{- This file is part of irc-fun-client.
 -
 - Written in 2015, 2016 by fr33domlover <fr33domlover@riseup.net>.
 -
 - ♡ 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)
import Network.IRC.Fun.Types

import qualified Data.Text as T

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 :: MsgContent -> Nickname -> Bool
(MsgContent mc) `mentions` (Nickname n) = m mc n True
    where
    m msg nick previnc =
        case T.uncons msg of
            Nothing     -> False
            Just (c, r) ->
                if not previnc && nick `T.isPrefixOf` msg
                    then case T.uncons $ T.drop (T.length nick) msg of
                            Nothing     -> True
                            Just (d, s) ->
                                if isNameChar d
                                    then m r nick $ isNameChar c
                                    else True
                    else m r nick $ isNameChar c