var PolylineTool = MapTool.extend(function (base) {
  var exports = {}
  exports.down = function(e, cursor){

    // rightclick?
    if (e.ctrlKey || e.which === 3) {
      e.preventDefault()
      e.stopPropagation()
      if (map.ui.placing) {
        // close polyline or cancel
        map.ui.placing = false
        if (line.points.length > 2) {
          line.build()
        }
        else {
          line.reset()
        }
        return
      }
      map.ui.tools.position.rightclick(e, cursor)
      return
    }

    // compare to initial point
    var p = last_point.clone()
    if (map.ui.placing) {
      if (line.canCloseWith(p)) {
        line.close()
        line.build()
        map.ui.placing = false
      }
      else {
        line.add(p)
      }
    }
    else {
      map.ui.placing = true
      line = new Polyline ()
      line.add(p)
    }
  }
  exports.move = function(e, cursor){
    last_point.a = cursor.x.a
    last_point.b = cursor.y.a
    if (map.ui.placing && line.canCloseWith(last_point)) {
      document.body.style.cursor = "pointer"
      last_point.assign(line.points[0])
      cursor.x.a = cursor.x.b = last_point.a
      cursor.y.a = cursor.y.b = last_point.b
      return
    }
    var end_point = shapes.findClosestEndPoint(last_point)
    if (end_point) {
      document.body.style.cursor = "pointer"
      last_point.assign(end_point.point)
      cursor.x.a = cursor.x.b = last_point.a
      cursor.y.a = cursor.y.b = last_point.b
      return
    }
    else {
      document.body.style.cursor = "crosshair"
    }
  }
  exports.cancel = function(){
    if (map.ui.placing) { line.reset() }
    map.ui.placing = false
  }
  return exports
})