gistfile1.coffee

# Example Usage:
# $('#facey').draggable({
#     droppables: '.droppable',
#     onDrop: function (droppable) {
#         $('#facey').text('DROPPED');
#     },
#     onNoDrop: function (originalOffset) {
#         $('#facey').offset(originalOffset);
#     },
#     onHover: function(droppable) {
#         droppable.addClass('dropHover');
#     },
#     onNoHover: function() {
#        $('.droppable').removeClass('dropHover');
#     }
# });


$ ->
  centerOf = ($e) ->
    offset = $e.offset()
    width = $e.width()
    height = $e.height()

    {
      x: offset.left + width / 2
      y: offset.top + height / 2
    }

  isPointInElement = (point, $e) ->
    offset = $e.offset()
    width = $e.width()
    height = $e.height()
    top = offset.top
    left = offset.left

    (point.x > left && point.x < (left + width)) && (point.y > top && point.y < (top + height))

  findDroppablesUnderPoint = (selector, point) ->
    $(selector).filter ->
      isPointInElement point, $(this)

  findDroppablesUnderElement = (selector, element) ->
    findDroppablesUnderPoint selector, centerOf($(element))

  defineDraggableJquery = (Draggabilly) ->
    $.fn.draggable = (options) ->
      return if @length < 1

      originalOffset = 0
      d = new Draggabilly this[0]

      d.on('dragStart', (draggie, event, pointer) ->
        originalOffset = $(draggie.element).offset()

      d.on('dragMove', (draggie, event, pointer) ->
        droppables = findDroppablesUnderElement options.droppables, draggie.element

        if (droppables.length > 0)
          options.onHover droppables
        else
          options.onNoHover()

      d.on('dragEnd', (draggie, event, pointer) ->
        droppables = findDroppablesUnderElement options.droppables, draggie.element

        if droppables.length > 0
          options.onDrop(droppables)
        else
          options.onNoDrop(originalOffset)

  if ( typeof define is 'function' && define.amd )
    # AMD
    define ['draggabilly'], defineDraggableJquery
  else
    defineDraggableJquery window.Draggabilly