module Browse where

import Directory

-- shorter names for some imported utilities

(getDir,isDir) = (getDirectoryContents,doesDirectoryExist)


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-- a DTree type for picture files and directories
-- (Show instance below gives outlines, or derive it if you prefer)

data DTree = Pic FilePath | Dir FilePath [DTree]  -- deriving Show


dirtree  fp = if  (dotted fp) then return []       else
              if  (isGIF  fp) then return [Pic fp] else
              iff (isDir  fp) (subtrees fp) (return [])

subtrees fp = getDir fp >>= mapM (dirtree . path fp) >>= 
              \ts -> return [Dir fp (concat ts)]


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-- put a nested directory of pictures on your 
-- H drive and adjust this path to point to it

test = dirtree path >>= print . head
       where path = "/Users/fruehr/hugs/pics"


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-- some utility functions for readability

-- for unix directories (and Windows?) with "dot" links

dotted fp = take 1 (reverse fp) == "."

-- expand this definition if you use JPEGs, PNGs, etc.

isGIF  fp = ".gif" == snd (break (=='.') fp)

path p f = p ++ '/' : f

iff p q r = p >>= (\b -> if b then q else r)


-- outline-style show function for DTrees

instance Show (DTree) where
  show = sh "" where sh i (Pic f)     = i ++ f
                     sh i (Dir d [])  = i ++ d ++ " [D]"
                     sh i (Dir d ds)  = i ++ d ++ " [D] \n" ++ 
                                        unline (map (sh ('\t':i)) ds)

unline = foldr1 (\x y->x++'\n':y)