wmd.js

;(function() {
    
WMDEditor = function(options) {
    this.options = WMDEditor.util.extend({}, WMDEditor.defaults, options || {});
    wmdBase(this, this.options);

    this.startEditor();
};
top.WMDEditor = WMDEditor;

WMDEditor.defaults = { // {{{
    version: 2.0, 
    output_format:"markdown", 
    lineLength:40, 

    button_bar: "wmd-button-bar",
    preview: "wmd-preview",
    output: "wmd-output",
    input: "wmd-input",
    
    // The text that appears on the upper part of the dialog box when
    // entering links.
    imageDialogText: 
        "<p style='margin-top: 0px'><b>Enter the image URL.</b></p>" + 
        "<p>You can also add a title, which will be displayed as a tool tip.</p>" +
        "<p>Example:<br />http://wmd-editor.com/images/cloud1.jpg   \"Optional title\"</p>",
    linkDialogText: 
        "<p style='margin-top: 0px'><b>Enter the web address.</b></p>" + 
        "<p>You can also add a title, which will be displayed as a tool tip.</p>" + 
        "<p>Example:<br />http://wmd-editor.com/   \"Optional title\"</p>",

    // The default text that appears in the dialog input box when entering
    // links.
    imageDefaultText: "http://",
    linkDefaultText: "http://",
    imageDirectory: "images/",

    // The link and title for the help button
    helpLink: "http://wmd-editor.com/",
    helpHoverTitle: "WMD website",
    helpTarget: "_blank",

    // Some intervals in ms.  These can be adjusted to reduce the control's load.
    previewPollInterval: 500,
    pastePollInterval: 100,

    buttons: "bold italic link blockquote code image ol ul heading hr"
}; // }}}

WMDEditor.prototype = {
    getPanels: function() {
        return {
            buttonBar: doc.getElementById(this.options.button_bar),
            preview: doc.getElementById(this.options.preview),
            output: doc.getElementById(this.options.output),
            input: doc.getElementById(this.options.input)
        };
    },

    startEditor: function() {
        this.panels = this.getPanels();
        this.previewMgr = new PreviewManager(this);
        edit = new this.editor(this.previewMgr.refresh);
        this.previewMgr.refresh(true);
    }
};


var util = { // {{{

    // Returns true if the DOM element is visible, false if it's hidden.
    // Checks if display is anything other than none.
    isVisible: function (elem) {
        // shamelessly copied from jQuery
        return elem.offsetWidth > 0 || elem.offsetHeight > 0;
    },

    // Adds a listener callback to a DOM element which is fired on a specified
    // event.
    addEvent: function(elem, event, listener){
        if (elem.attachEvent) {
            // IE only.  The "on" is mandatory.
            elem.attachEvent("on" + event, listener);
        }
        else {
            // Other browsers.
            elem.addEventListener(event, listener, false);
        }
    },

    // Removes a listener callback from a DOM element which is fired on a specified
    // event.
    removeEvent: function(elem, event, listener){
        if (elem.detachEvent) {
            // IE only.  The "on" is mandatory.
            elem.detachEvent("on" + event, listener);
        }
        else {
            // Other browsers.
            elem.removeEventListener(event, listener, false);
        }
    },

    // Converts \r\n and \r to \n.
    fixEolChars: function(text){
        text = text.replace(/\r\n/g, "\n");
        text = text.replace(/\r/g, "\n");
        return text;
    },

    // Extends a regular expression.  Returns a new RegExp
    // using pre + regex + post as the expression.
    // Used in a few functions where we have a base
    // expression and we want to pre- or append some
    // conditions to it (e.g. adding "$" to the end).
    // The flags are unchanged.
    //
    // regex is a RegExp, pre and post are strings.
    extendRegExp: function(regex, pre, post){
    
        if (pre === null || pre === undefined)
        {
            pre = "";
        }
        if(post === null || post === undefined)
        {
            post = "";
        }
    
        var pattern = regex.toString();
        var flags = "";
    
        // Replace the flags with empty space and store them.
        // Technically, this can match incorrect flags like "gmm".
        var result = pattern.match(/\/([gim]*)$/);
        if (result === null) {
            flags = result[0];
        }
        else {
            flags = "";
        }
    
        // Remove the flags and slash delimiters from the regular expression.
        pattern = pattern.replace(/(^\/|\/[gim]*$)/g, "");
        pattern = pre + pattern + post;
    
        return new RegExp(pattern, flags);
    },

    // Sets the image for a button passed to the WMD editor.
    // Returns a new element with the image attached.
    // Adds several style properties to the image.
    //
    // XXX-ANAND: Is this used anywhere?
    createImage: function(img){
    
        var imgPath = imageDirectory + img;
    
        var elem = doc.createElement("img");
        elem.className = "wmd-button";
        elem.src = imgPath;

        return elem;
    },

    // This simulates a modal dialog box and asks for the URL when you
    // click the hyperlink or image buttons.
    //
    // text: The html for the input box.
    // defaultInputText: The default value that appears in the input box.
    // makeLinkMarkdown: The function which is executed when the prompt is dismissed, either via OK or Cancel
    prompt: function(text, defaultInputText, makeLinkMarkdown){

        // These variables need to be declared at this level since they are used
        // in multiple functions.
        var dialog;            // The dialog box.
        var background;        // The background beind the dialog box.
        var input;            // The text box where you enter the hyperlink.
    

        if (defaultInputText === undefined) {
            defaultInputText = "";
        }
    
        // Used as a keydown event handler. Esc dismisses the prompt.
        // Key code 27 is ESC.
        var checkEscape = function(key){
            var code = (key.charCode || key.keyCode);
            if (code === 27) {
                close(true);
            }
        };
    
        // Dismisses the hyperlink input box.
        // isCancel is true if we don't care about the input text.
        // isCancel is false if we are going to keep the text.
        var close = function(isCancel){
            util.removeEvent(doc.body, "keydown", checkEscape);
            var text = input.value;

            if (isCancel){
                text = null;
            }
            else{
                // Fixes common pasting errors.
                text = text.replace('http://http://', 'http://');
                text = text.replace('http://https://', 'https://');
                text = text.replace('http://ftp://', 'ftp://');
                
                if (text.indexOf('http://') === -1 && text.indexOf('ftp://') === -1 && text.indexOf('https://') === -1) {
                    text = 'http://' + text;
                }
            }
            
            dialog.parentNode.removeChild(dialog);
            background.parentNode.removeChild(background);
            makeLinkMarkdown(text);
            return false;
        };
    
        // Creates the background behind the hyperlink text entry box.
        // Most of this has been moved to CSS but the div creation and
        // browser-specific hacks remain here.
        var createBackground = function(){
            background = doc.createElement("div");
            background.className = "wmd-prompt-background";
            style = background.style;
            style.position = "absolute";
            style.top = "0";
            
            style.zIndex = "1000";
            
            // Some versions of Konqueror don't support transparent colors
            // so we make the whole window transparent.
            //
            // Is this necessary on modern konqueror browsers?
            if (browser.isKonqueror){
                style.backgroundColor = "transparent";
            }
            else if (browser.isIE){
                style.filter = "alpha(opacity=50)";
            }
            else {
                style.opacity = "0.5";
            }
            
            var pageSize = position.getPageSize();
            style.height = pageSize[1] + "px";
            
            if(browser.isIE){
                style.left = doc.documentElement.scrollLeft;
                style.width = doc.documentElement.clientWidth;
            }
            else {
                style.left = "0";
                style.width = "100%";
            }
            
            doc.body.appendChild(background);
        };
    
        // Create the text input box form/window.
        var createDialog = function(){
    
            // The main dialog box.
            dialog = doc.createElement("div");
            dialog.className = "wmd-prompt-dialog";
            dialog.style.padding = "10px;";
            dialog.style.position = "fixed";
            dialog.style.width = "400px";
            dialog.style.zIndex = "1001";
            
            // The dialog text.
            var question = doc.createElement("div");
            question.innerHTML = text;
            question.style.padding = "5px";
            dialog.appendChild(question);
            
            // The web form container for the text box and buttons.
            var form = doc.createElement("form");
            form.onsubmit = function(){ return close(false); };
            style = form.style;
            style.padding = "0";
            style.margin = "0";
            style.cssFloat = "left";
            style.width = "100%";
            style.textAlign = "center";
            style.position = "relative";
            dialog.appendChild(form);
            
            // The input text box
            input = doc.createElement("input");
            input.type = "text";
            input.value = defaultInputText;
            style = input.style;
            style.display = "block";
            style.width = "80%";
            style.marginLeft = style.marginRight = "auto";
            form.appendChild(input);
            
            // The ok button
            var okButton = doc.createElement("input");
            okButton.type = "button";
            okButton.onclick = function(){ return close(false); };
            okButton.value = "OK";
            style = okButton.style;
            style.margin = "10px";
            style.display = "inline";
            style.width = "7em";

            
            // The cancel button
            var cancelButton = doc.createElement("input");
            cancelButton.type = "button";
            cancelButton.onclick = function(){ return close(true); };
            cancelButton.value = "Cancel";
            style = cancelButton.style;
            style.margin = "10px";
            style.display = "inline";
            style.width = "7em";

            // The order of these buttons is different on macs.
            if (/mac/.test(nav.platform.toLowerCase())) {
                form.appendChild(cancelButton);
                form.appendChild(okButton);
            }
            else {
                form.appendChild(okButton);
                form.appendChild(cancelButton);
            }

            util.addEvent(doc.body, "keydown", checkEscape);
            dialog.style.top = "50%";
            dialog.style.left = "50%";
            dialog.style.display = "block";
            if(browser.isIE_5or6){
                dialog.style.position = "absolute";
                dialog.style.top = doc.documentElement.scrollTop + 200 + "px";
                dialog.style.left = "50%";
            }
            doc.body.appendChild(dialog);
            
            // This has to be done AFTER adding the dialog to the form if you
            // want it to be centered.
            dialog.style.marginTop = -(position.getHeight(dialog) / 2) + "px";
            dialog.style.marginLeft = -(position.getWidth(dialog) / 2) + "px";
        };
    
        createBackground();
    
        // Why is this in a zero-length timeout?
        // Is it working around a browser bug?
        top.setTimeout(function(){
            createDialog();

            var defTextLen = defaultInputText.length;
            if (input.selectionStart !== undefined) {
                input.selectionStart = 0;
                input.selectionEnd = defTextLen;
            }
            else if (input.createTextRange) {
                var range = input.createTextRange();
                range.collapse(false);
                range.moveStart("character", -defTextLen);
                range.moveEnd("character", defTextLen);
                range.select();
            }
            input.focus();
        }, 0);
    },
    
    extend: function() {
        function _update(a, b) {
            for (var k in b) {
                a[k] = b[k];
            }
            return a;
        }
        
        var d = {};
        for (var i=0; i < arguments.length; i++) {
            _update(d, arguments[i]);
        }
        return d;
    }
}; // }}}

var position = { // {{{ 

    // UNFINISHED
    // The assignment in the while loop makes jslint cranky.
    // I'll change it to a better loop later.
    getTop: function(elem, isInner){
        var result = elem.offsetTop;
        if (!isInner) {
            while (elem = elem.offsetParent) {
                result += elem.offsetTop;
            }
        }
        return result;
    },

    getHeight: function (elem) {
        return elem.offsetHeight || elem.scrollHeight;
    },

    getWidth: function (elem) {
        return elem.offsetWidth || elem.scrollWidth;
    },

    getPageSize: function() {
        var scrollWidth, scrollHeight;
        var innerWidth, innerHeight;
        
        // It's not very clear which blocks work with which browsers.
        if(self.innerHeight && self.scrollMaxY){
            scrollWidth = doc.body.scrollWidth;
            scrollHeight = self.innerHeight + self.scrollMaxY;
        }
        else if(doc.body.scrollHeight > doc.body.offsetHeight){
            scrollWidth = doc.body.scrollWidth;
            scrollHeight = doc.body.scrollHeight;
        }
        else{
            scrollWidth = doc.body.offsetWidth;
            scrollHeight = doc.body.offsetHeight;
        }
        
        if(self.innerHeight){
            // Non-IE browser
            innerWidth = self.innerWidth;
            innerHeight = self.innerHeight;
        }
        else if(doc.documentElement && doc.documentElement.clientHeight){
            // Some versions of IE (IE 6 w/ a DOCTYPE declaration)
            innerWidth = doc.documentElement.clientWidth;
            innerHeight = doc.documentElement.clientHeight;
        }
        else if(doc.body){
            // Other versions of IE
            innerWidth = doc.body.clientWidth;
            innerHeight = doc.body.clientHeight;
        }
            
        var maxWidth = Math.max(scrollWidth, innerWidth);
        var maxHeight = Math.max(scrollHeight, innerHeight);
        return [maxWidth, maxHeight, innerWidth, innerHeight];
    }
}; // }}}

// The input textarea state/contents.
// This is used to implement undo/redo by the undo manager.
var TextareaState = function(textarea){ // {{{
    // Aliases
    var stateObj = this;
    var inputArea = textarea;
    
    this.init = function() {
    
        if (!util.isVisible(inputArea)) {
            return;
        }
            
        this.setInputAreaSelectionStartEnd();
        this.scrollTop = inputArea.scrollTop;
        if (!this.text && inputArea.selectionStart || inputArea.selectionStart === 0) {
            this.text = inputArea.value;
        }
        
    }
    
    // Sets the selected text in the input box after we've performed an
    // operation.
    this.setInputAreaSelection = function(){
    
        if (!util.isVisible(inputArea)) {
            return;
        }
        
        if (inputArea.selectionStart !== undefined && !browser.isOpera) {
        
            inputArea.focus();
            inputArea.selectionStart = stateObj.start;
            inputArea.selectionEnd = stateObj.end;
            inputArea.scrollTop = stateObj.scrollTop;
        }
        else if (doc.selection) {
            
            if (doc.activeElement && doc.activeElement !== inputArea) {
                return;
            }
                
            inputArea.focus();
            var range = inputArea.createTextRange();
            range.moveStart("character", -inputArea.value.length);
            range.moveEnd("character", -inputArea.value.length);
            range.moveEnd("character", stateObj.end);
            range.moveStart("character", stateObj.start);
            range.select();
        }
    };
    
    this.setInputAreaSelectionStartEnd = function(){
    
        if (inputArea.selectionStart || inputArea.selectionStart === 0) {
        
            stateObj.start = inputArea.selectionStart;
            stateObj.end = inputArea.selectionEnd;
        }
        else if (doc.selection) {
            
            stateObj.text = util.fixEolChars(inputArea.value);
            
            // IE loses the selection in the textarea when buttons are
            // clicked.  On IE we cache the selection and set a flag
            // which we check for here.
            var range;
            if(wmd.ieRetardedClick && wmd.ieCachedRange) {
                range = wmd.ieCachedRange;
                wmd.ieRetardedClick = false;
            }
            else {
                range = doc.selection.createRange();
            }

            var fixedRange = util.fixEolChars(range.text);
            var marker = "\x07";
            var markedRange = marker + fixedRange + marker;
            range.text = markedRange;
            var inputText = util.fixEolChars(inputArea.value);
                
            range.moveStart("character", -markedRange.length);
            range.text = fixedRange;

            stateObj.start = inputText.indexOf(marker);
            stateObj.end = inputText.lastIndexOf(marker) - marker.length;
                
            var len = stateObj.text.length - util.fixEolChars(inputArea.value).length;
                
            if (len) {
                range.moveStart("character", -fixedRange.length);
                while (len--) {
                    fixedRange += "\n";
                    stateObj.end += 1;
                }
                range.text = fixedRange;
            }
                
            this.setInputAreaSelection();
        }
    };
    
    // Restore this state into the input area.
    this.restore = function(){
    
        if (stateObj.text != undefined && stateObj.text != inputArea.value) {
            inputArea.value = stateObj.text;
        }
        this.setInputAreaSelection();
        inputArea.scrollTop = stateObj.scrollTop;
    };
    
    // Gets a collection of HTML chunks from the inptut textarea.
    this.getChunks = function(){
    
        var chunk = new Chunks();
        
        chunk.before = util.fixEolChars(stateObj.text.substring(0, stateObj.start));
        chunk.startTag = "";
        chunk.selection = util.fixEolChars(stateObj.text.substring(stateObj.start, stateObj.end));
        chunk.endTag = "";
        chunk.after = util.fixEolChars(stateObj.text.substring(stateObj.end));
        chunk.scrollTop = stateObj.scrollTop;
        
        return chunk;
    };
    
    // Sets the TextareaState properties given a chunk of markdown.
    this.setChunks = function(chunk){
    
        chunk.before = chunk.before + chunk.startTag;
        chunk.after = chunk.endTag + chunk.after;
        
        if (browser.isOpera) {
            chunk.before = chunk.before.replace(/\n/g, "\r\n");
            chunk.selection = chunk.selection.replace(/\n/g, "\r\n");
            chunk.after = chunk.after.replace(/\n/g, "\r\n");
        }
        
        this.start = chunk.before.length;
        this.end = chunk.before.length + chunk.selection.length;
        this.text = chunk.before + chunk.selection + chunk.after;
        this.scrollTop = chunk.scrollTop;
    };

    this.init();
}; // }}}

// Chunks {{{

// before: contains all the text in the input box BEFORE the selection.
// after: contains all the text in the input box AFTER the selection.
var Chunks = function(){
};

// startRegex: a regular expression to find the start tag
// endRegex: a regular expresssion to find the end tag
Chunks.prototype.findTags = function(startRegex, endRegex){

    var chunkObj = this;
    var regex;
    
    if (startRegex) {
        
        regex = util.extendRegExp(startRegex, "", "$");
        
        this.before = this.before.replace(regex, 
            function(match){
                chunkObj.startTag = chunkObj.startTag + match;
                return "";
            });
        
        regex = util.extendRegExp(startRegex, "^", "");
        
        this.selection = this.selection.replace(regex, 
            function(match){
                chunkObj.startTag = chunkObj.startTag + match;
                return "";
            });
    }
    
    if (endRegex) {
        
        regex = util.extendRegExp(endRegex, "", "$");
        
        this.selection = this.selection.replace(regex,
            function(match){
                chunkObj.endTag = match + chunkObj.endTag;
                return "";
            });

        regex = util.extendRegExp(endRegex, "^", "");
        
        this.after = this.after.replace(regex,
            function(match){
                chunkObj.endTag = match + chunkObj.endTag;
                return "";
            });
    }
};

// If remove is false, the whitespace is transferred
// to the before/after regions.
//
// If remove is true, the whitespace disappears.
Chunks.prototype.trimWhitespace = function(remove){

    this.selection = this.selection.replace(/^(\s*)/, "");
    
    if (!remove) {
        this.before += re.$1;
    }
    
    this.selection = this.selection.replace(/(\s*)$/, "");
    
    if (!remove) {
        this.after = re.$1 + this.after;
    }
};


Chunks.prototype.addBlankLines = function(nLinesBefore, nLinesAfter, findExtraNewlines){

    if (nLinesBefore === undefined) {
        nLinesBefore = 1;
    }
    
    if (nLinesAfter === undefined) {
        nLinesAfter = 1;
    }
    
    nLinesBefore++;
    nLinesAfter++;
    
    var regexText;
    var replacementText;
    
    this.selection = this.selection.replace(/(^\n*)/, "");
    this.startTag = this.startTag + re.$1;
    this.selection = this.selection.replace(/(\n*$)/, "");
    this.endTag = this.endTag + re.$1;
    this.startTag = this.startTag.replace(/(^\n*)/, "");
    this.before = this.before + re.$1;
    this.endTag = this.endTag.replace(/(\n*$)/, "");
    this.after = this.after + re.$1;
    
    if (this.before) {
    
        regexText = replacementText = "";
        
        while (nLinesBefore--) {
            regexText += "\\n?";
            replacementText += "\n";
        }
        
        if (findExtraNewlines) {
            regexText = "\\n*";
        }
        this.before = this.before.replace(new re(regexText + "$", ""), replacementText);
    }
    
    if (this.after) {
    
        regexText = replacementText = "";
        
        while (nLinesAfter--) {
            regexText += "\\n?";
            replacementText += "\n";
        }
        if (findExtraNewlines) {
            regexText = "\\n*";
        }
        
        this.after = this.after.replace(new re(regexText, ""), replacementText);
    }
}; 
// }}} - END CHUNKS

// Watches the input textarea, polling at an interval and runs
// a callback function if anything has changed.
var InputPoller = function(textarea, callback, interval){ // {{{

    var pollerObj = this;
    var inputArea = textarea;
    
    // Stored start, end and text.  Used to see if there are changes to the input.
    var lastStart;
    var lastEnd;
    var markdown;
    
    var killHandle; // Used to cancel monitoring on destruction.
    // Checks to see if anything has changed in the textarea.
    // If so, it runs the callback.
    this.tick = function(){
    
        if (!util.isVisible(inputArea)) {
            return;
        }
        
        // Update the selection start and end, text.
        if (inputArea.selectionStart || inputArea.selectionStart === 0) {
            var start = inputArea.selectionStart;
            var end = inputArea.selectionEnd;
            if (start != lastStart || end != lastEnd) {
                lastStart = start;
                lastEnd = end;
                
                if (markdown != inputArea.value) {
                    markdown = inputArea.value;
                    return true;
                }
            }
        }
        return false;
    };
    
    
    var doTickCallback = function(){
    
        if (!util.isVisible(inputArea)) {
            return;
        }
        
        // If anything has changed, call the function.
        if (pollerObj.tick()) {
            callback();
        }
    };
    
    // Set how often we poll the textarea for changes.
    var assignInterval = function(){
        killHandle = top.setInterval(doTickCallback, interval);
    };
    
    this.destroy = function(){
        top.clearInterval(killHandle);
    };
    
    assignInterval();
}; // }}}
    
var PreviewManager = function(wmd){ // {{{
    var managerObj = this;
    var converter;
    var poller;
    var timeout;
    var elapsedTime;
    var oldInputText;
    var htmlOut;
    var maxDelay = 3000;
    var startType = "delayed"; // The other legal value is "manual"
    
    // Adds event listeners to elements and creates the input poller.
    var setupEvents = function(inputElem, listener){
    
        util.addEvent(inputElem, "input", listener);
        inputElem.onpaste = listener;
        inputElem.ondrop = listener;
        
        util.addEvent(inputElem, "keypress", listener);
        util.addEvent(inputElem, "keydown", listener);
        // previewPollInterval is set at the top of this file.
        poller = new InputPoller(wmd.panels.input, listener, wmd.options.previewPollInterval);
    };
    
    var getDocScrollTop = function(){
    
        var result = 0;
        
        if (top.innerHeight) {
            result = top.pageYOffset;
        }
        else 
            if (doc.documentElement && doc.documentElement.scrollTop) {
                result = doc.documentElement.scrollTop;
            }
            else 
                if (doc.body) {
                    result = doc.body.scrollTop;
                }
        
        return result;
    };
    
    var makePreviewHtml = function(){
    
        // If there are no registered preview and output panels
        // there is nothing to do.
        if (!wmd.panels.preview && !wmd.panels.output) {
            return;
        }
        
        var text = wmd.panels.input.value;
        if (text && text == oldInputText) {
            return; // Input text hasn't changed.
        }
        else {
            oldInputText = text;
        }
        
        var prevTime = new Date().getTime();
        
        if (!converter && wmd.showdown) {
            converter = new wmd.showdown.converter();
        }
        
        if (converter) {
            text = converter.makeHtml(text);
        }
        
        // Calculate the processing time of the HTML creation.
        // It's used as the delay time in the event listener.
        var currTime = new Date().getTime();
        elapsedTime = currTime - prevTime;
        
        pushPreviewHtml(text);
        htmlOut = text;
    };
    
    // setTimeout is already used.  Used as an event listener.
    var applyTimeout = function(){
    
        if (timeout) {
            top.clearTimeout(timeout);
            timeout = undefined;
        }
        
        if (startType !== "manual") {
        
            var delay = 0;
            
            if (startType === "delayed") {
                delay = elapsedTime;
            }
            
            if (delay > maxDelay) {
                delay = maxDelay;
            }
            timeout = top.setTimeout(makePreviewHtml, delay);
        }
    };
    
    var getScaleFactor = function(panel){
        if (panel.scrollHeight <= panel.clientHeight) {
            return 1;
        }
        return panel.scrollTop / (panel.scrollHeight - panel.clientHeight);
    };
    
    var setPanelScrollTops = function(){
    
        if (wmd.panels.preview) {
            wmd.panels.preview.scrollTop = (wmd.panels.preview.scrollHeight - wmd.panels.preview.clientHeight) * getScaleFactor(wmd.panels.preview);
            ;
        }
        
        if (wmd.panels.output) {
            wmd.panels.output.scrollTop = (wmd.panels.output.scrollHeight - wmd.panels.output.clientHeight) * getScaleFactor(wmd.panels.output);
            ;
        }
    };
    
    this.refresh = function(requiresRefresh){
    
        if (requiresRefresh) {
            oldInputText = "";
            makePreviewHtml();
        }
        else {
            applyTimeout();
        }
    };
    
    this.processingTime = function(){
        return elapsedTime;
    };
    
    // The output HTML
    this.output = function(){
        return htmlOut;
    };
    
    // The mode can be "manual" or "delayed"
    this.setUpdateMode = function(mode){
        startType = mode;
        managerObj.refresh();
    };
    
    var isFirstTimeFilled = true;
    
    var pushPreviewHtml = function(text){
    
        var emptyTop = position.getTop(wmd.panels.input) - getDocScrollTop();
        
        // Send the encoded HTML to the output textarea/div.
        if (wmd.panels.output) {
            // The value property is only defined if the output is a textarea.
            if (wmd.panels.output.value !== undefined) {
                wmd.panels.output.value = text;
                wmd.panels.output.readOnly = true;
            }
            // Otherwise we are just replacing the text in a div.
            // Send the HTML wrapped in <pre><code>
            else {
                var newText = text.replace(/&/g, "&amp;");
                newText = newText.replace(/</g, "&lt;");
                wmd.panels.output.innerHTML = "<pre><code>" + newText + "</code></pre>";
            }
        }
        
        if (wmd.panels.preview) {
            wmd.panels.preview.innerHTML = text;
        }
        
        setPanelScrollTops();
        
        if (isFirstTimeFilled) {
            isFirstTimeFilled = false;
            return;
        }
        
        var fullTop = position.getTop(wmd.panels.input) - getDocScrollTop();
        
        if (browser.isIE) {
            top.setTimeout(function(){
                top.scrollBy(0, fullTop - emptyTop);
            }, 0);
        }
        else {
            top.scrollBy(0, fullTop - emptyTop);
        }
    };
    
    var init = function(){
    
        setupEvents(wmd.panels.input, applyTimeout);
        makePreviewHtml();
        
        if (wmd.panels.preview) {
            wmd.panels.preview.scrollTop = 0;
        }
        if (wmd.panels.output) {
            wmd.panels.output.scrollTop = 0;
        }
    };
    
    this.destroy = function(){
        if (poller) {
            poller.destroy();
        }
    };
    
    init();
}; // }}}

// Handles pushing and popping TextareaStates for undo/redo commands.
// I should rename the stack variables to list.
var UndoManager = function(textarea, pastePollInterval, callback){ // {{{

    var undoObj = this;
    var undoStack = []; // A stack of undo states
    var stackPtr = 0; // The index of the current state
    var mode = "none";
    var lastState; // The last state
    var poller;
    var timer; // The setTimeout handle for cancelling the timer
    var inputStateObj;
    
    // Set the mode for later logic steps.
    var setMode = function(newMode, noSave){
    
        if (mode != newMode) {
            mode = newMode;
            if (!noSave) {
                saveState();
            }
        }
        
        if (!browser.isIE || mode != "moving") {
            timer = top.setTimeout(refreshState, 1);
        }
        else {
            inputStateObj = null;
        }
    };
    
    var refreshState = function(){
        inputStateObj = new TextareaState(textarea);
        poller.tick();
        timer = undefined;
    };
    
    this.setCommandMode = function(){
        mode = "command";
        saveState();
        timer = top.setTimeout(refreshState, 0);
    };
    
    this.canUndo = function(){
        return stackPtr > 1;
    };
    
    this.canRedo = function(){
        if (undoStack[stackPtr + 1]) {
            return true;
        }
        return false;
    };
    
    // Removes the last state and restores it.
    this.undo = function(){
    
        if (undoObj.canUndo()) {
            if (lastState) {
                // What about setting state -1 to null or checking for undefined?
                lastState.restore();
                lastState = null;
            }
            else {
                undoStack[stackPtr] = new TextareaState(textarea);
                undoStack[--stackPtr].restore();
                
                if (callback) {
                    callback();
                }
            }
        }
        
        mode = "none";
        textarea.focus();
        refreshState();
    };
    
    // Redo an action.
    this.redo = function(){
    
        if (undoObj.canRedo()) {
        
            undoStack[++stackPtr].restore();
            
            if (callback) {
                callback();
            }
        }
        
        mode = "none";
        textarea.focus();
        refreshState();
    };
    
    // Push the input area state to the stack.
    var saveState = function(){
    
        var currState = inputStateObj || new TextareaState(textarea);
        
        if (!currState) {
            return false;
        }
        if (mode == "moving") {
            if (!lastState) {
                lastState = currState;
            }
            return;
        }
        if (lastState) {
            if (undoStack[stackPtr - 1].text != lastState.text) {
                undoStack[stackPtr++] = lastState;
            }
            lastState = null;
        }
        undoStack[stackPtr++] = currState;
        undoStack[stackPtr + 1] = null;
        if (callback) {
            callback();
        }
    };
    
    var handleCtrlYZ = function(event){
    
        var handled = false;
        
        if (event.ctrlKey || event.metaKey) {
        
            // IE and Opera do not support charCode.
            var keyCode = event.charCode || event.keyCode;
            var keyCodeChar = String.fromCharCode(keyCode);
            
            switch (keyCodeChar) {
            
                case "y":
                    undoObj.redo();
                    handled = true;
                    break;
                    
                case "z":
                    if (!event.shiftKey) {
                        undoObj.undo();
                    }
                    else {
                        undoObj.redo();
                    }
                    handled = true;
                    break;
            }
        }
        
        if (handled) {
            if (event.preventDefault) {
                event.preventDefault();
            }
            if (top.event) {
                top.event.returnValue = false;
            }
            return;
        }
    };
    
    // Set the mode depending on what is going on in the input area.
    var handleModeChange = function(event){
    
        if (!event.ctrlKey && !event.metaKey) {
        
            var keyCode = event.keyCode;
            
            if ((keyCode >= 33 && keyCode <= 40) || (keyCode >= 63232 && keyCode <= 63235)) {
                // 33 - 40: page up/dn and arrow keys
                // 63232 - 63235: page up/dn and arrow keys on safari
                setMode("moving");
            }
            else if (keyCode == 8 || keyCode == 46 || keyCode == 127) {
                // 8: backspace
                // 46: delete
                // 127: delete
                setMode("deleting");
            }
            else if (keyCode == 13) {
                // 13: Enter
                setMode("newlines");
            }
            else if (keyCode == 27) {
                // 27: escape
                setMode("escape");
            }
            else if ((keyCode < 16 || keyCode > 20) && keyCode != 91) {
                // 16-20 are shift, etc. 
                // 91: left window key
                // I think this might be a little messed up since there are
                // a lot of nonprinting keys above 20.
                setMode("typing");
            }
        }
    };
    
    var setEventHandlers = function(){
    
        util.addEvent(textarea, "keypress", function(event){
            // keyCode 89: y
            // keyCode 90: z
            if ((event.ctrlKey || event.metaKey) && (event.keyCode == 89 || event.keyCode == 90)) {
                event.preventDefault();
            }
        });
        
        var handlePaste = function(){
            if (browser.isIE || (inputStateObj && inputStateObj.text != textarea.value)) {
                if (timer == undefined) {
                    mode = "paste";
                    saveState();
                    refreshState();
                }
            }
        };
        
        poller = new InputPoller(textarea, handlePaste, pastePollInterval);
        
        util.addEvent(textarea, "keydown", handleCtrlYZ);
        util.addEvent(textarea, "keydown", handleModeChange);
        
        util.addEvent(textarea, "mousedown", function(){
            setMode("moving");
        });
        textarea.onpaste = handlePaste;
        textarea.ondrop = handlePaste;
    };
    
    var init = function(){
        setEventHandlers();
        refreshState();
        saveState();
    };
    
    this.destroy = function(){
        if (poller) {
            poller.destroy();
        }
    };
    
    init();
}; //}}}

WMDEditor.util = util;
WMDEditor.position = position;
WMDEditor.TextareaState = TextareaState;
WMDEditor.Checks = Checks;
WMDEditor.InputPoller = InputPoller;
WMDEditor.PreviewManager = PreviewManager;
WMDEditor.UndoManager = UndoManager;

// A few handy aliases for readability.
var doc  = top.document;
var re   = top.RegExp;
var nav  = top.navigator;
    
function get_browser() {
    var b = {};
    b.isIE         = /msie/.test(nav.userAgent.toLowerCase());
    b.isIE_5or6     = /msie 6/.test(nav.userAgent.toLowerCase()) || /msie 5/.test(nav.userAgent.toLowerCase());
    b.isIE_7plus     = b.isIE && !b.isIE_5or6;
    b.isOpera         = /opera/.test(nav.userAgent.toLowerCase());
    b.isKonqueror     = /konqueror/.test(nav.userAgent.toLowerCase());
    return b;
}

// Used to work around some browser bugs where we can't use feature testing.
var browser = get_browser();

var wmdBase = function(wmd, wmd_options){ // {{{

    // Some namespaces.
    //wmd.Util = {};
    //wmd.Position = {};
    wmd.Command = {};
    wmd.Global = {};
    wmd.buttons = {};
    
    wmd.showdown = top.Attacklab && top.Attacklab.showdown;
    
    var util = WMDEditor.util;
    var position = WMDEditor.position;
    var command = wmd.Command;
    
    // Internet explorer has problems with CSS sprite buttons that use HTML
    // lists.  When you click on the background image "button", IE will 
    // select the non-existent link text and discard the selection in the
    // textarea.  The solution to this is to cache the textarea selection
    // on the button's mousedown event and set a flag.  In the part of the
    // code where we need to grab the selection, we check for the flag
    // and, if it's set, use the cached area instead of querying the
    // textarea.
    //
    // This ONLY affects Internet Explorer (tested on versions 6, 7
    // and 8) and ONLY on button clicks.  Keyboard shortcuts work
    // normally since the focus never leaves the textarea.
    wmd.ieCachedRange = null;        // cached textarea selection
    wmd.ieRetardedClick = false;    // flag
    
    // I think my understanding of how the buttons and callbacks are stored in the array is incomplete.
    wmd.editor = function(previewRefreshCallback){ // {{{
    
        if (!previewRefreshCallback) {
            previewRefreshCallback = function(){};
        }
        
        var inputBox = wmd.panels.input;
        
        var offsetHeight = 0;
        
        var editObj = this;
        
        var mainDiv;
        var mainSpan;
        
        var div; // This name is pretty ambiguous.  I should rename this.
        
        // Used to cancel recurring events from setInterval.
        var creationHandle;
        
        var undoMgr; // The undo manager
        
        // Perform the button's action.
        var doClick = function(button){
        
            inputBox.focus();
            
            if (button.textOp) {
                
                if (undoMgr) {
                    undoMgr.setCommandMode();
                }
                
                var state = new TextareaState(wmd.panels.input);
                
                if (!state) {
                    return;
                }
                
                var chunks = state.getChunks();
                
                // Some commands launch a "modal" prompt dialog.  Javascript
                // can't really make a modal dialog box and the WMD code
                // will continue to execute while the dialog is displayed.
                // This prevents the dialog pattern I'm used to and means
                // I can't do something like this:
                //
                // var link = CreateLinkDialog();
                // makeMarkdownLink(link);
                // 
                // Instead of this straightforward method of handling a
                // dialog I have to pass any code which would execute
                // after the dialog is dismissed (e.g. link creation)
                // in a function parameter.
                //
                // Yes this is awkward and I think it sucks, but there's
                // no real workaround.  Only the image and link code
                // create dialogs and require the function pointers.
                var fixupInputArea = function(){
                
                    inputBox.focus();
                    
                    if (chunks) {
                        state.setChunks(chunks);
                    }
                    
                    state.restore();
                    previewRefreshCallback();
                };
                
                var useDefaultText = true;
                var noCleanup = button.textOp(chunks, fixupInputArea, useDefaultText);
                
                if(!noCleanup) {
                    fixupInputArea();
                }
                
            }
            
            if (button.execute) {
                button.execute(editObj);
            }
        };
            
        var setUndoRedoButtonStates = function(){
            if(undoMgr){
                setupButton(wmd.buttons["wmd-undo-button"], undoMgr.canUndo());
                setupButton(wmd.buttons["wmd-redo-button"], undoMgr.canRedo());
            }
        };
        
        var setupButton = function(button, isEnabled) {
        
            var normalYShift = "0px";
            var disabledYShift = "-20px";
            var highlightYShift = "-40px";
            
            if(isEnabled) {
                button.style.backgroundPosition = button.XShift + " " + normalYShift;
                button.onmouseover = function(){
                    this.style.backgroundPosition = this.XShift + " " + highlightYShift;
                };
                            
                button.onmouseout = function(){
                    this.style.backgroundPosition = this.XShift + " " + normalYShift;
                };
                
                // IE tries to select the background image "button" text (it's
                // implemented in a list item) so we have to cache the selection
                // on mousedown.
                if(browser.isIE) {
                    button.onmousedown =  function() { 
                        wmd.ieRetardedClick = true;
                        wmd.ieCachedRange = document.selection.createRange(); 
                    };
                }
                
                if (!button.isHelp)
                {
                    button.onclick = function() {
                        if (this.onmouseout) {
                            this.onmouseout();
                        }
                        doClick(this);
                        return false;
                    }
                }
            }
            else {
                button.style.backgroundPosition = button.XShift + " " + disabledYShift;
                button.onmouseover = button.onmouseout = button.onclick = function(){};
            }
        }
    
        var makeSpritedButtonRow = function(){
             
            var buttonBar = document.getElementById(wmd_options.button_bar || "wmd-button-bar");
     
            var normalYShift = "0px";
            var disabledYShift = "-20px";
            var highlightYShift = "-40px";
            
            var buttonRow = document.createElement("ul");
            buttonRow.className = "wmd-button-row"
            buttonRow = buttonBar.appendChild(buttonRow);
            
            var xoffset = 0;
            
            function createButton(name, title, textOp) {
                var button = document.createElement("li");
                wmd.buttons[name] = button;
                button.className = "wmd-button " + name;
                            button.XShift = xoffset + "px";
                            xoffset -= 20;
                
                if (title)
                    button.title = title;
                    
                if (textOp)
                    button.textOp = textOp;

                return button;
            }
            
            function addButton(name, title, textOp) {
                var button = createButton(name, title, textOp);

                setupButton(button, true);
                buttonRow.appendChild(button);
                return button;
            }
            
            function addSpacer() {
                var spacer = document.createElement("li");
                spacer.className = "wmd-spacer";
                buttonRow.appendChild(spacer);
                return spacer;
            }
            
            var boldButton = addButton("wmd-bold-button", "Strong <strong> Ctrl+B", command.doBold);
            var italicButton = addButton("wmd-italic-button", "Emphasis <em> Ctrl+I", command.doItalic);
            var spacer1 = addSpacer();
            
            var linkButton = addButton("wmd-link-button", "Hyperlink <a> Ctrl+L", function(chunk, postProcessing, useDefaultText) {
                return command.doLinkOrImage(chunk, postProcessing, false);
            });        
            var quoteButton = addButton("wmd-quote-button", "Blockquote <blockquote> Ctrl+Q", command.doBlockquote);
            var codeButton = addButton("wmd-code-button", "Code Sample <pre><code> Ctrl+K", command.doCode);
            var imageButton = addButton("wmd-image-button", "Image <img> Ctrl+G", function(chunk, postProcessing, useDefaultText) {
                return command.doLinkOrImage(chunk, postProcessing, true);
            });
            
            var spacer2 = addSpacer();

            var olistButton = addButton("wmd-olist-button", "Numbered List <ol> Ctrl+O", function(chunk, postProcessing, useDefaultText) {
                command.doList(chunk, postProcessing, true, useDefaultText);
            });
            var ulistButton = addButton("wmd-ulist-button", "Bulleted List <ul> Ctrl+U", function(chunk, postProcessing, useDefaultText) {
                command.doList(chunk, postProcessing, false, useDefaultText);
            });
            var headingButton = addButton("wmd-heading-button", "Heading <h1>/<h2> Ctrl+H", command.doHeading);
            var hrButton = addButton("wmd-hr-button", "Horizontal Rule <hr> Ctrl+R", command.doHorizontalRule);
            var spacer3 = addSpacer();
            
            var undoButton = addButton("wmd-undo-button", "Undo - Ctrl+Z");
            undoButton.execute = function(manager){
                manager.undo();
            };
            
            var redo_title = null;
            
            var redoButton = addButton("wmd-redo-button", "Redo - Ctrl+Y");
            if (/win/.test(nav.platform.toLowerCase())) {
                redoButton.title = "Redo - Ctrl+Y";
            }
            else {
                // mac and other non-Windows platforms
                redoButton.title = "Redo - Ctrl+Shift+Z";
            }
            redoButton.execute = function(manager){
                manager.redo();
            };
            
            var helpButton = createButton("wmd-help-button");
            helpButton.isHelp = true;
            setupButton(helpButton, true);
            buttonRow.appendChild(helpButton);
            
            var helpAnchor = document.createElement("a");
            helpAnchor.href = wmd_options.helpLink;
            helpAnchor.target = wmd_options.helpTarget
            helpAnchor.title = wmd_options.helpHoverTitle;
            helpButton.appendChild(helpAnchor);
                        
            setUndoRedoButtonStates();
        }
        
        var setupEditor = function(){
        
            if (/\?noundo/.test(doc.location.href)) {
                wmd.nativeUndo = true;
            }
            
            if (!wmd.nativeUndo) {
                undoMgr = new UndoManager(wmd.panels.input, wmd.options.pastePollInterval, function(){
                    previewRefreshCallback();
                    setUndoRedoButtonStates();
                });
            }
            
            makeSpritedButtonRow();
            
            
            var keyEvent = "keydown";
            if (browser.isOpera) {
                keyEvent = "keypress";
            }
            
            util.addEvent(inputBox, keyEvent, function(key){
                
                // Check to see if we have a button key and, if so execute the callback.
                if (key.ctrlKey || key.metaKey) {
            
                    var keyCode = key.charCode || key.keyCode;
                    var keyCodeStr = String.fromCharCode(keyCode).toLowerCase();
                    
                    switch(keyCodeStr) {
                        case "b":
                            doClick(wmd.buttons["wmd-bold-button"]);
                            break;
                        case "i":
                            doClick(wmd.buttons["wmd-italic-button"]);
                            break;
                        case "l":
                            doClick(wmd.buttons["wmd-link-button"]);
                            break;
                        case "q":
                            doClick(wmd.buttons["wmd-quote-button"]);
                            break;
                        case "k":
                            doClick(wmd.buttons["wmd-code-button"]);
                            break;
                        case "g":
                            doClick(wmd.buttons["wmd-image-button"]);
                            break;
                        case "o":
                            doClick(wmd.buttons["wmd-olist-button"]);
                            break;
                        case "u":
                            doClick(wmd.buttons["wmd-ulist-button"]);
                            break;
                        case "h":
                            doClick(wmd.buttons["wmd-heading-button"]);
                            break;
                        case "r":
                            doClick(wmd.buttons["wmd-hr-button"]);
                            break;
                        case "y":
                            doClick(wmd.buttons["wmd-redo-button"]);
                            break;
                        case "z":
                            if(key.shiftKey) {
                                doClick(wmd.buttons["wmd-redo-button"]);
                            }
                            else {
                                doClick(wmd.buttons["wmd-undo-button"]);
                            }
                            break;
                        default:
                            return;
                    }
                    

                    if (key.preventDefault) {
                        key.preventDefault();
                    }
                    
                    if (top.event) {
                        top.event.returnValue = false;
                    }
                }
            });
            
            // Auto-continue lists, code blocks and block quotes when
            // the enter key is pressed.
            util.addEvent(inputBox, "keyup", function(key){
                if (!key.shiftKey && !key.ctrlKey && !key.metaKey) {
                    var keyCode = key.charCode || key.keyCode;
                    // Key code 13 is Enter
                    if (keyCode === 13) {
                        fakeButton = {};
                        fakeButton.textOp = command.doAutoindent;
                        doClick(fakeButton);
                    }
                }
            });
            
            // Disable ESC clearing the input textarea on IE
            if (browser.isIE) {
                util.addEvent(inputBox, "keydown", function(key){
                    var code = key.keyCode;
                    // Key code 27 is ESC
                    if (code === 27) {
                        return false;
                    }
                });
            }
            
            if (inputBox.form) {
                var submitCallback = inputBox.form.onsubmit;
                inputBox.form.onsubmit = function(){
                    convertToHtml();
                    if (submitCallback) {
                        return submitCallback.apply(this, arguments);
                    }
                };
            }
        };
        
        // Convert the contents of the input textarea to HTML in the output/preview panels.
        var convertToHtml = function(){
        
            if (wmd.showdown) {
                var markdownConverter = new wmd.showdown.converter();
            }
            var text = inputBox.value;
            
            var callback = function(){
                inputBox.value = text;
            };
            
            if (!/markdown/.test(wmd_options.output_format.toLowerCase())) {
                if (markdownConverter) {
                    inputBox.value = markdownConverter.makeHtml(text);
                    top.setTimeout(callback, 0);
                }
            }
            return true;
        };
        
        
        this.undo = function(){
            if (undoMgr) {
                undoMgr.undo();
            }
        };
        
        this.redo = function(){
            if (undoMgr) {
                undoMgr.redo();
            }
        };
        
        // This is pretty useless.  The setupEditor function contents
        // should just be copied here.
        var init = function(){
            setupEditor();
        };
        
        this.destroy = function(){
            if (undoMgr) {
                undoMgr.destroy();
            }
            if (div.parentNode) {
                div.parentNode.removeChild(div);
            }
            if (inputBox) {
                inputBox.style.marginTop = "";
            }
            top.clearInterval(creationHandle);
        };
        
        init();
    }; // }}}

    // command {{{

    // The markdown symbols - 4 spaces = code, > = blockquote, etc.
    command.prefixes = "(?:\\s{4,}|\\s*>|\\s*-\\s+|\\s*\\d+\\.|=|\\+|-|_|\\*|#|\\s*\\[[^\n]]+\\]:)";
    
    // Remove markdown symbols from the chunk selection.
    command.unwrap = function(chunk){
        var txt = new re("([^\\n])\\n(?!(\\n|" + command.prefixes + "))", "g");
        chunk.selection = chunk.selection.replace(txt, "$1 $2");
    };
    
    command.wrap = function(chunk, len){
        command.unwrap(chunk);
        var regex = new re("(.{1," + len + "})( +|$\\n?)", "gm");
        
        chunk.selection = chunk.selection.replace(regex, function(line, marked){
            if (new re("^" + command.prefixes, "").test(line)) {
                return line;
            }
            return marked + "\n";
        });
        
        chunk.selection = chunk.selection.replace(/\s+$/, "");
    };
    
    command.doBold = function(chunk, postProcessing, useDefaultText){
        return command.doBorI(chunk, 2, "strong text");
    };
    
    command.doItalic = function(chunk, postProcessing, useDefaultText){
        return command.doBorI(chunk, 1, "emphasized text");
    };
    
    // chunk: The selected region that will be enclosed with */**
    // nStars: 1 for italics, 2 for bold
    // insertText: If you just click the button without highlighting text, this gets inserted
    command.doBorI = function(chunk, nStars, insertText){
    
        // Get rid of whitespace and fixup newlines.
        chunk.trimWhitespace();
        chunk.selection = chunk.selection.replace(/\n{2,}/g, "\n");
        
        // Look for stars before and after.  Is the chunk already marked up?
        chunk.before.search(/(\**$)/);
        var starsBefore = re.$1;
        
        chunk.after.search(/(^\**)/);
        var starsAfter = re.$1;
        
        var prevStars = Math.min(starsBefore.length, starsAfter.length);
        
        // Remove stars if we have to since the button acts as a toggle.
        if ((prevStars >= nStars) && (prevStars != 2 || nStars != 1)) {
            chunk.before = chunk.before.replace(re("[*]{" + nStars + "}$", ""), "");
            chunk.after = chunk.after.replace(re("^[*]{" + nStars + "}", ""), "");
        }
        else if (!chunk.selection && starsAfter) {
            // It's not really clear why this code is necessary.  It just moves
            // some arbitrary stuff around.
            chunk.after = chunk.after.replace(/^([*_]*)/, "");
            chunk.before = chunk.before.replace(/(\s?)$/, "");
            var whitespace = re.$1;
            chunk.before = chunk.before + starsAfter + whitespace;
        }
        else {
        
            // In most cases, if you don't have any selected text and click the button
            // you'll get a selected, marked up region with the default text inserted.
            if (!chunk.selection && !starsAfter) {
                chunk.selection = insertText;
            }
            
            // Add the true markup.
            var markup = nStars <= 1 ? "*" : "**"; // shouldn't the test be = ?
            chunk.before = chunk.before + markup;
            chunk.after = markup + chunk.after;
        }
        
        return;
    };
    
    command.stripLinkDefs = function(text, defsToAdd){
    
        text = text.replace(/^[ ]{0,3}\[(\d+)\]:[ \t]*\n?[ \t]*<?(\S+?)>?[ \t]*\n?[ \t]*(?:(\n*)["(](.+?)[")][ \t]*)?(?:\n+|$)/gm, 
            function(totalMatch, id, link, newlines, title){    
                defsToAdd[id] = totalMatch.replace(/\s*$/, "");
                if (newlines) {
                    // Strip the title and return that separately.
                    defsToAdd[id] = totalMatch.replace(/["(](.+?)[")]$/, "");
                    return newlines + title;
                }
                return "";
            });
        
        return text;
    };
    
    command.addLinkDef = function(chunk, linkDef){
    
        var refNumber = 0; // The current reference number
        var defsToAdd = {}; //
        // Start with a clean slate by removing all previous link definitions.
        chunk.before = command.stripLinkDefs(chunk.before, defsToAdd);
        chunk.selection = command.stripLinkDefs(chunk.selection, defsToAdd);
        chunk.after = command.stripLinkDefs(chunk.after, defsToAdd);
        
        var defs = "";
        var regex = /(\[(?:\[[^\]]*\]|[^\[\]])*\][ ]?(?:\n[ ]*)?\[)(\d+)(\])/g;
        
        var addDefNumber = function(def){
            refNumber++;
            def = def.replace(/^[ ]{0,3}\[(\d+)\]:/, "  [" + refNumber + "]:");
            defs += "\n" + def;
        };
        
        var getLink = function(wholeMatch, link, id, end){
        
            if (defsToAdd[id]) {
                addDefNumber(defsToAdd[id]);
                return link + refNumber + end;
                
            }
            return wholeMatch;
        };
        
        chunk.before = chunk.before.replace(regex, getLink);
        
        if (linkDef) {
            addDefNumber(linkDef);
        }
        else {
            chunk.selection = chunk.selection.replace(regex, getLink);
        }
        
        var refOut = refNumber;
        
        chunk.after = chunk.after.replace(regex, getLink);
        
        if (chunk.after) {
            chunk.after = chunk.after.replace(/\n*$/, "");
        }
        if (!chunk.after) {
            chunk.selection = chunk.selection.replace(/\n*$/, "");
        }
        
        chunk.after += "\n\n" + defs;
        
        return refOut;
    };
    
    command.doLinkOrImage = function(chunk, postProcessing, isImage){
    
        chunk.trimWhitespace();
        chunk.findTags(/\s*!?\[/, /\][ ]?(?:\n[ ]*)?(\[.*?\])?/);
        
        if (chunk.endTag.length > 1) {
        
            chunk.startTag = chunk.startTag.replace(/!?\[/, "");
            chunk.endTag = "";
            command.addLinkDef(chunk, null);
            
        }
        else {
        
            if (/\n\n/.test(chunk.selection)) {
                command.addLinkDef(chunk, null);
                return;
            }
            
            // The function to be executed when you enter a link and press OK or Cancel.
            // Marks up the link and adds the ref.
            var makeLinkMarkdown = function(link){
            
                if (link !== null) {
                
                    chunk.startTag = chunk.endTag = "";
                    var linkDef = " [999]: " + link;
                    
                    var num = command.addLinkDef(chunk, linkDef);
                    chunk.startTag = isImage ? "![" : "[";
                    chunk.endTag = "][" + num + "]";
                    
                    if (!chunk.selection) {
                        if (isImage) {
                            chunk.selection = "alt text";
                        }
                        else {
                            chunk.selection = "link text";
                        }
                    }
                }
                postProcessing();
            };
            
            if (isImage) {
                util.prompt(wmd_options.imageDialogText, wmd_options.imageDefaultText, makeLinkMarkdown);
            }
            else {
                util.prompt(wmd_options.linkDialogText, wmd_options.linkDefaultText, makeLinkMarkdown);
            }
            return true;
        }
    };

    // Moves the cursor to the next line and continues lists, quotes and code.
    command.doAutoindent = function(chunk, postProcessing, useDefaultText){
        
        chunk.before = chunk.before.replace(/(\n|^)[ ]{0,3}([*+-]|\d+[.])[ \t]*\n$/, "\n\n");
        chunk.before = chunk.before.replace(/(\n|^)[ ]{0,3}>[ \t]*\n$/, "\n\n");
        chunk.before = chunk.before.replace(/(\n|^)[ \t]+\n$/, "\n\n");
        
        useDefaultText = false;
        
        if(/(\n|^)[ ]{0,3}([*+-])[ \t]+.*\n$/.test(chunk.before)){
            if(command.doList){
                command.doList(chunk, postProcessing, false, true);
            }
        }
        if(/(\n|^)[ ]{0,3}(\d+[.])[ \t]+.*\n$/.test(chunk.before)){
            if(command.doList){
                command.doList(chunk, postProcessing, true, true);
            }
        }
        if(/(\n|^)[ ]{0,3}>[ \t]+.*\n$/.test(chunk.before)){
            if(command.doBlockquote){
                command.doBlockquote(chunk, postProcessing, useDefaultText);
            }
        }
        if(/(\n|^)(\t|[ ]{4,}).*\n$/.test(chunk.before)){
            if(command.doCode){
                command.doCode(chunk, postProcessing, useDefaultText);
            }
        }
    };
    
    command.doBlockquote = function(chunk, postProcessing, useDefaultText){
        
        chunk.selection = chunk.selection.replace(/^(\n*)([^\r]+?)(\n*)$/,
            function(totalMatch, newlinesBefore, text, newlinesAfter){
                chunk.before += newlinesBefore;
                chunk.after = newlinesAfter + chunk.after;
                return text;
            });
            
        chunk.before = chunk.before.replace(/(>[ \t]*)$/,
            function(totalMatch, blankLine){
                chunk.selection = blankLine + chunk.selection;
                return "";
            });
        
        var defaultText = useDefaultText ? "Blockquote" : "";
        chunk.selection = chunk.selection.replace(/^(\s|>)+$/ ,"");
        chunk.selection = chunk.selection || defaultText;
        
        if(chunk.before){
            chunk.before = chunk.before.replace(/\n?$/,"\n");
        }
        if(chunk.after){
            chunk.after = chunk.after.replace(/^\n?/,"\n");
        }
        
        chunk.before = chunk.before.replace(/(((\n|^)(\n[ \t]*)*>(.+\n)*.*)+(\n[ \t]*)*$)/,
            function(totalMatch){
                chunk.startTag = totalMatch;
                return "";
            });
            
        chunk.after = chunk.after.replace(/^(((\n|^)(\n[ \t]*)*>(.+\n)*.*)+(\n[ \t]*)*)/,
            function(totalMatch){
                chunk.endTag = totalMatch;
                return "";
            });
        
        var replaceBlanksInTags = function(useBracket){
            
            var replacement = useBracket ? "> " : "";
            
            if(chunk.startTag){
                chunk.startTag = chunk.startTag.replace(/\n((>|\s)*)\n$/,
                    function(totalMatch, markdown){
                        return "\n" + markdown.replace(/^[ ]{0,3}>?[ \t]*$/gm, replacement) + "\n";
                    });
            }
            if(chunk.endTag){
                chunk.endTag = chunk.endTag.replace(/^\n((>|\s)*)\n/,
                    function(totalMatch, markdown){
                        return "\n" + markdown.replace(/^[ ]{0,3}>?[ \t]*$/gm, replacement) + "\n";
                    });
            }
        };
        
        if(/^(?![ ]{0,3}>)/m.test(chunk.selection)){
            command.wrap(chunk, wmd_options.lineLength - 2);
            chunk.selection = chunk.selection.replace(/^/gm, "> ");
            replaceBlanksInTags(true);
            chunk.addBlankLines();
        }
        else{
            chunk.selection = chunk.selection.replace(/^[ ]{0,3}> ?/gm, "");
            command.unwrap(chunk);
            replaceBlanksInTags(false);
            
            if(!/^(\n|^)[ ]{0,3}>/.test(chunk.selection) && chunk.startTag){
                chunk.startTag = chunk.startTag.replace(/\n{0,2}$/, "\n\n");
            }
            
            if(!/(\n|^)[ ]{0,3}>.*$/.test(chunk.selection) && chunk.endTag){
                chunk.endTag=chunk.endTag.replace(/^\n{0,2}/, "\n\n");
            }
        }
        
        if(!/\n/.test(chunk.selection)){
            chunk.selection = chunk.selection.replace(/^(> *)/,
            function(wholeMatch, blanks){
                chunk.startTag += blanks;
                return "";
            });
        }
    };

    command.doCode = function(chunk, postProcessing, useDefaultText){
        
        var hasTextBefore = /\S[ ]*$/.test(chunk.before);
        var hasTextAfter = /^[ ]*\S/.test(chunk.after);
        
        // Use 'four space' markdown if the selection is on its own
        // line or is multiline.
        if((!hasTextAfter && !hasTextBefore) || /\n/.test(chunk.selection)){
            
            chunk.before = chunk.before.replace(/[ ]{4}$/,
                function(totalMatch){
                    chunk.selection = totalMatch + chunk.selection;
                    return "";
                });
                
            var nLinesBefore = 1;
            var nLinesAfter = 1;
            
            
            if(/\n(\t|[ ]{4,}).*\n$/.test(chunk.before) || chunk.after === ""){
                nLinesBefore = 0; 
            }
            if(/^\n(\t|[ ]{4,})/.test(chunk.after)){
                nLinesAfter = 0; // This needs to happen on line 1
            }
            
            chunk.addBlankLines(nLinesBefore, nLinesAfter);
            
            if(!chunk.selection){
                chunk.startTag = "    ";
                chunk.selection = useDefaultText ? "enter code here" : "";
            }
            else {
                if(/^[ ]{0,3}\S/m.test(chunk.selection)){
                    chunk.selection = chunk.selection.replace(/^/gm, "    ");
                }
                else{
                    chunk.selection = chunk.selection.replace(/^[ ]{4}/gm, "");
                }
            }
        }
        else{
            // Use backticks (`) to delimit the code block.
            
            chunk.trimWhitespace();
            chunk.findTags(/`/, /`/);
            
            if(!chunk.startTag && !chunk.endTag){
                chunk.startTag = chunk.endTag="`";
                if(!chunk.selection){
                    chunk.selection = useDefaultText ? "enter code here" : "";
                }
            }
            else if(chunk.endTag && !chunk.startTag){
                chunk.before += chunk.endTag;
                chunk.endTag = "";
            }
            else{
                chunk.startTag = chunk.endTag="";
            }
        }
    };
    
    command.doList = function(chunk, postProcessing, isNumberedList, useDefaultText){
                
        // These are identical except at the very beginning and end.
        // Should probably use the regex extension function to make this clearer.
        var previousItemsRegex = /(\n|^)(([ ]{0,3}([*+-]|\d+[.])[ \t]+.*)(\n.+|\n{2,}([*+-].*|\d+[.])[ \t]+.*|\n{2,}[ \t]+\S.*)*)\n*$/;
        var nextItemsRegex = /^\n*(([ ]{0,3}([*+-]|\d+[.])[ \t]+.*)(\n.+|\n{2,}([*+-].*|\d+[.])[ \t]+.*|\n{2,}[ \t]+\S.*)*)\n*/;
        
        // The default bullet is a dash but others are possible.
        // This has nothing to do with the particular HTML bullet,
        // it's just a markdown bullet.
        var bullet = "-";
        
        // The number in a numbered list.
        var num = 1;
        
        // Get the item prefix - e.g. " 1. " for a numbered list, " - " for a bulleted list.
        var getItemPrefix = function(){
            var prefix;
            if(isNumberedList){
                prefix = " " + num + ". ";
                num++;
            }
            else{
                prefix = " " + bullet + " ";
            }
            return prefix;
        };
        
        // Fixes the prefixes of the other list items.
        var getPrefixedItem = function(itemText){
        
            // The numbering flag is unset when called by autoindent.
            if(isNumberedList === undefined){
                isNumberedList = /^\s*\d/.test(itemText);
            }
            
            // Renumber/bullet the list element.
            itemText = itemText.replace(/^[ ]{0,3}([*+-]|\d+[.])\s/gm,
                function( _ ){
                    return getItemPrefix();
                });
                
            return itemText;
        };
        
        chunk.findTags(/(\n|^)*[ ]{0,3}([*+-]|\d+[.])\s+/, null);
        
        if(chunk.before && !/\n$/.test(chunk.before) && !/^\n/.test(chunk.startTag)){
            chunk.before += chunk.startTag;
            chunk.startTag = "";
        }
        
        if(chunk.startTag){
            
            var hasDigits = /\d+[.]/.test(chunk.startTag);
            chunk.startTag = "";
            chunk.selection = chunk.selection.replace(/\n[ ]{4}/g, "\n");
            command.unwrap(chunk);
            chunk.addBlankLines();
            
            if(hasDigits){
                // Have to renumber the bullet points if this is a numbered list.
                chunk.after = chunk.after.replace(nextItemsRegex, getPrefixedItem);
            }
            if(isNumberedList == hasDigits){
                return;
            }
        }
        
        var nLinesBefore = 1;
        
        chunk.before = chunk.before.replace(previousItemsRegex,
            function(itemText){
                if(/^\s*([*+-])/.test(itemText)){
                    bullet = re.$1;
                }
                nLinesBefore = /[^\n]\n\n[^\n]/.test(itemText) ? 1 : 0;
                return getPrefixedItem(itemText);
            });
            
        if(!chunk.selection){
            chunk.selection = useDefaultText ? "List item" : " ";
        }
        
        var prefix = getItemPrefix();
        
        var nLinesAfter = 1;
        
        chunk.after = chunk.after.replace(nextItemsRegex,
            function(itemText){
                nLinesAfter = /[^\n]\n\n[^\n]/.test(itemText) ? 1 : 0;
                return getPrefixedItem(itemText);
            });
            
        chunk.trimWhitespace(true);
        chunk.addBlankLines(nLinesBefore, nLinesAfter, true);
        chunk.startTag = prefix;
        var spaces = prefix.replace(/./g, " ");
        command.wrap(chunk, wmd_options.lineLength - spaces.length);
        chunk.selection = chunk.selection.replace(/\n/g, "\n" + spaces);
        
    };
    
    command.doHeading = function(chunk, postProcessing, useDefaultText){
        
        // Remove leading/trailing whitespace and reduce internal spaces to single spaces.
        chunk.selection = chunk.selection.replace(/\s+/g, " ");
        chunk.selection = chunk.selection.replace(/(^\s+|\s+$)/g, "");
        
        // If we clicked the button with no selected text, we just
        // make a level 2 hash header around some default text.
        if(!chunk.selection){
            chunk.startTag = "## ";
            chunk.selection = "Heading";
            chunk.endTag = " ##";
            return;
        }
        
        var headerLevel = 0;        // The existing header level of the selected text.
        
        // Remove any existing hash heading markdown and save the header level.
        chunk.findTags(/#+[ ]*/, /[ ]*#+/);
        if(/#+/.test(chunk.startTag)){
            headerLevel = re.lastMatch.length;
        }
        chunk.startTag = chunk.endTag = "";
        
        // Try to get the current header level by looking for - and = in the line
        // below the selection.
        chunk.findTags(null, /\s?(-+|=+)/);
        if(/=+/.test(chunk.endTag)){
            headerLevel = 1;
        }
        if(/-+/.test(chunk.endTag)){
            headerLevel = 2;
        }
        
        // Skip to the next line so we can create the header markdown.
        chunk.startTag = chunk.endTag = "";
        chunk.addBlankLines(1, 1);

        // We make a level 2 header if there is no current header.
        // If there is a header level, we substract one from the header level.
        // If it's already a level 1 header, it's removed.
        var headerLevelToCreate = headerLevel == 0 ? 2 : headerLevel - 1;
        
        if(headerLevelToCreate > 0){
            
            // The button only creates level 1 and 2 underline headers.
            // Why not have it iterate over hash header levels?  Wouldn't that be easier and cleaner?
            var headerChar = headerLevelToCreate >= 2 ? "-" : "=";
            var len = chunk.selection.length;
            if(len > wmd_options.lineLength){
                len = wmd_options.lineLength;
            }
            chunk.endTag = "\n";
            while(len--){
                chunk.endTag += headerChar;
            }
        }
    };    
    
    command.doHorizontalRule = function(chunk, postProcessing, useDefaultText){
        chunk.startTag = "----------\n";
        chunk.selection = "";
        chunk.addBlankLines(2, 1, true);
    }
    // }}}
    
}; // }}}

})();

// For backward compatibility
function setup_wmd(options) {
    return new WMDEditor(options);
}