Event.register('load', textAreaAutoAttach);

function textAreaAutoAttach(event, parent) {
	var textareas;
	if (typeof parent == 'undefined') {
		textareas = document.getElementsByTagName('textarea');
	} else {
		textareas = parent.getElementsByTagName('textarea');
	}
	var textarea;
	for (var i = 0; textarea = textareas[i]; ++i) {
		if (hasClass(textarea, 'resizable') && !hasClass(textarea.nextSibling, 'grippie')) {
			if (typeof dimensions(textarea).width != 'undefined' && dimensions(textarea).width != 0) {
				new textArea(textarea);
			}
		}
	}
}

function textAreaDettach(event, parent) {
	var divs;
	if (typeof parent == 'undefined') {
		divs = document.getElementsByTagName('div');
	} else {
		divs = parent.getElementsByTagName('div');
	}
	var div;
	for (var i = 0; div = divs[i]; ++i) {
		if (!hasClass(div, 'resizable-textarea')) continue;
		var ta = div.childNodes[0].cloneNode(true);
		ta.setAttribute('style', '');
		ta.value = div.childNodes[0].value;
		div.parentNode.insertBefore(ta, div);
		div.parentNode.removeChild(div);
	}
}

function textArea(element) {
  var ta = this;
  this.element = element;
  this.parent = this.element.parentNode;
  this.dimensions = dimensions(element);

  // Prepare wrapper
  this.wrapper = document.createElement('div');
  this.wrapper.className = 'resizable-textarea';
  this.parent.insertBefore(this.wrapper, this.element);

  // Add grippie and measure it
  this.grippie = document.createElement('div');
  this.grippie.className = 'grippie';
  this.wrapper.appendChild(this.grippie);
  this.grippie.dimensions = dimensions(this.grippie);
  this.grippie.onmousedown = function (e) { ta.beginDrag(e); };

  // Set wrapper and textarea dimensions
  this.wrapper.style.height = this.dimensions.height + this.grippie.dimensions.height + 1 +'px';
  this.element.style.marginBottom = '0px';
// fixme?  this.element.style.width = '100%';
  this.element.style.height = this.dimensions.height +'px';

  // Wrap textarea
  removeNode(this.element);
  this.wrapper.insertBefore(this.element, this.grippie);

  // Measure difference between desired and actual textarea dimensions to account for padding/borders
  this.widthOffset = dimensions(this.wrapper).width - this.dimensions.width;

  // Make the grippie line up in various browsers
  if (window.opera) {
    // Opera
    this.grippie.style.marginRight = '4px';
  }
  if (document.all && !window.opera) {
    // IE
// fixme?    this.grippie.style.width = '100%';
    /*this.grippie.style.paddingLeft = '2px';
    this.element.style.marginLeft = '20px';*/
  }
  this.grippie.style.width = dimensions(this.element).width - 2;

  // Mozilla
  this.element.style.MozBoxSizing = 'border-box';

  this.heightOffset = absolutePosition(this.grippie).y - absolutePosition(this.element).y - this.dimensions.height;
}

textArea.prototype.beginDrag = function (event) {
  if (document.isDragging) {
    return;
  }
  document.isDragging = true;

  event = event || window.event;
  // Capture mouse
  var cp = this;
  this.oldMoveHandler = document.onmousemove;
  document.onmousemove = function(e) { cp.handleDrag(e); };
  this.oldUpHandler = document.onmouseup;
  document.onmouseup = function(e) { cp.endDrag(e); };

  // Store drag offset from grippie top
  var pos = absolutePosition(this.grippie);
  this.dragOffset = event.clientY - pos.y;

  // Make transparent
  this.element.style.opacity = 0.5;

  // Process
  this.handleDrag(event);
}

textArea.prototype.handleDrag = function (event) {
  event = event || window.event;
  // Get coordinates relative to text area
  var pos = absolutePosition(this.element);
  var y = event.clientY - pos.y;

  // Set new height
  var height = Math.max(32, y - this.dragOffset - this.heightOffset);
  this.wrapper.style.height = height + this.grippie.dimensions.height + 1 + 'px';
  this.element.style.height = height + 'px';

  // Avoid text selection
  stopEvent(event);
}

textArea.prototype.endDrag = function (event) {
  // Uncapture mouse
  document.onmousemove = this.oldMoveHandler;
  document.onmouseup = this.oldUpHandler;

  // Restore opacity
  this.element.style.opacity = 1.0;
  document.isDragging = false;
}

function dimensions(el) {
  return { width: el.offsetWidth, height: el.offsetHeight };
}

function removeNode(node) {
  if (typeof node == 'string') {
    node = $(node);
  }
  if (node && node.parentNode) {
    return node.parentNode.removeChild(node);
  }
  else {
    return false;
  }
}

function absolutePosition(el) {
  var sLeft = 0, sTop = 0;
  var isDiv = /^div$/i.test(el.tagName);
  if (isDiv && el.scrollLeft) {
    sLeft = el.scrollLeft;
  }
  if (isDiv && el.scrollTop) {
    sTop = el.scrollTop;
  }
  var r = { x: el.offsetLeft - sLeft, y: el.offsetTop - sTop };
  if (el.offsetParent) {
    var tmp = absolutePosition(el.offsetParent);
    r.x += tmp.x;
    r.y += tmp.y;
  }
  return r;
};