/*
 * jQuery AutoTab plugin
 * http://dev.lousyllama.com/auto-tab
 * 
 * Copyright (c) 2007 Matthew Miller
 * Licensed under the MIT License:
 *   http://www.opensource.org/licenses/mit-license.php
 * 
 * Updated: 2007/06/26 16:50:52
 * Version: 1.00
 */

(function($) {

/**
 * autotab provides an easy way to apply auto tabbing to input
 * elements on a form. On top of auto tabbing forward, if the
 * user presses the backspace key on a box that is empty, the
 * supplied previous element will gain focus.
 * 
 * The maxlength attribute is required on each auto tab element.
 * 
 * @example  $('#area_code').autotab('#number1');
 * @desc Auto tabs to the #number1 element
 * 
 * @example  $('#number1').autotab('#number2', '#area_code');
 * @desc Auto tabs to the #number2 element, backspaces to the #area_code element
 * 
 * @name autotab
 * @param String (required) Element to focus on when maxlength is reached
 * @param String (optional) Element to focus on when backspacing
 * @cat Plugins/AutoTab
 */
$.fn.autotab = function(options) {
    var defaults = {
        format: 'all',        // text, numeric, alphanumeric, all
        limit: 5,            // Defaults to maxlength value
        uppercase: false,    // Converts a string to UPPERCASE
        lowercase: false,    // Converts a string to lowecase
        no_space: false,    // Remove spaces in the user input
        target: null,        // Where to auto tab to
        previous: null        // Backwards auto tab when all data is backspaced
    };

    $.extend(defaults, options);

    var limit = $(this).attr('maxlength');

    if(limit != 2147483647)
        defaults.limit = limit;

    var key = function(e) {
        if(!e)
            e = window.event;

        return e.keyCode;
    };

    // IE does not recognize the backspace key
    // with keypress in a blank input box
    if($.browser.msie)
    {
        this.keydown(function(e) {
            if(key(e) == 8)
            {
                var val = $(this).val();

                if(val.length == 0 && defaults.previous)
                    defaults.previous.focus();
            }
        });
    }

    this.keypress(function(e) {
        if(key(e) == 8)
        {
            var val = $(this).val();

            if(val.length == 0 && defaults.previous)
                defaults.previous.focus();
        }
    }).keyup(function(e) {
        var val = $(this).val();

        switch(defaults.format)
        {
            case 'text':
                var pattern = new RegExp('[0-9]+', 'g');
                var val = val.replace(pattern, '');
                break;

            case 'alpha':
                var pattern = new RegExp('[^a-zA-Z]+', 'g');
                var val = val.replace(pattern, '');
                break;

            case 'numeric':
                var pattern = new RegExp('[^0-9]+', 'g');
                var val = val.replace(pattern, '');
                break;

            case 'alphanumeric':
                var pattern = new RegExp('[^0-9a-zA-Z]+', 'g');
                var val = val.replace(pattern, '');
                break;

            case 'all':
            default:
                break;
        }

        if(defaults.no_space)
        {
            pattern = new RegExp('[ ]+', 'g');
            val = val.replace(pattern, '');
        }

        if(defaults.uppercase)
            val = val.toUpperCase();

        if(defaults.lowercase)
            val = val.toLowerCase();

        $(this).val(val);

        switch(key(e))
        {
            // Do not auto tab when the following keys are pressed
            case 8:        // Backspace
            case 9:        // Tab
            case 16:    // Shift
            case 17:    // Ctrl
            case 18:    // Alt
            case 32:    // [SPACE]
            case 33:    // Page Up
            case 34:    // Page Down
            case 35:    // End
            case 36:    // Home
            case 37:    // Left Arrow
            case 38:    // Up Arrow
            case 39:    // Right Arrow
            case 40:    // Down Arrow
                break;

            default:
                if(val.length == defaults.limit && defaults.target)
                    defaults.target.focus();
                break;
        }
    });

    return this;
};

})(jQuery);