TreeFarm

wood_id = "minecraft:spruce_log"
sapling_id = "minecraft:spruce_sapling"
dirt_id = "minecraft:dirt"
grass_id = "minecraft:grass_block"
sleep_time = 5

function FindItemSlot (item_id)

    for i = 1, 16, 1 do

        turtle.select(i)
        local data = turtle.getItemDetail()
        if data then

            if data.name == item_id then

                return i

            end

        end

    end

    return -1

end

function PlantTree ()

    slot = FindItemSlot(sapling_id)
    turtle.select(slot)
    turtle.place()

end

function ReturnToStart ()

    local ground_level = false

    while not ground_level do

        local _, data = turtle.inspectDown()
        if data.name == dirt_id or data.name == grass_id then

            ground_level = true

        else

            while turtle.detectDown() do

                turtle.digDown()

            end
            turtle.down()

        end

    end

end

function ChopTree ()

    tree_exists = true

    while tree_exists do

        local _, data = turtle.inspect()

        if data.name == wood_id then

            turtle.dig()
            while turtle.detectUp() do

                turtle.digUp()

            end
            turtle.up()

        else

            tree_exists = false

        end

    end
    ReturnToStart()
    PlantTree()

end

while true do

    local _, data = turtle.inspect()
    if data.name == wood_id then

        ChopTree()

    else

        os.sleep(sleep_time)

    end

end