{-# LANGUAGE FlexibleContexts #-}

{- | Module for pretty-printing epub guide info

   Used internally by Codec.Epub.Format
-}
module Codec.Epub.Format.Guide
   ( formatGuide
   )
   where

import Control.Monad.Writer.Lazy ( MonadWriter, execWriter )
import Data.Foldable ( toList )
import Text.Printf ( printf )

import Codec.Epub.Format.Util
import Codec.Epub.Data.Guide


tellGuideRef :: MonadWriter (Seq Char) m => GuideRef -> m ()
tellGuideRef (GuideRef grty title href) =
   tellSeq $ printf "   type: %s%s, href: %s\n"
      grty (titleToString title) href

   where
      titleToString = maybe "" (printf ", title: %s")


tellGuide :: MonadWriter (Seq Char) m => [GuideRef] -> m ()
tellGuide []  = return ()
tellGuide grs = do
   tellSeq "guide items:\n"
   mapM_ tellGuideRef grs


{- | Format an epub Guide structure for pretty printing
-}
formatGuide :: [GuideRef] -> String
formatGuide guideRefs = toList . execWriter $ tellGuide guideRefs