// Copyright (c) 2010 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 NET_BASE_UPLOAD_DATA_STREAM_H_
#define NET_BASE_UPLOAD_DATA_STREAM_H_
#pragma once

#include "base/scoped_ptr.h"
#include "net/base/upload_data.h"

namespace net {

class FileStream;
class IOBuffer;

class UploadDataStream {
 public:
  // Returns a new instance of UploadDataStream if it can be created and
  // initialized successfully. If not, NULL will be returned and the error
  // code will be set if the output parameter error_code is not empty.
  static UploadDataStream* Create(UploadData* data, int* error_code);

  ~UploadDataStream();

  // Returns the stream's buffer and buffer length.
  IOBuffer* buf() const { return buf_; }
  size_t buf_len() const { return buf_len_; }

  // Call to indicate that a portion of the stream's buffer was consumed.  This
  // call modifies the stream's buffer so that it contains the next segment of
  // the upload data to be consumed.
  void DidConsume(size_t num_bytes);

  // Returns the total size of the data stream and the current position.
  // size() is not to be used to determine whether the stream has ended
  // because it is possible for the stream to end before its size is reached,
  // for example, if the file is truncated.
  uint64 size() const { return total_size_; }
  uint64 position() const { return current_position_; }

  // Returns whether there is no more data to read, regardless of whether
  // position < size.
  bool eof() const { return eof_; }

 private:
  // Protects from public access since now we have a static creator function
  // which will do both creation and initialization and might return an error.
  explicit UploadDataStream(UploadData* data);

  // Fills the buffer with any remaining data and sets eof_ if there was nothing
  // left to fill the buffer with.
  // Returns OK if the operation succeeds. Otherwise error code is returned.
  int FillBuf();

  UploadData* data_;

  // This buffer is filled with data to be uploaded.  The data to be sent is
  // always at the front of the buffer.  If we cannot send all of the buffer at
  // once, then we memmove the remaining portion and back-fill the buffer for
  // the next "write" call.  buf_len_ indicates how much data is in the buffer.
  enum { kBufSize = 16384 };
  scoped_refptr<IOBuffer> buf_;
  size_t buf_len_;

  // Iterator to the upload element to be written to the send buffer next.
  std::vector<UploadData::Element>::iterator next_element_;

  // The byte offset into next_element_'s data buffer if the next element is
  // a TYPE_BYTES element.
  size_t next_element_offset_;

  // A stream to the currently open file, for next_element_ if the next element
  // is a TYPE_FILE element.
  scoped_ptr<FileStream> next_element_stream_;

  // The number of bytes remaining to be read from the currently open file
  // if the next element is of TYPE_FILE.
  uint64 next_element_remaining_;

  // Size and current read position within the stream.
  uint64 total_size_;
  uint64 current_position_;

  // Whether there is no data left to read.
  bool eof_;

  DISALLOW_COPY_AND_ASSIGN(UploadDataStream);
};

}  // namespace net

#endif  // NET_BASE_UPLOAD_DATA_STREAM_H_