local Screen = require("screen")
local redball, greenblue, blueball
local redbox, greenbox, bluebox
local scrn

function _init()
  redball = image.load(_DIR .. "images/red_ball.gif")[1]
  greenball = image.load(_DIR .. "images/green_ball.gif")[1]
  blueball = image.load(_DIR .. "images/blue_ball.gif")[1]

  scrn = Screen:new("Let's drop some balls!", 10, 4)
  scrn:usepalette(redball)
  scrn:autocolor()
  image.copymode(3, true)

  redbox = view.new(scrn.mainvp, 16, 16, 16, 16)
  image.draw(redball, 0, 0, 0, 0, 16, 16)
  greenbox = view.new(scrn.mainvp, 16, 48, 16, 16)
  image.draw(greenball, 0, 0, 0, 0, 16, 16)
  bluebox = view.new(scrn.mainvp, 16, 80, 16, 16)
  image.draw(blueball, 0, 0, 0, 0, 16, 16)
end

function _step()
  scrn:step()
  view.active(scrn.mainvp)
  local mx, my, mb = input.mouse()
  local drop = input.drop()
  while drop do
    if drop == "red" then
      image.draw(redball, mx - 8, my - 8, 0, 0, 16, 16)
    end
    if drop == "green" then
      image.draw(greenball, mx - 8, my - 8, 0, 0, 16, 16)
    end
    if drop == "blue" then
      image.draw(blueball, mx - 8, my - 8, 0, 0, 16, 16)
    end
    drop = input.drop()
  end

  view.active(redbox)
  mx, my, mb = input.mouse()
  if mb == 1 then
    input.drag("red", redball)
  end

  view.active(greenbox)
  mx, my, mb = input.mouse()
  if mb == 1 then
    input.drag("green", greenball)
  end

  view.active(bluebox)
  mx, my, mb = input.mouse()
  if mb == 1 then
    input.drag("blue", blueball)
  end

  view.active(scrn.rootvp)
  if input.hotkey() == "q" then
    sys.exit()
  end
end