/**
* Copyright 2009 Google Inc.
*
* 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.waveprotocol.wave.model.supplement;
import org.waveprotocol.wave.model.conversation.ConversationThread;
/**
* A set of pluggable strategies for determining presentation behaviour based on
* user actions and user data.
*
*/
public interface PresentationPolicy {
/**
* Determines the presentation state of a thread according to the policy.
*
* @param thread Thread for which thread state is requested
* @param specified Current thread state in user-data (may be null to
* indicate unspecified state)
* @return the thread state as it should be presented - never null.
*/
ThreadState getThreadState(ConversationThread thread, ThreadState specified);
/** @return the state to store in order to expand a thread. */
ThreadState expand(ConversationThread thread, ThreadState current);
/** @return the state to store in order to expand a thread. */
ThreadState collapse(ConversationThread thread, ThreadState current);
/** A default presentation policy. */
public final PresentationPolicy DEFAULT = new SimplePresentationPolicy(ThreadState.EXPANDED);
}