local tau = math.pi * 2
local game = {}

function love.load(arg)
  game.window_width, game.window_height = love.graphics.getDimensions()

  game.bubble_diameter = 60
  game.bubble_radius = game.bubble_diameter / 2

  -- vertical distance between bubble center points
  game.row_gap = math.ceil(math.sqrt(
    (game.bubble_diameter * game.bubble_diameter) -
    (game.bubble_radius * game.bubble_radius)
  ))

  game.background_image = love.graphics.newImage('images/background.png')
  game.background_width = game.background_image:getWidth()

  local bubbles_wide = 8
  local bubbles_high = 14
  game.level_width = bubbles_wide * game.bubble_diameter
  game.level_height = (bubbles_high - 1) * game.row_gap + game.bubble_diameter
  game.level_x = (game.window_width - game.level_width) / 2
  game.level_y = game.bubble_radius

  game.launcher_image = love.graphics.newImage('images/launcher.png')
  game.launcher_height = game.launcher_image:getHeight()
  game.launcher_width = game.launcher_image:getWidth()
  game.launcher_x = game.window_width / 2
  game.launcher_y = game.level_y + game.level_height + game.bubble_diameter
  game.launcher_offset_x = 90 -- rotation point in launcher image
  game.launcher_offset_y = game.launcher_height / 2
  game.launcher_rotation = -tau / 4 -- up
end

function love.draw()
  -- draw background
  love.graphics.setColor(1, 1, 1, 1)
  love.graphics.draw(game.background_image, 0, 0)
  love.graphics.draw(game.background_image, game.background_width, 0)

  -- draw level border
  love.graphics.setColor(0, 0, 0, 1)
  love.graphics.rectangle(
    'line',
    game.level_x,
    game.level_y,
    game.level_width,
    game.level_height
  )

  -- draw launcher
  love.graphics.setColor(1, 1, 1, 1)
  love.graphics.draw(
    game.launcher_image,
    game.launcher_x,
    game.launcher_y,
    game.launcher_rotation,
    1,
    1,
    game.launcher_offset_x,
    game.launcher_offset_y
  )
end

function love.mousemoved(x, y, dx, dy, is_touch)
  local diff_x = x - game.launcher_x
  local diff_y = y - game.launcher_y
  game.launcher_rotation = math.atan2(diff_y, diff_x)
end

function love.keypressed(key, scan_code, is_repeat)
  if key == 'escape' then
    love.event.quit()
  end
end