Typograph.hs

{-# LANGUAGE ScopedTypeVariables #-}

{-
  This module is part of Chatty.
  Copyleft (c) 2014 Marvin Cohrs

  All wrongs reversed. Sharing is an act of love, not crime.
  Please share Antisplice with everyone you like.

  Chatty is free software: you can redistribute it and/or modify
  it under the terms of the GNU Affero General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.

  Chatty is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  GNU Affero General Public License for more details.

  You should have received a copy of the GNU Affero General Public License
  along with Chatty. If not, see <http://www.gnu.org/licenses/>.
-}

-- | Provides functions that typeset the input to a limited output width (to avoid ugly word cuts).
module Text.Chatty.Typograph where

import Control.Monad
import Control.Monad.Trans.Class
import Data.Char
import Data.List
import Text.Chatty.Interactor
import Text.Chatty.Printer
import Text.Chatty.Scanner
import Text.Chatty.Scanner.Buffered

-- | Simple flush-left typesetter without support for syllabification.
simpleTypesetter :: (Functor m,ChScanner m,ChPrinter m) => Int -> m ()
simpleTypesetter width = void $ runScannerBufferT (typeset width) [""]
  where scanw = mscannable >>= \b -> if not b then return [] else do
          k <- mpeek1
          if isSpace k then return [] else do
            mscan1
            ks <- scanw
            return (k:ks)
        skipw :: ChBufferedScanner m => m Int
        skipw = mscannable >>= \b -> if not b then return 0 else do
          k <- mpeek1
          if not (isSpace k) then return 0 else do
            mscan1
            w <- skipw
            return (w + if k == '\n' then 1 else 0)
        tsetw i w
          | length w < i = mprint (w ++ " ") >> typeset (i - 1 - length w)
          | length w == i = mprintLn w >> typeset width
          | length w > width && i == width = mprintLn (take i w) >> tsetw width (drop i w)
          | otherwise = mprintLn "" >> tsetw width w
        typeset i = mscannable >>= \b -> when b $ do
          ls <- skipw
          if ls > 0
            then forM_ [1..ls] (const $ mprintLn "") >> typeset width
            else do
              w <- scanw
              tsetw i w

-- | Backtracking flush-left typesetter using the given hyphenator function.
leftTypesetter :: (Functor m,ChScanner m,ChPrinter m) => Int -> (String -> [String]) -> m ()
leftTypesetter width hyphen = void $ runScannerBufferT paragraphs [""]
  where scanw :: ChBufferedScanner m => m String
        scanw = mscannable >>= \b -> if not b then return [] else do
          k <- mpeek1
          if isSpace k then return [] else do
            mscan1
            ks <- scanw
            return (k:ks)
        skipw :: ChBufferedScanner m => m Int
        skipw = mscannable >>= \b -> if not b then return 0 else do
          k <- mpeek1
          if not (isSpace k) then return 0 else do
            mscan1
            w <- skipw
            return (w + if k == '\n' then 1 else 0)
        combis [] [] = []
        combis w (a:as) = (w,concat (a:as)) : combis (w++a) as
        tsetw :: Int -> String -> [(String,Int,Int)]
        tsetw i w = do
              a <- [("",i),("\n",width)]
              concatMap (\(b,c) -> if b == "" then return (fst a++c++if length c < snd a then " " else "", snd a-length c - 1, 0) else do
                           (dw,di,du) <- tsetw width c
                           return (fst a++b++"-\n"++dw, di, du+1)
                       ) $ filter (\(b,c) -> if b /= "" then length b < snd a else length c <= snd a) $ combis [] $ hyphen w
        paragraphs =
          paragraph >>= \x -> case x of
            Nothing -> return ()
            Just s -> mprint s >> paragraphs
        paragraph = mscannable >>= \b -> if not b then return Nothing else do
          ts <- typeset width
          case map (\(w,i,u) -> (w, u*u + sum (map (\s -> (width - length s) * (width - length s)) $ lines w))) ts of
            [] -> return Nothing
            cs -> return $ Just $ fst $ minimumBy (\a b -> snd a `compare` snd b) cs
        typeset i = mscannable >>= \b -> if not b then return [("",i,0)] else do
          ls <- skipw
          if ls > 0 then return [(replicate ls '\n', width, 0)] else do
            w <- scanw
            let ts = tsetw i w
            tx <- return ()
            return []
            -- IMPLEMENT THIS!!!!