/* *******************************************************************
 * Copyright (c) 1999-2001 Xerox Corporation, 
 *               2002 Palo Alto Research Center, Incorporated (PARC).
 * All rights reserved. 
 * This program and the accompanying materials are made available 
 * under the terms of the Eclipse Public License v1.0 
 * which accompanies this distribution and is available at 
 * http://www.eclipse.org/legal/epl-v10.html 
 *  
 * Contributors: 
 *     Xerox/PARC     initial implementation 
 * ******************************************************************/

package org.aspectj.bridge;

import java.util.Enumeration;
import java.util.Hashtable;

import org.aspectj.util.LangUtil;

/**
 * Wrap an IMessageHandler to count messages handled. Messages being ignored by the delegate IMessageHandler are not counted.
 */
public class CountingMessageHandler implements IMessageHandler {

	public final IMessageHandler delegate;
	public final CountingMessageHandler proxy;
	private final Hashtable<IMessage.Kind, IntHolder> counters;

	public static CountingMessageHandler makeCountingMessageHandler(IMessageHandler handler) {
		if (handler instanceof CountingMessageHandler) {
			return (CountingMessageHandler) handler;
		} else {
			return new CountingMessageHandler(handler);
		}
	}

	public CountingMessageHandler(IMessageHandler delegate) {
		LangUtil.throwIaxIfNull(delegate, "delegate");
		this.delegate = delegate;
		this.counters = new Hashtable<IMessage.Kind, IntHolder>();
		proxy = (delegate instanceof CountingMessageHandler ? (CountingMessageHandler) delegate : null);
	}

	/** @return delegate.handleMessage(IMessage) */
	public boolean handleMessage(IMessage message) throws AbortException {
		if (null != proxy) {
			return proxy.handleMessage(message);
		}
		if (null != message) {
			IMessage.Kind kind = message.getKind();
			if (!isIgnoring(kind)) {
				increment(kind);
			}
		}
		return delegate.handleMessage(message);
	}

	/** @return delegate.isIgnoring(IMessage.Kind) */
	public boolean isIgnoring(IMessage.Kind kind) {
		return delegate.isIgnoring(kind);
	}

	/**
	 * Delegate
	 * 
	 * @see org.aspectj.bridge.IMessageHandler#isIgnoring(org.aspectj.bridge.IMessage.Kind)
	 * @param kind
	 */
	public void dontIgnore(IMessage.Kind kind) {
		delegate.dontIgnore(kind);
	}

	/**
	 * Delegate
	 * 
	 * @see org.aspectj.bridge.IMessageHandler#ignore(org.aspectj.bridge.IMessage.Kind)
	 * @param kind
	 */
	public void ignore(IMessage.Kind kind) {
		delegate.ignore(kind);
	}

	/** @return delegate.toString() */
	public String toString() {
		return delegate.toString();
	}

	/**
	 * Return count of messages seen through this interface.
	 * 
	 * @param kind the IMessage.Kind of the messages to count (if null, count all)
	 * @param orGreater if true, then count this kind and any considered greater by the ordering of IMessage.Kind.COMPARATOR
	 * @return number of messages of this kind (optionally or greater)
	 * @see IMessage.Kind.COMPARATOR
	 */
	public int numMessages(IMessage.Kind kind, boolean orGreater) {
		if (null != proxy) {
			return proxy.numMessages(kind, orGreater);
		}
		int result = 0;
		if (null == kind) {
			for (Enumeration<IntHolder> enu = counters.elements(); enu.hasMoreElements();) {
				result += (enu.nextElement()).count;
			}
		} else if (!orGreater) {
			result = numMessages(kind);
		} else {
			for (IMessage.Kind k : IMessage.KINDS) {
				if (kind.isSameOrLessThan(k)) {
					result += numMessages(k);
				}
			}
		}
		return result;
	}

	/**
	 * @return true if 0 is less than <code>numMessages(IMessage.ERROR, true)</code>
	 */
	public boolean hasErrors() {
		return (0 < numMessages(IMessage.ERROR, true));
	}

	private int numMessages(IMessage.Kind kind) {
		if (null != proxy) {
			return proxy.numMessages(kind);
		}
		IntHolder counter = counters.get(kind);
		return (null == counter ? 0 : counter.count);
	}

	private void increment(IMessage.Kind kind) {
		if (null != proxy) {
			throw new IllegalStateException("not called when proxying");
		}

		IntHolder counter = counters.get(kind);
		if (null == counter) {
			counter = new IntHolder();
			counters.put(kind, counter);
		}
		counter.count++;
	}

	private static class IntHolder {
		int count;
	}

	public void reset() {
		if (proxy != null) {
			proxy.reset();
		}
		counters.clear();
	}

}