ComputerCraft Shafter Program

-- Variables ----------------------------------------------------------

    local tArgs = { ... }

    local tFuel = tonumber (turtle.getFuelLevel())
    local tSlot = 1

    if #tArgs < 1 then
        term.clear()
        term.setCursorPos(1,1)
        print("Usage: shafter <length> <height> <width> <Direction>");
        print("Type shafter and a '?' or 'help' for more info.")
        return
    elseif (tArgs[1] == '?' or tArgs[1] == 'help') then
        term.clear()
        term.setCursorPos(1,1)
        print("shafter <length> <height> <width> <Direction>");
        print("Examples:")
        print("shafter 20 2 5 1")
        print("Creates a 20 long, 5 wide, 2 high room from right to left.")
        print("If details are omitted,")
        print("default height is 2,")
        print("default width is 1,")
        print("default direction is 2 (left to right).")
        print("Shaft length is mandatory.")
        return
    end

    local sLength = tonumber ( tArgs[1] )




    local sWidth = tonumber (tArgs [3] )
    local sHeight = tonumber (tArgs [2] )
    local sDirection = tonumber (tArgs [4] )

    if sWidth == nil then
        sWidth = 1
    end

    if sHeight == nil then
        sHeight = 2
    end
    if sDirection == nil then
        sDirection = 2
    end

--  local turns = sWidth - 1
    local aSize = (sLength * sWidth) * sHeight
    local sRows = sWidth

    hasTurned = false
-- Functions ------------------------------------------------------------

    local function digShaft(length, height)
        if hasTurned == true then
            length = length - 1
        end

        for i = 1, length do
            turtle.dig()

            for j = 1, height - 1 do
                turtle.up()
                turtle.dig()
            end

            if (turtle.detectUp() == false) then
                turtle.select(2)
                turtle.placeUp()
            end

            for j = 1, height - 1 do
                turtle.down()
            end
            turtle.forward()

            if (turtle.detectDown() == false) then
                turtle.select(2)
                turtle.placeDown()
            end
        end
        sRows = sRows - 1
    end

    local function swapTurn(direction)
        if direction == 1 then
            sDirection = 2
        elseif direction == 2 then
            sDirection = 1
        end
    end

    local function turnTurtle(direction)
        if direction == 1 then
            turtle.turnLeft()
        elseif direction == 2 then
            turtle.turnRight()
        end
    end

    local function makeTurn(height)

        turnTurtle(sDirection)
        turtle.dig()

        for u = 1, height - 1 do
            turtle.up()
            turtle.dig()
        end

        if (turtle.detectUp() == false) then
            turtle.select(2)
            turtle.placeUp()
        end

        for d = 1, height - 1 do
            turtle.down()
        end

        turtle.forward()

        if (turtle.detectDown() == false) then
            turtle.select(2)
            turtle.placeDown()
        end

        turnTurtle(sDirection)
        swapTurn(sDirection)
        hasTurned = true
    end


            -- Check fuel ----------------------------
            -------------------------------------------

    local function checkFuel(size)
        fuel = turtle.getFuelLevel()
        trips = (size / 2) * 3 -- wrong!
        fuelNeeded = trips - fuel

        if fuelNeeded < 0 then
            fuelNeeded = 0
        end

        print("Remaining fuel: "..fuel)
        print("Area to dig: "..size)
        print("Fuel needed: "..fuelNeeded)

        --- fuel = size + length if turtle finishes job away from starting point

        if fuelNeeded > 0 then
            print("Attempting to get enough fuel for the job...")
            while fuel < trips and tSlot < 17 do
                turtle.select(tSlot)

                if  turtle.refuel(1) == false then
                    tSlot = tSlot + 1
                end

                if tSlot == 17 then
                    print ("Not enough accessible tFuel. Aborting!")
                    return false
                end

                if tSlot < 17 and fuelNeeded == 0 then
                    print ("Done refueling. Commencing job!")
                    turtle.select(2)
                end

                fuel = turtle.getFuelLevel()

            end
            print ("fuel: "..fuel)
        end
        return true
    end

-- Temporary function to prevent getting stuck if there's a block above at start
local function checkSpace()
    while turtle.detectUp() do
        turtle.back()
    end
end

local function doJob()
    while sRows ~= 0 do
        digShaft(sLength, sHeight)
        if sRows ~= 0 then
            makeTurn(sHeight)
        end
    end
end

-- Do the job ------------------------------------------------------
--------------------------------------------------------------------

-- Debug stuff
print ("sLength: "..sLength.." \\ sHeight: "..sHeight.." \\ sWidth: "..sWidth)
print ("tFuel: "..tFuel.. " \\ aSize: "..aSize)
print ("sDirection: "..sDirection.." \\ sRows: "..sRows)

-- actual actions
if checkFuel(aSize) then
    checkSpace()
    doJob()
end