var BBCode = function(){
  window.undefined = window.undefined;
  this.initDone = false;
}
BBCode.prototype.init = function(t) {
  if(this.initDone) return false;
  if(t == undefined) return false;
  this._target = t ? document.getElementById(t) : t;
  this.initDone = true;
  return true;
}
BBCode.prototype.noForm = function(){
  return this._target == undefined;
}
// insertcode is used for bold, italic, underline and quote and just
// wraps the tags around a selection or prompts the user for some
// text to apply the tag to
BBCode.prototype.insertCode = function (tag, desc, endtag) {
  if(this.noForm()) return false;
  
  var isDesc = (desc == undefined || desc == '') ? false : true;
  
  // our textfield
  var textarea = this._target;
  // our open tag
  var open = '['+tag+']';
  var close = '[/'+((endtag == undefined) ? tag : endtag)+']';
  
  if (!textarea.setSelectionRange) {
    var selected = document.selection.createRange().text;
    if (selected.length<=0) {
      // no text was selected so prompt the user for some text
      textarea.value += open+((isDesc) ? prompt("Please enter the text you'd like to "+desc, "")+close : '');
    } else {
      // put the code around the selected text
      document.selection.createRange().text = open+selected+((isDesc) ? close : '');
    }
  } else {
    // the text before the selection
    var pretext = textarea.value.substring(0, textarea.selectionStart);
    // the selected text with tags before and after
    var codetext = open+textarea.value.substring(textarea.selectionStart, textarea.selectionEnd)+((isDesc) ? close : '');
    // the text after the selection
    var posttext = textarea.value.substring(textarea.selectionEnd, textarea.value.length);
    // check if there was a selection
    if (codetext == open+close) {
      //prompt the user
      codetext = open+((isDesc) ? prompt("Please enter the text you'd like to "+desc, "")+close : '');
    }
    // update the text field
    textarea.value = pretext+codetext+posttext;
  }
  // set the focus on the text field
  textarea.focus();
}
// inserts an image by prompting the user for the url
BBCode.prototype.insertImage = function (html) {
  if(this.noForm()) return false;
  
  var src = prompt('Please enter the name', html);
  this.insertCode('img='+src);
}

// inserts a link by prompting the user for a url
BBCode.prototype.insertLink = function (html) {
  if(this.noForm()) return false;
  this.insertCode('url='+prompt("Please enter the url", "http://"), 'as text of the link', 'url')
}