/*
 * Copyright (C) 2011 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 *     * Neither the name of Google Inc. nor the names of its
 * contributors may be used to endorse or promote products derived from
 * this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "platform/SharedBufferChunkReader.h"

#include "platform/SharedBuffer.h"

namespace blink {

SharedBufferChunkReader::SharedBufferChunkReader(
    PassRefPtr<const SharedBuffer> buffer,
    const Vector<char>& separator)
    : m_buffer(buffer),
      m_bufferPosition(0),
      m_segment(0),
      m_segmentLength(0),
      m_segmentIndex(0),
      m_reachedEndOfFile(false),
      m_separator(separator),
      m_separatorIndex(0) {}

SharedBufferChunkReader::SharedBufferChunkReader(
    PassRefPtr<const SharedBuffer> buffer,
    const char* separator)
    : m_buffer(buffer),
      m_bufferPosition(0),
      m_segment(0),
      m_segmentLength(0),
      m_segmentIndex(0),
      m_reachedEndOfFile(false),
      m_separatorIndex(0) {
  setSeparator(separator);
}

void SharedBufferChunkReader::setSeparator(const Vector<char>& separator) {
  m_separator = separator;
}

void SharedBufferChunkReader::setSeparator(const char* separator) {
  m_separator.clear();
  m_separator.append(separator, strlen(separator));
}

bool SharedBufferChunkReader::nextChunk(Vector<char>& chunk,
                                        bool includeSeparator) {
  if (m_reachedEndOfFile)
    return false;

  chunk.clear();
  while (true) {
    while (m_segmentIndex < m_segmentLength) {
      char currentCharacter = m_segment[m_segmentIndex++];
      if (currentCharacter != m_separator[m_separatorIndex]) {
        if (m_separatorIndex > 0) {
          SECURITY_DCHECK(m_separatorIndex <= m_separator.size());
          chunk.append(m_separator.data(), m_separatorIndex);
          m_separatorIndex = 0;
        }
        chunk.append(currentCharacter);
        continue;
      }
      m_separatorIndex++;
      if (m_separatorIndex == m_separator.size()) {
        if (includeSeparator)
          chunk.appendVector(m_separator);
        m_separatorIndex = 0;
        return true;
      }
    }

    // Read the next segment.
    m_segmentIndex = 0;
    m_bufferPosition += m_segmentLength;
    m_segmentLength = m_buffer->getSomeData(m_segment, m_bufferPosition);
    if (!m_segmentLength) {
      m_reachedEndOfFile = true;
      if (m_separatorIndex > 0)
        chunk.append(m_separator.data(), m_separatorIndex);
      return !chunk.isEmpty();
    }
  }
  ASSERT_NOT_REACHED();
  return false;
}

String SharedBufferChunkReader::nextChunkAsUTF8StringWithLatin1Fallback(
    bool includeSeparator) {
  Vector<char> data;
  if (!nextChunk(data, includeSeparator))
    return String();

  return data.size()
             ? String::fromUTF8WithLatin1Fallback(data.data(), data.size())
             : emptyString();
}

size_t SharedBufferChunkReader::peek(Vector<char>& data, size_t requestedSize) {
  data.clear();
  if (requestedSize <= m_segmentLength - m_segmentIndex) {
    data.append(m_segment + m_segmentIndex, requestedSize);
    return requestedSize;
  }

  size_t readBytesCount = m_segmentLength - m_segmentIndex;
  data.append(m_segment + m_segmentIndex, readBytesCount);

  size_t bufferPosition = m_bufferPosition + m_segmentLength;
  const char* segment = 0;
  while (size_t segmentLength =
             m_buffer->getSomeData(segment, bufferPosition)) {
    if (requestedSize <= readBytesCount + segmentLength) {
      data.append(segment, requestedSize - readBytesCount);
      readBytesCount += (requestedSize - readBytesCount);
      break;
    }
    data.append(segment, segmentLength);
    readBytesCount += segmentLength;
    bufferPosition += segmentLength;
  }
  return readBytesCount;
}

}  // namespace blink