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 Player(p: player):
	open chest with 6 rows named "&6-=&e&nPSK&6=- &8Player" to {_p}
	set {_s} to 0
	loop all players:
		if {Group::%loop-player%} is not set:
			set slot {_s} of {_p}'s current inventory to ("%loop-player%" parsed as offline player)'s skull named "&e%loop-player%" with lore "&7Click to view settings.||&r||&7Group: &eDefault"
		else:
			set slot {_s} of {_p}'s current inventory to ("%loop-player%" parsed as offline player)'s skull named "&e%loop-player%" with lore "&7Click to view settings.||&r||&7Group: &e%{Group::%loop-player%}%"
		add 1 to {_s}
	set slot 49 of {_p}'s current inventory to sign named "&e<<< Go Back <<<"
	
function groups(p: player):
	open chest with 6 rows named "&6-=&e&nPSK&6=- &7Groups" to {_p}
	set {_s} to 0
	loop {PermissionG::*}:
		if {PermissionGP::%loop-index%} is set:
			set {_pr} to "%colored {PermissionGP::%loop-index%}%"
		else:
			set {_pr} to "&cNone"
		set slot {_s} of {_p}'s current inventory to book named "&e%loop-index%" with lore "&7Click to view settings.||&r||&7Prefix: &r%{_pr}%"
		add 1 to {_s}
	set slot 48 of {_p}'s current inventory to sign named "&e<<< Go Back <<<"
	set slot 50 of {_p}'s current inventory to redstone named "&aAdd a new Group"
		
function settings(p: player, t: text):
	open chest with 6 rows named "&6-=&e&nPSK&6=- &8Settings" to {_p}
	set slot 4 of {_p}'s current inventory to ("%{_t}%" parsed as offline player)'s skull named "&e%{_t}%"
	set slot 13 of {_p}'s current inventory to book named "&aPer Player Permissions" with lore "&7Click to view all personal permission||&r||&7Amount of Permission: &e%size of {PermissionP::%{_t}%::*}%"
	if {Group::%{_t}%} is set:
		set slot 28 of {_p}'s current inventory to paper named "&aChange Group" with lore "&7Click to change the group||&r||&7Current Group: &e%{Group::%{_t}%}%"
	else:
		set slot 28 of {_p}'s current inventory to paper named "&aChange Group" with lore "&7Click to change the group||&r||&7Current Group: &eDefault"
	if {PermissionPP::%{_t}%} is set:
		set {_bla} to "%colored {PermissionPP::%{_t}%}%"
	else:
		set {_bla} to "&cNone"
	set slot 34 of {_p}'s current inventory to name tag named "&aChange Coustom Prefix" with lore "&7Click to set a custom prefix||&r||&7Current Prefix: &r%{_bla}%"
	set slot 49 of {_p}'s current inventory to sign named "&e<<< Go Back <<<"
		
function Permission(p: text, pl: player):
	set {_s} to 9
	loop {PermissionP::%{_p}%::*}:
		set slot {_s} of {_pl}'s current inventory to paper named "&7%loop-index%" with lore "&8Right click to delete Permission"
		add 1 to {_s}
	loop 36-{_s} times:
		set slot {_s} of {_pl}'s current inventory to air
		add 1 to {_s}
		
function group(p: player, t: text):
	set {_s} to 9
	loop {PermissionG::*}:
		if {PermissionGP::%loop-index%} is set:
			set {_pr} to "%colored {PermissionGP::%loop-index%}%"
		else:
			set {_pr} to "&cNone"
		if {Group::%{_t}%} is "%loop-index%":
			set slot {_s} of {_p}'s current inventory to green stained glass pane named "&e%loop-index%" with lore "&7Prefix: &r%{_pr}%"
		else:
			set slot {_s} of {_p}'s current inventory to red stained glass pane named "&e%loop-index%" with lore "&7Prefix: &r%{_pr}%"
		add 1 to {_s}
	if {Group::%{_t}%} is not set:
		set slot {_s} of {_p}'s current inventory to green stained glass pane named "&eDefault" with lore "&7No way to get Prefix"
	else:
		set slot {_s} of {_p}'s current inventory to red stained glass pane named "&eDefault" with lore "&7No way to get Prefix"
		
function gsettings(p: player, n: text):
	open chest with 6 rows named "&6-=&e&nPSK&6=- &7Settings" to {_p}
	set slot 4 of {_p}'s current inventory to stick named "&e%{_n}%"
	set slot 13 of {_p}'s current inventory to book named "&ePer Group Permission" with lore "&7Click to view all groups permission||&r||&7Amount of Permission: &e%size of {PermissionG::%{_n}%::*}%"
	set slot 28 of {_p}'s current inventory to paper named "&eManage Inherits" with lore "&7Click to open the menu"
	if {PermissionGP::%{_n}%} is set:
		set {_pr} to "%colored {PermissionGP::%{_n}%}%"
	else:
		set {_pr} to "&cNone"
	set slot 34 of {_p}'s current inventory to name tag named "&eChange prefix" with lore "&7Click to change prefix of Group||&r||&8Current Prefix: &r%{_pr}%"
	set slot 48 of {_p}'s current inventory to sign named "&e<<< Go Back <<<"
	set slot 50 of {_p}'s current inventory to redstone named "&cDelete this Group"
	
function gpermission(p: player, n: text):
	open chest with 6 rows named "&6-=&e&nPSK&6=- &7Permission" to {_p}
	set slot 4 of {_p}'s current inventory to stick named "&e%{_n}%"
	set {_s} to 9
	loop {PermissionG::%{_n}%::*}:
		set slot {_s} of {_p}'s current inventory to paper named "%loop-index%" with lore "&7Right click to delete this Permission"
		add 1 to {_s}
	loop 36-{_s} times:
		set slot {_s} of {_pl}'s current inventory to air
		add 1 to {_s}
	set slot 48 of {_p}'s current inventory to sign named "&e<<< Go Back <<<"
	set slot 50 of {_p}'s current inventory to redstone named "&aAdd a Permission"
			
on inventory click:
	if name of player's current inventory is "&6-=&e&nPSK&6=- &8Overview":
		cancel event
		if clicked slot is 20:
			Player(player)
		else if clicked slot is 24:
			groups(player)
			
	else if name of player's current inventory is "&6-=&e&nPSK&6=- &8Player":
		cancel event
		clicked item is not air
		if clicked slot is 49:
			open chest with 6 rows named "&6-=&e&nPSK&6=- &8Overview" to player
			set slot 20 of player's current inventory to player head named "&6Player Permission"
			set slot 24 of player's current inventory to book named "&6Groups Permission"
		else:
			set {_p} to "%uncolored name of clicked item%"
			settings(player, {_p})
			
	else if name of player's current inventory is "&6-=&e&nPSK&6=- &8Settings":
		cancel event
		clicked item is not air
		set {_p} to "%uncolored name of slot 4 of player's current inventory%"
		if clicked slot is 13:
			open chest with 6 rows named "&6-=&e&nPSK&6=- &8Permission" to player
			set slot 4 of player's current inventory to ("%{_p}%" parsed as offline player)'s skull named "&e%{_p}%" with lore "&7Right click on paper to remove Permission"
			Permission({_p}, player)
			set slot 48 of player's current inventory to sign named "&e<<< Go Back <<<"
			set slot 50 of player's current inventory to redstone named "&eAdd a Permission" with lore "&7It will close GUI||&7and you need enter||&7Permission in Chat!"
		else if clicked slot is 28:
			open chest with 6 rows named "&6-=&e&nPSK&6=- &8Groups" to player
			set slot 4 of player's current inventory to ("%{_p}%" parsed as offline player)'s skull named "&e%{_p}%" with lore "&7Change player group"
			group(player, {_p})
			set slot 49 of player's current inventory to sign named "&e<<< Go Back <<<"
			
		else if clicked slot is 34:
			close player's inventory
			set {Answer::%player%} to "PPrefix"
			set {bla::%player%} to "%{_p}%"
			send "&aPlease enter in Chat a Prefix Name. Enter ""cancel"" to cancel it."
			
		else if clicked slot is 49:
			Player(player)
				
	else if name of player's current inventory is "&6-=&e&nPSK&6=- &8Permission":
		cancel event
		if clicked slot is 48:
			settings(player, uncolored name of slot 4 of player's current inventory) 
		else:
			clicked item is paper
			"%click type%" is "right mouse button"
			set {_p} to "%uncolored name of slot 4 of player's current inventory%"
			make player execute command "/psk rem %{_p}% %uncolored name of clicked item%"
			Permission({_p}, player)
			
	else if name of player's current inventory is "&6-=&e&nPSK&6=- &8Groups":
		cancel event
		if clicked item is red stained glass pane:
			set {_n} to "%uncolored name of clicked item%"
			set {_p} to "%uncolored name of slot 4 of player's current inventory%"
			if {_n} is not "Default":
				make player execute command "/psk set %{_p}% %{_n}%"
			else:
				make player execute command "/psk set %{_p}%"
			group(player, {_p})
		else if clicked slot is 49:
			set {_n} to "%uncolored name of slot 4 of player's current inventory%"
			settings(player, {_n})
			
	#Groups
			
	else if name of player's current inventory is "&6-=&e&nPSK&6=- &7Groups":
		cancel event
		if clicked item is sign:
			open chest with 6 rows named "&6-=&e&nPSK&6=- &8Overview" to player
			set slot 20 of player's current inventory to player head named "&6Player Permission"
			set slot 24 of player's current inventory to book named "&6Groups Permission"
		else if clicked item is redstone:
			close player's inventory
			set {Answer::%player%} to "Groups"
			send "&aPlease enter in Chat a new Groups! enter ""cancel"" to cancel it."
		else if clicked item is book:
			set {_n} to "%uncolored name of clicked item%"
			gsettings(player, {_n})
		
	else if name of player's current inventory is "&6-=&e&nPSK&6=- &7Settings":
		cancel event
		clicked item is not air
		set {_n} to "%uncolored name of slot 4 of player's current inventory%"
		if clicked item is sign:
			groups(player)
		else if clicked item is name tag:
			close player's inventory
			set {Answer::%player%} to "GPrefix"
			set {Bla::%player%} to "%{_n}%"
			send "&aPlease enter in Chat a Prefix Name. Enter ""cancel"" to cancel it."
		else if clicked item is book:
			gpermission(player, {_n})
			
	else if name of player's current inventory is "&6-=&e&nPSK&6=- &7Permission":
		cancel event
		clicked item is not air
		set {_n} to "%uncolored name of slot 4 of player's current inventory%"
		if clicked item is sign:
			gsettings(player, {_n})
		else if clicked item is redstone:
			close player's inventory
			set {Answer::%player%} to "GPermission"
			set {Bla::%player%} to "%{_n}%"
			send "&aPlease enter in Chat a Permission. Enter ""cancel"" to cancel it."
		else if clicked item is paper:
			"%click type%" is "right mouse button"
			make player execute command "/psk grem %{_n}% %name of clicked item%"
			gpermission(player, {_n})			
			
on chat:
	if {Answer::%player%} is set:
		cancel event
		if {Answer::%player%} is "Groups":
			if message is "cancel":
				groups(player)
			else:
				make player execute command "/psk gadd %message% useless.permission"
				groups(player)
		else if {Answer::%player%} is "GPrefix":
			if message is "cancel":
				gsettings(player, {bla::%player%})
			else:
				make player execute command "/psk gpset %{Bla::%player%}% %message%"
				gsettings(player, {bla::%player%})
			delete {Bla::%player%}
		else if {Answer::%player%} is "GPermission":
			if message is "cancel":
				gpermission(player, {Bla::%player%})
			else:
				make player execute command "/psk gadd %{Bla::%player%}% %message%"
				gpermission(player, {Bla::%player%})
			delete {Bla::%player%}
		else if {Answer::%player%} is "PPrefix":
			if message is "canecl":
				settings(Player, {Bla::%player%})
			else:
				make player execute command "/psk ppset %{Bla::%player%}% %message%"
				settings(Player, {Bla::%player%})
			delete {Bla::%player%}
		delete {Answer::%player%}