microexpansion/modules/storage/api.lua

-- storage/api.lua

local BASENAME = "microexpansion"

-- [function] register cell
function microexpansion.register_cell(itemstring, def)
	if not def.inventory_image then
		def.inventory_image = itemstring
	end

	-- register craftitem
	minetest.register_craftitem(BASENAME..":"..itemstring, {
		description = def.description,
		inventory_image = BASENAME.."_"..def.inventory_image..".png",
		groups = {microexpansion_cell = 1},
		stack_max = 1,
		microexpansion = {
			base_desc = def.description,
			drive = {
				capacity = def.capacity or 5000,
			},
		},
	})

	-- if recipe, register recipe
	if def.recipe then
		-- if recipe, register recipe
		if def.recipe then
			microexpansion.register_recipe(BASENAME..":"..itemstring, def.recipe)
		end
	end
end

-- [function] Get cell size
function microexpansion.get_cell_size(name)
	local item = minetest.registered_craftitems[name]
	if item then
		return item.microexpansion.drive.capacity
	end
end

-- [function] Calculate max stacks
function microexpansion.int_to_stacks(int)
	return math.floor(int / 99)
end

-- [function] Calculate number of pages
function microexpansion.int_to_pagenum(int)
	return math.floor(microexpansion.int_to_stacks(int) / 32)
end

-- [function] Move items from inv to inv
function microexpansion.move_inv(inv1, inv2)
	local finv, tinv   = inv1.inv, inv2.inv
	local fname, tname = inv1.name, inv2.name

	for i,v in ipairs(finv:get_list(fname) or {}) do
		if tinv and tinv:room_for_item(tname, v) then
			local leftover = tinv:add_item( tname, v )
			finv:remove_item(fname, v)
			if leftover and not(leftover:is_empty()) then
				finv:add_item(fname, v)
			end
		end
	end
end

-- [function] Update cell description
function microexpansion.cell_desc(inv, listname, spos)
	local stack = inv:get_stack(listname, spos)

	if stack:get_name() ~= "" then
		local meta      = stack:get_meta()
		local base_desc = minetest.registered_craftitems[stack:get_name()].microexpansion.base_desc
		local max_slots = inv:get_size("main")
		local max_items = math.floor(max_slots * 99)

		local slots, items = 0, 0
		-- Get amount of items in drive
		for i = 1, max_items do
			local stack = inv:get_stack("main", i)
			local item = stack:get_name()
			if item ~= "" then
				slots = slots + 1
				local num = stack:get_count()
				if num == 0 then num = 1 end
				items = items + num
			end
		end

		-- Calculate Percentage
		local percent = math.floor(items / max_items * 100)

		-- Update description
		meta:set_string("description", base_desc.."\n"..
			minetest.colorize("grey", tostring(items).."/"..tostring(max_items).." Items ("..tostring(percent).."%)"))
		-- Update stack
		inv:set_stack(listname, spos, stack)
	end
end