LiftServer

--VAR
Clutch = "right"
Gearshift = "back"
IsInitializing = false -- lift is in process of initialization
IsReady = false -- lift is ready, don't moving and await for commands
IsMoving = false -- lift is currently moving
CurrentLevel = 0
TargetLevel = 0
--initialize
rs.setOutput(Clutch , true) --set true to off
rs.setOutput(Gearshift , true) --true to move up
modem = peripheral.wrap("top")
modem.open(21)
------------------

---lift server start up
function Initialize()
  print("INITIALIZE")
  IsInitializing = true
  TargetLevel = 0
  --send command to reset all clients
  modem.transmit(21, 22, "init")
  --set lift to move down
  rs.setOutput(Gearshift, false)
  sleep(0.5)
  --start lift move down
  rs.setOutput(Clutch, false)
end

--
function ProcessCommand(command)
  write("received=")
  print(command)
  --
  if (command == "request") then
    if (IsReady) then
      modem.transmit(21, 22, "ready")
      return
    end
    if (IsMoving) then
      modem.transmit(21, 22, "moving "..TargetLevel )
      return
    end
    return
  end
  --
  if (IsInitializing and command == "contact 0") then
    CurrentLevel = 0
    rs.setOutput(Clutch , true) --set true to off
    rs.setOutput(Gearshift , false) --true to move up
    IsInitializing = false
    IsReady = true
    modem.transmit(21, 22, "ready")
    return
  end
  --
  if (IsMoving) then
    if (command == "contact 0") then
        ProcessContactCommand(0)
    end
    if (command == "contact 1") then
        ProcessContactCommand(1)
    end
    return
  end
  --
  if (IsReady) then
    if (command == "call 0") then
        CallLiftToLevel(0)
    end
    if (command == "call 1") then
        CallLiftToLevel(1)
    end
    return
  end
end

--Call lift moving to specified level
function CallLiftToLevel(level)
  if (IsReady == false) then
    return
  end
 --
 if (level == CurrentLevel) then
   return
 end
 if (level > CurrentLevel) then
   --move up
   TargetLevel = level
   IsMoving = true
   modem.transmit(21, 22, "lock 1 UP")
   modem.transmit(21, 22, "moving 1")
   rs.setOutput(Gearshift , true) --true to move up
   -- WAIT FOR RESPONSE
   sleep(0.5)
   rs.setOutput(Clutch , false) --set false to on
 end
 if (level < CurrentLevel) then
   --move down
   TargetLevel = level
   IsMoving = true
   modem.transmit(21, 22, "lock 0 DOWN")
   modem.transmit(21, 22, "moving 0")
   rs.setOutput(Gearshift , false) --false to move down
   -- WAIT FOR RESPONSE
   sleep(0.5)
   rs.setOutput(Clutch , false) --set false to on
 end
end

--Process contact command while lift is moving
function ProcessContactCommand(level)
  if (level == TargetLevel) then
    rs.setOutput(Clutch , true) --set true to off
    sleep(0.5)
    CurrentLevel = TargetLevel
    modem.transmit(21, 22, "ready")
    IsMoving = false
  end
end

--
function ProcessRedstone()
  detector = rs.getInput("left")
  if (detector == true) then
    modem.transmit(21, 22, "contact 1")
    ProcessCommand("contact 1")
  end
end

--initialize
Initialize()
--Main loop
repeat
    --local myTimer = os.startTimer(1)

    event,p1,p2,p3,p4,p5 = os.pullEvent()
    if (event=="redstone") then
      ProcessRedstone()
    end
    if (event=="modem_message") then
        --event, side, channel, replyChannel, message, distance
        ProcessCommand(p4)
    end

    if event=="timer" then
      print("test")
    end
until event=="char" and p1==("q")