/*
    * 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.logging.log4j.core.impl;
  
  import java.util.Arrays;
  import java.util.Comparator;
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Objects;
  
  import org.apache.logging.log4j.util.BiConsumer;
  import org.apache.logging.log4j.util.ReadOnlyStringMap;
  import org.apache.logging.log4j.util.StringMap;
  import org.apache.logging.log4j.util.TriConsumer;
  
  /**
   * Provides a read-only {@code StringMap} view of a {@code Map<String, String>}.
   */
  class JdkMapAdapterStringMap implements StringMap {
      private static final long serialVersionUID = -7348247784983193612L;
      private static final String FROZEN = "Frozen collection cannot be modified";
      private static final Comparator<? super String> NULL_FIRST_COMPARATOR = new Comparator<String>() {
          @Override
          public int compare(final String left, final String right) {
              if (left == null) {
                  return -1;
              }
              if (right == null) {
                  return 1;
              }
              return left.compareTo(right);
          }
      };
  
      private final Map<String, String> map;
      private boolean immutable = false;
      private transient String[] sortedKeys;
  
      public JdkMapAdapterStringMap() {
          this(new HashMap<String, String>());
      }
  
      public JdkMapAdapterStringMap(final Map<String, String> map) {
          this.map = Objects.requireNonNull(map, "map");
      }
  
      @Override
      public Map<String, String> toMap() {
          return map;
      }
  
      private void assertNotFrozen() {
          if (immutable) {
              throw new UnsupportedOperationException(FROZEN);
          }
      }
  
      @Override
      public boolean containsKey(final String key) {
          return map.containsKey(key);
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public <V> void forEach(final BiConsumer<String, ? super V> action) {
          final String[] keys = getSortedKeys();
          for (int i = 0; i < keys.length; i++) {
              action.accept(keys[i], (V) map.get(keys[i]));
          }
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public <V, S> void forEach(final TriConsumer<String, ? super V, S> action, final S state) {
          final String[] keys = getSortedKeys();
          for (int i = 0; i < keys.length; i++) {
              action.accept(keys[i], (V) map.get(keys[i]), state);
          }
      }
  
      private String[] getSortedKeys() {
          if (sortedKeys == null) {
              sortedKeys = map.keySet().toArray(new String[map.size()]);
              Arrays.sort(sortedKeys, NULL_FIRST_COMPARATOR);
          }
         return sortedKeys;
     }
 
     @SuppressWarnings("unchecked")
     @Override
     public <V> V getValue(final String key) {
         return (V) map.get(key);
     }
 
     @Override
     public boolean isEmpty() {
         return map.isEmpty();
     }
 
     @Override
     public int size() {
         return map.size();
     }
 
     @Override
     public void clear() {
         if (map.isEmpty()) {
             return;
         }
         assertNotFrozen();
         map.clear();
         sortedKeys = null;
     }
 
     @Override
     public void freeze() {
         immutable = true;
     }
 
     @Override
     public boolean isFrozen() {
         return immutable;
     }
 
     @Override
     public void putAll(final ReadOnlyStringMap source) {
         assertNotFrozen();
         source.forEach(PUT_ALL, map);
         sortedKeys = null;
     }
 
     private static TriConsumer<String, String, Map<String, String>> PUT_ALL = new TriConsumer<String, String, Map<String, String>>() {
         @Override
         public void accept(final String key, final String value, final Map<String, String> stringStringMap) {
             stringStringMap.put(key, value);
         }
     };
 
     @Override
     public void putValue(final String key, final Object value) {
         assertNotFrozen();
         map.put(key, value == null ? null : String.valueOf(value));
         sortedKeys = null;
     }
 
     @Override
     public void remove(final String key) {
         if (!map.containsKey(key)) {
             return;
         }
         assertNotFrozen();
         map.remove(key);
         sortedKeys = null;
     }
 
     @Override
     public String toString() {
         final StringBuilder result = new StringBuilder(map.size() * 13);
         result.append('{');
         final String[] keys = getSortedKeys();
         for (int i = 0; i < keys.length; i++) {
             if (i > 0) {
                 result.append(", ");
             }
             result.append(keys[i]).append('=').append(map.get(keys[i]));
         }
         result.append('}');
         return result.toString();
     }
 
     @Override
     public boolean equals(final Object object) {
         if (object == this) {
             return true;
         }
         if (!(object instanceof JdkMapAdapterStringMap)) {
             return false;
         }
         final JdkMapAdapterStringMap other = (JdkMapAdapterStringMap) object;
         return map.equals(other.map) && immutable == other.immutable;
     }
 
     @Override
     public int hashCode() {
         return map.hashCode() + (immutable ? 31 : 0);
     }
 }