use framework "Foundation"

-- Must be stored in ~/Library/Script Libraries as a .scptd file
-- Sample use from a script:
-- 
-- use theLib : script "TagLibrary"
-- use scripting additions
-- set fileName to "/Users/kevin/Temp/image-and-text.pdf"
-- theLib's setTags:{"tag1", "tag2"} forPath:(fileName)
-- theLib's addTags:{"tag3", "tag4"} forPath:(fileName)
-- set s to theLib's returnTagsFor:(fileName)
-- repeat with x in s
-- 	display dialog x
-- end repeat

on returnTagsFor:posixPath -- get the tags
    set aURL to current application's |NSURL|'s fileURLWithPath:posixPath -- make URL
    set {theResult, theTags} to aURL's getResourceValue:(reference) forKey:(current application's NSURLTagNamesKey) |error|:(missing value)
    if theTags = missing value then return {} -- because when there are none, it returns missing value
    return theTags as list
end returnTagsFor:

on setTags:tagList forPath:posixPath -- set the tags, replacing any existing
    set aURL to current application's |NSURL|'s fileURLWithPath:posixPath -- make URL
    aURL's setResourceValue:tagList forKey:(current application's NSURLTagNamesKey) |error|:(missing value)
end setTags:forPath:

on addTags:tagList forPath:posixPath -- add to existing tags
    set aURL to current application's |NSURL|'s fileURLWithPath:posixPath -- make URL
    -- get existing tags
    set {theResult, theTags} to aURL's getResourceValue:(reference) forKey:(current application's NSURLTagNamesKey) |error|:(missing value)
    if theTags ≠ missing value then -- add new tags
        set tagList to (theTags as list) & tagList
        set tagList to (current application's NSOrderedSet's orderedSetWithArray:tagList)'s allObjects() -- delete any duplicates
    end if
    aURL's setResourceValue:tagList forKey:(current application's NSURLTagNamesKey) |error|:(missing value)
end addTags:forPath: