ComputerCraft mine program

local tArgs={...}
if #tArgs~=1 then
    print("Usage: mine <diameter>")
    print("ex: mine 10 will mine a 10x10x2 area")
    return
end

local size=tonumber(tArgs[1])
if size<1 then
    print("mine diameter must be positve")
    return
end

local torches

local function torch()
    torches=turtle.getItemCount(1)
    if torches==0 then
        return false
    end
    return true
end

while not torch() do
    print("Please put torches in slot 1")
    sleep(2)
end

local collected=0

local function collect()
    collected=collected+1
    if math.fmod(collected,25)==0 then
        print("Mined "..collected.." items")
    end
end

local function tryDig()
    while turtle.detect() do
        if turtle.dig() then
            collect()
            sleep(0.5)
        else
            return false
        end
    end
    return true
end

local function tryDigUp()
    while turtle.detectUp() do
        if turtle.digUp() then
            collect()
            sleep(0.5)
        else
            return false
        end
    end
    return true
end

local function refuel()
    local fuelLevel=turtle.getFuelLevel()
    if fuelLevel == "unlimited" or fuelLevel>0 then
        return
    end

    local function tryRefuel()
        for n=1,16 do
            if turtle.getItemCount(n)>0 then
                turtle.select(n)
                if turtle.refuel(1) then
                    turtle.select(1)
                    return true
                end
            end
        end
        turtle.select(1)
        return false
    end

    if not tryRefuel() then
        print("Add more fuel to continue.")
        while not tryRefuel() do
            sleep(1)
        end
        print("Resumming mine")
    end
end

local function tryForward()
    refuel()
    while not turtle.forward() do
        if turtle.detect() then
            if not tryDig() then
                return false
            end
        elseif turtle.attack() then
            collect()
        else
            sleep( 0.5 )
        end
    end
    return true
end

local function placeTorch()
    if torch() then
        turtle.turnLeft()
        turtle.turnLeft()
        turtle.select(1)
        turtle.place()
        torches=torches-1
        turtle.turnLeft()
        turtle.turnLeft()
    else
        while not torch() do
            sleep(2)
        end
        turtle.turnLeft()
        turtle.turnLeft()
        turtle.select(1)
        turtle.place()
        torches=torches-1
        turtle.turnLeft()
        turtle.turnLeft()
    end
    if torches==0 then
        while not torch() do
            print("Out of torches")
            print("put torches in slot 1")
            sleep(2)
        end
    end
end

local function checkinv()
    local inv=0

    for i=1,16 do
        if turtle.getItemCount(i)>0 then
            inv=inv+1
        end
    end

    if inv==16 then
        return false
    else
        inv=0
        return true
    end
end

local modN,modB

local function dig()
    for b=1,size-1 do
        modB=b%5
        while not checkinv() do
            print("Inventory full")
            sleep(3)
        end
        if modB==0 and modN==0 then
            placeTorch()
            tryDigUp()
            tryForward()
            tryDigUp()
        else
            tryDigUp()
            tryForward()
            tryDigUp()
        end
        if b==size-1 and modN==0 then
            placeTorch()
        end
    end
end

local function left()
    turtle.turnLeft()
    tryDigUp()
    tryForward()
    tryDigUp()
    turtle.turnLeft()
end

local function right()
    turtle.turnRight()
    tryDigUp()
    tryForward()
    tryDigUp()
    turtle.turnRight()
end

print("Minning...")

local alternate=0
local start=true

for n=1,size do
    modN=n%7
    if n==size or start then
        modN=0
        start=false
    end
    dig()
    if n<size then
        if math.fmod(n + alternate,2) == 0 then
            right()
        else
            left()
        end
    end
end

print("Minning Done")
print("Mined a total of "..collected.." items")