Most Efficient Turtle Quarry

----------------------
-- Efficient Quarry --
--  Made By Vilsol  --
--     1/20/2012    --
----------------------

term.clear()
term.setCursorPos(1, 1)

tArgs = { ... }
depth = 0
left = false

if(tArgs[1] == "update")then
    shell.run("rm", "eQuarry")
    shell.run("pastebin", "get", "PMfpn37Z", "eQuarry")
    print "Update successfull!"
    error()
end

function bringHome()
    turtle.digUp()
    turtle.select(13)
    turtle.placeUp()
    for slots = 1, 12 do
        turtle.select(slots)
        if(turtle.getItemCount(slots) > 0)then
            turtle.dropUp()
        end
    end
    turtle.select(13)
    turtle.digUp()
    turtle.select(1)
end

function isFull()
    slot = turtle.getItemCount(12)
    if(slot >= 1)then
        bringHome()
    end
end

function checkSlots()
    enderchest = turtle.getItemCount(13)
    dirt = turtle.getItemCount(14)
    stone = turtle.getItemCount(15)
    fuel = turtle.getItemCount(16)
    if(enderchest == 1 and dirt == 1 and stone == 1 and fuel >= 1)then
        return true
    else
        return false
    end
end

function checkFuel()
    if(turtle.getFuelLevel() < 100)then
        turtle.select(16)
        if (turtle.refuel())then
            print "Refueled successfully"
            return true
        else
            print "Out of fuel!"
            error()
        end
        turtle.select(1)
    else
        return true
    end
end

function safeDig()
    isFull()
    if(not turtle.dig())then
        if(not turtle.detect())then
            return true
        else
            if(turtle.attack())then
                for attack = 1, 50 do
                    turtle.attack()
                    if(turtle.dig())then
                        dig = 1
                        break
                    end
                    sleep(0.1)
                end
                if dig then
                    dig = 0
                    return true
                else
                    print "Unknown problem!"
                    error()
                end
            else
                print "Unknown problem!"
                error()
            end
        end
    else
        return true
    end
end

function safeForward()
    isFull()
    if(not turtle.forward())then
        sleep(1)
        if(turtle.attack())then
            for attack = 1, 50 do
                turtle.attack()
                if(turtle.forward())then
                    forward = 1
                    break
                end
                sleep(0.1)
            end
            if forward then
                forward = 0
                return true
            else
                print "Unknown problem!"
                error()
            end
        else
            if(turtle.dig())then
                sleep(1)
                for graveler = 1, 8 do
                    if(not turtle.dig())then
                        break
                    end
                    sleep(1)
                end
                if(turtle.forward())then
                    return true
                else
                    print "Unknown problem!"
                    error()
                end
            else
                print "Unknown problem!"
                error()
            end
        end
    else
        return true
    end
end

function compareOre()
    digup = 0
    digdown = 0
    turtle.select(14)
    if not turtle.compareUp() then
        digup = 1
    end
    if not turtle.compareDown() then
        digdown = 1
    end
    turtle.select(15)
    if not turtle.compareUp() then
        digup = digup + 1
    end
    if not turtle.compareDown() then
        digdown = digdown + 1
    end
    turtle.select(1)
    if(digup == 2)then turtle.digUp() end
    if(digdown == 2)then turtle.digDown() end
end

function turn()
    if left then
        left = false
        turtle.turnLeft()
        safeDig()
        safeForward()
        turtle.turnLeft()
    else
        left = true
        turtle.turnRight()
        safeDig()
        safeForward()
        turtle.turnRight()
    end
end

function checkLayer(x, z)
    for widthz = 1, z do
        for heightx = 1, x do
            compareOre()
            safeDig()
            safeForward()
        end
        compareOre()
        if tonumber(widthz) < tonumber(z) then
            turn()
        end
    end
    if left then
        turtle.turnRight()
        for back = 1, z-1 do
            safeForward()
        end
        turtle.turnRight()
    else
        turtle.turnLeft()
        for back = 1, z-1 do
            safeForward()
        end
        turtle.turnLeft()
        for back = 1, x do
            safeForward()
        end
        turtle.turnLeft()
        turtle.turnLeft()
    end
    left = false
end

function backUp()
    for up = 1, y do
        turtle.up()
    end
end

function digQuarry(x, z, y)
    while true do
        checkLayer(x, z)
        for down = 1, 3 do
            depth = depth + 1
            turtle.digDown()
            turtle.down()
        end
        if(depth >= y)then
            backUp()
            print "Done!"
            break
        end
    end
end

if(#tArgs < 3)then
    print "Usage: eQuarry x z y"
    error()
else
    x = tonumber(tArgs[1]) - 1
    z = tonumber(tArgs[2])
    y = tonumber(tArgs[3])
    if(tonumber(x) and tonumber(z) and tonumber(y))then
        if(true)then
            if(checkFuel())then
                print ("Digging a " .. x+1 .. "x" .. z .. "x" .. y .. " quarry!")
                digQuarry(x, z, y)
            else
                print "Something went very wrong!"
                error()
            end
        else
            print "Please fill in the slot as follows:"
            print "Slot 13: Enderchest for dumping items."
            print "Slot 14: Dirt"
            print "Slot 15: Stone"
            print "Slot 16: Fuel"
            error()
        end
    else
        print "Please use only numbers!"
        error()
    end
end