/**
 * Logback: the reliable, generic, fast and flexible logging framework.
 * Copyright (C) 1999-2015, QOS.ch. All rights reserved.
 *
 * This program and the accompanying materials are dual-licensed under
 * either the terms of the Eclipse Public License v1.0 as published by
 * the Eclipse Foundation
 *
 *   or (per the licensee's choosing)
 *
 * under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation.
 */
package ch.qos.logback.classic.spi;

public class EventArgUtil {

    public static final Throwable extractThrowable(Object[] argArray) {
        if (argArray == null || argArray.length == 0) {
            return null;
        }

        final Object lastEntry = argArray[argArray.length - 1];
        if (lastEntry instanceof Throwable) {
            return (Throwable) lastEntry;
        }
        return null;
    }

    /**
     * This method should be called only if {@link #successfulExtraction(Throwable)} returns true.
     *
     * @param argArray
     * @return
     */
    public static Object[] trimmedCopy(Object[] argArray) {
        if (argArray == null || argArray.length == 0) {
            throw new IllegalStateException("non-sensical empty or null argument array");
        }
        final int trimemdLen = argArray.length - 1;
        Object[] trimmed = new Object[trimemdLen];
        System.arraycopy(argArray, 0, trimmed, 0, trimemdLen);
        return trimmed;
    }

    public static Object[] arrangeArguments(Object[] argArray) {
        return argArray;
    }

    public static boolean successfulExtraction(Throwable throwable) {
        return throwable != null;
    }
}
