command /backpack [<offline player>] [<text>]:
    trigger:
        if arg 1 is not set:
            open virtual chest inventory with size 3 named "Your Backpack" to player
            loop {backpack::%uuid of player%::*}:
                add loop-value to current inventory of player
            play sound "CHEST_OPEN" with volume 100 and pitch 1 at player for player
        else:
            if player does not have permission "rank.srmod":
                message "&cYou do not have permission to edit the backpack of others."
                stop
            set {-backpack::opened::%uuid of player%} to arg 1
            play sound "CHEST_OPEN" with volume 100 and pitch 1 at player for player
            open virtual chest inventory with size 3 named "Backpack: %player%" to player
            loop {backpack::%uuid of arg-1%::*}:
                add loop-value to current inventory of player

on inventory click:
    if name of current inventory of player contains "Backpack":
        if type of event-item is stone sword or chain helmet or chain chestplate or chain leggings or chain boots: # configure this to your liking.
            cancel event
            message "&cYou cannot add this item to your backpack."


on inventory close:
    if name of event-inventory is "Your Backpack":
        clear {backpack::%uuid of player%::*}
        loop all items in event-inventory:
            set {_l} to loop-item
            if loop-item is any sword or any boots or any leggings or any chestplate or any helmet:
                remove loop-item from event-inventory
                add {_l} to {_give-back-items::*}
                send "&cYou cannot add this item to your backpack."
            else:
                add loop-item to {backpack::%uuid of player%::*}
        send "&aYour backpack has been saved."
        wait 1 tick
        loop {_give-back-items::*}:
            give player loop-value
        play sound "CHEST_CLOSE" with volume 100 and pitch 1 at player for player
    else if name of event-inventory contains "Backpack: ":
        set {_u} to uuid of {-backpack::opened::%uuid of player%}
        clear {backpack::%{_u}%::*}
        loop all items in event-inventory:
            add loop-item to {backpack::%{_u}%::*}
        send "&aBackpack of &7%{-backpack::opened::%uuid of player%}% &ahas been saved."
        play sound "CHEST_CLOSE" with volume 100 and pitch 1 at player for player