local component = require("component")
local sides = require("sides")
local os = require("os")

local in_side = sides.south
local out_side = sides.up
local sleep_t = 0.1
local tp = component.transposer

local function is_empty(tp, side)
    local max = tp.getInventorySize(side)
    for idx = 1, max do
        if tp.getStackInSlot(side, idx) ~= nil then return false end
    end
    return true
end

local function transfer_single(tp, in_, in_slot, out_, out_slot)
    tp.transferItem(in_, out_, tp.getStackInSlot(in_, in_slot).count, in_slot, out_slot)
end

local function transfer_all(tp, in_, out_)
    local out_slot = 1
    local max = tp.getInventorySize(in_)
    for idx = 1, max do
        while tp.getStackInSlot(out_, out_slot) ~= nil do out_slot = out_slot + 1 end
        transfer_single(tp, in_, idx, out_, out_slot)
    end
end

local function main()
    while true do
        while tp.getStackInSlot(in_side, 1) == nil do os.sleep(sleep_t) end
        local prev = tp.getStackInSlot(in_side, 1)
        local function is_same(lstack, rstack)
            return lstack ~= nil and lstack.label == rstack.label and lstack.count == rstack.count
        end
        while is_same(tp.getStackInSlot(in_side, 1), prev) do os.sleep(sleep_t) end
        while not is_empty(tp, in_side) do transfer_all(tp, in_side, out_side) end
        os.sleep(sleep_t)
    end
end

main()