/*
*	Tabby jQuery plugin version 0.12
*
*	Ted Devito - http://teddevito.com/demos/textarea.html
*
*	You should have received a copy of the GNU General Public License
*	along with Easy Widgets. If not, see <http://www.gnu.org/licenses/>
*
*	Plugin development pattern based on:	http://www.learningjquery.com/2007/10/a-plugin-development-pattern
*
*/

// create closure

(function($) {

    // plugin definition

    $.fn.tabby = function(options) {
        //debug(this);
        // build main options before element iteration
        var opts = $.extend({}, $.fn.tabby.defaults, options);
        var pressed = $.fn.tabby.pressed;

        // iterate and reformat each matched element
        return this.each(function() {
            $this = $(this);

            // build element specific options
            var options = $.meta ? $.extend({}, opts, $this.data()) : opts;

            $this.bind('keydown', function(e) {
                var kc = $.fn.tabby.catch_kc(e);
                if (16 == kc) pressed.shft = true;
                /*
                because both CTRL+TAB and ALT+TAB default to an event (changing tab/window) that 
                will prevent js from capturing the keyup event, we'll set a timer on releasing them.
                */
                if (17 == kc) { pressed.ctrl = true; setTimeout("$.fn.tabby.pressed.ctrl = false;", 1000); }
                if (18 == kc) { pressed.alt = true; setTimeout("$.fn.tabby.pressed.alt = false;", 1000); }

                if (9 == kc && !pressed.ctrl && !pressed.alt) {
                    e.preventDefault; // does not work in O9.63 ??
                    pressed.last = kc; setTimeout("$.fn.tabby.pressed.last = null;", 0);
                    process_keypress($(e.target).get(0), pressed.shft, options);
                    return false;
                }

            }).bind('keyup', function(e) {
                if (16 == $.fn.tabby.catch_kc(e)) pressed.shft = false;
            }).bind('blur', function(e) { // workaround for Opera -- http://www.webdeveloper.com/forum/showthread.php?p=806588
                if (9 == pressed.last) $(e.target).one('focus', function(e) { pressed.last = null; }).get(0).focus();
            });

        });
    };

    // define and expose any extra methods
    $.fn.tabby.catch_kc = function(e) { return e.keyCode ? e.keyCode : e.charCode ? e.charCode : e.which; };
    $.fn.tabby.pressed = { shft: false, ctrl: false, alt: false, last: null };

    // private function for debugging
    function debug($obj) {
        if (window.console && window.console.log)
            window.console.log('textarea count: ' + $obj.size());
    };

    function process_keypress(o, shft, options) {
        var scrollTo = o.scrollTop;
        //var tabString = String.fromCharCode(9);

        // gecko; o.setSelectionRange is only available when the text box has focus
        if (o.setSelectionRange) gecko_tab(o, shft, options);

        // ie; document.selection is always available
        else if (document.selection) ie_tab(o, shft, options);

        o.scrollTop = scrollTo;
    }

    // plugin defaults
    $.fn.tabby.defaults = { tabString: String.fromCharCode(9) };

    function gecko_tab(o, shft, options) {
        var ss = o.selectionStart;
        var es = o.selectionEnd;

        // when there's no selection and we're just working with the caret, we'll add/remove the tabs at the caret, providing more control
        if (ss == es) {
            // SHIFT+TAB
            if (shft) {
                // check to the left of the caret first
                if ("\t" == o.value.substring(ss - options.tabString.length, ss)) {
                    o.value = o.value.substring(0, ss - options.tabString.length) + o.value.substring(ss); // put it back together omitting one character to the left
                    o.focus();
                    o.setSelectionRange(ss - options.tabString.length, ss - options.tabString.length);
                }
                // then check to the right of the caret
                else if ("\t" == o.value.substring(ss, ss + options.tabString.length)) {
                    o.value = o.value.substring(0, ss) + o.value.substring(ss + options.tabString.length); // put it back together omitting one character to the right
                    o.focus();
                    o.setSelectionRange(ss, ss);
                }
            }
            // TAB
            else {
                o.value = o.value.substring(0, ss) + options.tabString + o.value.substring(ss);
                o.focus();
                o.setSelectionRange(ss + options.tabString.length, ss + options.tabString.length);
            }
        }
        // selections will always add/remove tabs from the start of the line
        else {
            // split the textarea up into lines and figure out which lines are included in the selection
            var lines = o.value.split("\n");
            var indices = new Array();
            var sl = 0; // start of the line
            var el = 0; // end of the line
            var sel = false;
            for (var i in lines) {
                el = sl + lines[i].length;
                indices.push({ start: sl, end: el, selected: (sl <= ss && el > ss) || (el >= es && sl < es) || (sl > ss && el < es) });
                sl = el + 1; // for "\n"
            }

            // walk through the array of lines (indices) and add tabs where appropriate						
            var modifier = 0;
            for (var i in indices) {
                if (indices[i].selected) {
                    var pos = indices[i].start + modifier; // adjust for tabs already inserted/removed
                    // SHIFT+TAB
                    if (shft && options.tabString == o.value.substring(pos, pos + options.tabString.length)) { // only SHIFT+TAB if there's a tab at the start of the line
                        o.value = o.value.substring(0, pos) + o.value.substring(pos + options.tabString.length); // omit the tabstring to the right
                        modifier -= options.tabString.length;
                    }
                    // TAB
                    else if (!shft) {
                        o.value = o.value.substring(0, pos) + options.tabString + o.value.substring(pos); // insert the tabstring
                        modifier += options.tabString.length;
                    }
                }
            }
            o.focus();
            var ns = ss + ((modifier > 0) ? options.tabString.length : (modifier < 0) ? -options.tabString.length : 0);
            var ne = es + modifier;
            o.setSelectionRange(ns, ne);
        }
    }

    function ie_tab(o, shft, options) {
        var range = document.selection.createRange();

        if (o == range.parentElement()) {
            // when there's no selection and we're just working with the caret, we'll add/remove the tabs at the caret, providing more control
            if ('' == range.text) {
                // SHIFT+TAB
                if (shft) {
                    var bookmark = range.getBookmark();
                    //first try to the left by moving opening up our empty range to the left
                    range.moveStart('character', -options.tabString.length);
                    if (options.tabString == range.text) {
                        range.text = '';
                    } else {
                        // if that didn't work then reset the range and try opening it to the right
                        range.moveToBookmark(bookmark);
                        range.moveEnd('character', options.tabString.length);
                        if (options.tabString == range.text)
                            range.text = '';
                    }
                    // move the pointer to the start of them empty range and select it
                    range.collapse(true);
                    range.select();
                }

                else {
                    // very simple here. just insert the tab into the range and put the pointer at the end
                    range.text = options.tabString;
                    range.collapse(false);
                    range.select();
                }
            }
            // selections will always add/remove tabs from the start of the line
            else {

                var selection_text = range.text;
                var selection_len = selection_text.length;
                var selection_arr = selection_text.split("\r\n");

                var before_range = document.body.createTextRange();
                before_range.moveToElementText(o);
                before_range.setEndPoint("EndToStart", range);
                var before_text = before_range.text;
                var before_arr = before_text.split("\r\n");
                var before_len = before_text.length; // - before_arr.length + 1;

                var after_range = document.body.createTextRange();
                after_range.moveToElementText(o);
                after_range.setEndPoint("StartToEnd", range);
                var after_text = after_range.text; // we can accurately calculate distance to the end because we're not worried about MSIE trimming a \r\n

                var end_range = document.body.createTextRange();
                end_range.moveToElementText(o);
                end_range.setEndPoint("StartToEnd", before_range);
                var end_text = end_range.text; // we can accurately calculate distance to the end because we're not worried about MSIE trimming a \r\n

                var check_html = $(o).html();
                $("#r3").text(before_len + " + " + selection_len + " + " + after_text.length + " = " + check_html.length);
                if ((before_len + end_text.length) < check_html.length) {
                    before_arr.push("");
                    before_len += 2; // for the \r\n that was trimmed	
                    if (shft && options.tabString == selection_arr[0].substring(0, options.tabString.length))
                        selection_arr[0] = selection_arr[0].substring(options.tabString.length);
                    else if (!shft) selection_arr[0] = options.tabString + selection_arr[0];
                } else {
                    if (shft && options.tabString == before_arr[before_arr.length - 1].substring(0, options.tabString.length))
                        before_arr[before_arr.length - 1] = before_arr[before_arr.length - 1].substring(options.tabString.length);
                    else if (!shft) before_arr[before_arr.length - 1] = options.tabString + before_arr[before_arr.length - 1];
                }

                for (var i = 1; i < selection_arr.length; i++) {
                    if (shft && options.tabString == selection_arr[i].substring(0, options.tabString.length))
                        selection_arr[i] = selection_arr[i].substring(options.tabString.length);
                    else if (!shft) selection_arr[i] = options.tabString + selection_arr[i];
                }

                if (1 == before_arr.length && 0 == before_len) {
                    if (shft && options.tabString == selection_arr[0].substring(0, options.tabString.length))
                        selection_arr[0] = selection_arr[0].substring(options.tabString.length);
                    else if (!shft) selection_arr[0] = options.tabString + selection_arr[0];
                }

                if ((before_len + selection_len + after_text.length) < check_html.length) {
                    selection_arr.push("");
                    selection_len += 2; // for the \r\n that was trimmed
                }

                before_range.text = before_arr.join("\r\n");
                range.text = selection_arr.join("\r\n");

                var new_range = document.body.createTextRange();
                new_range.moveToElementText(o);

                if (0 < before_len) new_range.setEndPoint("StartToEnd", before_range);
                else new_range.setEndPoint("StartToStart", before_range);
                new_range.setEndPoint("EndToEnd", range);

                new_range.select();

            }
        }
    }

    // end of closure
})(jQuery);