package com.atlassian.sal.trustedapps;
   
   import com.atlassian.plugin.StateAware;
   import com.atlassian.sal.core.trusted.CertificateFactory;
   import com.atlassian.security.auth.trustedapps.EncryptedCertificate;
   import org.osgi.framework.BundleContext;
   import org.osgi.util.tracker.ServiceTracker;
   import org.slf4j.Logger;
   import org.slf4j.LoggerFactory;
  
  /**
   * This factory has a weak classloading dependency on {@link com.atlassian.security.auth.trustedapps.api.CertificateFactory}
   * through an OSGi ServiceTracker, hence the trusted apps plugin does not need to be installed for this class to work
   * (it will simply throw an exception saying that trusted apps isn't supported).
   */
  public class TrustedAppsPluginCertificateFactory implements CertificateFactory, StateAware
  {
      private static final Logger log = LoggerFactory.getLogger(TrustedAppsPluginCertificateFactory.class);
      private static final String CERTIFICATE_FACTORY = "com.atlassian.security.auth.trustedapps.api.CertificateFactory";
      private ServiceTracker serviceTracker;
      private final BundleContext bundleContext;
  
      public TrustedAppsPluginCertificateFactory(BundleContext bundleContext)
      {
          this.bundleContext = bundleContext;
          serviceTracker = new ServiceTracker(bundleContext, CERTIFICATE_FACTORY, null);
          serviceTracker.open();
      }
  
      public EncryptedCertificate createCertificate(String username)
      {
          if (serviceTracker != null)
          {
              try
              {
                  com.atlassian.security.auth.trustedapps.api.CertificateFactory certificateFactory =
                      (com.atlassian.security.auth.trustedapps.api.CertificateFactory) serviceTracker.getService();
                  if (certificateFactory != null)
                  {
                      return certificateFactory.createCertificate(username);
                  }
              }
              catch (NoClassDefFoundError ncdfe)
              {
                  // This probably won't happen, if trustedapps isn't installed then this method will return null,
                  // so no cast will be attempted, so the class won't need to be loaded, and so this error won't be
                  // thrown. Whether the class is loaded though may be platform dependent, I can't see anything in the
                  // Java Language Specification that indicates what should happen, so for safety, we ignore this
                  // exception here as it indicates that trusted apps is not installed.  It could also mean that the
                  // class hasn't been wired appropriately, which the OSGi framework will warn us about anyway.
              }
              catch (ClassCastException cce)
              {
                  // This exception is possible if CertificateFactory has been uninstalled and installed. Warn.
                  log.warn(
                      "A CertificateFactory was found, but a ClassCastException was thrown when attempting to cast it.",
                      cce);
              }
          }
          throw new UnsupportedOperationException("Trusted apps support is not installed.");
      }
  
      public void enabled()
      {
          if (serviceTracker == null)
          {
              serviceTracker = new ServiceTracker(bundleContext, CERTIFICATE_FACTORY, null);
              serviceTracker.open();
          }
      }
  
      public void disabled()
      {
          serviceTracker.close();
          serviceTracker = null;
      }
  }