import Data.Maybe
import Data.List
import qualified Data.Map  as Map

-- |Sort list by function result (don't use Schwarznegian transform!)
sortOn f  =  sortBy (map2cmp f)

-- |Group list by function result
groupOn f  =  groupBy (map2eq f)

-- |Sort and Group list by function result
sort_and_groupOn  f  =  groupOn f . sortOn  f

-- Utility functions for list operations
keyval  f x    =  (f x, x)                -- |Return pair containing computed key and original value
map2cmp f x y  =  (f x) `compare` (f y)   -- |Converts "key_func" to "compare_func"
map2eq  f x y  =  (f x) == (f y)          -- |Converts "key_func" to "eq_func"



data Title = Title { id    :: !Int
                   , title :: String
                   }                      deriving (Show,Eq,Ord)

data Elem = Elem { count  :: !Int
                 , titles :: [Title]
                 }                        deriving (Show,Eq,Ord)

main = do database <- readFile "database"
          -- database is "A big fish\nRed eye\n..."
          let k = zip [1..] . lines
              -- k is [(1,"A big fish"), (2,"Red eye"), ...]
              m = concatMap (\(n,str) -> map (\w -> (w,Title n str)) (words str))
              -- m is [("A", Title 1 "A big fish"), ("big", Title 1 "A big fish"),
              --       ("fish", Title 1 "A big fish"), ("Red", Title 2 "Red eye")...]
              g = sort_and_groupOn fst
              -- g is [[("A", Title 1 "A big fish"), ("A", Title 66 "A silly thing")],
              --       [("big", Title 77 "A big fish"), ("big", Title 88 "Bad big boys")]...]
              h = map (\list -> let w = fst (head list)       -- "A"
                                    titles = map snd list     -- [Title 1 "A big fish", Title 66 "A silly thing"]
                                    size = length list        -- 2
                                in (w, Elem size titles))
              -- h is [("A", (Elem 2 [Title 1 "A big fish", Title 66 "A silly thing"]))... ]
              fm = (Map.fromDistinctAscList .h.g.m.k) database
              -- fm maps "A" to (Elem 2 [Title 1 "A big fish", Title 66 "A silly thing"])

          let m = sortOn count . catMaybes . map (`Map.lookup` fm) . words
              -- m is [Elem 2 [Title 1 "A big fish", Title 66 "A silly thing"], Elem 5 [...], ...]
              title1 = title . head . titles . head
              -- title1 is "A big fish", a closest-matching title

          new <- readFile "new"
          putStr$ (unlines . map (title1 . m) . filter (not.null) . lines) new