URL-decode.applescript

use AppleScript version "2.4" -- Yosemite (10.10) or later
use scripting additions

on handle_string(lbText)
	set _res to urldecode(lbText)
	-- to return the result to launchbar instead of copying it substitute
	-- the next line for the line after it (set the clipboard to _res)
	-- open location "x-launchbar:select?string="&urldecode(_res)
	set the clipboard to _res
end handle_string

on run
	set the clipboard to urldecode(the clipboard as text)
end run

on urldecode(theText) -- http://harvey.nu/applescript_url_decode_routine.html
	set sDst to ""
	set sHex to "0123456789ABCDEF"
	set i to 1
	repeat while i ≤ length of theText
		set c to character i of theText
		if c = "+" then
			set sDst to sDst & " "
		else if c = "%" then
			if i > ((length of theText) - 2) then
				display dialog ("Invalid URL Encoded string - missing hex char") buttons {"Crap..."} with icon stop
				return ""
			end if
			set iCVal1 to (offset of (character (i + 1) of theText) in sHex) - 1
			set iCVal2 to (offset of (character (i + 2) of theText) in sHex) - 1
			if iCVal1 = -1 or iCVal2 = -1 then
				display dialog ("Invalid URL Encoded string - not 2 hex chars after % sign") buttons {"Crap..."} with icon stop
				return ""
			end if
			set sDst to sDst & (ASCII character (iCVal1 * 16 + iCVal2))
			set i to i + 2
		else
			set sDst to sDst & c
		end if
		set i to i + 1
	end repeat
	return sDst
end urldecode