Turtlescript Dig Command

--[[
======================= A KreezCo Production =============================
==  Written by: Kreezxil                                                ==
==  Orignal Code by: M_I_Z_E                                            ==
==  Many Parts of this code was barrowed from the original turtle       ==
==    programs that come with computer craft.                           ==
==    http://www.computercraft.info/                                    ==
==  YouTube channel Name: Adventures in Casual Gaming                   ==
==  URL: http://www.youtube.com/user/kreezxil                           ==
==  Original URL: http://www.youtube.com/user/MIZ3craft                 ==
==  Please link to my channel and give proper credit if using my code.  ==
==  Thanks for watching!                                                ==
==========================================================================
--]]

--[[ Begin Library
     Libary by Kreezxil 7/29/2013
--]]

function refuel()
    --Check fuel and refuel if nessesary
    --Code source: sethbling http://www.youtube.com/watch?v=DSsx4VSe-Uk&feature=share&list=SP2Qvl4gaBge02Eh4AqtDSWg3sojt3jeRO
    if turtle.getFuelLevel() < 200 then
        turtle.select(1)
        turtle.refuel(1)
    end
end

function dig(direction, distance)
    travel = 0
    repeat
        --[[ do we have fuel? --]]
        refuel()
        travel = travel + 1
        if direction == "f" then
            if turtle.dig() then
                turtle.suck()
            end
            if distance > 0 then
                turtle.forward()
            end
        elseif direction == "u" then
            if turtle.digUp() then
                turtle.suckUp()
            end
            if distance > 0 then
                turtle.up()
            end
        elseif direction == "d" then
            if turtle.digDown() then
                turtle.suckDown()
            end
            if distance > 0 then
                turtle.down()
            end
        elseif direction == "b" then
            turtle.back()
        end
    until travel == distance
end

--[[ End Library --]]

local tArgs = { ... }
local dist = 1
--[[ test how many args were passed, if none set dist to 0 and assume
forward facing. --]]
if #tArgs < 1 then
    --[[ print usage --]]
    print("Usage: dig [direction] <distance>")
    print()
    print("Place fuel in slot 1")
    print("Give command to dig")
    return
else
    --[[ dist = tonumber( tArgs[1] ) --]]
    --[[ parses passed parameters and sets variables despite order of values --]]
    print("Args Present: "..#tArgs)
    for n=1,#tArgs do
        if n == 3 then
            --[[ in the future subsequent arguments will be accepted
            as commandline mapping instructions
            --]]
            break
        end
        test = string.sub( tArgs[n], 1, 1)
        test = string.lower( test )
        if string.find("fdub",test) ~= nil then
            direction = test
        else
            dist = tonumber(tArgs[n])
        end
    end
end

--[[ Process command directives --]]
paramError = 0
if dist == nil or tonumber(dist) < 0 then
    print("Distance must be a number from 0 on up.")
    paramError = paramError + 1
end
if string.find("fdub",direction) == nil then
    print("Direction must be one of: forward, down, up, back, f, d, u, b")
    paramError = paramError + 1
end

if paramError > 0 then
    print("Number of parameter errors are " .. paramError)
    print("Please think about your options.")
    return
end

dig(direction,dist)