local component = require("component")
local sides = require("sides")
local os = require("os")
local thread = require("thread")
local event = require("event")
local shell = require("shell")

local modem = component.modem
local port = 666

local sleep_t = 0.10
local timeout_t = 1.00

function transfer_to(tp, in_side, in_slot, out_side, out_slot)
    tp.transferItem(in_side, out_side, tp.getStackInSlot(in_side, in_slot).count, in_slot, out_slot)
end

function transfer_all(tp, in_side, out_side)
    local in_stacks = tp.getAllStacks(in_side)
    local out_slot = 1
    for in_slot = 1, in_stacks.count() do
        while tp.getStackInSlot(out_side, out_slot) ~= nil do out_slot = out_slot + 1 end
        if in_stacks[in_slot] ~= nil then tp.transferItem(in_side, out_side, in_stacks[in_slot].count, in_slot, out_slot) end
    end
end

function is_empty(tp, side)
    local stacks = tp.getAllStacks(side)
    for slot = 1, stacks.count() do
        if stacks[slot] ~= nil then return false end
    end
    return true
end

function slave_loop()
    local tp = component.transposer
    local prim_in_side = sides.west
    local prim_out_side = sides.down
    local auxl_in_side = sides.east
    local auxl_out_side = sides.south
    local output_side = sides.north
    modem.open(port)
    modem.setStrength(512)
    while true do
        function wait_for_crafting_request(event_name, ...)
            if event_name == "modem_message" then
                local message = select(5, ...)
                if message == "reply_if_available" then return true end
            end
            return false
        end
        local master_addr, port = select(1 + 2, event.pullFiltered(wait_for_crafting_request))
        modem.send(master_addr, port, "altar_available")
        function wait_for_master_response(event_name, ...)
            if event_name == "modem_message" then
                local message = select(5, ...)
                if message == "proceed" or message == "cease" then return true end
            end
            return false
        end
        local message = select(1 + 5, event.pullFiltered(wait_for_master_response))
        if message == "proceed" then
            modem.send(master_addr, port, "proceed_ack")
            transfer_all(tp, auxl_in_side, auxl_out_side)
            while not is_empty(tp, auxl_out_side) do os.sleep(sleep_t) end
            local orig = tp.getStackInSlot(prim_in_side, 1)
            transfer_to(tp, prim_in_side, 1, prim_out_side, 1)
            modem.send(master_addr, port, "buffers_freed")
            local function is_same(stack, cmp)
              return stack ~= nil and stack.label == cmp.label and stack.count == cmp.count
            end
            while is_same(tp.getStackInSlot(prim_out_side, 1), orig) do os.sleep(sleep_t) end
            transfer_to(tp, prim_out_side, 1, output_side, 1)
            while not is_empty(tp, output_side) do os.sleep(sleep_t) end
        end
    end
end

slave_loop()