-- We got to do this shit because enqueueInventory calls enqueueItem
-- And enqueueItem calls enqueueInventory
-- So unless we define them both before using them
-- We will get an error saying either is undefined
local enqueueItem
local enqueueSlot
local enqueueInventory
local _

---@alias FilterPredicate fun(item: Barotrauma.Item, inventoryRef?: Barotrauma.ItemInventory, slotRef: Barotrauma.ItemInventory.Slot): boolean

---@param item Barotrauma.Item
---@param queue Barotrauma.Item[]
---@param predicate? FilterPredicate
---@param loadRefs? boolean
---@param slotRef? Barotrauma.ItemInventory.Slot
---@param inventoryRef? Barotrauma.ItemInventory
---@return Barotrauma.Item[], string?
enqueueItem = function(item, queue, predicate, loadRefs, slotRef, inventoryRef)
    queue = queue or {}
    predicate = predicate or function() return true end
    -- debugPrint(string.format("Enqueuing item: %s", item.Prefab.Identifier.Value))
    -- local err
    -- This should make it breadth first, right...?
    -- No, not yet...
    if not item then return queue, "No item" end

    local ok, stop = predicate(item, inventoryRef, slotRef)
    if ok then
        queue[#queue + 1] = item
    end
    if stop then return queue, "Stop" end
    if item.OwnInventory then
        -- As far as I know every item has only one inventory
        -- Only machines have multiple
        -- So inventrorY should be fine here
        -- debugPrint("Item has its own inventory, enqueuing inventory...")
        if loadRefs then
            queue, _ = enqueueInventory(item.OwnInventory, queue, predicate, loadRefs)
        else
            queue, _ = enqueueInventory(item.OwnInventory, queue, predicate)
        end
        -- if err then
        --     debugPrint(string.format("Error enqueuing inventory: %s", err))
        -- end
    end
    -- debugPrint(string.format("Item enqueued. Current queue size: %d", #queue))
    return queue, nil
end

---@param slot Barotrauma.ItemInventory.Slot
---@param queue Barotrauma.Item[]
---@param predicate? FilterPredicate
---@param loadRefs? boolean
---@param inventoryRef? Barotrauma.ItemInventory
---@return Barotrauma.Item[], string?
enqueueSlot = function(slot, queue, predicate, loadRefs, inventoryRef)
    queue = queue or {}
    predicate = predicate or function() return true end
    -- debugPrint(string.format("Enqueuing slot with %d items.", #slot.items))
    -- We don't want to shadow queue
    local err
    -- If the slot is empty there's nothing to iterate
    -- And we will naturally return queue as is
    if not slot then return queue, "No slot" end
    if not slot.items then return queue, "No items" end

    for _, item in ipairs(slot.items) do
        -- Only the final leaf nodes decide upon the predicate
        if loadRefs then
            queue, err = enqueueItem(item, queue, predicate, loadRefs, inventoryRef, slot)
        else
            queue, err = enqueueItem(item, queue, predicate)
        end
        if err then
            return queue, err
        end
    end
    -- debugPrint(string.format("Finished enqueuing slot. Current queue size: %d", #queue))
    return queue
end

---@param inventory Barotrauma.ItemInventory
---@param queue Barotrauma.Item[]
---@param predicate? FilterPredicate
---@param loadRefs? boolean
---@return Barotrauma.Item[], string?
enqueueInventory = function(inventory, queue, predicate, loadRefs)
    queue = queue or {}
    predicate = predicate or function() return true end
    -- debugPrint(string.format("Enqueuing inventory with %d slots.", #inventory.slots))
    local err
    if not inventory then return queue, "No inventory" end
    if not inventory.slots then return queue, "No slots" end

    for _, slot in ipairs(inventory.slots) do
        -- Only the final leaf nodes decide upon the predicate
        if loadRefs then
            queue, err = enqueueSlot(slot, queue, predicate, loadRefs, inventory)
        else
            queue, err = enqueueSlot(slot, queue, predicate)
        end
        if err then
            return queue, err
        end
    end
    -- debugPrint(string.format("Finished enqueuing inventory. Current queue size: %d", #queue))
    return queue
end

return {
    enqueueItem = enqueueItem,
    enqueueSlot = enqueueSlot,
    enqueueInventory = enqueueInventory
}