--[[ Running this script on a turtle with saplings in slot 1, Wood in slot 2  and a chest behind the turtle for the wood drop off point will create an automatic tree farm. combining this with a chest to the left of the turtle for sapling replenishment and chest to the right for coal replenishment will ensure a long running automated process.]]

-- This function lays saplings and applies bone-meal
function plant()
    turtle.select(1)                --selects sapling
    turtle.place()                  --places sapling
    turtle.suck()                   --picks up any saplings that have fallen
end

-- This function cuts a column directly above the turtle and then returns to ground level
function column()
    while turtle.detectUp() == true do      --cut tree down
        turtle.digUp()
        turtle.up()
        turtle.suck()               --picks up any saplings that have fallen
    end
    while turtle.detectDown() == false do       -- return to ground level
        turtle.down()
        turtle.suck()               --picks up any saplings that have fallen
    end
end

-- This function moves from start position, runs column and returns to start position
function fell()
    turtle.dig()                    --breaks bottom block of tree
    turtle.forward()                --move into gap
    column()                    --run column function
    turtle.turnRight()              --return to start
    turtle.turnRight()
    turtle.forward()
end

-- This function empties all collected wood into chest, checks sapling and fuel supplies and restocks
function empty()
    for j = 3, 16 do                -- empty slots 3 to 16 into chest
        turtle.select(j)
        turtle.drop()
    end
    turtle.turnLeft()
    turtle.turnLeft()
    if turtle.getItemCount(1) < 5 then      --replenish sapling stocks
        turtle.turnLeft()
        turtle.select(1)
        turtle.suck()
        turtle.turnRight()
    end
end

-- This function checks to see if the sapling has been fertilized into a full tree
function compare()
    turtle.select(2)
    if turtle.compare() == true then
        return true             -- false could indicate that there is no grown Baum
    else
        return false
    end
end

-- This block triggers the appropriate functions in the correct order.
repeat                          --start loop
    plant()                     --plant and fertilize tree
    turtle.digUp()
    turtle.up()
    repeat
        if compare() == true then           --if tree has grown cut down tree
            turtle.down()
            fell()
        else                        --if tree hasn't grown display error
            sleep(10)
            turtle.suck()
            until 1 > 2
    end
    empty()                     --empty harvest and restock fuel and materials
until 1 > 2                     -- always false creating infinite loop