var OrthoPolylineTool = MapTool.extend(function (base) {
  // this will work like normal polyline except all walls will be orthogonal
  
  var prev_point, horizontal = false, first_edge_is_horizontal = false
  
  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
      }
      else {
        map.ui.tools.position.rightclick(e, cursor)
      }
      return
    }

    // compare to initial point
    var p = last_point.clone()
    if (map.ui.placing) {
      if (line.lastPoint().eq(p)) {
        return
      }
      else if (line.canCloseWith(p)) {
        line.close()
        line.build()
        map.ui.placing = false
      }
      else {
        line.add(p)
        prev_point = p
        horizontal = ! horizontal
      }
    }
    else {
      map.ui.placing = true
      line = new Polyline ()
      line.add(p)
      first_point = prev_point = p
      horizontal = false
    }
  }
  exports.move = function(e, cursor){
    last_point.a = cursor.x.a
    last_point.b = cursor.y.a
    if (map.ui.placing) {
      if (line.points.length == 1) {
        var x = abs(prev_point.a - last_point.a)
        var y = abs(prev_point.b - last_point.b)
        if (x > y) {
          last_point.b = prev_point.b
          first_edge_is_horizontal = horizontal = true
        }
        else {
          last_point.a = prev_point.a
          first_edge_is_horizontal = horizontal = false
        }
      }
      else {
        if (horizontal) {
          last_point.b = prev_point.b
        }
        else {
          last_point.a = prev_point.a
        }
        if (horizontal == first_edge_is_horizontal) {
          // check if this point is within N pixels of the normal
          // and lock it into place if so
          if (horizontal && abs( first_point.a - last_point.a ) < 10/map.zoom) {
            last_point.a = first_point.a
          }
          else if (! horizontal && abs( first_point.b - last_point.b ) < 10/map.zoom) {
            last_point.b = first_point.b
          }
        }
      }

      if (line.canCloseWith(last_point)) {
        document.body.style.cursor = "pointer"
        last_point.assign(first_point)
        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() }
    first_point = null
    map.ui.placing = false
  }
  return exports
})