such that the new data extends beyond the end of the current AudioVector,
  // the vector is extended to accommodate the new data.
  virtual void OverwriteAt(const int16_t* insert_this,
                           size_t length,
                           size_t position);

  // Appends |append_this| to the end of the current vector. Lets the two
  // vectors overlap by |fade_length| samples, and cross-fade linearly in this
  // region.
  virtual void CrossFade(const AudioVector& append_this, size_t fade_length);

  // Returns the number of elements in this AudioVector.
  virtual size_t Size() const;

  // Returns true if this AudioVector is empty.
  virtual bool Empty() const;

  // Accesses and modifies an element of AudioVector.
  inline const int16_t& operator[](size_t index) const {
    return array_[WrapIndex(index, begin_index_, capacity_)];
  }

  inline int16_t& operator[](size_t index) {
    return array_[WrapIndex(index, begin_index_, capacity_)];
  }

 private:
  static const size_t kDefaultInitialSize = 10;

  // This method is used by the [] operators to calculate an index within the
  // capacity of the array, but without using the modulo operation (%).
  static inline size_t WrapIndex(size_t index,
                                 size_t begin_index,
                                 size_t capacity) {
    RTC_DCHECK_LT(index, capacity);
    RTC_DCHECK_LT(begin_index, capacity);
    size_t ix = begin_index + index;
    RTC_DCHECK_GE(ix, index);  // Check for overflow.
    if (ix >= capacity) {
      ix -= capacity;
    }
    RTC_DCHECK_LT(ix, capacity);
    return ix;
  }

  void Reserve(size_t n);

  void InsertByPushBack(const int16_t* insert_this,
                        size_t length,
                        size_t position);

  void InsertByPushFront(const int16_t* insert_this,
                         size_t length,
                         size_t position);

  void InsertZerosByPushBack(size_t length, size_t position);

  void InsertZerosByPushFront(size_t length, size_t position);

  std::unique_ptr<int16_t[]> array_;

  size_t capacity_;  // Allocated number of samples in the array.

  // The index of the first sample in |array_|, except when
  // |begin_index_ == end_index_|, which indicates an empty buffer.
  size_t begin_index_;

  // The index of the sample after the last sample in |array_|.
  size_t end_index_;

  RTC_DISALLOW_COPY_AND_ASSIGN(AudioVector);
};

}  // namespace webrtc
#endif  // MODULES_AUDIO_CODING_NETEQ_AUDIO_VECTOR_H_