diff --git a/cargo-elevator.lua b/cargo-elevator.lua
index 4e674c7..1717d56 100644
--- a/cargo-elevator.lua
+++ b/cargo-elevator.lua
@@ -9,157 +9,53 @@ local FLOORS = {
             return first_char == "A" or first_char == "W"
         end,
         detect = function ()
-            return redstone.getOutput("top")
+            -- TODO
         end,
         call = function ()
-            redstone.setOutput("top", true)
-            os.sleep(0.5)
-            redstone.setOutput("top", false)
+            -- TODO
         end
-        storage = "create:item_vault_17",
-        elevator_storage = "bottom",
-    },
-    {
-        match = function (input)
-            local first_char = string.sub(input, 1, 1)
-            return first_char == "F"
-        end,
-        detect = function ()
-            local relay = "redstone_relay_21"
-            peripheral.call(relay, "getOutput", "top")
-        end,
-        call = function ()
-            local relay = "redstone_relay_21"
-            peripheral.call(relay, "setOutput", "top", true)
-            os.sleep(0.5)
-            peripheral.call(relay, "setOutput", "top", false)
-        end
-        storage = "create:item_vault_18",
-        elevator_storage = "create:portable_storage_interface_8",
-    },
-    {
-        match = function (input)
-            local first_char = string.sub(input, 1, 1)
-            return first_char == "L"
-        end,
-        detect = function ()
-            local relay = "redstone_relay_22"
-            peripheral.call(relay, "getOutput", "top")
-        end,
-        call = function ()
-            local relay = "redstone_relay_22"
-            peripheral.call(relay, "setOutput", "top", true)
-            os.sleep(0.5)
-            peripheral.call(relay, "setOutput", "top", false)
-        end
-        storage = "create:item_vault_19",
-        elevator_storage = "create:portable_storage_interface_9",
-    },
-    {
-        match = function (input)
-            local first_char = string.sub(input, 1, 1)
-            return first_char == "E"
-        end,
-        detect = function ()
-            local relay = "redstone_relay_23"
-            peripheral.call(relay, "getOutput", "top")
-        end,
-        call = function ()
-            local relay = "redstone_relay_23"
-            peripheral.call(relay, "setOutput", "top", true)
-            os.sleep(0.5)
-            peripheral.call(relay, "setOutput", "top", false)
-        end
-        storage = "create:item_vault_20",
-        elevator_storage = "create:portable_storage_interface_10",
-    },
+        storage = "",
+        elevator_storage = "",
+    }
 }
 
 local SLEEP_T = 5
 
-local PKG_QUEUE = {
-    insert = function (self, floor_i)
-        local is_in = function (item, list)
-            for _, l_item in ipairs(list) do
-                if l_item == item then return true end
-            end
-            return false
-        end
-        if not is_in(floor_i, self.queue) then
-            table.insert(self.queue, floor_i)
-        end
-    end,
-    check_floors = function (self, floors)
-        for i, floor in pairs(floors) do
-            if #(peripheral.call(floor.storage, "list")) > 0 then
-                self:insert(i)
-            end
-        end
-    end,
-    check_cargo = function (self, inv, floors)
-        for slot, item in pairs(peripheral.call(inv, "list")) do
-            local item_detail = peripheral.call(src, "getItemDetail", slot)
-            for i, floor in ipairs(floors) do
-                if item_detail.package ~= nil and
-                    floor.match(item_detail.package.getAddress()) then
-                    self:insert(i)
-                    break
-                end
-            end
-        end
-    end
-    transfer_all = function (self, src, dest, floors)
-        -- assumption: this always transfers into the cargo box
-        for slot, item in pairs(peripheral.call(src, "list")) do
-            local item_detail = peripheral.call(src, "getItemDetail", slot)
-            for i, floor in ipairs(floors) do
-                if item_detail.package ~= nil and
-                    floor.match(item_detail.package.getAddress()) then
-                    self:insert(i)
-                    peripheral.call(src, "pushItems", dest, slot)
-                    break
-                end
-            end
-        end
+local PKG_STACK = {
+    transfer_all = function (self, src, dest)
+        -- TODO
     end,
     transfer_matching = function (self, src, dest, match_f)
-        -- assumption: this always transfers out of the cargo box
-        for slot, item in pairs(peripheral.call(src, "list")) do
-            local item_detail = peripheral.call(src, "getItemDetail", slot)
-            if item_detail.package ~= nil and
-                match_f(item_detail.package.getAddress()) then
-                peripheral.call(src, "pushItems", dest, slot)
-            end
-        end
+        -- TODO
     end,
     get_next_floor = function (self)
-        return table.remove(self.queue, 1)
+        -- TODO
     end
-    queue = {},
+    stack = {},
 }
 
-function run (floors, queue, first_run)
-    local next_floor = nil
-    queue:check_floors(floors)
-    for i, floor in pairs(floors) do
+function run (floors, stack)
+    local next_addr = nil
+    for _, floor in pairs(floors) do
         if floor.detect() then
-            if first_run then
-                queue:check_cargo(floor.elevator_storage, floors)
-            end
-            queue:transfer_all(floor.storage, floor.elevator_storage, floors)
-            queue:transfer_matching(
+            stack:transfer_all(floor.storage, floor.elevator_storage)
+            stack:transfer_matching(
                 floor.elevator_storage, floor.storage, floor.match
             )
-            next_floor = queue:get_next_floor()
+            next_addr = stack:get_next_floor()
         end
     end
-    if next_floor ~= nil then
-        floors[next_floor].call()
+    if next_addr ~= nil then
+        for _, floor in pairs(floors) do
+            if floor.match(next_addr) then
+                floor.call()
+                break
+            end
+        end
     end
-    os.sleep(SLEEP_T)
-    return run(floors, queue, false)
 end
 
-if arg ~= nil and arg[1] == "run" then
-    run(FLOORS, queue, true)
+while true do
+    run(FLOORS)
+    os.sleep(SLEEP_T)
 end