Wither Farm

rednet.open("right")

local control = 107

local function up()
    while not turtle.up() do
        turtle.attackUp()
        sleep(0.1)
    end
end

while true do
    local id, message = rednet.receive()
    if id == control and message == "construct" then
        if turtle.getItemCount(1) > 0 then
            turtle.select(1)
            turtle.refuel(64)
        end
        if turtle.getFuelLevel() < 24 then
            rednet.send(control, "fuel")
        end
        turtle.down()
        turtle.turnLeft()
        turtle.select(1)
        turtle.suck()
        turtle.drop(turtle.getItemCount(1) - 4)
        turtle.turnRight()
        turtle.turnRight()
        turtle.select(2)
        turtle.suck()
        turtle.drop(turtle.getItemCount(2) - 3)
        turtle.turnLeft()
        turtle.up()
        turtle.forward()
        turtle.forward()
        for i = 1, 4 do
            turtle.down()
        end
        turtle.select(1)
        turtle.placeDown()
        turtle.turnRight()
        turtle.place()
        turtle.turnLeft()
        turtle.turnLeft()
        turtle.place()
        turtle.up()
        turtle.placeDown()
        turtle.select(2)
        turtle.place()
        turtle.turnRight()
        turtle.turnRight()
        turtle.place()
        turtle.up()
        turtle.turnLeft()
        turtle.placeDown()
        up()
        up()
        turtle.back()
        turtle.back()
        rednet.send(control, "ok")
    end
end