Minecraft ComputerCraft Tunnel

shell.run("clear")

while tunnelLength == nil do
    term.setCursorPos(1, 1)
    term.clearLine()
    term.write("Tunnel Length: ")
    tunnelLength = tonumber(read())
end

while tunnelWidth == nil do
    term.setCursorPos(1, 2)
    term.clearLine()
    term.write("Tunnel Width: ")
    tunnelWidth = tonumber(read())
end

while tunnelHeight == nil do
    term.setCursorPos(1, 3)
    term.clearLine()
    term.write("Tunnel Height: ")
    tunnelHeight = tonumber(read())
end

-- while torchSpacing == nil do
--     term.setCursorPos(1, 4)
--     term.clearLine()
--     term.write("Torch spacing (0 for no torches): ")
--     torchSpacing = tonumber(read())
-- end

local estimatedFuelUsage = tunnelWidth*2*tunnelLength*tunnelHeight
estimatedFuelUsage = tunnelHeight*2*tunnelLength + estimatedFuelUsage + tunnelLength
estimatedFuelUsage = math.ceil(estimatedFuelUsage)

term.clear()
term.setCursorPos(1,1)
print("This turtle will dig a tunnel "..tunnelLength.." blocks long, "..tunnelWidth.." blocks wide, and "..tunnelHeight.." blocks tall")
-- if torchSpacing == 0 then
--     print("No torches will be placed")
-- else
--     print("A torch will be placed every "..torchSpacing.." blocks")
-- end
print("")
print("Current fuel: "..turtle.getFuelLevel())
print("Estimated fuel usage: "..estimatedFuelUsage)
if turtle.getFuelLevel() < estimatedFuelUsage then
    print("!!! Turtle may run out of fuel before finishing !!!")
end
print("")
print("Press ENTER to confirm or type <restart> and press enter to start over or type <exit> and press enter to exit program")
term.write("Confirm: ")
confirmStart = read()
if confirmStart == "restart" then
    shell.run(shell.getRunningProgram())
end
if confirmStart == "exit" then
    shell.exit()
end
term.clear()
term.setCursorPos(1, 1)

local fuelUsed = 0
local turtleLengthProgress = 0
local blocksBroken = 0
local blocksToBreak = tunnelWidth*tunnelHeight*tunnelLength
local currentTunnelLength = 1

function digHeight(h)
    for u = 1, h-1 do
        turtle.digUp()
        blocksBroken = blocksBroken + 1
        turtle.up()
        fuelUsed = fuelUsed + 1
        printTurtleStats()
    end
end

function digWidth(w)
    for u = 1, w-1 do
        turtle.dig()
        blocksBroken = blocksBroken + 1
        turtle.forward()
        fuelUsed = fuelUsed + 1
        printTurtleStats()
    end
end

function reverse(w)
    for u = 1, w-1 do
        turtle.back()
        fuelUsed = fuelUsed + 1
        printTurtleStats()
    end
end

function digOutNextSection()
    turtle.dig()
    blocksBroken = blocksBroken + 1
    turtle.forward()
    fuelUsed = fuelUsed + 1

    digHeight(tunnelHeight)
    turtle.turnRight()
    for h = 1, tunnelHeight do
        digWidth(tunnelWidth)
        reverse(tunnelWidth)
        turtle.down()
        fuelUsed = fuelUsed + 1
    end
    turtle.turnLeft()
end

function moveTurtleToChest()
    turtle.turnRight()
    turtle.turnRight()
    for i = 1, turtleLengthProgress do
        turtle.forward()
        fuelUsed = fuelUsed + 1
    end
end

function moveTurtleBackToFront()
    turtle.turnLeft()
    turtle.turnLeft()
    for i = 1, turtleLengthProgress do
        turtle.forward()
        fuelUsed = fuelUsed + 1
    end
end

function emptyTurtleToChest()
    for i = 1, 16 do
        turtle.select(i)
        turtle.drop()
        i = i + 1
    end
end

function turtleShouldEmpty()
    local occupiedSlots = 0
    for i = 1, 16 do
        if turtle.getItemCount(i) > 0 then
            occupiedSlots = occupiedSlots + 1
        end
        i = i + 1
    end
    return 16 - occupiedSlots <= 4
end

function printTurtleStats()
    term.clear()
    term.setCursorPos(1, 1)
    local percent = math.ceil(blocksBroken/blocksToBreak*100)
    print("Progress "..percent.."% complete ("..blocksBroken.."/"..blocksToBreak..")")
    print("Fuel used: "..fuelUsed.."/"..estimatedFuelUsage)
    print("Remaining estimated fuel usage: "..estimatedFuelUsage-fuelUsed)
    print("Fuel remaining: "..turtle.getFuelLevel())
end

for tl = 1, tunnelLength-1 do
    digOutNextSection()
    printTurtleStats()
    turtleLengthProgress = turtleLengthProgress + 1
    if turtleShouldEmpty() then
        print("Going to empty inventory")
        moveTurtleToChest()
        emptyTurtleToChest()
        moveTurtleBackToFront()
    end
    currentTunnelLength = currentTunnelLength + 1
end

moveTurtleToChest()
printTurtleStats()
emptyTurtleToChest()