length = 1
currentLength = 0
width = 1
currentWidth = 0
height = 1
currentHeight = 0
onOddRow= true
confirmed = "y"
skipAirSpaces = false

-- Asking user for input
print "How far am I going?"
length = tonumber(read())
print "How wide is the tunnel?"
width = tonumber(read())
print "How high am I going?"
height = tonumber(read())
print "Skip empty spaces above? (y/n)"
_ = read()
if (_ == "y") then
    skipAirSpaces = true
end

function GetFuelLevel()
    local coal = 0
    local details = turtle.getItemDetail()
    while coal == 0 do
        print ("I have " ..turtle.getFuelLevel().. " fuel")
        print ("Would you like to add more fuel? y/n")
        input = read()
        if input("y") then
            print "Confirmed"
        else
            print "Please add coal to slot 1"
            turtle.select(1)
            print "Please confirm when done <Enter>"
            input = read()
            if details.name ~= "minecraft.coal" then
                print "I do not see coal in slot 1"
            else
                print "Refueling"
                turtle.refuel()
                coal = 1
            end
        end
    end
end

function Poke()
    if (onOddRow) then
        if (currentLength < length - 1) then
            turtle.dig()
        end
    else
        if (currentLength > 1) then
            turtle.dig()
        end
    end
end

function Advance()
    Poke()
    turtle.forward()
    if onOddRow then
        currentLength = currentLength + 1
    else
        currentLength = currentLength - 1
    end
end
function AdvanceUpward ()
    turtle.digUp()
    turtle.up()
    currentHeight = currentHeight + 1
end
function AdvanceDownward ()
    turtle.digDown()
    turtle.down()
    currentHeight = currentHeight - 1
end

function DigUpToTop(poke)
    if height < 2 then return end

    while currentHeight < height do
        if (skipAirSpaces and turtle.detectUp() == false) then
            break
        end
        Poke()
        AdvanceUpward()
    end
end

function DigDownToZero (poke)
    while currentHeight > 0 do
        Poke()
        AdvanceDownward()
    end
end

function Turn ()
    if onOddRow then
        turtle.turnRight()
    else
        turtle.turnLeft()
    end
end

function UTurn ()
    Turn()
    Advance()
    DigUpToTop()
    DigDownToZero()
    Turn()
end

while (currentWidth < width) do
    currentWidth = currentWidth + 1

    atDestination = false
    while not atDestination do
        if (onOddRow) then
            currentLength = currentLength + 1
            atDestination = (currentLength >= length)
        else
            currentLength = currentLength - 1
            atDestination = (currentLength <= 0)
        end
        Advance()
        DigUpToTop()
        Advance()
        DigDownToZero()
    end

    UTurn()
    onOddRow = not onOddRow

end