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* Parts copyright (c) 2009 by /k/ Embedded Java Solutions.                *
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package java.security;

import wonka.security.DefaultPolicy;

public abstract class Policy {

  public Policy() { }

  private static void permissionCheck(String permission) {
    if (wonka.vm.SecurityConfiguration.ENABLE_SECURITY_CHECKS) {
      SecurityManager sm = System.getSecurityManager();
      if (sm != null) {
        sm.checkSecurityAccess(permission);
      }
    }
  }

  public static Policy getPolicy() {
    permissionCheck("getPolicy");
    return Singleton.policy;
  }

  public static void setPolicy (Policy policy) {
    if(policy == null){
      throw new SecurityException("cannot intall a 'null' policy");
    }
    permissionCheck("setPolicy");
    Singleton.policy = policy;
  }

  public boolean implies(ProtectionDomain domain, Permission permission) {
    return getPermissions(domain).implies(permission);
  }
  
  public PermissionCollection getPermissions(ProtectionDomain domain) {
    if(domain.loader != null) {
      //TODO use loader && principals to generate a permissioncollection
    }
    return domain.getPermissions();
  }
  
  public abstract PermissionCollection getPermissions(CodeSource codesource);

  public abstract void refresh();

  private static class Singleton {
    static Policy policy;

    static {
      try {
        String policy_provider = Security.getProperty("policy.provider");
        policy = policy_provider == null ? new DefaultPolicy() :
          (Policy)Class.forName(policy_provider).newInstance();
      }
      catch(Exception e){
        policy = new DefaultPolicy();
      }
    }
  }
}