/*
 * Copyright (c) 2000, 2017 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License v. 2.0, which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * This Source Code may also be made available under the following Secondary
 * Licenses when the conditions for such availability set forth in the
 * Eclipse Public License v. 2.0 are satisfied: GNU General Public License,
 * version 2 with the GNU Classpath Exception, which is available at
 * https://www.gnu.org/software/classpath/license.html.
 *
 * SPDX-License-Identifier: EPL-2.0 OR GPL-2.0 WITH Classpath-exception-2.0
 */

/*
 * @(#)Debug.java	1.5 06/29/07
 */

package com.sun.messaging.jmq.util;

import java.util.Properties;
import java.util.Enumeration;
import java.lang.reflect.Field;

/**
 * Debug
 */
public class Debug {

    public final static String debugFieldName = "DEBUG";

    /**
     * Set the DEBUG flag on the specified class. The DEBUG field is assumed to be declared:
     *
     * <pre>
     * public static boolean DEBUG;
     * </pre>
     *
     * @param className Fully qualified classname to set DEBUG on
     * @param debug Value to set DEBUG to
     *
     *
     * @throws ClassNotFoundException if class is not found
     * @throws NoSuchFieldExcetpion if DEBUG field is not found in class
     */
    public static void setDebug(String className, boolean debug)
            throws ClassNotFoundException, NoSuchFieldException, IllegalArgumentException, IllegalAccessException {

        Class cl = Class.forName(className);
        Field[] fields = cl.getDeclaredFields();
        for (int i = 0; i < fields.length; i++) {
            if (fields[i].getName().equals(debugFieldName)) {
                fields[i].setAccessible(true);
                fields[i].setBoolean(null, debug);
                return;
            }
        }
        throw new NoSuchFieldException(debugFieldName);

    }

    /**
     * Set the DEBUG flag on the classes specified by values in a a Properties object. The Properties object should contain
     * a series of properties of the format:
     *
     * <pre>
     * <prefix>.<classname>=true|false
     * </pre>
     *
     * This method will set the DEBUG flag on <classname> to the specified value. For example if "jmq.debug." is the prefix
     * then
     *
     * <pre>
     * jmq.debug.com.sun.messaging.jmq.jmsserver.data.AcknowledgeList = true
     * </pre>
     *
     * Will set com.sun.messaging.jmq.jmsserver.data.AcknowledgeList.DEBUG to true.
     * <p>
     * If an error occurs when processing the properties further processing stops and the appropriate exception is thrown.
     *
     * @param props Properties object containing entries to set DEBUG on
     * @param prefix String that the prefixes each classname. If a property does not begin with this string then it is
     * ignored.
     *
     * @throws ClassNotFoundException if class is not found
     * @throws NoSuchFieldExcetpion if DEBUG field is not found in class
     */
    public static void setDebug(Properties props, String prefix) throws ClassNotFoundException, NoSuchFieldException, IllegalAccessException {

        // Scan through properties
        for (Enumeration e = props.propertyNames(); e.hasMoreElements();) {
            String key = (String) e.nextElement();

            // Find properties that match prefix
            if (key.startsWith(prefix)) {

                // Get className and value and set debug
                String className = key.substring(prefix.length());
                if (className.length() != 0) {
                    String value = props.getProperty(key);
                    if (value != null && value.length() != 0) {
                        try {
                            setDebug(className, (Boolean.valueOf(value)).booleanValue());
                        } catch (NoSuchFieldException ex) {
                            throw new NoSuchFieldException(className + "." + debugFieldName);
                        } catch (IllegalAccessException ex) {
                            throw new IllegalAccessException(className + "." + debugFieldName);
                        }
                    }
                }
            }
        }
    }
}
