Trim File Names AppleScript

(*
Trim File Names

This script is designed to trim the name of specific folders in the front window of the desktop.
If no folder windows are open, the script will affect folders on the desktop.

Copyright © 2001–2007 Apple Inc.

You may incorporate this Apple sample code into your program(s) without
restriction.  This Apple sample code has been provided "AS IS" and the
responsibility for its operation is yours.  You are not permitted to
redistribute this Apple sample code as "Apple sample code" after having
made changes.  If you're going to redistribute the code, we require
that you make it clear that the code was descended from Apple sample
code, but that you've made changes.
*)

-- The following line is disabled due to a Menu Manager bug
--set the source_folder to (choose folder with prompt "Pick the folder containing the folders to rename:")

try
    tell application "Finder" to set the source_folder to (folder of the front window) as alias
on error -- no open folder windows
    set the source_folder to path to desktop folder as alias
end try
repeat
    display dialog "Text to trim from every file name:" default answer "" buttons {"Cancel", "Trim Start", "Trim End"} default button 2
    copy the result as list to {the text_to_trim, the button_pressed}
    --if the button_pressed is "Cancel" then return "user cancelled"
    if the text_to_trim is not "" then exit repeat
end repeat
set the character_count to the number of characters of the text_to_trim
set the item_list to list folder source_folder without invisibles
set source_folder to source_folder as string
repeat with i from 1 to number of items in the item_list
    set this_item to item i of the item_list
    set this_item to (source_folder & this_item) as alias
    set this_info to info for this_item
    if folder of this_info is false then
        set the current_name to the name of this_info
        if the button_pressed is "Trim Start" then
            if the current_name begins with the text_to_trim then
                set the new_name to (characters (the character_count + 1) thru -1 of the current_name) as string
                set_item_name(this_item, new_name)
            end if
        else
            if the current_name ends with the text_to_trim then
                set the new_name to (characters 1 thru -(the character_count + 1) of the current_name) as string
                set_item_name(this_item, new_name)
            end if
        end if
    end if
end repeat
beep 2

on set_item_name(this_item, new_item_name)
    tell application "Finder"
        --activate
        set the parent_container_path to (the container of this_item) as text
        if not (exists item (the parent_container_path & new_item_name)) then
            try
                set the name of this_item to new_item_name
            on error the error_message number the error_number
                if the error_number is -59 then
                    set the error_message to "This name contains improper characters, such as a colon (:)."
                else --the suggested name is too long
                    set the error_message to error_message -- "The name is more than 31 characters long."
                end if
                --beep
                tell me to display dialog the error_message default answer new_item_name buttons {"Cancel", "Skip", "OK"} default button 3
                copy the result as list to {new_item_name, button_pressed}
                if the button_pressed is "Skip" then return 0
                my set_item_name(this_item, new_item_name)
            end try
        else --the name already exists
            --beep
            tell me to display dialog "This name is already taken, please rename." default answer new_item_name buttons {"Cancel", "Skip", "OK"} default button 3
            copy the result as list to {new_item_name, button_pressed}
            if the button_pressed is "Skip" then return 0
            my set_item_name(this_item, new_item_name)
        end if
    end tell
end set_item_name