module GramLab.Morfette.MWE ( detectMwes
                            , mweSet
                            , saveMwes
                            , loadMwes 
                            )
where
import GramLab.Utils (join,splitWith,lowercase)
import GramLab.Morfette.Token
import qualified Data.List as List
import qualified Data.Map as Map
import Data.Ord (comparing)
import Data.Char
import Data.Binary
import qualified Data.ByteString.Lazy as BS

mweSep = '_'

mweSet :: [Token] -> [[String]]
mweSet toks = List.sortBy (flip (comparing length))
              . map fst
              . filter ((> 1) . snd)
              . Map.toList
              . Map.fromListWith (+)
              . map (\x -> (x,1)) 
              . map (splitWith (==mweSep))
              . filter common
              . map tokenForm $ toks
    where common = all (\c -> isLower c || c `elem` [mweSep,'-'])

detectMwes :: [[String]] -> [String] -> [String]
detectMwes mwes [] = []
detectMwes mwes (x:xs) = case List.find (`List.isPrefixOf` xs') mwes of
                           Nothing -> x:detectMwes mwes xs
                           Just mwe -> let len = length mwe 
                                       in join [mweSep] (take len (x:xs)) : drop len (x:xs)
    where  xs' = map lowercase (x:xs)                         

saveMwes path mwes = do
  BS.writeFile path (encode mwes)
  
loadMwes path = do
  s <- BS.readFile path
  return $ decode s