/*
    * Licensed to the Apache Software Foundation (ASF) under one or more
    * contributor license agreements.  See the NOTICE file distributed with
    * this work for additional information regarding copyright ownership.
    * The ASF licenses this file to You under the Apache License, Version 2.0
    * (the "License"); you may not use this file except in compliance with
    * the License.  You may obtain a copy of the License at
    *
    *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  package org.apache.commons.vfs2.provider.local;
  
  import org.apache.commons.vfs2.FileName;
  import org.apache.commons.vfs2.FileSystemException;
  import org.apache.commons.vfs2.FileType;
  
  /**
   * A parser for Windows file names.
   */
  public class WindowsFileNameParser extends LocalFileNameParser {
  
      /**
       * Constructs a new instance.
       */
      public WindowsFileNameParser() {
          // empty
      }
  
      @Override
      protected FileName createFileName(final String scheme, final String rootFile, final String path,
              final FileType type) {
          return new WindowsFileName(scheme, rootFile, path, type);
      }
  
      /**
       * Extracts a drive prefix from a path. Leading '/' chars have been removed.
       */
      private String extractDrivePrefix(final StringBuilder name) {
          // Looking for <letter> ':' '/'
          if (name.length() < 3) {
              // Too short
              return null;
          }
          final char ch = name.charAt(0);
          if (ch == '/' || ch == ':') {
              // Missing drive letter
              return null;
          }
          if (name.charAt(1) != ':') {
              // Missing ':'
              return null;
          }
          if (name.charAt(2) != '/') {
              // Missing separator
              return null;
          }
  
          final String prefix = name.substring(0, 2);
          name.delete(0, 2);
  
          return prefix.intern();
      }
  
      /**
       * Pops the root prefix off a URI, which has had the scheme removed.
       */
      @Override
      protected String extractRootPrefix(final String uri, final StringBuilder name) throws FileSystemException {
          return extractWindowsRootPrefix(uri, name);
      }
  
      /**
       * Extracts a UNC name from a path. Leading '/' chars have been removed.
       */
      private String extractUNCPrefix(final String uri, final StringBuilder name) throws FileSystemException {
          // Looking for <name> '/' <name> ( '/' | <end> )
  
          // Look for first separator
          final int maxpos = name.length();
          int pos = 0;
          while (pos < maxpos && name.charAt(pos) != '/') {
              pos++;
          }
          pos++;
          if (pos >= maxpos) {
              throw new FileSystemException("vfs.provider.local/missing-share-name.error", uri);
          }
  
          // Now have <name> '/'
          final int startShareName = pos;
          while (pos < maxpos && name.charAt(pos) != '/') {
              pos++;
          }
         if (pos == startShareName) {
             throw new FileSystemException("vfs.provider.local/missing-share-name.error", uri);
         }
 
         // Now have <name> '/' <name> ( '/' | <end> )
         final String prefix = name.substring(0, pos);
         name.delete(0, pos);
         return prefix;
     }
 
     /**
      * Extracts a Windows root prefix from a name.
      */
     private String extractWindowsRootPrefix(final String uri, final StringBuilder name) throws FileSystemException {
         // Looking for:
         // ('/'){0, 3} <letter> ':' '/'
         // ['/'] '//' <name> '/' <name> ( '/' | <end> )
 
         // Skip over first 4 (unc) leading '/' chars
         int startPos = 0;
         final int maxlen = Math.min(4, name.length());
         while (startPos < maxlen && name.charAt(startPos) == '/') {
             startPos++;
         }
         if (startPos == maxlen && name.length() > startPos + 1 && name.charAt(startPos + 1) == '/') {
             // Too many '/'
             throw new FileSystemException("vfs.provider.local/not-absolute-file-name.error", uri);
         }
         name.delete(0, startPos);
 
         // Look for drive name
         final String driveName = extractDrivePrefix(name);
         if (driveName != null) {
             return driveName;
         }
 
         // Look for UNC name
         if (startPos < 2) {
             throw new FileSystemException("vfs.provider.local/not-absolute-file-name.error", uri);
         }
 
         return "//" + extractUNCPrefix(uri, name);
     }
 }