Tree Farm

-- Tree Farm
-- By Fenthis

spacing_forward = 3 -- Spaces between trees
spacing_left = 4
trees = 3 -- Trees in row
rows = 3 -- Rows of trees
offset = 5 -- Start position from first trees
sapling_slot = 1 -- Where to keep the reference saplings
delay = 120 -- Delay in seconds between runs

-- Misg globals
total_count = 0
saplings = 0

if not act then
    os.loadAPI("act")
    if not act then
        print("act api required.")
        exit()
    end
end

-- We have arrived in front of what might be a trunk
function do_tree()
    if turtle.dig() then -- Got a tree?
        act.try()
        turtle.digDown() -- get the stump
        height = 0
        while turtle.digUp() do
            turtle.up()
            height = height + 1
        end
        for i = 1, height do
            act.tryDown()
        end
    else
        act.try()
    end

    if not turtle.detectDown() and saplings > 1 then
        saplings = saplings - 1
        act.placeDown()
    end

    -- And just in case something landed on the dirt
    turtle.suckDown()
end

function do_left_or_right(dir)
    if dir then
        turtle.turnLeft()
    else
        turtle.turnRight()
    end
end

function is_odd(n)
    return ((n % 2) == 1)
end

function try_n(times)
    for i = 1, times do
        act.try()
    end
end

function do_round ()
    local count = 0

    saplings = count_saplings()
    print("Starting round with "..saplings.." saplings.")

    act.tryUp()
    try_n(offset - 1)

    for row = 1, rows do
        for tree = 1, trees do
            do_tree() -- this should leave us above the tree
            if tree ~= trees then
                try_n(spacing_forward)
            end
        end
        if row ~= rows then
            act.try()
            do_left_or_right(is_odd(row))
            try_n(spacing_left + 1)
            do_left_or_right(is_odd(row))
        end
    end

    -- Now return
    if not is_odd(rows) then
        act.try()
    else
        turtle.turnLeft()
        act.try()
        turtle.turnLeft()
        try_n(((spacing_forward + 1) * (trees - 1)) + 1)
        turtle.turnLeft()
        act.try()
        turtle.turnRight()
    end

    do_left_or_right(is_odd(rows))
    try_n((spacing_left + 1) * (rows - 1))
    do_left_or_right(not is_odd(rows))
    try_n(offset - 1)
    turtle.down()

    -- Dump logs
    act.select(sapling_slot)
    for i = 1, 16 do
        if i ~= sapling_slot then
            if not turtle.compareTo(i) then
                act.select(i)
                count = count + turtle.getItemCount(i)
                turtle.drop()
                act.select(sapling_slot)
            end
        end
    end

    -- Turn around
    turtle.turnLeft()
    turtle.turnLeft()

    -- Are we low sapplings?
    saplings = count_saplings() -- Recount, sometimes we pick them up

    if saplings < ((trees * rows) + 1) then
        old = saplings
        -- Move to second chest and face it.
        turtle.turnLeft()
        act.try()
        turtle.turnLeft()
        -- Try and get two stacks
        turtle.suck()
        turtle.suck()
        -- Return to starting
        turtle.turnLeft()
        act.try()
        turtle.turnLeft()
        -- Recount
        saplings = count_saplings()
        print("Picked up "..(saplings - old).." more saplings.")
    end

    -- Print something
    total_count = total_count + count
    print("Loop complete, collected " .. count .. " items for a total of " ..
        total_count .. " with " .. turtle.getFuelLevel() .. " fuel " ..
        saplings .. " saplings remaining.")
end

function count_saplings()
    s = 0
    act.select(sapling_slot)
    for i = 1,16 do
        if turtle.compareTo(i) then
            s = s + turtle.getItemCount(i)
        end
    end
    return s
end

-- Setup
act.select(sapling_slot)

-- Do something
print("Running with a delay of " .. delay .. " seconds. Press Q to quit.")
while true do
    -- First, go for it.
    do_round()

    -- Then wait
    os.startTimer(delay)
    repeat
        e, a1 = os.pullEvent()
        if e == "char" and (a1 == "Q" or a1 == "q") then
            print("Quitting!")
            return
        end
    until e == "timer"
end