//------------------------------------------------------------------------------
//      Compilation Unit Header
//------------------------------------------------------------------------------
//
//  Copyright (c) 2006 Waysys, LLC. All Rights Reserved.
//
//  Permission to use, copy, modify, and distribute this software
//  and its documentation for NON-COMMERCIAL purposes and without
//  fee is hereby granted provided that this copyright notice
//  appears in all copies.
//
//  Waysys MAKES NO REPRESENTATIONS OR WARRANTIES ABOUT THE SUITABILITY OF
//  THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
//  TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
//  PARTICULAR PURPOSE, OR NON-INFRINGEMENT. Waysys SHALL NOT BE LIABLE FOR
//  ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF USING, MODIFYING OR
//  DISTRIBUTING THIS SOFTWARE OR ITS DERIVATIVES.
//
//  For further information, contact Waysys Inc. at wshaffer@waysysweb.com
//  or 800-622-5315 (USA).
//
//------------------------------------------------------------------------------
//      Maintenance History
//------------------------------------------------------------------------------
//
//  Person    Date          Change
//  ------    -----------   ----------------------------------------------------
//
//  Shaffer   09-May-1997   File create
//  Shaffer   17-Jun-2000   Package name updated and adapted to JBuilder
//  Shaffer   17-Jun-2000   Modified to add displays
//  Shaffer   12-Nov-2006   Modified to make compatible with PalmDateBench
//
//------------------------------------------------------------------------------
//      Package Declaration
//------------------------------------------------------------------------------

package com.waysysweb.util;

//------------------------------------------------------------------------------
//      Import Declarations
//------------------------------------------------------------------------------


//------------------------------------------------------------------------------
//      Public Class Declaration
//------------------------------------------------------------------------------

/**
 * Represent information about an Exception.
 *
 * @author   William A. Shaffer
 * @version  1.01  17-Jun-2000
 */

public abstract class WayException extends Exception
{
    protected int    err = 0;
    protected String argument = "";
    
    /**
     * Create a WayException
     *
     * @param errorNum the number identifying the error.
     * @param arg an argument inserted into the error message.
     */
    public WayException(int errorNum, String arg)
    {
        super();
        err = errorNum;
        argument = arg;
        return;
    }
    
    /**
     * Create a WayException
     *
     * @param errorNum the number identifying the error.
     * @param arg an integer argument inserted into the error message
     */
    public WayException(int errorNum, int arg)
    {
        super();
        err = errorNum;
        argument = String.valueOf(arg);
        return;
    }
    
    /**
     * Display the error message associated with this exception.
     * To be implemented in subclasses.
     * 
     */
    abstract public String getMessage();
        
    /**
     * Build and display an error message.
     *
     * <P>Example:</P>
     * <PRE>
     *    display(errNum, errMessage);
     * </PRE>
     * @param  errNum an array of integers with error numbers
     * @param  errMessage an array of error messages
     * @return a string with the error message 
     */
    
    protected String buildMessage(int[] errNum, String[] errMessage)
    {
        String message = findError(errNum, errMessage, err, argument);
        return message;
    }
    
    /**
     * Find an error message, given an error number, and substitute
     * the argument into the string.
     *
     * <P>Example:</P>
     * <PRE>
     *    message = findError(errorNum, arg);
     * </PRE>
     * @return the desired error message
     * @param  errNum an array of error numbers
     * @param  errMessage an array of error messages
     * @param  errorNum the error number to be looked up
     * @param  arg argument to be substituted into error message
     */
    private static String findError(int[] errNum, String[] errMessage, int errorNum, String arg)
    {
        int i;
        int j;
        int e;
        String message;
        
        // precondition:  MIN_VALUE <= errorNum <= MAX_VALUE
        
        i = 0;
        j = errNum.length - 1;
        e = (i + j)/2;
        
        // Loop invariant:
        //      0 <= i, j < errNum.length
        //      and
        //      errNum[i] <= errorNum <= errNum[j]
        // Termination Function:  j - i
        //
        
        while ((i + 1) <  j)
        {
            if      (errNum[e] <  errorNum) i = e;
            else if (errNum[e] >  errorNum) j = e;
            else    break;
            e = (i + j)/2;
        }
        
        // Proof:
        //
        // (1)  Invariant holds at beginning of first iteration because of
        //      initialization and precondition.
        // (2)  Invariant holds at end of each iteration because:
        //         1 <= e < errNum.length
        //         errNum[i] <= errorNum <= errNum[j] because of if statement
        // (3)  t function always decreases since, if j > i
        //         if j = e, then
        //         j' - i' = (i + j)/2 - i
        //         i/2 + j/2 - i = j/2 - i/2 = (j - i)/2 < j - i
        //
        //         similarly if i = e, then
        //         j' - i' = j - (j + i)/2 = j/2 - i/2 < j - i
        
        if (errNum[e] == errorNum)
        {
            WayString str = new WayString(errMessage[e]);
            message = str.substitute('%', arg);
        }
        else message = "Error number not found: " + errorNum;
        return message;
    }
}