bake_bread.lua

local crafted = 0

local function get_used_slots()
    local used = 0
    for s = 1,15 do
        if turtle.getItemCount(s) > 0 then
            used = used + 1
        end
    end
    return used
end

local function get_items_in_slots(slots)
    local items = 0
    for s = 1, slots do
        items = items + turtle.getItemCount(s)
    end
    return items
end

local function dump_bread()
    turtle.turnRight()
    turtle.turnRight()
    turtle.select(16)
    crafted = crafted + turtle.getItemCount(16)
    turtle.drop(64)
    turtle.turnLeft()
    turtle.turnLeft()
end

local function do_crafting()
    -- Select slot 16 for the destination
    turtle.select(16)
    -- Should only have bread-stuff now, craft
    turtle.craft()

    -- Will now have bread in slot 16
    -- move the bread into the destination chest
    dump_bread()
end

local function selected_is_wheat()
    if turtle.getItemCount() == 0 then
        return false
    end
    if turtle.getItemDetail().name == "minecraft:wheat" then
        return true
    else
        return false
    end
end

local function selected_is_seeds()
    if turtle.getItemCount() == 0 then
        return false
    end
    if turtle.getItemDetail().name == "minecraft:wheat_seeds" then
        return true
    else
        return false
    end
end

local function check_fuel(required)
    -- Always assumes the turtle is currently at the
    -- bread creation place

    if turtle.getFuelLevel() == 'unlimited' or turtle.getFuelLevel() > required + 1 then
        return
    end

    -- Not enough fuel
    -- Try to refuel through inventory
    turtle.select(16)
    if turtle.refuel() then
        return
    end

    -- Turn right and check the chest for fuel
    turtle.turnRight()

    -- We need an additional action now (turn left)
    -- so increment required
    required = required + 1

    empty_spots = {}

    -- Suck it all up and call refuel on every item
    for s = 1, 16 do
        if turtle.getItemCount(s) == 0 then
            empty_spots[s] = 1
            turtle.suck()
            turtle.refuel()
            if turtle.getFuelLevel() > required + 1 then
                return
            end
        else
            empty_spots[s] = 0
        end
    end
    for s = 1, 16 do
        if empty_spots[s] == 1 then
            turtle.dump()
        end
    end

    -- Ask for fuel
    turtle.select(16)
    print("Need fuel!")

    -- Will be reduced by 3 at the destination
    redstone.setAnalogOutput("bottom", 14)
    while not turtle.refuel() or turtle.getFuelLevel() < required + 1 do
        os.pullEvent( "turtle_inventory")
    end
    redstone.setOutput("bottom", false)
    print("Got fuel!")

    turtle.turnLeft()
end

local function dump_drops()
    turtle.turnRight()
    for s = 1, 15 do
        turtle.select(s)
        turtle.drop(64)
    end
    turtle.turnLeft()
end

local function dump_fuel(slot)
    if not slot then
        slot = 16
    end
    turtle.turnLeft()
    turtle.select(slot)
    turtle.drop()
    turtle.turnRight()
end


-- Returns 0 if it got wheat,
-- 1 if it got seeds and
-- 2 if it got fuel or nothing
local function get_wheat_stack(slot)
    turtle.select(slot)
    turtle.suck(64)
    if turtle.getItemCount() == 0 then
        -- Picked up nothing, end
        return 2
    end
    if selected_is_seeds() == true then
        -- Drop seeds off at the seed box
        turtle.turnLeft()
        turtle.turnLeft()
        turtle.drop(64)
        turtle.turnRight()
        turtle.turnRight()
        return 1
    end
    if selected_is_wheat() == false then
        -- Just picked up fuel,
        -- drop it off again
        dump_fuel(s)
        return 2
    end
    return 0
end

local function get_wheat()
    turtle.turnRight()
    for s = 1, 3 do
        while get_wheat_stack(s) == 1 do
            -- Repeat this to remove all seeds from
            -- storage
        end
    end
    turtle.turnLeft()
end

local function balance(used_slots, items_per_slot)
    if used_slots == 1 then
        -- Just move one third at a time from the
        -- first slot to the second and third
        turtle.select(1)
        turtle.transferTo(2, items_per_slot)
        turtle.transferTo(3, items_per_slot)
    else
        -- Get the amount the first slot has to "lose"
        -- then check howmuch we can transfer to slot
        -- 2 and then transfer the rest to slot 3
        local first_too_many = turtle.getItemCount(1) - items_per_slot
        local second_needed = items_per_slot - turtle.getItemCount(2)
        if second_needed < 0 then
            -- Must get rid of some items,
            -- this means we just have to dump the first's items in
            -- the third slot
            turtle.select(1)
            turtle.transferTo(3, first_too_many)
            -- as well as the second's
            turtle.select(2)
            turtle.transferTo(3, -second_needed)
        else
            -- Transfer what the second one needs to
            -- the second one and the rest to the third
            turtle.select(1)
            turtle.transferTo(2, second_needed)
            -- as well as the second's
            turtle.select(1)
            turtle.transferTo(3, first_too_many - second_needed)
        end
    end
end

local function suck_all()
    for s = 1, 15 do
        turtle.select(s)
        turtle.suck()
    end
end

local function get_fuel()
    turtle.turnLeft()

    for s = 1, 15 do
        turtle.select(s)
        turtle.suck()
        if not selected_is_wheat() and not selected_is_seeds() then
            -- Picked up fuel
            turtle.transferTo(16, 64)
            break
        end
    end

    -- Dump it all again
    for s = 1, 15 do
        turtle.select(s)
        if turtle.getItemCount() > 0 then
            turtle.drop(64)
        end
    end

    turtle.turnRight()
end

local function make_bread()
    dump_fuel()

    -- Suck it all up
    suck_all()

    -- If we picked up nothing, just end
    if get_used_slots() == 0 then
        get_fuel()
        return
    end
    print("Making bread")

    -- Dump all wheat for now
    dump_drops()


    local used_slots = get_used_slots()
    local items = get_items_in_slots(used_slots)

    while true do
        -- Pick up a max of 3 stacks from the chest
        get_wheat()

        local used_slots = get_used_slots()
        local items = get_items_in_slots(used_slots)


        if items == 0 then
            break
        elseif items < 3 then
            -- Spit it out
            turtle.select(1)
            turtle.drop(64)
        end

        local remaining_items = items % 3
        if remaining_items > 0 then
            -- Got some items left, dump those in the chest
            turtle.select(used_slots)
            turtle.turnRight()
            turtle.drop(items % 3)
            turtle.turnLeft()
            items = get_items_in_slots(used_slots)
        end

        local items_per_slot = items / 3
        balance(used_slots, items_per_slot)

        do_crafting()
    end

    get_fuel()

    print("Made a total of ", crafted, " breads")
    print("Going back to sleep")
end

local function faces_chest()
    local success, data = turtle.inspect()
    if not success then
        return false
    end
    if data.name == "minecraft:chest" or data.name == "IronChest:BlockIronChest" then
        return true
    else
        return false
    end
end

local function is_at_start()
    turtle.turnLeft()
    if not faces_chest() then
        turtle.turnRight()
        return false
    end

    turtle.turnLeft()
    if not faces_chest() then
        turtle.turnRight()
        turtle.turnRight()
        return false
    end

    turtle.turnLeft()
    if not faces_chest() then
        turtle.turnRight()
        turtle.turnRight()
        turtle.turnRight()
        return false
    end


    turtle.turnLeft()
    return true
end

local function init()
    -- Check fuel first
    check_fuel(1)
    print("Fuel remaining: ", turtle.getFuelLevel())
    make_bread()
end

init()