var RegionList = (function(){

  var RegionList = {}
  var regions = RegionList.regions

  RegionList.build = function(){
    var segments = RegionList.getSortedSegments()

    // loop over them from left to right
//    console.log(segments.map(function(s){ return s.toString() }).join("\n"))

    var rooms = []
    var open_segments = []
    
    var segment, open_segment, vertical, other_side

    for (var i = 0; i < segments.length; i++) {
      segment = segments[i]
      if (! isVertical(segment)) {
        continue
      }
      for (var j = 0; j < open_segments.length; j++) {
        open_segment = open_segments[j]
        if (overlaps(segment, open_segment)) {
          // if we have overlap, it means we have made a full room
          other_side = clone_segment(open_segment)
          other_side[0].a = segment[0].a
          other_side[1].a = segment[1].a
          rooms.push([open_segment, other_side])
          open_segments.splice(j, 1)
          j--
        }
      }
      open_segments.push(segment) 
    }
    
//    console.log(rooms.map(function(s){ return s[0][0].toString() + " " + s[0][1].toString() + " " + s[1][0].toString() + " " + s[1][1].toString() }).join("\n"))
    
    return rooms
  }
  
  RegionList.getSortedSegments = function(){
    // get a list of all segments from these polylines
    var segments = shapes.getAllSegments()

    // re-orientate them so they're either facing up or right
    segments.forEach(function(segment){
      // vertical
      if (segment[0].a == segment[1].a) {
        if (segment[0].b > segment[1].b) {
          segment.push(segment.shift())
        }
      }
      // horizontal
      else if (segment[0].b == segment[1].b) {
        if (segment[0].a > segment[1].a) {
          segment.push(segment.shift())
        }
      }
    })
    
    // sort them from top to bottom, left to right
    segments = segments.sort(function(a,b){
      if (a[0].a < b[0].a) {
        return -1
      }
      else if (a[0].a == b[0].a) {
        if (a[0].b < b[0].b) {
          return -1
        }
        else if (a[0].b == b[0].b) {
          return 0
        }
        else {
          return 1
        }
      }
      else {
        return 1
      }
    })
    
    return segments
  }
  
  function isVertical (segment) { return segment[0].a == segment[1].a }
  function isHorizontal (segment) { return segment[0].b == segment[1].b }
  function overlaps (a,b) { return (a[0].b > b[0].b || a[1].b < b[1].b) }
  function clone_segment(a){ return [a[0].clone(), a[1].clone()] }
  return RegionList
  
})()