addressbook/src/Control/Addressbook/Query.hs

49 lines
1.3 KiB
Haskell

{-# LANGUAGE TypeApplications #-}
module Control.Addressbook.Query where
import Data.Text
(Text)
import qualified Data.Text as T
import qualified Data.Text.Encoding as TE
import Conduit
import qualified Data.Conduit.Binary as CB
import qualified Data.Conduit.Combinators as C
import qualified Data.Conduit.List as CL
import qualified Data.Conduit.Text as CT
import qualified Data.Trie as Trie
import System.IO
(stdout)
import Data.Maybe
(fromMaybe)
import System.Environment
(lookupEnv)
import System.FilePath
((</>))
import Control.Exception
(catch)
query :: Text -> IO ()
query prefix = do
datDir <- fromMaybe "./" <$> lookupEnv "HOME"
state <- catch @IOError (runResourceT $ runConduit $ readState datDir) (\_ -> pure Trie.empty)
runConduit $ outputResults state
where
readState :: FilePath -> ConduitM () Void (ResourceT IO) (Trie.Trie [Text])
readState dir =
CB.sourceFile (dir </> ".addressbook.dat")
.| CT.decode CT.utf8
.| CT.lines
.| C.foldMap (\s -> Trie.singleton (TE.encodeUtf8 $ T.toLower s) [s])
outputResults :: Trie.Trie [Text] -> ConduitM () Void IO ()
outputResults state =
CL.sourceList (Trie.elems $ Trie.submap (TE.encodeUtf8 prefix) state)
.| C.concat
.| C.map (<> "\n")
.| CT.encode CT.utf8
.| CB.sinkHandle stdout