Nomo's TreeFarm

local tArgs = { ... }
if #tArgs == 1 then
    amount = tonumber( tArgs[1] )
else
    amount = 1
end

if turtle.getItemCount(16) < amount then
    print("Please supply sufficient saplings in bottom right slot.")
    return
end

-- -- -- -- functions -- -- -- --
local function tryDig()
    while turtle.detect() do
        if turtle.dig() then
            sleep(0.1)
        else    return false
    end end
    return true
end

local function tryForward()
    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
-- -- -- -- main loop -- -- -- --

turtle.select(16)
for i = 1, amount do
    repeat turtle.forward() until turtle.detect()
    tryForward()
    repeat
        turtle.digUp()
        turtle.up()
    until not turtle.detectUp()
    repeat turtle.down()
    until turtle.detectDown()
    turtle.digDown()
    turtle.placeDown()
end