local screen_width, screen_height = 960, 540
love.window.setMode(screen_width, screen_height)
local game_time = os.time()
love.math.setRandomSeed(game_time)

local star = {
  x = 0, y = 0, orbital_radius = 0,
  children = {
    {
      orbital_radius = 100,
      children = {
        {
          orbital_radius = 10,
        }
      }
    },
    {
      orbital_radius = 50
    },
    {
      orbital_radius = 200,
      children = {
        {
          orbital_radius = 25,
          children = {
            {
              orbital_radius = 5
            }
          }
        }
      }
    }
  }
}
local set_offsets
set_offsets = function(object)
  object.rotation_offset = math.pi * 2 * love.math.random()
  if object.children then
    for i = 1, #object.children do
      set_offsets(object.children[i])
    end
  end
end
set_offsets(star)

function love.update(dt)
  game_time = game_time + dt

  local update_object_position
  update_object_position = function(object, parent_x, parent_y)
    local temporary_speed_up = 100
    local argument = game_time / object.orbital_radius^1.337 * temporary_speed_up + object.rotation_offset
    if (argument == math.huge) or (argument ~= argument) then
      argument = 0
    end
    object.x, object.y = parent_x + object.orbital_radius * math.cos(argument), parent_y + object.orbital_radius * math.sin(argument)
    if object.children then
      for i = 1, #object.children do
        update_object_position(object.children[i], object.x, object.y)
      end
    end
  end
  update_object_position(star, 0, 0)
end

function love.draw()
  love.graphics.setColor(1, 1, 1, 1)
  love.graphics.translate(screen_width / 2, screen_height / 2)

  local draw_object
  draw_object = function(object, parent_x, parent_y)
    love.graphics.circle("fill", object.x, object.y, 3)
    love.graphics.circle("line", parent_x, parent_y, object.orbital_radius)
    if object.children then
      for i = 1, #object.children do
        draw_object(object.children[i], object.x, object.y)
      end
    end
  end
  draw_object(star, 0, 0)
end

function love.keypressed(key)
  if key == "escape" then
    love.event.quit()
  end
end