/*
    * 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.myfaces.tobago.internal.util;
  
  import javax.faces.context.FacesContext;
  import java.util.HashSet;
  import java.util.Locale;
  import java.util.Map;
  
  public class AccessKeyMap {
  
    private static final char[] KEYS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
        'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
        'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z'};
  
    private static final String REQUEST_MAP_KEY = "accessKeysRequestMapKey";
  
    private HashSet set;
    private StringBuilder duplicated = new StringBuilder();
  
  
    public static AccessKeyMap getInstance(FacesContext facesContext) {
      final Map requestMap = facesContext.getExternalContext().getRequestMap();
      AccessKeyMap keyMap = (AccessKeyMap) requestMap.get(REQUEST_MAP_KEY);
      if (keyMap == null) {
        keyMap = new AccessKeyMap();
        requestMap.put(REQUEST_MAP_KEY, keyMap);
      }
      return keyMap;
    }
  
    private AccessKeyMap() {
      set = new HashSet();
    }
  
    private HashSet getSet() {
      return set;
    }
  
    private String getDuplicated() {
      return duplicated.toString();
    }
  
    private void addDublicated(char key) {
      duplicated = duplicated.append(key);
    }
  
    public static boolean addAccessKey(FacesContext facesContext, Character key) {
      key = key.toString().toLowerCase(Locale.ENGLISH).charAt(0);
      final AccessKeyMap instance = getInstance(facesContext);
      if (instance.getSet().contains(key)) {
        instance.addDublicated(key);
        return false;
      } else {
        instance.getSet().add(key);
        return true;
      }
    }
  
    public static String getDublicatedKeys(FacesContext facesContext) {
      return getInstance(facesContext).getDuplicated();
    }
  
    public static String getUnusedKeys(FacesContext facesContext) {
      HashSet set = getInstance(facesContext).getSet();
      StringBuilder sb = new StringBuilder();
      for (char key : KEYS) {
        if (!set.contains(Character.valueOf(key))) {
          sb.append(key);
        }
      }
      return sb.toString();
    }
  }