/**
 * Distribution License:
 * JSword is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License, version 2.1 as published by
 * the Free Software Foundation. This program is distributed in the hope
 * that it will be useful, but WITHOUT ANY WARRANTY; without even the
 * implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU Lesser General Public License for more details.
 *
 * The License is available on the internet at:
 *       http://www.gnu.org/copyleft/lgpl.html
 * or by writing to:
 *      Free Software Foundation, Inc.
 *      59 Temple Place - Suite 330
 *      Boston, MA 02111-1307, USA
 *
 * Copyright: 2005
 *     The copyright to this program is held by it's authors.
 *
 * ID: $Id: CallContext.java 2099 2011-03-07 17:13:00Z dmsmith $
 */
package org.crosswire.common.util;

import org.crosswire.jsword.JSOtherMsg;

/**
 * This singleton class provides a way for a method to determine which class
 * called it.
 * <p>
 * It has been tested to work in command line and WebStart environments.
 * 
 * @see gnu.lgpl.License for license details.<br>
 *      The copyright to this program is held by it's authors.
 * @author DM Smith [ dmsmith555 at yahoo dot com]
 */
public final class CallContext{
    /**
     * Prevent instantiation
     */
    private CallContext() {
    }

    /**
     * Singleton accessor
     */
    public static CallContext instance() {
        try {
            if (resolver == null) {
                resolver = new CallContext();
            }

            return resolver;
        } catch (SecurityException se) {
            throw new LucidRuntimeException(JSOtherMsg.lookupText("Could not create ClassResolver:"), se);
        }
    }

//    /*
//     * (non-Javadoc)
//     * 
//     * @see java.lang.SecurityManager#getClassContext()
//     */
//    @Override
//    protected Class<?>[] getClassContext() {
//        return super.getClassContext();
//    }

    /**
     * When called from a method it will return the class calling that method.
     */
    public static Class<?> getCallingClass() {
        return getCallingClass(1); // add 1 for this method
    }

    /**
     * When called from a method it will return the i-th class calling that
     * method, up the call chain. If used with a -1 it will return the class
     * making the call -2 and -3 will return this class
     * 
     * @throws ArrayIndexOutOfBoundsException
     *             if the index is not valid
     */
    public static Class<?> getCallingClass(int i) {
    	try {
	// Android 4.0 does not return anything from getClassContext() so using the default JSword code causes Exception in Initializer resulting from an NPE
	        return Class.forName(Thread.currentThread().getStackTrace()[CALL_CONTEXT_OFFSET + i].getClassName());
	//        return instance().getClassContext()[CALL_CONTEXT_OFFSET + i];
    	} catch (Exception e) {
    		System.out.println("Error finding calling class");
    		e.printStackTrace();
    		//this is a frig to make this more robust in different environments - this method is not critical to JSword's operation
    		return CallContext.class;
    	}
    }

    // may need to change if this class is redesigned
    /**
     * Offset needed to represent the caller of the method that called this
     * method.
     * 
     */
    private static final int CALL_CONTEXT_OFFSET = 3;

    private static volatile CallContext resolver;
}