import Data.List (intersperse)


{-
Translates, for example

> putStr $ show ["hej", "du", "glade"]
["hej", "du", "glade"]
to

> putStr $ box ["hej", "du", "glade"]
╒═╤═╤═╤═╤═╕
│h│e│j│ │ │
├─┼─┼─┼─┼─┤
│d│u│ │ │ │
├─┼─┼─┼─┼─┤
│g│l│a│d│e│
╘═╧═╧═╧═╧═╛

-}
box :: [String] -> String
box ss | len < 0   = error "can't make an empty box!"
       | otherwise = topLine
                     ++ (concat $ intersperse divider $ map row' ss)
                     ++ bottomLine
  where
    len = (maximum $ map length ss) - 1
    liney pre line cross suf
      = (++ "\n") $ intersperse line $ pre ++ replicate len cross ++ suf

    strLine pre str line suf
      = (++ "\n") $ pre ++ (intersperse line str) ++ suf

    row' str | length str < (len+1) = row $ str
                                      ++ (replicate (len + 1 - length str) ' ')
             | otherwise = row str
    topLine    = liney   "╒" '═' '╤' "╕"
    row str    = strLine "│" str '│' "│"
    divider    = liney   "├" '─' '┼' "┤"
    bottomLine = liney   "╘" '═' '╧' "╛"