/*
 * Copyright (C) 2010 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 "modules/filesystem/DOMFilePath.h"

#include "wtf/Vector.h"
#include "wtf/text/CString.h"
#include "wtf/text/StringBuilder.h"

namespace blink {

const char DOMFilePath::separator = '/';
const char DOMFilePath::root[] = "/";

String DOMFilePath::append(const String& base, const String& components) {
  return ensureDirectoryPath(base) + components;
}

String DOMFilePath::ensureDirectoryPath(const String& path) {
  if (!DOMFilePath::endsWithSeparator(path))
    return path + DOMFilePath::separator;
  return path;
}

String DOMFilePath::getName(const String& path) {
  int index = path.reverseFind(DOMFilePath::separator);
  if (index != -1)
    return path.substring(index + 1);
  return path;
}

String DOMFilePath::getDirectory(const String& path) {
  int index = path.reverseFind(DOMFilePath::separator);
  if (!index)
    return DOMFilePath::root;
  if (index != -1)
    return path.substring(0, index);
  return ".";
}

bool DOMFilePath::isParentOf(const String& parent, const String& mayBeChild) {
  ASSERT(DOMFilePath::isAbsolute(parent));
  ASSERT(DOMFilePath::isAbsolute(mayBeChild));
  if (parent == DOMFilePath::root && mayBeChild != DOMFilePath::root)
    return true;
  if (parent.length() >= mayBeChild.length() ||
      !mayBeChild.startsWith(parent, TextCaseUnicodeInsensitive))
    return false;
  if (mayBeChild[parent.length()] != DOMFilePath::separator)
    return false;
  return true;
}

String DOMFilePath::removeExtraParentReferences(const String& path) {
  ASSERT(DOMFilePath::isAbsolute(path));
  Vector<String> components;
  Vector<String> canonicalized;
  path.split(DOMFilePath::separator, components);
  for (size_t i = 0; i < components.size(); ++i) {
    if (components[i] == ".")
      continue;
    if (components[i] == "..") {
      if (canonicalized.size() > 0)
        canonicalized.pop_back();
      continue;
    }
    canonicalized.append(components[i]);
  }
  if (canonicalized.isEmpty())
    return DOMFilePath::root;
  StringBuilder result;
  for (size_t i = 0; i < canonicalized.size(); ++i) {
    result.append(DOMFilePath::separator);
    result.append(canonicalized[i]);
  }
  return result.toString();
}

bool DOMFilePath::isValidPath(const String& path) {
  if (path.isEmpty() || path == DOMFilePath::root)
    return true;

  // Embedded NULs are not allowed.
  if (path.find(static_cast<UChar>(0)) != WTF::kNotFound)
    return false;

  // While not [yet] restricted by the spec, '\\' complicates implementation for
  // Chromium.
  if (path.find('\\') != WTF::kNotFound)
    return false;

  // This method is only called on fully-evaluated absolute paths. Any sign of
  // ".." or "." is likely an attempt to break out of the sandbox.
  Vector<String> components;
  path.split(DOMFilePath::separator, components);
  for (size_t i = 0; i < components.size(); ++i) {
    if (components[i] == ".")
      return false;
    if (components[i] == "..")
      return false;
  }
  return true;
}

bool DOMFilePath::isValidName(const String& name) {
  if (name.isEmpty())
    return true;
  // '/' is not allowed in name.
  if (name.contains('/'))
    return false;
  return isValidPath(name);
}

}  // namespace blink