SafeFileNamePhrase.java

/**
 * Licensed to Apereo under one or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information regarding copyright ownership. Apereo
 * 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 the
 * following location:
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>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.jasig.portlet.calendar.io;

import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
import org.danann.cernunnos.EntityConfig;
import org.danann.cernunnos.Formula;
import org.danann.cernunnos.Phrase;
import org.danann.cernunnos.Reagent;
import org.danann.cernunnos.ReagentType;
import org.danann.cernunnos.SimpleFormula;
import org.danann.cernunnos.SimpleReagent;
import org.danann.cernunnos.TaskRequest;
import org.danann.cernunnos.TaskResponse;

/**
 * @author Eric Dalquist
 * @version $Revision$
 */
public class SafeFileNamePhrase implements Phrase {

  // Reserved names on Windows (see http://en.wikipedia.org/wiki/Filename)
  private static final Pattern[] WINDOWS_INVALID_PATTERNS =
      new Pattern[] {
        Pattern.compile("AUX"),
        Pattern.compile("CLOCK\\$"),
        Pattern.compile("COM\\d*"),
        Pattern.compile("CON"),
        Pattern.compile("LPT\\d*"),
        Pattern.compile("NUL"),
        Pattern.compile("PRN")
      };

  private static final Map<Pattern, String> REPLACEMENT_PAIRS;

  static {
    final Map<Pattern, String> pairs = new LinkedHashMap<Pattern, String>();
    pairs.put(Pattern.compile("/|\\\\"), ".");
    pairs.put(Pattern.compile("[~`@\\|\\s#$\\*]"), "_");
    REPLACEMENT_PAIRS = Collections.unmodifiableMap(pairs);
  }

  public static final Reagent HUMAN_FILE_NAME =
      new SimpleReagent(
          "HUMAN_FILE_NAME",
          "descendant-or-self::text()",
          ReagentType.PHRASE,
          String.class,
          "Human readable version of the file name to make safe");

  // Instance Members.
  private Phrase humanFileNamePhrase;

  /* (non-Javadoc)
   * @see org.danann.cernunnos.Bootstrappable#init(org.danann.cernunnos.EntityConfig)
   */
  public void init(EntityConfig config) {
    this.humanFileNamePhrase = (Phrase) config.getValue(HUMAN_FILE_NAME);
  }

  /* (non-Javadoc)
   * @see org.danann.cernunnos.Bootstrappable#getFormula()
   */
  public Formula getFormula() {
    return new SimpleFormula(SafeFileNamePhrase.class, new Reagent[] {HUMAN_FILE_NAME});
  }

  /* (non-Javadoc)
   * @see org.danann.cernunnos.Phrase#evaluate(org.danann.cernunnos.TaskRequest, org.danann.cernunnos.TaskResponse)
   */
  public Object evaluate(TaskRequest req, TaskResponse res) {
    final String humanFileName = (String) this.humanFileNamePhrase.evaluate(req, res);

    return this.getSafeFileName(humanFileName);
  }

  protected String getSafeFileName(String name) {
    //Replace invalid characters
    for (final Map.Entry<Pattern, String> pair : REPLACEMENT_PAIRS.entrySet()) {
      final Pattern pattern = pair.getKey();
      final Matcher matcher = pattern.matcher(name);
      name = matcher.replaceAll(pair.getValue());
    }

    // Make sure the name doesn't violate a Windows reserved word...
    final String upperCaseName = name.toUpperCase();
    for (Pattern pattern : WINDOWS_INVALID_PATTERNS) {
      if (pattern.matcher(upperCaseName).matches()) {
        name = "uP-" + name;
        break;
      }
    }

    return name;
  }
}