var selection = (function(){

  var creating = false, moving = false, copying = false
  
	var selection_canvas = new Matrix (1, 1, function(x,y){
		var lex = new Lex (x,y)
		lex.build()
		return lex
	})

  // in selection mode..
  // - we start by clicking the canvas. this positions the selection, and copies
  //   the character
  // - then we drag down and to the right. this resizes the selection and pushes new
  //   rows and columns. each of these copies the character underneath.
  // - on mouseup, the selection is locked. then..
  // - drag the selection to move it -- this "cuts" it and leaves a blank space on the canvas.
  // - shift-drag the selection to copy it
  
  var corner = [-1, -1]
  var dimensions = [0, 0]
  
  function contains (point) {
    var contains_x = corner[0] < point[0] && point[0] < corner[0] + dimensions[0]
    var contains_y = corner[1] < point[1] && point[1] < corner[1] + dimensions[1]
    return (contains_x && contains_y)
  }
  function reposition () {
    var top_left = canvas.aa[corner[1]][corner[0]].span
    var left = top_left.offsetLeft
    var top = top_left.offsetTop
    var width = top_left.offsetWidth
    var height = top_left.offsetHeight
  }
  function down (e, lex, point){
    if (contains(point)) {
      copying = false
      moving = true
      creating = false
    }
    else {
      copying = false
      moving = false
      creating = true
      corner[0] = point[0]
      corner[1] = point[1]
      dimensions[0] = 1
      dimensions[1] = 1
    }
    show()
    reposition()
  }
  function move (e, lex, point){
    if (creating) {
      var x = point[0] - corner[0]
      var y = point[1] - corner[1]
      if (x < 0) {
        corner[0] = point[0]
      }
      if (y < 0) {
        corner[0] = point[0]
      }
      dimensions[0] = abs(x)
      reposition()
    }
    else if (moving) {
    }
  }
  function up (e) {
  }
  
  function show () {
    selecting = true
  }
  function hide () {
    selecting = false
  }
  
  var selection = {}
  selection.down = down
  selection.move = move
  selection.up = up
  selection.canvas = selection_canvas
  selection.show = show
  selection.hide = hide
	return selection

})()