//
   //  ========================================================================
   //  Copyright (c) 1995-2013 Mort Bay Consulting Pty. Ltd.
   //  ------------------------------------------------------------------------
   //  All rights reserved. This program and the accompanying materials
   //  are made available under the terms of the Eclipse Public License v1.0
   //  and Apache License v2.0 which accompanies this distribution.
   //
   //      The Eclipse Public License is available at
  //      http://www.eclipse.org/legal/epl-v10.html
  //
  //      The Apache License v2.0 is available at
  //      http://www.opensource.org/licenses/apache2.0.php
  //
  //  You may elect to redistribute this code under either of these licenses.
  //  ========================================================================
  //
  
  package org.eclipse.jetty.policy;
  
  import java.io.PrintStream;
  import java.io.PrintWriter;
  import java.security.AccessControlException;
  import java.security.CodeSource;
  import java.security.Permission;
  import java.security.PermissionCollection;
  import java.security.Permissions;
  import java.security.Policy;
  import java.security.Principal;
  import java.security.ProtectionDomain;
  import java.security.cert.Certificate;
  import java.security.cert.CertificateException;
  import java.util.Enumeration;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.Map;
  import java.util.Set;
  import java.util.concurrent.ConcurrentHashMap;
  
  import org.eclipse.jetty.util.log.Log;
  import org.eclipse.jetty.util.log.Logger;
  import org.eclipse.jetty.util.security.CertificateValidator;
  
  
  /**
   * Policy implementation that will load a set of policy files and manage the mapping of permissions and protection domains
   * 
   * Features of JettyPolicy are:
   * 
   * - we are able to follow the startup mechanic that jetty uses with jetty-start using OPTIONS=policy,default to be able to startup a security manager and policy implementation without have to rely on the existing JVM cli options 
   * - support for specifying multiple policy files to source permissions from
   * - support for merging protection domains across multiple policy files for the same codesource
   * - support for directories of policy files, just specify directory and all *.policy files will be loaded.
  
   * Possible additions are: 
   * - scan policy directory for new policy files being added
   * - jmx reporting
   * - proxying of system security policy where we can proxy access to the system policy should the jvm have been started with one, I had support for this but ripped it
   * out to add in again later 
   * - an xml policy file parser, had originally added this using modello but tore it out since it would have been a
   * nightmare to get its dependencies through IP validation, could do this with jvm xml parser instead sometime 
   * - check performance of the synch'd map I am using for the protection domain mapping
   */
  public class JettyPolicy extends Policy
  {
      private static final Logger LOG = Log.getLogger(JettyPolicy.class);
      
      private static boolean __DEBUG = false;
      private static boolean __RELOAD = false;
  
      private boolean _STARTED = false;
      
      private String _policyDirectory;
      
      private final Set<PolicyBlock> _grants = new HashSet<PolicyBlock>();
  
      /*
       * TODO: make into a proper cache
       */
      private final Map<Object, PermissionCollection> _cache = new ConcurrentHashMap<Object, PermissionCollection>();
  
      private final static PolicyContext _context = new PolicyContext();
  
      private CertificateValidator _validator = null;
          
      private PolicyMonitor _policyMonitor = new PolicyMonitor()
      {        
          @Override
          public void onPolicyChange(PolicyBlock grant)
          {
              boolean setGrant = true;     
              
              if ( _validator != null )
              {
                  if (grant.getCertificates() != null)
                  {
                      for ( Certificate cert : grant.getCertificates() )
                      {
                          try
                         {
                             _validator.validate(_context.getKeystore(), cert);
                         }
                         catch ( CertificateException ce )
                         {
                             setGrant = false;
                         }
                     }                
                 }
             }
                   
             if ( setGrant )
             {
                 _grants.add( grant );
                 _cache.clear();
             }
         }
     };
     
     public JettyPolicy(String policyDirectory, Map<String, String> properties)
     {
         try
         {
             __RELOAD = Boolean.getBoolean("org.eclipse.jetty.policy.RELOAD");
             __DEBUG = Boolean.getBoolean("org.eclipse.jetty.policy.DEBUG");
         }
         catch (AccessControlException ace)
         {
             __RELOAD = false;
             __DEBUG = false;
         }
         
         _policyDirectory = policyDirectory;
         _context.setProperties(properties);
         
         try
         {
             _policyMonitor.setPolicyDirectory(_policyDirectory);
             //_policyMonitor.setReload( __RELOAD );
         }
         catch ( Exception e)
         {
             throw new PolicyException(e);
         }
     }
     
     
     
     @Override
     public void refresh()
     {        
         if ( !_STARTED )
         {
             initialize();
         }
     }
 
     /**
      * required for the jetty policy to start function, initializes the 
      * policy monitor and blocks for a full cycle of policy grant updates
      */
     public void initialize()
     {
         if ( _STARTED )
         {
             return;         
         }
         
         try
         {
             _policyMonitor.start();
             _policyMonitor.waitForScan();
         }
         catch (Exception e)
         {
             e.printStackTrace();
             throw new PolicyException(e);
         }
         
         _STARTED = true;
     }
     
     @Override
     public PermissionCollection getPermissions(ProtectionDomain domain)
     {
 
         if (!_STARTED)
         {
             throw new PolicyException("JettyPolicy must be started.");
         }
 
         synchronized (_cache)
         {
             if (_cache.containsKey(domain))
             {
                 return copyOf(_cache.get(domain));
             }
 
             PermissionCollection perms = new Permissions();
 
             for (Iterator<PolicyBlock> i = _grants.iterator(); i.hasNext();)
             {
                 PolicyBlock policyBlock = i.next();
                 ProtectionDomain grantPD = policyBlock.toProtectionDomain();
 
                 if (__DEBUG)
                 {
                     debug("----START----");
                     debug("PDCS: " + policyBlock.getCodeSource());
                     debug("CS: " + domain.getCodeSource());
 
                 }
 
                 // 1) if protection domain codesource is null, it is the global permissions (grant {})
                 // 2) if protection domain codesource implies target codesource and there are no prinicpals
                 if (grantPD.getCodeSource() == null 
                         || 
                         grantPD.getCodeSource().implies(domain.getCodeSource()) 
                         && 
                         grantPD.getPrincipals() == null 
                         || 
                         grantPD.getCodeSource().implies(domain.getCodeSource()) 
                         && 
                         validate(grantPD.getPrincipals(),domain.getPrincipals()))
 
                 {
 
                     for (Enumeration<Permission> e = policyBlock.getPermissions().elements(); e.hasMoreElements();)
                     {
                         Permission perm = e.nextElement();
                         if (__DEBUG)
                         {
                             debug("D: " + perm);
                         }
                         perms.add(perm);
                     }
                 }
                 if (__DEBUG)
                 {
                     debug("----STOP----");
                 }
             }
 
             _cache.put(domain,perms);
 
             return copyOf(perms);
         }
     }
 
     @Override
     public PermissionCollection getPermissions(CodeSource codesource)
     {
         if (!_STARTED)
         {
             throw new PolicyException("JettyPolicy must be started.");
         }
 
         synchronized (_cache)
         {
             if (_cache.containsKey(codesource))
             {
                 return copyOf(_cache.get(codesource));
             }
 
             PermissionCollection perms = new Permissions();
 
             for (Iterator<PolicyBlock> i = _grants.iterator(); i.hasNext();)
             {
                 PolicyBlock policyBlock = i.next();
                 ProtectionDomain grantPD = policyBlock.toProtectionDomain();
 
                 if (grantPD.getCodeSource() == null 
                         || 
                         grantPD.getCodeSource().implies(codesource))
                 {
                     if (__DEBUG)
                     {
                         debug("----START----");
                         debug("PDCS: " + grantPD.getCodeSource());
                         debug("CS: " + codesource);
                     }
 
                     for (Enumeration<Permission> e = policyBlock.getPermissions().elements(); e.hasMoreElements();)
                     {
                         Permission perm = e.nextElement();
                         if (__DEBUG)
                         {
                             debug("D: " + perm);
                         }
                         perms.add(perm);
                     }
 
                     if (__DEBUG)
                     {
                         debug("----STOP----");
                     }
                 }
             }
 
             _cache.put(codesource,perms);
 
             return copyOf(perms);
         }
     }
 
     @Override
     public boolean implies(ProtectionDomain domain, Permission permission)
     {
         if (!_STARTED)
         {
             throw new PolicyException("JettyPolicy must be started.");
         }
         
         PermissionCollection pc = getPermissions(domain);
         
         return (pc == null ? false : pc.implies(permission));
     }
     
 
     private static boolean validate(Principal[] permCerts, Principal[] classCerts)
     {
         if (classCerts == null)
         {
             return false;
         }
 
         for (int i = 0; i < permCerts.length; ++i)
         {
             boolean found = false;
             for (int j = 0; j < classCerts.length; ++j)
             {
                 if (permCerts[i].equals(classCerts[j]))
                 {
                     found = true;
                     break;
                 }
             }
             // if we didn't find the permCert in the classCerts then we don't match up
             if (found == false)
             {
                 return false;
             }
         }
 
         return true;
     }
 
 
     /**
      * returns the policy context which contains the map of properties that
      * can be referenced in policy files and the keystore for validation
      * 
      * @return the policy context
      */
     public static PolicyContext getContext()
     {
         return _context;
     }
     
    
     
     /**
      * Try and log to normal logging channels and should that not be allowed
      * debug to system.out
      * 
      * @param message
      */
     private void debug( String message )
     {
         try
         {
             LOG.info(message);
         }
         catch ( AccessControlException ace )
         {
             System.out.println( "[DEBUG] " +  message );
         }
         catch ( NoClassDefFoundError ace )
         {
             System.out.println( "[DEBUG] " + message );
             //ace.printStackTrace();
         }
     }
     /**
      * Try and log to normal logging channels and should that not be allowed
      * log to system.out
      * 
      * @param message
      */
     private void log( String message )
     {
         log( message, null );
     }
     
     /**
      * Try and log to normal logging channels and should that not be allowed
      * log to system.out
      * 
      * @param message
      */
     private void log( String message, Throwable t )
     {
         try
         {
             LOG.info(message, t);
         }
         catch ( AccessControlException ace )
         {
             System.out.println( message );
             t.printStackTrace();
         }
         catch ( NoClassDefFoundError ace )
         {
             System.out.println( message );
             t.printStackTrace();
         }
     }
     
 
     public void dump(PrintStream out)
     {
         PrintWriter write = new PrintWriter(out);
         write.println("JettyPolicy: policy settings dump");
 
         synchronized (_cache)
         {
             for (Iterator<Object> i = _cache.keySet().iterator(); i.hasNext();)
             {
                 Object o = i.next();
                 write.println(o.toString());
             }
         }
         write.flush();
     }
     
     private PermissionCollection copyOf(final PermissionCollection in)
     {
         PermissionCollection out  = new Permissions();
         synchronized (in)
         {
             for (Enumeration<Permission> el = in.elements() ; el.hasMoreElements() ;)
             {
                 out.add((Permission)el.nextElement());
             }
         }
         return out;
     }
 
     public CertificateValidator getCertificateValidator()
     {
         return _validator;
     }
 
     public void setCertificateValidator(CertificateValidator validator)
     {
         if (_STARTED)
         {
             throw new PolicyException("JettyPolicy already started, unable to set validator on running policy");
         }
         
         _validator = validator;
     }
 }