/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

//
// This source code implements specifications defined by the Java
// Community Process. In order to remain compliant with the specification
// DO NOT add / change / or delete method signatures!
//

package javax.security.jacc;

import java.security.SecurityPermission;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;


/**
 * @version $Rev$ $Date$
 */
public final class PolicyContext {

    private final static ThreadLocal<String> contextId = new ThreadLocal<String>();
    private final static ThreadLocal<Object> handlerData = new ThreadLocal<Object>();
    private static volatile Map<String, PolicyContextHandler> handlers = new HashMap<String, PolicyContextHandler>();
    private final static SecurityPermission SET_POLICY = new SecurityPermission("setPolicy");

    private PolicyContext() {
    }

    public static void setContextID(String contextID) {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) sm.checkPermission(SET_POLICY);

        contextId.set(contextID);
    }

    public static String getContextID() {
        return contextId.get();
    }

    public static void setHandlerData(Object data) {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) sm.checkPermission(SET_POLICY);

        handlerData.set(data);
    }

    public static void registerHandler(String key, PolicyContextHandler handler, boolean replace) throws PolicyContextException {
        if (key == null) throw new IllegalArgumentException("Key must not be null");
        if (handler == null) throw new IllegalArgumentException("Handler must not be null");
        if (!handler.supports(key)) throw new IllegalArgumentException("Registered handler does not support the key '" + key + "'");

        SecurityManager sm = System.getSecurityManager();
        if (sm != null) sm.checkPermission(SET_POLICY);

        synchronized (PolicyContext.class) {
            if (!replace && handlers.containsKey(key))
                throw new IllegalArgumentException("A handler has already been registered under '" + key + "' and replace is false.");
            Map<String, PolicyContextHandler> newHandlers = new HashMap<String, PolicyContextHandler>(handlers);
            newHandlers.put(key, handler);
            handlers = newHandlers;
        }
    }

    public static Set getHandlerKeys() {
        return handlers.keySet();
    }

    public static Object getContext(String key) throws PolicyContextException {
        if (key == null) throw new IllegalArgumentException("Key must not be null");

        PolicyContextHandler handler = handlers.get(key);

        if (handler == null) throw new IllegalArgumentException("No handler can be found for the key '" + key + "'");
        if (!handler.supports(key)) throw new IllegalArgumentException("Registered handler no longer supports the key '" + key + "'");

        SecurityManager sm = System.getSecurityManager();
        if (sm != null) sm.checkPermission(SET_POLICY);

        return handler.getContext(key, handlerData.get());
    }
}