/*
    * Copyright 2014 The Netty Project
    *
    * The Netty Project 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 io.netty.util;
  
  import io.netty.util.internal.StringUtil;
  
  import java.net.IDN;
  import java.util.Collections;
  import java.util.LinkedHashMap;
  import java.util.Locale;
  import java.util.Map;
  
  import static io.netty.util.internal.ObjectUtil.checkNotNull;
  import static io.netty.util.internal.StringUtil.commonSuffixOfLength;
  
  /**
   * Maps a domain name to its associated value object.
   * <p>
   * DNS wildcard is supported as hostname, so you can use {@code *.netty.io} to match both {@code netty.io}
   * and {@code downloads.netty.io}.
   * </p>
   */
  public class DomainNameMapping<V> implements Mapping<String, V> {
  
      final V defaultValue;
      private final Map<String, V> map;
      private final Map<String, V> unmodifiableMap;
  
      /**
       * Creates a default, order-sensitive mapping. If your hostnames are in conflict, the mapping
       * will choose the one you add first.
       *
       * @param defaultValue the default value for {@link #map(String)} to return when nothing matches the input
       * @deprecated use {@link DomainNameMappingBuilder} to create and fill the mapping instead
       */
      @Deprecated
      public DomainNameMapping(V defaultValue) {
          this(4, defaultValue);
      }
  
      /**
       * Creates a default, order-sensitive mapping. If your hostnames are in conflict, the mapping
       * will choose the one you add first.
       *
       * @param initialCapacity initial capacity for the internal map
       * @param defaultValue    the default value for {@link #map(String)} to return when nothing matches the input
       * @deprecated use {@link DomainNameMappingBuilder} to create and fill the mapping instead
       */
      @Deprecated
      public DomainNameMapping(int initialCapacity, V defaultValue) {
          this(new LinkedHashMap<String, V>(initialCapacity), defaultValue);
      }
  
      DomainNameMapping(Map<String, V> map, V defaultValue) {
          this.defaultValue = checkNotNull(defaultValue, "defaultValue");
          this.map = map;
          unmodifiableMap = map != null ? Collections.unmodifiableMap(map)
                                        : null;
      }
  
      /**
       * Adds a mapping that maps the specified (optionally wildcard) host name to the specified output value.
       * <p>
       * <a href="http://en.wikipedia.org/wiki/Wildcard_DNS_record">DNS wildcard</a> is supported as hostname.
       * For example, you can use {@code *.netty.io} to match {@code netty.io} and {@code downloads.netty.io}.
       * </p>
       *
       * @param hostname the host name (optionally wildcard)
       * @param output   the output value that will be returned by {@link #map(String)} when the specified host name
       *                 matches the specified input host name
       * @deprecated use {@link DomainNameMappingBuilder} to create and fill the mapping instead
       */
      @Deprecated
      public DomainNameMapping<V> add(String hostname, V output) {
          map.put(normalizeHostname(checkNotNull(hostname, "hostname")), checkNotNull(output, "output"));
          return this;
      }
  
      /**
       * Simple function to match <a href="http://en.wikipedia.org/wiki/Wildcard_DNS_record">DNS wildcard</a>.
       */
      static boolean matches(String template, String hostName) {
          if (template.startsWith("*.")) {
              return template.regionMatches(2, hostName, 0, hostName.length())
                  || commonSuffixOfLength(hostName, template, template.length() - 1);
         }
         return template.equals(hostName);
     }
 
     /**
      * IDNA ASCII conversion and case normalization
      */
     static String normalizeHostname(String hostname) {
         if (needsNormalization(hostname)) {
             hostname = IDN.toASCII(hostname, IDN.ALLOW_UNASSIGNED);
         }
         return hostname.toLowerCase(Locale.US);
     }
 
     private static boolean needsNormalization(String hostname) {
         final int length = hostname.length();
         for (int i = 0; i < length; i++) {
             int c = hostname.charAt(i);
             if (c > 0x7F) {
                 return true;
             }
         }
         return false;
     }
 
     @Override
     public V map(String hostname) {
         if (hostname != null) {
             hostname = normalizeHostname(hostname);
 
             for (Map.Entry<String, V> entry : map.entrySet()) {
                 if (matches(entry.getKey(), hostname)) {
                     return entry.getValue();
                 }
             }
         }
         return defaultValue;
     }
 
     /**
      * Returns a read-only {@link Map} of the domain mapping patterns and their associated value objects.
      */
     public Map<String, V> asMap() {
         return unmodifiableMap;
     }
 
     @Override
     public String toString() {
         return StringUtil.simpleClassName(this) + "(default: " + defaultValue + ", map: " + map + ')';
     }
 }