local Tween  = require('ui.tween')

local Transition = { }

function Transition.slideLeft(args)
  local ticks      = args.ticks or 6
  local easing     = args.easing or 'outQuint'
  local pos        = { x = args.ex }
  local tween      = Tween.new(ticks, pos, { x = args.x }, easing)
  local lastScreen = args.canvas:copy()

  return function(device)
    local finished = tween:update(1)
    local x = math.floor(pos.x)
    lastScreen:dirty()
    lastScreen:blit(device, {
      x = args.ex - x + args.x,
      y = args.y,
      ex = args.ex,
      ey = args.ey },
      { x = args.x, y = args.y })
    args.canvas:blit(device, {
      x = args.x,
      y = args.y,
      ex = args.ex - x + args.x,
      ey = args.ey },
      { x = x, y = args.y })
    return not finished
  end
end

function Transition.slideRight(args)
  local ticks      = args.ticks or 6
  local easing     = args.easing or'outQuint'
  local pos        = { x = args.x }
  local tween      = Tween.new(ticks, pos, { x = args.ex }, easing)
  local lastScreen = args.canvas:copy()

  return function(device)
    local finished = tween:update(1)
    local x = math.floor(pos.x)
    lastScreen:dirty()
    lastScreen:blit(device, {
      x = args.x,
      y = args.y,
      ex = args.ex - x + args.x,
      ey = args.ey },
      { x = x, y = args.y })
    args.canvas:blit(device, {
      x = args.ex - x + args.x,
      y = args.y,
      ex = args.ex,
      ey = args.ey },
      { x = args.x, y = args.y })
    return not finished
  end
end

function Transition.expandUp(args)
  local ticks  = args.ticks or 3
  local easing = args.easing or 'linear'
  local pos    = { y = args.ey + 1 }
  local tween  = Tween.new(ticks, pos, { y = args.y }, easing)

  return function(device)
    local finished = tween:update(1)
    args.canvas:blit(device, nil, { x = args.x, y = math.floor(pos.y) })
    return not finished
  end
end

function Transition.grow(args)
  local ticks  = args.ticks or 3
  local easing = args.easing or 'linear'
  local tween  = Tween.new(ticks,
    { x = args.width / 2 - 1, y = args.height / 2 - 1, w = 1, h = 1 },
    { x = 1, y = 1, w = args.width, h = args.height }, easing)

  return function(device)
    local finished = tween:update(1)
    local subj = tween.subject
    local rect = { x = math.floor(subj.x), y = math.floor(subj.y) }
    rect.ex = math.floor(rect.x + subj.w - 1)
    rect.ey = math.floor(rect.y + subj.h - 1)
    args.canvas:blit(device, rect, { x = args.x + rect.x - 1, y = args.y + rect.y - 1})
    return not finished
  end
end

return Transition