// libTorrent - BitTorrent library
// Copyright (C) 2005-2011, Jari Sundell
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
// (at your option) any later version.
// 
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
//
// In addition, as a special exception, the copyright holders give
// permission to link the code of portions of this program with the
// OpenSSL library under certain conditions as described in each
// individual source file, and distribute linked combinations
// including the two.
//
// You must obey the GNU General Public License in all respects for
// all of the code used other than OpenSSL.  If you modify file(s)
// with this exception, you may extend this exception to your version
// of the file(s), but you are not obligated to do so.  If you do not
// wish to do so, delete this exception statement from your version.
// If you delete this exception statement from all source files in the
// program, then also delete it here.
//
// Contact:  Jari Sundell <jaris@ifi.uio.no>
//
//           Skomakerveien 33
//           3185 Skoppum, NORWAY

#include "config.h"

#include "torrent/exceptions.h"

#include "file.h"
#include "file_list_iterator.h"

namespace torrent {

bool
FileListIterator::is_file() const {
  return m_depth >= 0 && m_depth + 1 == static_cast<int32_t>((*m_position)->path()->size());
}

bool
FileListIterator::is_empty() const {
  return (*m_position)->path()->empty();
}

bool
FileListIterator::is_entering() const {
  return m_depth >= 0 && m_depth + 1 != static_cast<int32_t>((*m_position)->path()->size());
}

FileListIterator&
FileListIterator::operator ++() {
  int32_t size = (*m_position)->path()->size();

  if (size == 0) {
    m_position++;
    return *this;
  }

  m_depth++;
  
  if (m_depth > size)
    throw internal_error("FileListIterator::operator ++() m_depth > size.");

  if (m_depth == size)
    m_depth = -(size - 1);

  if (m_depth == -static_cast<int32_t>((*m_position)->match_depth_next())) {
    m_depth = (*m_position)->match_depth_next();
    m_position++;
  }

  return *this;
}

FileListIterator&
FileListIterator::operator --() {
  // We're guaranteed that if m_depth != 0 then so is the path size,
  // so there's no need to check for it.
  if (m_depth == 0) {
    m_position--;

    // This ensures we properly start iterating the paths in a tree
    // without failing badly when size == 0.
    if ((*m_position)->path()->size() > 1)
      m_depth = -1;

  } else if (m_depth == static_cast<int32_t>((*m_position)->match_depth_prev())) {
    m_position--;

    // If only the last element differs, then we don't switch to
    // negative depth. Also make sure we skip the negative of the
    // current depth, as we index by the depth we're exiting from.
    if (m_depth + 1 != static_cast<int32_t>((*m_position)->path()->size()))
      m_depth = -(m_depth + 1);

  } else {
    auto size = static_cast<int32_t>((*m_position)->path()->size());
    m_depth--;

    if (m_depth < -size)
      throw internal_error("FileListIterator::operator --() m_depth < -size.");

    if (m_depth == -size)
      m_depth = size - 1;
  }

  return *this;
}

FileListIterator&
FileListIterator::forward_current_depth() {
  uint32_t baseDepth = depth();

  if (!is_entering())
    return ++(*this);

  // If the above test was false then we know there must be a
  // 'leaving' at baseDepth before the end of the list.
  do {
    ++(*this);
  } while (depth() > baseDepth);

  return *this;
}

FileListIterator&
FileListIterator::backward_current_depth() {
  --(*this);

  if (is_entering() || is_file() || is_empty())
    return *this;

  if (depth() == 0)
    throw internal_error("FileListIterator::backward_current_depth() depth() == 0.");

  uint32_t baseDepth = depth();
  
  while (depth() >= baseDepth)
    --(*this);

  return *this;
}

} // namespace torrent
