dynamic_rtree

defmodule ElixirRtree.Utils do
  @moduledoc false

  def format_bbox([{min_x,max_x} = x,{min_y,max_y} = y])do
    %{
      x: x,
      y: y,
      xm: min_x,
      xM: max_x,
      ym: min_y,
      yM: max_y
    }
  end

  def ets_value([raw],atom)do
    case atom do
      :bbox -> raw |> elem(1)
      :type -> raw |> elem(2)
    end
  end

  def ets_index(atom)do
    case atom do
      :bbox -> 2
      :type -> 3
    end
  end

  # Combine two bounding boxes into one
  def combine(box1,box2)do
    a = box1 |> format_bbox
    b = box2 |> format_bbox
    xm = Kernel.min(a.xm,b.xm)
    xM = Kernel.max(a.xM,b.xM)
    ym = Kernel.min(a.ym,b.ym)
    yM = Kernel.max(a.yM,b.yM)
    result = [{xm,xM},{ym,yM}]
    result = if area(box1) === 0, do: box2, else: result
    if area(box2) === 0, do: box1, else: result
  end

  #Combine multiple bbox
  def combine_multiple(list)when length(list) > 1 do
    real_list = list |> Enum.filter(fn x -> area(x) > 0 end)
    tl(real_list) |> Enum.reduce(hd(real_list),fn [{a,b},{c,d}] = _e, [{x,y},{z,w}] = _acc ->
      [{Kernel.min(a,x),Kernel.max(b,y)},{Kernel.min(c,z),Kernel.max(d,w)}]
    end)
  end

  def combine_multiple(list)do
    hd(list)
  end

  # Returns de percent of the overlap area (of the box1) between box1 and box2
  def overlap_area(box1,box2)do
    a = box1 |> format_bbox
    b = box2 |> format_bbox
    x_overlap = Kernel.max(0,Kernel.min(a.xM,b.xM) - Kernel.max(a.xm,b.xm))
    y_overlap = Kernel.max(0,Kernel.min(a.yM,b.yM) - Kernel.max(a.ym,b.ym))
    ((x_overlap * y_overlap)/area(box1)) * 100
  end

  # Return if those 2 boxes are overlapping
  def overlap?(box1,box2)do
    if overlap_area(box1,box2) > 0, do: true, else: false
  end

  # Return if box 1 contains box 2
  def contained?(box1,box2)do
    a = box1 |> format_bbox
    b = box2 |> format_bbox

    a.xm <= b.xm and a.xM >= b.xM and a.ym <= b.ym and a.yM >= b.yM
  end

  # Enlargement area after adding new box
  def enlargement_area(box,new_box)do
    a1 = area(box)
    a2 = combine_multiple([box,new_box]) |> area
    a2 - a1
  end

  # Checks if box is at some border of parent_box
  def in_border?(parent_box,box)do
    p = parent_box |> format_bbox
    b = box |> format_bbox

    p.xm == b.xm or p.xM == b.xM or p.ym == b.ym or p.yM == b.yM
  end

  # Return the area of a bounding box
  def area([{a,b},{c,d}]) when ((b - a) * (d - c) != 0) do
    (b - a) * (d - c)
  end

  def area([{_a,_b},{_c,_d}])do
    -1
  end

  # Return de the middle bounding box value
  def middle_value([{a,b},{c,d}])do
    (a + b + c + d) / 2
  end

  def get_posxy([{a,b},{c,d}])do
    %{x: (b + a) / 2, y: (c + d) / 2 }
  end

  def box_move([{a,b},{c,d}],move)do
    x = move[:x]
    y = move[:y]
    [{a+x,b+x},{c+y,d+y}]
  end


end