/*
 * Copyright (c) 2010-2016 Evolveum
 *
 * 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 com.evolveum.midpoint.web.component.refresh;

import com.evolveum.midpoint.util.logging.Trace;
import com.evolveum.midpoint.util.logging.TraceManager;
import org.apache.wicket.Component;
import org.apache.wicket.ajax.AbstractAjaxTimerBehavior;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.behavior.Behavior;
import org.apache.wicket.util.time.Duration;
import org.jetbrains.annotations.NotNull;

import java.util.ArrayList;
import java.util.List;

/**
 * EXPERIMENTAL. (Working with these timers is very tricky. What we really need is flexible re-scheduling of these timers.)
 *
 * @author mederly
 */
public abstract class RemovableAjaxTimerBehavior extends AbstractAjaxTimerBehavior {

	private static final Trace LOGGER = TraceManager.getTrace(RemovableAjaxTimerBehavior.class);

	@NotNull private final Component parent;
	private final long updateInterval;
	private boolean enabled = true;
	private long expires;

	public RemovableAjaxTimerBehavior(@NotNull Component parent, long updateInterval) {
		super(Duration.milliseconds(updateInterval));
		this.updateInterval = updateInterval;
		this.parent = parent;
	}

	@Override
	protected void onTimer(AjaxRequestTarget target) {
		LOGGER.trace("onTimer called for {}; enabled = {}", this, enabled);
		if (enabled) {
			handleOnTimer(target);
		}
		cleanup();
	}

	public void cleanup() {
		synchronized (parent) {
			List<RemovableAjaxTimerBehavior> toBeRemoved = new ArrayList<>();
			for (Behavior behavior : parent.getBehaviors()) {
				if (behavior instanceof RemovableAjaxTimerBehavior && ((RemovableAjaxTimerBehavior) behavior).isExpired()) {
					toBeRemoved.add((RemovableAjaxTimerBehavior) behavior);
				}
			}
			for (RemovableAjaxTimerBehavior behavior : toBeRemoved) {
				LOGGER.trace("Removing {} from {}", behavior, parent);
				parent.remove(behavior);
			}
		}
	}

	private boolean isExpired() {
		return expires != 0 && System.currentTimeMillis() >= expires;
	}

	protected abstract void handleOnTimer(AjaxRequestTarget target);

	public void remove(AjaxRequestTarget target) {
		LOGGER.trace("remove() called, setting enabled := false and calling stop() method [{}]", this);
		enabled = false;
		expires = System.currentTimeMillis() + 2*updateInterval;
		stop(target);
		cleanup();			// just to call cleanup at every possible place
	}

}