--
-- | Nickname equality subsystem.
--
-- This component is responsible for deciding whether two nicknames
-- refer to the same person, for the purposes of @tell et al.  Nickname
-- equality must be monadic because it uses mutable state maintained
-- by the @link and @unlink commands.
--
-- Also provided is a concept of polynicks (by analogy to polytypes);
-- polynicks can refer to an (open) set of nicknames.  For instance '@tell
-- *lambdabot Why does X do Y' could tell a message to anyone who has
-- identified as a lambdabot maintainer.  A polynick consists of a
-- bar-separated list of (nicks or open terms); an open term is like a
-- nick but preceded with a star.

module NickEq ( Polynick, nickMatches, readPolynick, showPolynick, lookupMononickMap, mononickToPolynick ) where

import Message( Message, Nick, readNick, showNick )
import Lambdabot
import Lib.Util (concatWith, split)
import Data.Maybe (mapMaybe)

import qualified Data.Map as M

data Polynick = Polynick [Nick] deriving (Eq) -- for now

-- |Determine if a nick matches a polynick.  The state is read at the
-- point of binding.
nickMatches :: LB (Nick -> Polynick -> Bool)
nickMatches = return m'
    where
      m' nck (Polynick nck2) = nck `elem` nck2

-- | Parse a read polynick.
readPolynick :: Message a => a -> String -> Polynick
readPolynick m = Polynick . map (readNick m) . split "|"

-- | Format a polynick.
showPolynick :: Message a => a -> Polynick -> String
showPolynick m (Polynick n) = concatWith "|" $ map (showNick m) n

-- | Convert a regular mononick into a polynick.
mononickToPolynick :: Nick -> Polynick
mononickToPolynick = Polynick . (:[])

-- | Lookup (using a polynick) in a map keyed on mononicks.
lookupMononickMap :: LB (Polynick -> M.Map Nick a -> [(Nick,a)])
lookupMononickMap = return $ look'
    where look' (Polynick ns) m = mapMaybe (\n -> (,) n `fmap` M.lookup n m) ns