Dig

local tArgs = { ... }

--predeclare functions
local printUsage
local digSuccess
local digFail
local turtleReturn

--predeclare variables
local nDistance
local sDirection
local nReturnDistance
local bTurtleReturn
local fnDigHandle
local fnMoveHandle
local fnReverseMove

--error avoidance
local sDirection = "forward"

local tDigHandle = {
    ["f"] = turtle.dig,
    ["fd"] = turtle.dig,
    ["fw"] = turtle.dig,
    ["forward"] = turtle.dig,
    ["forwards"] = turtle.dig,
    ["u"] = turtle.digUp,
    ["up"] = turtle.digUp,
    ["d"] = turtle.digDown,
    ["dn"] = turtle.digDown,
    ["down"] = turtle.digDown
}

local tMoveHandle = {
    ["f"] = turtle.forward,
    ["fd"] = turtle.forward,
    ["fw"] = turtle.forward,
    ["forward"] = turtle.forward,
    ["forwards"] = turtle.forward,
    ["u"] = turtle.up,
    ["up"] = turtle.up,
    ["d"] = turtle.down,
    ["dn"] = turtle.down,
    ["down"] = turtle.down,
}

--reverses original movement
local tReverseMove = {
    ["f"] = turtle.back,
    ["fd"] = turtle.back,
    ["fw"] = turtle.back,
    ["forward"] = turtle.back,
    ["forwards"] = turtle.back,
    ["u"] = turtle.down,
    ["up"] = turtle.down,
    ["d"] = turtle.up,
    ["dn"] = turtle.up,
    ["down"] = turtle.up,
}

function turtleReturn()
    while nReturnDistance > 0 do
        if fnReverseMove() then
            nReturnDistance = nReturnDistance - 1
        else
            sleep(0.5)
        end
    end
end

function printUsage()
    print( "Usage: dig <distance> <direction> <return?>" )
    return
end

if ( #tArgs < 1 ) or ( #tArgs > 3 ) then
    printUsage()
end

nDistance = tonumber(tArgs[1])
if #tArgs == 2 then
    sDirection = tArgs[2]
elseif ( #tArgs == 3 ) and ( ( string.lower(tArgs[3]) == "return" ) or ( string.lower(tArgs[3]) == "r" ) or ( string.lower(tArgs[3]) == "ret" ) ) then
    sDirection = tArgs[2]
    bTurtleReturn = true
    nReturnDistance = tonumber(tArgs[1])
elseif ( #tArgs == 3 ) and ( ( string.lower(tArgs[3]) ~= "return" ) or ( string.lower(tArgs[3]) ~= "r" ) or ( string.lower(tArgs[3]) ~= "ret" ) ) then
end

fnDigHandle = tDigHandle[string.lower(sDirection)]
fnMoveHandle = tMoveHandle[string.lower(sDirection)]
fnReverseMove = tReverseMove[string.lower(sDirection)]

if fnDigHandle then
    while nDistance > 0 do
        fnDigHandle()
        if fnMoveHandle() then
            nDistance = nDistance - 1
        else
            sleep(0.5)
        end
    end
    if bTurtleReturn == true then
        turtleReturn()
    end
else
    print( "No such direction: "..sDirection )
    print( "Try: forward, up, or down" )
    return
end