package com.atlassian.sal.core.net;
   
   import org.apache.commons.httpclient.HttpClient;
   import org.apache.commons.httpclient.UsernamePasswordCredentials;
   import org.apache.commons.httpclient.auth.AuthScope;
   import org.apache.commons.lang.StringUtils;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
   
  import java.net.URI;
  import java.net.URISyntaxException;
  
  /**
   * Configures the proxy on the HttpClient instance, reads the proxy configuration
   * from the following system properties:
   *
   *<ul>
   *     <li><b>http.proxyHost</b></li>
   *     <li><b>http.proxyPort</b> (optional, default to 80)</li>
   *</ul>
   * A list of excluded hosts can be provided to bypass the proxy:
   *<ul>
   *     <li><b>http.nonProxyHosts</b> (format: www.atlassian.com|*.example.com) - The only wildcard supported is the simple suffix match.</li>
   *</ul>
   * If the proxy needs authentication, the credentials must be provided using:
   *<ul>
   *     <li><b>http.proxyUser</b></li>
   *     <li><b>http.proxyPassword</b></li>
   *</ul>
   */
  public class HttpClientProxyConfig {
  
      private static final Logger log = LoggerFactory.getLogger(HttpClientProxyConfig.class);
  
      /**
       * @param client The client to configure the proxy of
       * @param remoteUrl The remote URL
       */
      protected void configureProxy(final HttpClient client, final String remoteUrl)
      {
          if (client == null)
          {
              throw new IllegalArgumentException("Please provide a valid HttpClient instance");
          }
          final String proxyHost = System.getProperty("http.proxyHost");
  
          URI uri;
          try
          {
              uri = new URI(remoteUrl);
          } catch (final URISyntaxException e)
          {
              log.warn("Invalid url: " + remoteUrl, e);
              return;
          }
          if (proxyHost != null && !isNonProxyHost(uri.getHost()))
          {
              int port = 80;
              try
              {
                  port = Integer.parseInt(System.getProperty("http.proxyPort", "80"));
              }
              catch (final NumberFormatException e)
              {
                  log.warn("System property 'http.proxyPort' is not a number. Defaulting to 80.");
              }
  
              client.getHostConfiguration().setProxy(proxyHost, port);
              if(proxyAuthenticationRequired())
              {
                  client.getState().setProxyCredentials(new AuthScope(proxyHost,port),
                          new UsernamePasswordCredentials(System.getProperty("http.proxyUser"),
                                  System.getProperty("http.proxyPassword")));
              }
          }
      }
  
      /**
       * Discover whether or not proxy authentication is required; if we are behind a proxy then it is required,
       * otherwise it isn't
       *
       * @return true if proxy authentication is required, false otherwise
       */
      private boolean proxyAuthenticationRequired()
      {
          return System.getProperty("http.proxyUser") != null;
      }
  
      private boolean isNonProxyHost(final String host)
      {
          if (StringUtils.isBlank(host))
          {
              return true;
          }
          final String httpNonProxyHosts = System.getProperty("http.nonProxyHosts");
          if (StringUtils.isBlank(httpNonProxyHosts))
          {
              // checking if property was misspelt, notice there is no 's' at the end of this property
              if (StringUtils.isBlank(System.getProperty("http.nonProxyHost")))
             {
                 log.warn("The system property http.nonProxyHost is set. You probably meant to set http.nonProxyHosts.");
             }
             return false;
         }
         final String[] nonProxyHosts = httpNonProxyHosts.split("\\|");
         for (final String nonProxyHost : nonProxyHosts) {
             if (nonProxyHost.startsWith("*")) {
                 if (host.endsWith(nonProxyHost.substring(1))) {
                     return true;
                 }
             } else if (host.equals(nonProxyHost)) {
                 return true;
             }
         }
         return false;
     }
 
 }