module Text.Blocks
               ( 
                docToBlock,
                blockToDoc,
                widthOfBlock,
                heightOfBlock,
                hcatBlocks,
                hsepBlocks
               )
where

import Text.PrettyPrint
import Data.List (transpose, intersperse)

data TextBlock = TextBlock Int Int [String] -- width height lines
instance Show TextBlock where
  show x = show $ blockToDoc x

docToBlock :: Int -> Doc -> TextBlock
docToBlock width doc =
  let rendered    = renderStyle (style {lineLength = width, 
                                        ribbonsPerLine = 1}) doc
      lns         = lines rendered
      chop []     = []
      chop (l:ls) = if length l > width
                       then (take width l):(chop ((drop width l):ls))
                       else l:(chop ls)
      lns'        = chop lns
  in  TextBlock width (length lns') lns' 

blockToDoc :: TextBlock -> Doc
blockToDoc (TextBlock _ _ lns) = 
  if null lns
     then empty
     else text $ unlines (init lns) ++ last lns  -- to avoid trailing \n

widthOfBlock :: TextBlock -> Int
widthOfBlock (TextBlock width _ _) = width

heightOfBlock :: TextBlock -> Int
heightOfBlock (TextBlock _ height _) = height

-- pad line out to width using spaces
hPad :: Int -> String -> String
hPad width line = 
  let lineLength = length line
  in  if lineLength <= width 
         then line ++ replicate (width - lineLength) ' '
         else take width line

hcatBlocks :: [TextBlock] -> TextBlock
hcatBlocks [] = TextBlock 0 0 []
hcatBlocks ((TextBlock width1 height1 lns1):xs) = 
  let (TextBlock width2 height2 lns2) = hcatBlocks xs
      height = max height1 height2
      width  = width1 + width2
      lns1'  = map (hPad width1) $ lns1 ++ replicate (height - height1) ""
      lns2'  = lns2 ++ replicate (height - height2) ""
      lns    = zipWith (++) lns1' lns2'
   in TextBlock width height lns 

hsepBlocks = hcatBlocks . (intersperse (TextBlock 1 1 [" "]))