// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef MEDIA_BASE_BYTE_QUEUE_H_
#define MEDIA_BASE_BYTE_QUEUE_H_

#include <stdint.h>

#include "packager/base/memory/scoped_ptr.h"

namespace edash_packager {
namespace media {

/// Represents a queue of bytes.
/// Data is added to the end of the queue via an Push() and removed via Pop().
/// The contents of the queue can be observed via the Peek() method. This class
/// manages the underlying storage of the queue and tries to minimize the
/// number of buffer copies when data is appended and removed.
class ByteQueue {
 public:
  ByteQueue();
  ~ByteQueue();

  /// Reset the queue to the empty state.
  void Reset();

  /// Append new bytes to the end of the queue.
  void Push(const uint8_t* data, int size);

  /// Get a pointer to the front of the queue and the queue size.
  /// These values are only valid until the next Push() or Pop() call.
  void Peek(const uint8_t** data, int* size) const;

  /// Remove a number of bytes from the front of the queue.
  /// @param count specifies number of bytes to be popped.
  void Pop(int count);

 private:
  // Returns a pointer to the front of the queue.
  uint8_t* front() const;

  scoped_ptr<uint8_t[]> buffer_;

  // Size of |buffer_|.
  size_t size_;

  // Offset from the start of |buffer_| that marks the front of the queue.
  size_t offset_;

  // Number of bytes stored in the queue.
  int used_;

  DISALLOW_COPY_AND_ASSIGN(ByteQueue);
};

}  // namespace media
}  // namespace edash_packager

#endif  // MEDIA_BASE_BYTE_QUEUE_H_