/*
    * Copyright 2012 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 org.jboss.netty.handler.ipfilter;
  
  import org.jboss.netty.logging.InternalLogger;
  import org.jboss.netty.logging.InternalLoggerFactory;
  import org.jboss.netty.util.internal.StringUtil;
  
  import java.net.InetAddress;
  import java.net.UnknownHostException;
  import java.util.regex.Pattern;
  
  /**
   * The Class PatternRule represents an IP filter rule using string patterns.
   * <br>
   * Rule Syntax:
   * <br>
   * <pre>
   * Rule ::= [n|i]:address          n stands for computer name, i for ip address
   * address ::= &lt;regex&gt; | localhost
   * regex is a regular expression with '*' as multi character and '?' as single character wild card
   * </pre>
   * <br>
   * Example: allow localhost:
   * <br>
   * new PatternRule(true, "n:localhost")
   * <br>
   * Example: allow local lan:
   * <br>
   * new PatternRule(true, "i:192.168.0.*")
   * <br>
   * Example: block all
   * <br>
   * new PatternRule(false, "n:*")
   * <br>
   */
  public class PatternRule implements IpFilterRule, Comparable<Object> {
      private static final InternalLogger logger = InternalLoggerFactory.getInstance(PatternRule.class);
  
      private Pattern ipPattern;
  
      private Pattern namePattern;
  
      private boolean isAllowRule = true;
  
      private boolean localhost;
  
      private final String pattern;
  
      /**
       * Instantiates a new pattern rule.
       *
       * @param allow   indicates if this is an allow or block rule
       * @param pattern the filter pattern
       */
      public PatternRule(boolean allow, String pattern) {
          isAllowRule = allow;
          this.pattern = pattern;
          parse(pattern);
      }
  
      /**
       * returns the pattern.
       *
       * @return the pattern
       */
      public String getPattern() {
          return pattern;
      }
  
      public boolean isAllowRule() {
          return isAllowRule;
      }
  
      public boolean isDenyRule() {
          return !isAllowRule;
      }
  
      public boolean contains(InetAddress inetAddress) {
          if (localhost) {
              if (isLocalhost(inetAddress)) {
                  return true;
              }
          }
          if (ipPattern != null) {
             if (ipPattern.matcher(inetAddress.getHostAddress()).matches()) {
                 return true;
             }
         }
         if (namePattern != null) {
             if (namePattern.matcher(inetAddress.getHostName()).matches()) {
                 return true;
             }
         }
         return false;
     }
 
     private void parse(String pattern) {
         if (pattern == null) {
             return;
         }
 
         String[] acls = StringUtil.split(pattern, ',');
 
         String ip = "";
         String name = "";
         for (String c : acls) {
             c = c.trim();
             if (c.equals("n:localhost")) {
                 localhost = true;
             } else if (c.startsWith("n:")) {
                 name = addRule(name, c.substring(2));
             } else if (c.startsWith("i:")) {
                 ip = addRule(ip, c.substring(2));
             }
         }
         if (ip.length() != 0) {
             ipPattern = Pattern.compile(ip);
         }
         if (name.length() != 0) {
             namePattern = Pattern.compile(name);
         }
     }
 
     private static String addRule(String pattern, String rule) {
         if (rule == null || rule.length() == 0) {
             return pattern;
         }
         if (pattern.length() != 0) {
             pattern += "|";
         }
         rule = rule.replaceAll("\\.", "\\\\.");
         rule = rule.replaceAll("\\*", ".*");
         rule = rule.replaceAll("\\?", ".");
         pattern += '(' + rule + ')';
         return pattern;
     }
 
     private static boolean isLocalhost(InetAddress address) {
         try {
             if (address.equals(InetAddress.getLocalHost())) {
                 return true;
             }
         } catch (UnknownHostException e) {
             if (logger.isInfoEnabled()) {
                 logger.info("error getting ip of localhost", e);
             }
         }
         try {
             InetAddress[] addrs = InetAddress.getAllByName("127.0.0.1");
             for (InetAddress addr : addrs) {
                 if (addr.equals(address)) {
                     return true;
                 }
             }
         } catch (UnknownHostException e) {
             if (logger.isInfoEnabled()) {
                 logger.info("error getting ip of localhost", e);
             }
         }
         return false;
 
     }
 
     public int compareTo(Object o) {
         if (o == null) {
             return -1;
         }
         if (!(o instanceof PatternRule)) {
             return -1;
         }
         PatternRule p = (PatternRule) o;
         if (p.isAllowRule() && !isAllowRule) {
             return -1;
         }
         if (pattern == null && p.pattern == null) {
             return 0;
         }
         if (pattern != null) {
             return pattern.compareTo(p.getPattern());
         }
         return -1;
     }
 
 }