"use strict"

var bounds = require("binary-search-bounds")

var NOT_FOUND = 0
var SUCCESS = 1
var EMPTY = 2

module.exports = createWrapper

function IntervalTreeNode(mid, left, right, leftPoints, rightPoints) {
  this.mid = mid
  this.left = left
  this.right = right
  this.leftPoints = leftPoints
  this.rightPoints = rightPoints
  this.count = (left ? left.count : 0) + (right ? right.count : 0) + leftPoints.length
}

var proto = IntervalTreeNode.prototype

function copy(a, b) {
  a.mid = b.mid
  a.left = b.left
  a.right = b.right
  a.leftPoints = b.leftPoints
  a.rightPoints = b.rightPoints
  a.count = b.count
}

function rebuild(node, intervals) {
  var ntree = createIntervalTree(intervals)
  node.mid = ntree.mid
  node.left = ntree.left
  node.right = ntree.right
  node.leftPoints = ntree.leftPoints
  node.rightPoints = ntree.rightPoints
  node.count = ntree.count
}

function rebuildWithInterval(node, interval) {
  var intervals = node.intervals([])
  intervals.push(interval)
  rebuild(node, intervals)    
}

function rebuildWithoutInterval(node, interval) {
  var intervals = node.intervals([])
  var idx = intervals.indexOf(interval)
  if(idx < 0) {
    return NOT_FOUND
  }
  intervals.splice(idx, 1)
  rebuild(node, intervals)
  return SUCCESS
}

proto.intervals = function(result) {
  result.push.apply(result, this.leftPoints)
  if(this.left) {
    this.left.intervals(result)
  }
  if(this.right) {
    this.right.intervals(result)
  }
  return result
}

proto.insert = function(interval) {
  var weight = this.count - this.leftPoints.length
  this.count += 1
  if(interval[1] < this.mid) {
    if(this.left) {
      if(4*(this.left.count+1) > 3*(weight+1)) {
        rebuildWithInterval(this, interval)
      } else {
        this.left.insert(interval)
      }
    } else {
      this.left = createIntervalTree([interval])
    }
  } else if(interval[0] > this.mid) {
    if(this.right) {
      if(4*(this.right.count+1) > 3*(weight+1)) {
        rebuildWithInterval(this, interval)
      } else {
        this.right.insert(interval)
      }
    } else {
      this.right = createIntervalTree([interval])
    }
  } else {
    var l = bounds.ge(this.leftPoints, interval, compareBegin)
    var r = bounds.ge(this.rightPoints, interval, compareEnd)
    this.leftPoints.splice(l, 0, interval)
    this.rightPoints.splice(r, 0, interval)
  }
}

proto.remove = function(interval) {
  var weight = this.count - this.leftPoints
  if(interval[1] < this.mid) {
    if(!this.left) {
      return NOT_FOUND
    }
    var rw = this.right ? this.right.count : 0
    if(4 * rw > 3 * (weight-1)) {
      return rebuildWithoutInterval(this, interval)
    }
    var r = this.left.remove(interval)
    if(r === EMPTY) {
      this.left = null
      this.count -= 1
      return SUCCESS
    } else if(r === SUCCESS) {
      this.count -= 1
    }
    return r
  } else if(interval[0] > this.mid) {
    if(!this.right) {
      return NOT_FOUND
    }
    var lw = this.left ? this.left.count : 0
    if(4 * lw > 3 * (weight-1)) {
      return rebuildWithoutInterval(this, interval)
    }
    var r = this.right.remove(interval)
    if(r === EMPTY) {
      this.right = null
      this.count -= 1
      return SUCCESS
    } else if(r === SUCCESS) {
      this.count -= 1
    }
    return r
  } else {
    if(this.count === 1) {
      if(this.leftPoints[0] === interval) {
        return EMPTY
      } else {
        return NOT_FOUND
      }
    }
    if(this.leftPoints.length === 1 && this.leftPoints[0] === interval) {
      if(this.left && this.right) {
        var p = this
        var n = this.left
        while(n.right) {
          p = n
          n = n.right
        }
        if(p === this) {
          n.right = this.right
        } else {
          var l = this.left
          var r = this.right
          p.count -= n.count
          p.right = n.left
          n.left = l
          n.right = r
        }
        copy(this, n)
        this.count = (this.left?this.left.count:0) + (this.right?this.right.count:0) + this.leftPoints.length
      } else if(this.left) {
        copy(this, this.left)
      } else {
        copy(this, this.right)
      }
      return SUCCESS
    }
    for(var l = bounds.ge(this.leftPoints, interval, compareBegin); l<this.leftPoints.length; ++l) {
      if(this.leftPoints[l][0] !== interval[0]) {
        break
      }
      if(this.leftPoints[l] === interval) {
        this.count -= 1
        this.leftPoints.splice(l, 1)
        for(var r = bounds.ge(this.rightPoints, interval, compareEnd); r<this.rightPoints.length; ++r) {
          if(this.rightPoints[r][1] !== interval[1]) {
            break
          } else if(this.rightPoints[r] === interval) {
            this.rightPoints.splice(r, 1)
            return SUCCESS
          }
        }
      }
    }
    return NOT_FOUND
  }
}

function reportLeftRange(arr, hi, cb) {
  for(var i=0; i<arr.length && arr[i][0] <= hi; ++i) {
    var r = cb(arr[i])
    if(r) { return r }
  }
}

function reportRightRange(arr, lo, cb) {
  for(var i=arr.length-1; i>=0 && arr[i][1] >= lo; --i) {
    var r = cb(arr[i])
    if(r) { return r }
  }
}

function reportRange(arr, cb) {
  for(var i=0; i<arr.length; ++i) {
    var r = cb(arr[i])
    if(r) { return r }
  }
}

proto.queryPoint = function(x, cb) {
  if(x < this.mid) {
    if(this.left) {
      var r = this.left.queryPoint(x, cb)
      if(r) { return r }
    }
    return reportLeftRange(this.leftPoints, x, cb)
  } else if(x > this.mid) {
    if(this.right) {
      var r = this.right.queryPoint(x, cb)
      if(r) { return r }
    }
    return reportRightRange(this.rightPoints, x, cb)
  } else {
    return reportRange(this.leftPoints, cb)
  }
}

proto.queryInterval = function(lo, hi, cb) {
  if(lo < this.mid && this.left) {
    var r = this.left.queryInterval(lo, hi, cb)
    if(r) { return r }
  }
  if(hi > this.mid && this.right) {
    var r = this.right.queryInterval(lo, hi, cb)
    if(r) { return r }
  }
  if(hi < this.mid) {
    return reportLeftRange(this.leftPoints, hi, cb)
  } else if(lo > this.mid) {
    return reportRightRange(this.rightPoints, lo, cb)
  } else {
    return reportRange(this.leftPoints, cb)
  }
}

function compareNumbers(a, b) {
  return a - b
}

function compareBegin(a, b) {
  var d = a[0] - b[0]
  if(d) { return d }
  return a[1] - b[1]
}

function compareEnd(a, b) {
  var d = a[1] - b[1]
  if(d) { return d }
  return a[0] - b[0]
}

function createIntervalTree(intervals) {
  if(intervals.length === 0) {
    return null
  }
  var pts = []
  for(var i=0; i<intervals.length; ++i) {
    pts.push(intervals[i][0], intervals[i][1])
  }
  pts.sort(compareNumbers)

  var mid = pts[pts.length>>1]

  var leftIntervals = []
  var rightIntervals = []
  var centerIntervals = []
  for(var i=0; i<intervals.length; ++i) {
    var s = intervals[i]
    if(s[1] < mid) {
      leftIntervals.push(s)
    } else if(mid < s[0]) {
      rightIntervals.push(s)
    } else {
      centerIntervals.push(s)
    }
  }

  //Split center intervals
  var leftPoints = centerIntervals
  var rightPoints = centerIntervals.slice()
  leftPoints.sort(compareBegin)
  rightPoints.sort(compareEnd)

  return new IntervalTreeNode(mid, 
    createIntervalTree(leftIntervals),
    createIntervalTree(rightIntervals),
    leftPoints,
    rightPoints)
}

//User friendly wrapper that makes it possible to support empty trees
function IntervalTree(root) {
  this.root = root
}

var tproto = IntervalTree.prototype

tproto.insert = function(interval) {
  if(this.root) {
    this.root.insert(interval)
  } else {
    this.root = new IntervalTreeNode(interval[0], null, null, [interval], [interval])
  }
}

tproto.remove = function(interval) {
  if(this.root) {
    var r = this.root.remove(interval)
    if(r === EMPTY) {
      this.root = null
    }
    return r !== NOT_FOUND
  }
  return false
}

tproto.queryPoint = function(p, cb) {
  if(this.root) {
    return this.root.queryPoint(p, cb)
  }
}

tproto.queryInterval = function(lo, hi, cb) {
  if(lo <= hi && this.root) {
    return this.root.queryInterval(lo, hi, cb)
  }
}

Object.defineProperty(tproto, "count", {
  get: function() {
    if(this.root) {
      return this.root.count
    }
    return 0
  }
})

Object.defineProperty(tproto, "intervals", {
  get: function() {
    if(this.root) {
      return this.root.intervals([])
    }
    return []
  }
})

function createWrapper(intervals) {
  if(!intervals || intervals.length === 0) {
    return new IntervalTree(null)
  }
  return new IntervalTree(createIntervalTree(intervals))
}