Music Player With BuildCraft: Automtically Switch Discs

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-- Minecraft Music Player with BuildCraft
-- By: Negeator, 2012
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-- When set up correcty, this program can automatically play and switch music discs without the player touching the disk drive.
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--Variables--
--DO NOT MODIFY THESE--
local side, title, time
local state = "none" --What the media player is currently doing
local stateView = "" --What to display
local quit = false --Whether to exit the program or not
local timing = false --Whether the program is timing (Autoplay0
local currTime = 0 --Current Time
local visual = 0 --Visualization state variable
--MODIFY THESE IF YOU WANT--
local timeAmount = 300 --How long (in seconds) until we switch disks for Autoplay
--Check for a disk in
function checkSide()
  if disk.isPresent("top") == true and disk.hasAudio("top") == true then
	side = "top"
  elseif disk.isPresent("bottom") == true and disk.hasAudio("bottom") == true  then
	side = "bottom"
  elseif disk.isPresent("left") == true and disk.hasAudio("left") == true  then
	side = "left"
  elseif disk.isPresent("right") == true and disk.hasAudio("right") == true  then
	side = "right"
  elseif disk.isPresent("front") == true and disk.hasAudio("front") == true  then
	side = "front"
  elseif disk.isPresent("back") == true and disk.hasAudio("back") == true  then
	side = "back"
  else
side = "No Disc Found"
  end
end
--Clears the Screen
function clear()
  term.clear()
  term.setCursorPos(1,1)
end
--Display
function printInfo()
  term.write("Minecraft Music Player")
  term.setCursorPos(1,2)
  term.write(stateView)
  term.setCursorPos(1,3)
   term.write("Side: " .. side)
  if side ~= "No Disc Found" and state ~= "play" then
if disk.hasAudio(side) then
	  term.setCursorPos(1,4)
	  term.write("Disk Inserted: "..disk.getAudioTitle(side))
end
  end
  term.setCursorPos(1,5)
  if timing == true then
	term.write("Autoplay Turned ON	"..timeAmount - currTime.." Seconds Remaining.")
  else
	term.write("Autoplay Turned OFF")
  end
  term.setCursorPos(1,6)
  term.write("-------------------------------------------------")
  term.setCursorPos(1,7)
  term.write("1 - Play | 2 - Stop | 3 - Switch Disk")
  term.setCursorPos(1,8)
  term.write("4 - Autoplay | 0 - Quit ")
  term.setCursorPos(1,9)
  term.write("-------------------------------------------------")
  term.setCursorPos(1,10)
end
--Does stuff based on the state variable
function musicControl()
  --Play the disk automatically if in Autoplay mode
  if timing == true and state ~= "stop" then
	if state ~= "play" then
   state = "play"
end
  end

  if state == "play" then
	if side ~= "No Disc Found" then
   if stateView ~= "<Playing>"  then
	 disk.playAudio(side)
	 stateView = "<Playing>"
   end
end
  elseif state == "stop" then
	if side ~= "No Disc Found" then
   timing = false
   disk.stopAudio(side)
   stateView = "<Stopped>"
end
  end

  --If no disc is present, change the display
  if side == "No Disc Found" then
	stateView = "<INSERT DISC>"
  end

  --Make sure it displays as stopped when a new disc is just inserted
  if stateView == "<INSERT DISC" and side ~= "No Disc Found" then
	stateView = "<Stopped>"
  end
  state = ""

end
--Switch Disks
function cycleDisk()
  clear()
  term.write("Switching Disk")
  rs.setOutput("bottom",true)
  sleep(1)
  rs.setOutput("bottom",false)
  if timing == true then
	os.startTimer(9) --Wait for new Disc
currTime = 0
  end
end
--Updates the timer
function updateTimer()
  if timing == true then
	currTime = currTime + 1
	if currTime >= timeAmount then
	  currTime = 0
   cycleDisk()
   os.startTimer(9) --Wait for new Disc
else
   os.startTimer(1)
end
  end
end
--Main Function
function main()
  while quit == false do
	clear()
	checkSide()
   musicControl()
	printInfo()
	event, p1, p2 = os.pullEvent()
	if event == "key" then
	  if p1 == 2 then
	 state = "play"
   elseif p1 == 3 then
	 state = "stop"
	  elseif p1 == 4 then
		cycleDisk()
	  elseif p1 == 5 then
		if timing == true then
	timing = false
  else
	timing = true
	currTime = 0
	os.startTimer(1)
  end
  sleep(.25)
	  elseif p1 == 11 then
	 clear()
		quit = true
	  end
	elseif event == "timer" then
   updateTimer()
end

  end
end
--START PROGRAM--
main()
--END PROGRAM--