Minecraft Turtle: Tesseract Tunnel (Robust)

--[[
    2014 (c) psychedelixx
    Minecraft Turtle: Tesseract Tunnel (Robust)
    2014-04-13

    Digs a tunnel and places mined items in a tesseract.

    Robust API:
    http://computercraft.info/wiki/Robust_Turtle_API

    Usage:
        - use turtle and type "label set <name>"
          (to give your turtle an unique name so it remembers its programs)
        - type "pastebin get TnEEWzLJ tt"
        - type "tt <length> [<return (0|1)>]"
        - place torches in slot 16
--]]

i = 0
ret = 1

function move()
    i = i+1

    print("----------------")
    print("Remaining fuel: " .. turtle.getFuelLevel())
    print("Digged: " .. i .. "/" .. length .. "(" .. math.floor(100/length*i) .. "%)")
    print("Next torch in " .. 9-i%8)
    print("")

    --[[ Vorwärts graben und bewegen ]]--
    t.dig()
    t.forward()

    --[[ Hoch bzw. runter graben ]]--
    if i%2 == 1 then
        t.digUp()
    else
        t.digDown()
    end

    --[[ Links graben ]]--
    t.left()
    t.dig()

    --[[ Rechts graben ]]--
    t.turnAround()
    t.dig()

    --[[ Fackel setzen ]]--
    if i%8 == 1 then
        turtle.select(16)
        turtle.place()
    end

    --[[ Hoch bzw. runter bewegen ]]--
    if i%2 == 1 then
        t.up()
        t.digUp()
    else
        t.digUp()
        t.down()
    end

    --[[ Rechts graben ]]--
    t.dig()

    --[[ Links graben ]]--
    t.turnAround()
    t.dig()

    --[[ Nach vorne drehen ]]--
    t.right()

    --[[ Sand/Kies entfernen ]]--
    t.digUp()
end

local args = { ... }
if #args < 1 then
    print("")
    print("tt <length> [<return (0|1)>]")
    print("place torches in slot 16")
    print("")

    error()
end

length = tonumber(args[1])

if #args == 2 then
    ret = tonumber(args[2])
end

if turtle.getFuelLevel() < length*2 + length*ret then
    print("I need fuel!")
    print((length*2 + length*ret) - turtle.getFuelLevel() .. " fuel missing")
    print("Refuel with " .. ((length*2 + length*ret) - turtle.getFuelLevel())/80+1 .. " pieces of coal")
else
    print("======== 2014 (c) psychedelixx ========")
    print("Let's go!")
    print("Digging " .. length)

    for l = 1, length do
        move()

        if i%2 == 0 then
            empty = 0
            for slot = 1, 15 do
                if turtle.getItemCount(slot) == 0 then
                    empty = empty + 1
                    if empty >= 2 then break end
                end
            end
            if empty <= 1 then
                t.turnAround()
                t.forward(l)
                for slot = 1, 15 do
                    turtle.select(slot)
                    turtle.drop()
                end
                t.turnAround()
                t.forward(l)
            end
        end
    end

    if ret == 1 then
        t.turnAround()
        t.forward(length)
        if i%2 == 1 then t.down() end

        for slot = 1, 16 do
            turtle.select(slot)
            turtle.drop()
        end
    end
end