/*
    * ====================================================================
    * 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.
   * ====================================================================
   *
   * This software consists of voluntary contributions made by many
   * individuals on behalf of the Apache Software Foundation.  For more
   * information on the Apache Software Foundation, please see
   * <http://www.apache.org/>.
   *
   */
  package org.apache.hc.client5.http.psl;
  
  import java.net.IDN;
  import java.util.Collection;
  import java.util.List;
  import java.util.Map;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.apache.hc.client5.http.utils.DnsUtils;
  import org.apache.hc.core5.annotation.Contract;
  import org.apache.hc.core5.annotation.ThreadingBehavior;
  import org.apache.hc.core5.util.Args;
  
  /**
   * Utility class that can test if DNS names match the content of the Public Suffix List.
   * <p>
   * An up-to-date list of suffixes can be obtained from
   * <a href="http://publicsuffix.org/">publicsuffix.org</a>
   * </p>
   *
   * @see PublicSuffixList
   *
   * @since 4.4
   */
  @Contract(threading = ThreadingBehavior.SAFE)
  public final class PublicSuffixMatcher {
  
      private final Map<String, DomainType> rules;
      private final Map<String, DomainType> exceptions;
  
      public PublicSuffixMatcher(final Collection<String> rules, final Collection<String> exceptions) {
          this(DomainType.UNKNOWN, rules, exceptions);
      }
  
      /**
       * @since 4.5
       */
      public PublicSuffixMatcher(
              final DomainType domainType, final Collection<String> rules, final Collection<String> exceptions) {
          Args.notNull(domainType,  "Domain type");
          Args.notNull(rules,  "Domain suffix rules");
          this.rules = new ConcurrentHashMap<>(rules.size());
          for (final String rule: rules) {
              this.rules.put(rule, domainType);
          }
          this.exceptions = new ConcurrentHashMap<>();
          if (exceptions != null) {
              for (final String exception: exceptions) {
                  this.exceptions.put(exception, domainType);
              }
          }
      }
  
      /**
       * @since 4.5
       */
      public PublicSuffixMatcher(final Collection<PublicSuffixList> lists) {
          Args.notNull(lists,  "Domain suffix lists");
          this.rules = new ConcurrentHashMap<>();
          this.exceptions = new ConcurrentHashMap<>();
          for (final PublicSuffixList list: lists) {
              final DomainType domainType = list.getType();
              final List<String> rules = list.getRules();
              for (final String rule: rules) {
                  this.rules.put(rule, domainType);
              }
              final List<String> exceptions = list.getExceptions();
              if (exceptions != null) {
                  for (final String exception: exceptions) {
                      this.exceptions.put(exception, domainType);
                  }
              }
          }
     }
 
     private static DomainType findEntry(final Map<String, DomainType> map, final String rule) {
         if (map == null) {
             return null;
         }
         return map.get(rule);
     }
 
     private static boolean match(final DomainType domainType, final DomainType expectedType) {
         return domainType != null && (expectedType == null || domainType.equals(expectedType));
     }
 
     /**
      * Returns registrable part of the domain for the given domain name or {@code null}
      * if given domain represents a public suffix.
      *
      * @param domain
      * @return domain root
      */
     public String getDomainRoot(final String domain) {
         return getDomainRoot(domain, null);
     }
 
     /**
      * Returns registrable part of the domain for the given domain name or {@code null}
      * if given domain represents a public suffix.
      *
      * @param domain
      * @param expectedType expected domain type or {@code null} if any.
      * @return domain root
      *
      * @since 4.5
      */
     public String getDomainRoot(final String domain, final DomainType expectedType) {
         if (domain == null) {
             return null;
         }
         if (domain.startsWith(".")) {
             return null;
         }
         String segment = DnsUtils.normalize(domain);
         String result = null;
         while (segment != null) {
             // An exception rule takes priority over any other matching rule.
             final String key = IDN.toUnicode(segment);
             final DomainType exceptionRule = findEntry(exceptions, key);
             if (match(exceptionRule, expectedType)) {
                 return segment;
             }
             final DomainType domainRule = findEntry(rules, key);
             if (match(domainRule, expectedType)) {
                 if (domainRule == DomainType.PRIVATE) {
                     return segment;
                 }
                 return result;
             }
 
             final int nextdot = segment.indexOf('.');
             final String nextSegment = nextdot != -1 ? segment.substring(nextdot + 1) : null;
 
             if (nextSegment != null) {
                 final DomainType wildcardDomainRule = findEntry(rules, "*." + IDN.toUnicode(nextSegment));
                 if (match(wildcardDomainRule, expectedType)) {
                     if (wildcardDomainRule == DomainType.PRIVATE) {
                         return segment;
                     }
                     return result;
                 }
             }
             result = segment;
             segment = nextSegment;
         }
 
         // If no expectations then this result is good.
         if (expectedType == null || expectedType == DomainType.UNKNOWN) {
             return result;
         }
 
         // If we did have expectations apparently there was no match
         return null;
     }
 
     /**
      * Tests whether the given domain matches any of entry from the public suffix list.
      */
     public boolean matches(final String domain) {
         return matches(domain, null);
     }
 
     /**
      * Tests whether the given domain matches any of entry from the public suffix list.
      *
      * @param domain
      * @param expectedType expected domain type or {@code null} if any.
      * @return {@code true} if the given domain matches any of the public suffixes.
      *
      * @since 4.5
      */
     public boolean matches(final String domain, final DomainType expectedType) {
         if (domain == null) {
             return false;
         }
         final String domainRoot = getDomainRoot(
                 domain.startsWith(".") ? domain.substring(1) : domain, expectedType);
         return domainRoot == null;
     }
 
 }