content: /*
   * Copyright 2014 Agorava
   *
   * Licensed 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.agorava.api.service;
  
  import org.agorava.api.exception.AgoravaException;
  
  import java.io.UnsupportedEncodingException;
  import java.net.URLDecoder;
  import java.net.URLEncoder;
  import java.util.Collections;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.regex.Pattern;
  
  /**
   * Utility class to encode and decode string for OAuth Format
   *
   * @author Pablo Fernandez
   * @author Antoine Sabot-Durand
   */
  public class OAuthEncoder {
      private static final Map<String, String> ENCODING_RULES;
  
      static {
          Map<String, String> rules = new HashMap<String, String>();
          rules.put("*", "%2A");
          rules.put("+", "%20");
          rules.put("%7E", "~");
          ENCODING_RULES = Collections.unmodifiableMap(rules);
      }
  
      private static String CHARSET = "UTF-8";
  
      /* preventing instantiation */
      private OAuthEncoder() {
      }
  
      /**
       * Encode a String in OAuth format
       *
       * @param plain string to encode
       * @return encoded string
       */
      public static String encode(String plain) {
          Preconditions.checkNotNull(plain, "Cannot encode null object");
          String encoded = "";
          try {
              encoded = URLEncoder.encode(plain, CHARSET);
          } catch (UnsupportedEncodingException uee) {
              throw new AgoravaException("Charset not found while encoding string: " + CHARSET, uee);
          }
          for (Map.Entry<String, String> rule : ENCODING_RULES.entrySet()) {
              encoded = applyRule(encoded, rule.getKey(), rule.getValue());
          }
          return encoded;
      }
  
      private static String applyRule(String encoded, String toReplace, String replacement) {
          return encoded.replaceAll(Pattern.quote(toReplace), replacement);
      }
  
      /**
       * Decode a String from OAuth format
       *
       * @param encoded the string to decode
       * @return decoded string
       */
      public static String decode(String encoded) {
          Preconditions.checkNotNull(encoded, "Cannot decode null object");
          try {
              return URLDecoder.decode(encoded, CHARSET);
          } catch (UnsupportedEncodingException uee) {
              throw new AgoravaException("Charset not found while decoding string: " + CHARSET, uee);
          }
      }
  }
  