UI = require("ui")

-- create our playback icons
my_icons = {}
for i=1,4 do
  my_icons[i] = UI.PlaybackIcon.new(24*i,30,6,4)
end

-- set all except my_icons[1] to inactive (ie, .active = false)
for i=2,4 do
  my_icons[i].active = false
end

-- set a counter for which track is active
active_track = 1

function redraw()
  screen.clear()
  for i=1,4 do
    screen.level(15)
    screen.move(24*i,20) -- label each icon
    screen.text(i)
    my_icons[i]:redraw() -- redraw all four icons
  end
  screen.update()
end

function key(n,z)
  if n == 1 then
    alt = z==1 
  elseif n == 2 and z == 1 then
    -- K2 plays active track, or pauses (if playing or reverse playing)
    if not alt then
      if my_icons[active_track].status == 1 or my_icons[active_track].status == 2 then my_icons[active_track].status = 3
      else my_icons[active_track].status = 1 end
    else 
      my_icons[active_track].status = 4 -- K1 + K2 stops the active track
    end
  elseif n == 3 and z == 1 then
    -- toggles between play and reverse play
    if my_icons[active_track].status == 1 then
      my_icons[active_track].status = 2
    elseif my_icons[active_track].status == 2 then
      my_icons[active_track].status = 1
    end
  end
redraw()
end

function enc(n,d)
  if n == 1 then
    active_track = util.clamp(active_track + d, 1, 4)
    for i=1,4 do
      my_icons[i].active = false -- we reset all active states to false
    end
    my_icons[active_track].active = true -- only the active track's icon is active
  end
redraw()
end