/*
 * Copyright 1999,2004 The Apache Software Foundation.
 * 
 * Licensed 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.apache.catalina;

import java.beans.PropertyChangeListener;
import java.io.IOException;
import java.security.Principal;
import java.security.cert.X509Certificate;

import org.apache.catalina.connector.Request;
import org.apache.catalina.connector.Response;
import org.apache.catalina.deploy.SecurityConstraint;
/**
 * A <b>Realm</b> is a read-only facade for an underlying security realm
 * used to authenticate individual users, and identify the security roles
 * associated with those users.  Realms can be attached at any Container
 * level, but will typically only be attached to a Context, or higher level,
 * Container.
 *
 * @author Craig R. McClanahan
 * @version $Revision$ $Date$
 */

public interface Realm {


    // ------------------------------------------------------------- Properties


    /**
     * Return the Container with which this Realm has been associated.
     */
    public Container getContainer();


    /**
     * Set the Container with which this Realm has been associated.
     *
     * @param container The associated Container
     */
    public void setContainer(Container container);


    /**
     * Return descriptive information about this Realm implementation and
     * the corresponding version number, in the format
     * <code>&lt;description&gt;/&lt;version&gt;</code>.
     */
    public String getInfo();


    // --------------------------------------------------------- Public Methods

    
    /**
     * Add a property change listener to this component.
     *
     * @param listener The listener to add
     */
    public void addPropertyChangeListener(PropertyChangeListener listener);


    /**
     * Return the Principal associated with the specified username and
     * credentials, if there is one; otherwise return <code>null</code>.
     *
     * @param username Username of the Principal to look up
     * @param credentials Password or other credentials to use in
     *  authenticating this username
     */
    public Principal authenticate(String username, String credentials);


    /**
     * Return the Principal associated with the specified username and
     * credentials, if there is one; otherwise return <code>null</code>.
     *
     * @param username Username of the Principal to look up
     * @param credentials Password or other credentials to use in
     *  authenticating this username
     */
    public Principal authenticate(String username, byte[] credentials);


    /**
     * Return the Principal associated with the specified username, which
     * matches the digest calculated using the given parameters using the
     * method described in RFC 2069; otherwise return <code>null</code>.
     *
     * @param username Username of the Principal to look up
     * @param digest Digest which has been submitted by the client
     * @param nonce Unique (or supposedly unique) token which has been used
     * for this request
     * @param realm Realm name
     * @param md5a2 Second MD5 digest used to calculate the digest :
     * MD5(Method + ":" + uri)
     */
    public Principal authenticate(String username, String digest,
                                  String nonce, String nc, String cnonce,
                                  String qop, String realm,
                                  String md5a2);


    /**
     * Return the Principal associated with the specified chain of X509
     * client certificates.  If there is none, return <code>null</code>.
     *
     * @param certs Array of client certificates, with the first one in
     *  the array being the certificate of the client itself.
     */
    public Principal authenticate(X509Certificate certs[]);
    
    
    /**
     * Execute a periodic task, such as reloading, etc. This method will be
     * invoked inside the classloading context of this container. Unexpected
     * throwables will be caught and logged.
     */
    public void backgroundProcess();


    /**
     * Return the SecurityConstraints configured to guard the request URI for
     * this request, or <code>null</code> if there is no such constraint.
     *
     * @param request Request we are processing
     */
    public SecurityConstraint [] findSecurityConstraints(Request request,
                                                     Context context);
    
    
    /**
     * Perform access control based on the specified authorization constraint.
     * Return <code>true</code> if this constraint is satisfied and processing
     * should continue, or <code>false</code> otherwise.
     *
     * @param request Request we are processing
     * @param response Response we are creating
     * @param constraint Security constraint we are enforcing
     * @param context The Context to which client of this class is attached.
     *
     * @exception IOException if an input/output error occurs
     */
    public boolean hasResourcePermission(Request request,
                                         Response response,
                                         SecurityConstraint [] constraint,
                                         Context context)
        throws IOException;
    
    
    /**
     * Return <code>true</code> if the specified Principal has the specified
     * security role, within the context of this Realm; otherwise return
     * <code>false</code>.
     *
     * @param principal Principal for whom the role is to be checked
     * @param role Security role to be checked
     */
    public boolean hasRole(Principal principal, String role);

        /**
     * Enforce any user data constraint required by the security constraint
     * guarding this request URI.  Return <code>true</code> if this constraint
     * was not violated and processing should continue, or <code>false</code>
     * if we have created a response already.
     *
     * @param request Request we are processing
     * @param response Response we are creating
     * @param constraint Security constraint being checked
     *
     * @exception IOException if an input/output error occurs
     */
    public boolean hasUserDataPermission(Request request,
                                         Response response,
                                         SecurityConstraint []constraint)
        throws IOException;
    
    /**
     * Remove a property change listener from this component.
     *
     * @param listener The listener to remove
     */
    public void removePropertyChangeListener(PropertyChangeListener listener);


}