/*******************************************************************************
 * Copyright (c) 2000, 2006 IBM Corporation and others.
 * 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:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.egit.core.internal.util;

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

import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.ILog;
import org.eclipse.core.runtime.IStatus;
import org.eclipse.core.runtime.MultiStatus;
import org.eclipse.core.runtime.Status;

/**
 * Collects exceptions and can be configured to ignore duplicates exceptions.
 * Exceptions can be logged and a MultiStatus containing all collected
 * exceptions can be returned.
 *
 * @see org.eclipse.core.runtime.MultiStatus
 * @see org.eclipse.core.runtime.IStatus
 *
 * @since 3.0
 */
public class ExceptionCollector {

	private final List<IStatus> statuses = new ArrayList<IStatus>();

	private final String message;

	private final String pluginId;

	private final int severity;

	private final ILog log;

	/**
	 * Creates a collector and initializes the parameters for the top-level
	 * exception that would be returned from <code>getStatus</code> is
	 * exceptions are collected.
	 *
	 * @param message
	 *            a human-readable message, localized to the current locale
	 * @param pluginId
	 *            the unique identifier of the relevant plug-in
	 * @param severity
	 *            the severity; one of <code>OK</code>, <code>ERROR</code>,
	 *            <code>INFO</code>, or <code>WARNING</code>
	 * @param log
	 *            the log to output the exceptions to, or <code>null</code> if
	 *            exceptions should not be logged.
	 */
	public ExceptionCollector(String message, String pluginId, int severity,
			ILog log) {
		this.message = message;
		this.pluginId = pluginId;
		this.severity = severity;
		this.log = log;
	}

	/**
	 * Clears the exceptions collected.
	 */
	public void clear() {
		statuses.clear();
	}

	/**
	 * Returns a status that represents the exceptions collected. If the
	 * collector is empty <code>IStatus.OK</code> is returned. Otherwise a
	 * MultiStatus containing all collected exceptions is returned.
	 *
	 * @return a multistatus containing the exceptions collected or IStatus.OK
	 *         if the collector is empty.
	 */
	public IStatus getStatus() {
		if (statuses.isEmpty()) {
			return Status.OK_STATUS;
		} else {
			final MultiStatus multiStatus = new MultiStatus(pluginId, severity,
					message, null);
			final Iterator it = statuses.iterator();
			while (it.hasNext()) {
				final IStatus status = (IStatus) it.next();
				multiStatus.merge(status);
			}
			return multiStatus;
		}
	}

	/**
	 * Add this exception to the collector. If a log was specified in the
	 * constructor then the exception will be output to the log. You can
	 * retreive exceptions using <code>getStatus</code>.
	 *
	 * @param exception
	 *            the exception to collect
	 */
	public void handleException(CoreException exception) {
		if (log != null) {
			log.log(new Status(severity, pluginId, 0, message, exception));
		}

		// Record each status individually to flatten the resulting multi-status
		final IStatus exceptionStatus = exception.getStatus();

		// Wrap the exception so the stack trace is not lost.
		final IStatus status = new Status(exceptionStatus.getSeverity(),
				exceptionStatus.getPlugin(), exceptionStatus.getCode(),
				exceptionStatus.getMessage(), exception);

		recordStatus(status);
		for (IStatus childStatus : status.getChildren())
			recordStatus(childStatus);
	}

	private void recordStatus(IStatus status) {
		statuses.add(status);
	}
}