Get current items and max amount of items from connected chests in ComputerCraft

check.lua

-- Tested on ComputerCraft: Restiched v1.101.0 on Minecraft 1.19
local function getChests()
    local chests = peripheral.getNames()
    local actual_chests = {}
    
    for i, chest in pairs(chests) do
        if chest:find("chest") or chest:find("barrel") then
            table.insert(actual_chests, chest)
        end
    end
    
    return actual_chests
end

local function getMaxSize() 
    local chests = getChests()
    local max_size = 0
    for i, chest in pairs(chests) do
        local wrap = peripheral.wrap(chest)
        local size = wrap.size()
        max_size = max_size + (size * 64)
    end
    
    return max_size
end

local function getCurrentSize()
    local chests = getChests()
    local current_size = 0
    
    for _, chest in pairs(chests) do
        local list = peripheral.call(chest, "list")
        for _, slot in pairs(list) do
            current_size = current_size + slot.count
        end
    end
    
    return current_size
end

local max_size = getMaxSize()
local current_size = getCurrentSize()

print(("Using %d items out of %d"):format(current_size, max_size))