Util.hs

{- This file is part of irc-fun-client.
 -
 - Written in 2015 by fr33domlover <fr33domlover@rel4tion.org>.
 -
 - ♡ Copying is an act of love. Please copy, reuse and share.
 -
 - The author(s) have dedicated all copyright and related and neighboring
 - rights to this software to the public domain worldwide. This software is
 - distributed without any warranty.
 -
 - You should have received a copy of the CC0 Public Domain Dedication along
 - with this software. If not, see
 - <http://creativecommons.org/publicdomain/zero/1.0/>.
 -}

module Network.IRC.Fun.Client.Util
    ( mentions
    )
where

import Data.Char (isAlphaNum)
import Data.List (isPrefixOf)

isNameChar :: Char -> Bool
isNameChar c = isAlphaNum c || c `elem` "-_|"

-- | Check if a message mentions a given nickname.
--
-- This isn't the same as substring search, since the nickname could appear
-- inside a longer word. For example, \"ron\" isn't really mentioned in
-- \"asynchronic\". Therefore, this function is a bit smarter about this,
-- trying to capturing real mentions, and works quite well in practice.
mentions :: String -- ^ Message content
         -> String -- ^ Nickname
         -> Bool
msg `mentions` nick = m msg nick True
    where
    m ""         _    _       = False
    m msg@(c:cs) nick previnc =
        if not previnc && nick `isPrefixOf` msg
            then case drop (length nick) msg of
                    ""     -> True
                    (d:ds) -> if not (isNameChar d)
                                then True
                                else m cs nick $ isNameChar c
            else m cs nick $ isNameChar c