local tArgs = { ... }

local uY, count, tX, tY, tZ, face = 1, 1, tArgs[1], tArgs[2], tArgs[3], tArgs[4]

function faceSouth()
  tZ = tZ + 1
  if face == 'N' then
        turtle.turnLeft()
        turtle.turnLeft()
  elseif face == 'W' then
        turtle.turnLeft()
  elseif face == 'E' then
        turtle.turnRight()
  else
        faceUsage()
        return false
  end
  goToSky()
end

function goToSky()
  while turtle.up() do
         uY = uY + 1
  end
  tY = tY + uY
  placeComputer()
end

function goToGround()
  while turtle.down() do
  end
end

function placeComputer()
  turtle.select(1)
  turtle.place()
  turtle.back()
  turtle.select(2)
  turtle.place()
  turtle.down()
  turtle.forward()
  turtle.select(4)
  turtle.place()
  turtle.select(3)
  turtle.drop()
  setComputer()
end

function goToSouthPos()
  turtle.turnLeft()
  turtle.turnLeft()
  for i = 1, 4 do
        turtle.forward()
        tZ = tZ + 1
  end
  tZ = tZ + 2 -- + 2 to compensate for turtle pos before turning left and the pos the computer is placed
  placeComputer()
end

function goToEastPos()
  turtle.down()
  turtle.down()
  turtle.down()
  tY = tY - 3
  for i = 1, 4 do
        turtle.forward()
  end
  tZ = tZ - 3
  turtle.turnRight()
  turtle.forward()
  turtle.forward()
  tX = tX + 3
  placeComputer()
end

function goToWestPos()
  turtle.down()
  for i = 1, 6 do
        turtle.forward()
        tX = tX - 1
  end
  turtle.up()
  placeComputer()
end

function setComputer()
  turtle.down()
  turtle.forward()
  turtle.forward()
  turtle.turnLeft()
  turtle.turnLeft()
  turtle.up()
  setUpDisk(tX,tY,tZ)
  turtle.up()
  peripheral.call("front", "turnOn")
  turtle.down()
  turtle.suck()
  turtle.dig()
  turtle.up()
  sleep(2)
  peripheral.call("front", "reboot")
  if count == 1 then
        count = count + 1
        goToSouthPos()

  elseif count == 2 then
        count = count + 1
        goToEastPos()

  elseif count == 3 then
        count = count + 1
        goToWestPos()
  elseif count == 4 then
        goToGround()
  end
end

function setUpDisk(x,y,z)
  print("Computer number "..count)
  print("<x>"..x.." <y>"..y.." <z>"..z)
  local st = fs.open("disk/startup", "w")
  local gps_run = "shell.run('gps','host',"..x..","..y..","..z..")"
  st.writeLine("local startup = fs.open('startup', 'w')")
  st.writeLine("startup.writeLine(\""..gps_run.."\")")
  st.writeLine("startup.close()")
  st.close()
end

function usage()
  print("usage:")
  print("setup_gps <x> <y> <z> <f>")
end

function placingSetUp()
  print("---------------------------------------")
  print("Please place items in the following order:")
  print("Slot 1: 4x computers")
  print("Slot 2: 4x wirelesse modems")
  print("Slot 3: 1x floopy disk")
  print("Slot 4: 1x disk drive")
  print("---------------------------------------")
end

function checkItems()
  if turtle.getItemCount(1) == 4
  and turtle.getItemCount(2) == 4
  and turtle.getItemCount(3) == 1
  and turtle.getItemCount(4) == 1
  then
        return true
  else
        placingSetUp()
        return false
  end
end

function checkTurtleType()

  turtle.select(4)
  turtle.place()
  if turtle.dig() then
        return true
  else
        print("You must use a mining turtle in order to run this program")
        return false
  end
end

function faceUsage()
  print("-----------------")
  print("face parameter:")
  print("S if facing south")
  print("N if facing north")
  print("E if facing east")
  print("W if facing west")
  print("-----------------")

  return false
end

function checkArguments()
  if #tArgs ~= 4 then
        usage()
        return false
  elseif type(tonumber(tX)) ~= "number" then
        print("<x> has to be a number")
        return false
  elseif type(tonumber(tY)) ~= "number" then
        print("<y> has to be a number")
        return false
  elseif type(tonumber(tZ)) ~= "number" then
        print("<z> has to be a number")
        return false
  else
        return true
  end
end

function checkFuel()
  if turtle.getFuelLevel() < 1000 then
        print("Not enough fuel")
        print("Fuel level has to be greater than 1000")
        return false
  else
        return true
  end
end

function initialChecking()
  if tX == "help" then
        usage()
        placingSetUp()
        return false
  elseif checkTurtleType() == false
  or checkArguments() == false
  or checkFuel() == false
  or checkItems() == false
  then
        return false
  else
        return true
  end
end

if initialChecking() == false then
  return false
else
  faceSouth()
end