Just so you know, we don't know the file format for every file. If it's just a bunch of random characters, it's probably a .zip or .jar.

function shop(p: player, n: text):
	wait a ticks
	set {_size} to size of {Shop.%{_n}%::*}
	if {_size} is between 0 and 7:
		set {_r} to 1
	else if {_size} is between 8 and 16:
		set {_r} to 2
	else if {_size} is between 17 and 25:
		set {_r} to 3
	else if {_size} is between 26 and 34:
		set {_r} to 4
	else if {_size} is between 35 and 43:
		set {_r} to 5
	else:
		set {_r} to 6
	open chest with {_r} rows named "&9Shop %{_n}%" to {_p}
	set {_s} to 0
	loop {Shop.%{_n}%::*}:
		set {_pr::*} to loop-value split at ":"
		if {_pr::2} is not set:
			set {_pr::2} to "Not sellable"
		if {_pr::1} is not set:
			set {_pr::1} to "Not buyable"
		if {_pr::1} is "0":
			set {_pr::1} to "Not buyable"
		if {_pr::2} is "0":
			set {_pr::2} to "Not sellable"
		set {_i} to loop-index
		replace every "object:" with "" in {_i}
		set {_i} to "%{_i}%" parsed as item
		#send "%loop-index%" to {_p}
		set slot {_s} of {_p}'s current inventory to {_i} with lore "&8------------||&r||&9Item: &e%loop-index%||&9Buyprice: &e%{_pr::1}%$||&9Sellprice: &e%{_pr::2}%$||&r||&8Rightclick to buy||&8Leftclick to sell||&r||&8------------"
		add 1 to {_s}
	if {_r} is 1:
		set {_s} to 8
	if {_r} is 2:
		set {_s} to 17
	if {_r} is 3:
		set {_s} to 26
	if {_r} is 4:
		set {_s} to 35
	if {_r} is 5:
		set {_s} to 44
	if {_r} is 6:
		set {_s} to 53
	set slot {_s} of {_p}'s current inventory to red stained glass pane named "&c<<< Back"
command /shop [<text>] [<text>] [<text>]:
	trigger:
		if arg-1 is not set:
			set {_size} to size of {Shop.Menu::*}
			if {_size} is between 0 and 8:
				set {_r} to 1
			else if {_size} is between 9 and 17:
				set {_r} to 2
			else if {_size} is between 18 and 26:
				set {_r} to 3
			else if {_size} is between 27 and 35:
				set {_r} to 4
			else if {_size} is between 36 and 45:
				set {_r} to 5
			else:
				set {_r} to 6
			open chest with {_r} rows named "&6Shop Menu" to player
			set {_s} to 0
			loop {Shop.Menu::*}:
				set slot {_s} of player's current inventory to loop-value named "&6%loop-index%" with lore "&9Click here to open %loop-index% Shop."
				add 1 to {_s}
		else if arg-1 is "menu":
			if player has permission "shop.add":
				if arg-2 is "add":
					if player's held item is air:
						send "&cSorry. But you need held some items for GUI. (Icons)"
					else:
						if arg-3 is not set:
							send "&cSorry, But you need set name for GUI. Example: Blocks."
						else if arg-3 is "menu":
							send "&cSorry, but dont use this name!"
						else:
							if {Shop.Menu::%arg-3%} is set:
								send "&cSorry, but this name is already set."
							else:
								set {Shop.Menu::%arg-3%} to player's held item
								send "&aSucessfully for Shop Menu added."
				else if arg-2 is "remove":
					if arg-3 is not set:
						send "&cSorry, but enter the Name, Do you want removed it."
					else:
						if {Shop.Menu::%arg-3%} is set:
							delete {Shop.Menu::%arg-3%}
							delete {Shop.%arg-3%::*}
							send "&aSucessfully removed."
						else:
							send "&a%arg-3% can't found it."
			else:
				send "&cSorry, you have no permission for it."
		else if arg-1 is not "help":
			if player has permission "Shop":
				if {Shop.Menu::%arg-1%} is set:
					if player's held item is air:
						send "&cSorry. But you need held some items for selling/removed from %arg-1%."
					else:
						if arg-2 is "add":
							if arg-3 is set:
								set {_i} to "%player's held item%:%data value of player's held item%"
								set {Shop.%arg-1%::%{_i}%} to "%arg-3%"
								send "&aScuessfully added!"
							else:
								send "&cPlease enter the Price."
						else if arg-2 is "remove":
							set {_i} to "%player's held item%:%data value of player's held item%"
							if {Shop.%arg-1%::%{_i}%} is set:
								delete {Shop.%arg-1%::%{_i}%}
								send "&aSucessfully removed."
							else:
								send "&cThe Items cannot found on %arg-1%"
				else:
					send "&cSorry, but you need add first &e%arg-1% &cto &eMenu&c."
			else:
				send "&cSorry, but you have no Permission."
		else if arg-1 is "help":
			send "&9 Info  &8--------------- &e Example"
			send "&9Add a Icons to Menu: &e/shop menu add Blocks"
			send "&9Add a Items to selling/Buying: &e/shop blocks add 100:20"
			send "&9Remove a Icons from Menu: &e/Shop menu remove Blocks"
			send "&9Remove a Items from selling/Buying: &e/shop blocks remove"
			send "&c(You need hold some items do you want to removed it)"
on inventory click:
	if inventory name of player's current inventory is "&6Shop Menu":
		cancel event
		set {_name} to "%uncolored clicked item name%"
		if {Shop.Menu::%{_name}%} is set:
			shop(player, {_name})
	else if inventory name of player's current inventory contains "&9Shop":
		cancel event
		set {_name} to "%uncolored clicked item name%"
		if {_name} is "<<< Back":
			close player's inventory
			wait a ticks
			make player execute command "/shop"
		else:
			set {_l::*} to uncolored clicked item lore split at ","
			replace every " Item: " with "" in {_l::3}
			replace every " Buyprice: " with "" in {_l::4}
			replace every "$" with "" in {_l::4}
			replace every " Sellprice: " with "" in {_l::5}
			replace every "$" with "" in {_l::5}
			set {_i} to {_l::3} parsed as item
			if click type is "LEFT":
				if {_l::4} is "Not buyable":
					send "&cThis is not buyable"
				else:
					set {_b} to {_l::4} parsed as integer
					if player's money is more than or equal to {_b}:
						remove {_b} from player's money
						give player {_i}
						send "&aYou scuessfully buying %{_i}%"
					else:
						send "&cSorry, you have low Money..."
			else if click type is "RIGHT":
				if {_l::5} is "Not sellable":
					send "&cThis is not sellable"
				else:
					set {_s} to {_l::5} parsed as integer
					if player has 1 of {_i}:
						remove {_i} from player's inventory
						add {_s} to player's money
						send "&aYou scuessfully selling %{_i}%"
					else:
						send "&cSorry, but you have no %{_i}% more..."