/*
    * 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.eclipse.aether.util.repository;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Locale;
  import java.util.Map;
  import java.util.StringTokenizer;
  import java.util.regex.Pattern;
  
  import org.eclipse.aether.repository.Proxy;
  import org.eclipse.aether.repository.ProxySelector;
  import org.eclipse.aether.repository.RemoteRepository;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * A simple proxy selector that selects the first matching proxy from a list of configured proxies.
   */
  public final class DefaultProxySelector implements ProxySelector {
  
      private final List<ProxyDef> proxies = new ArrayList<>();
  
      /**
       * Adds the specified proxy definition to the selector. Proxy definitions are ordered, the first matching proxy for
       * a given repository will be used.
       *
       * @param proxy The proxy definition to add, must not be {@code null}.
       * @param nonProxyHosts The list of (case-insensitive) host names to exclude from proxying, may be {@code null}.
       * @return This proxy selector for chaining, never {@code null}.
       */
      public DefaultProxySelector add(Proxy proxy, String nonProxyHosts) {
          requireNonNull(proxy, "proxy cannot be null");
          proxies.add(new ProxyDef(proxy, nonProxyHosts));
  
          return this;
      }
  
      public Proxy getProxy(RemoteRepository repository) {
          requireNonNull(repository, "repository cannot be null");
          Map<String, ProxyDef> candidates = new HashMap<>();
  
          String host = repository.getHost();
          for (ProxyDef proxy : proxies) {
              if (!proxy.nonProxyHosts.isNonProxyHost(host)) {
                  String key = proxy.proxy.getType().toLowerCase(Locale.ENGLISH);
                  if (!candidates.containsKey(key)) {
                      candidates.put(key, proxy);
                  }
              }
          }
  
          String protocol = repository.getProtocol().toLowerCase(Locale.ENGLISH);
  
          if ("davs".equals(protocol)) {
              protocol = "https";
          } else if ("dav".equals(protocol)) {
              protocol = "http";
          } else if (protocol.startsWith("dav:")) {
              protocol = protocol.substring("dav:".length());
          }
  
          ProxyDef proxy = candidates.get(protocol);
          if (proxy == null && "https".equals(protocol)) {
              proxy = candidates.get("http");
          }
  
          return (proxy != null) ? proxy.proxy : null;
      }
  
      static class NonProxyHosts {
  
          private final Pattern[] patterns;
  
          NonProxyHosts(String nonProxyHosts) {
              List<Pattern> patterns = new ArrayList<>();
              if (nonProxyHosts != null) {
                  for (StringTokenizer tokenizer = new StringTokenizer(nonProxyHosts, "|"); tokenizer.hasMoreTokens(); ) {
                      String pattern = tokenizer.nextToken();
                      pattern = pattern.replace(".", "\\.").replace("*", ".*");
                      patterns.add(Pattern.compile(pattern, Pattern.CASE_INSENSITIVE));
                 }
             }
             this.patterns = patterns.toArray(new Pattern[0]);
         }
 
         boolean isNonProxyHost(String host) {
             if (host != null) {
                 for (Pattern pattern : patterns) {
                     if (pattern.matcher(host).matches()) {
                         return true;
                     }
                 }
             }
             return false;
         }
     }
 
     static class ProxyDef {
 
         final Proxy proxy;
 
         final NonProxyHosts nonProxyHosts;
 
         ProxyDef(Proxy proxy, String nonProxyHosts) {
             this.proxy = proxy;
             this.nonProxyHosts = new NonProxyHosts(nonProxyHosts);
         }
     }
 }