Turtle refuel off lava (fluid transposer required)

-- Setup:
--
-- (1) - Place a fluid transposer with power and a lava
-- source (pipe) attached to it. These can be on any side
-- except the top and the side you want the turtle to put
-- the bucket in.
--
-- (2) - Place the turtle on top of the fluid transposer.
-- Open the transposer interface and make sure the lava
-- source's side is blue, the top side is orange, and
-- the side that the turtle has its back to is blue.
-- If the side the turtle has its back to is the front of
-- the transposer, the transposer must be turned.
--
-- (3) - Lastly, put a bucket in the transposer and run
-- the program.

-- Additional Options:
--
--  Arguments:
--      The first argument in the program is an option to make
--      turtle refuel to that fuel level instead of the default
--      1,000,000 fuel.
--
--  Pausing:
--      You can pause the turtle with a redstone signal to the
--      front of the turtle while it is above the transposer
--      example:         /      \       \
--                      []T     []T     []  = lever
--                      --F     --F     T   = turtle
--                                      --  = pipe
--                                      F   = fluid transposer

openSlot = 1

args = { ... }
if table.getn(args) < 1 then
    fullyFueled = 1000000
else
    fullyFueled = tonumber(args[1])
end

function saveFirstOpenSlot()
    for i=1,16 do
        if turtle.getItemCount(i) == 0 then
            openSlot = i
            break
        end
    end
end

function refuel()
    shell.run("refuel","all")
    turtle.select(openSlot)
    while not turtle.back() do
    end
    while not turtle.down() do
    end
    turtle.drop()
    while not turtle.up() do
    end
    saveFirstOpenSlot()
    while not turtle.forward() do
    end
    term.clear()
    term.setCursorPos(1,1)
    print("Waiting for bucket --> Is the transposer out of lava?")
    event = os.pullEvent("turtle_inventory")
end

term.clear()
term.setCursorPos(1,1)
print("Starting program...")
while turtle.getFuelLevel() < fullyFueled do
    -- will stop refueling while on top of the fluid transposer
    -- if a redstone signal is applied to the front of the turtle
    -- until the redstone signal is removed (flipped off) the
    -- turtle waits
    while (not redstone.getInput("front")) and (turtle.getFuelLevel() < fullyFueled) do
        term.clear()
        term.setCursorPos(1,1)
        print("No Redstone Signal --> Fueling")
        refuel()
    end
    term.clear()
    term.setCursorPos(1,1)
    print("Redstone Signal Detected --> Pausing")
    event = os.pullEvent("redstone")
end
term.clear()
term.setCursorPos(1,1)
print("Fuel Level: "..turtle.getFuelLevel())