Obsidian tower

-- Usage: tower <width / length> {direction [r|l]} {height}
-- height is automatically adjustable or if you decide to set it, start counting from the floor

-- v1.1: turtle's movement cant be disturbed by falling blocks or creeps

local dig = function ()
    if turtle.detect() then
        return turtle.dig()
    end
    return false
end

local digUp = function ()
    if turtle.detectUp() then
        return turtle.digUp()
    end
    return false
end

local digDown = function ()
    if turtle.detectDown() then
        return turtle.digDown()
    end
    return false
end

local forward = function()
    if turtle.forward() == false then

        while turtle.forward() == false do
            turtle.dig()
        end

    end
end

local function digRow(length)
    for i = 1, length do
        dig()
        digDown()
        digUp()
        forward()
    end
    digUp()
    digDown()
end

local function digLevel(a, b)
    if not a then a = 1 end
    if not b then b = args[1] end

    for i = a, b do
        digRow( args[1] - 1)
        if i~=b then -- don't turn in the last row
            turn()
        else
            turtle.turnLeft(); turtle.turnLeft()
            reverseDirection()
        end
    end
end

function turn()
    turtle[ nextTurn ]()
    dig()
    forward()
    turtle[ nextTurn ]()
    reverseDirection()
end

function reverseDirection()
    if nextTurn ~= "" then
        if nextTurn == "turnRight" then
            nextTurn = "turnLeft"

            return true
        else
            nextTurn = "turnRight"

            return true
        end
    else
        print("nextTurn variable not set! :(")
        error()

        return false
    end
end

function detectLayer() -- is there one more layer above? || moving 2 blocks up
    result = false
    for i = 1, 3 do
        if (turtle.detectUp() and turtle.digUp() and turtle.up()) or (turtle.up() and turtle.detectUp() or turtle.down() and false) then -- more lulz
            result = true
        else
            break
        end
    end
    print(tostring(result))
    return result
end

function isEven(n)
    if n%2 == 0 then
        return true
    end
    return false
end

args = {...}

args[1] = tonumber(args[1])
nextTurn = ""

    if args[1] == nil then
        print("First argument must be a number!")
        error()
    end

    if args[2] == "r" or args[2] == "l" then

    else
        print("Second argument is invalid! It can be either l or r")
    end

    args[3] = tonumber(args[3])
    if args[3] ~= nil then
        height = 2

        function detectLayer ( height )
            if height + 2 < args[3] then

                for i = 1, 3 do
                    digUp(); turtle.up()
                end
                return true

            else
                return false
            end
        end

    else
        height = 2
    end

print(args[2])
print("Size: "..args[1] .. "x" ..args[1] .. ", direction: ".. (tostring(args[2])~="nil" and args[2] or "not set")) -- for the lulz, without any if


sleep(2)
print("\nBeginning...")


turtle.up()

digRow( args[1] ) -- 1


if args[2] == "r" then
            nextTurn = "turnRight"
        else
            nextTurn = "turnLeft"
end
if nextTurn == "" then
    print("nexturn="..nextTurn)
    turtle.turnRight() -- where to continue?
    if turtle.detect() then
        nextTurn = "turnRight"
        turtle.turnLeft()
    else
        turtle.turnLeft(); turtle.turnLeft()
        if turtle.detect() then
            nextTurn = "turnLeft"
            turtle.turnRight()
        else
            print("Can't find the path around the corner!\n\nAborting!")
            error()
        end
    end
end

turn()

digLevel(2, args[1])

while detectLayer(height) do
    reverseDirection()
    digLevel(1, args[1])
    height = height + 2
end

print("Height: " .. height)

while height > 0 do
    turtle.down()
    height = height - 1
end