import Data.List
import Data.List.Split
import Text.Printf
import Text.Regex.Posix

toMonth :: Int -> String
toMonth m = chunk 3 "JanFebMarAprMayJunJulAugSepOctNovDec" !! (m - 1)

item :: [[String]] -> String
item xs = printf
    "<tr><td>%s</td><td>%02s %s %s</td><td>%s: %s</td>\
    \<td>%s%s<a href=\"http://programmingpraxis.codepad.org/%s\">\
    \codepad</a></td></tr>"
    (g "number") (g "pubday") (toMonth . read $ g "pubmon") (g "pubyear")
    (link "" (g "title")) (g "blurb") (link "" "exercise")
    (link ("/" ++ g "soln") "solution") (g "codepad")
    where g x = maybe "" last $ find ((== x) . head) xs
          link :: String -> String -> String
          link = printf "<a href=\"/%s/%02s/%02s/%s%s/\">%s</a>"
                 (g "pubyear") (g "pubmon") (g "pubday") (g "file")

items :: String -> [String]
items = map (item . map (splitOn "\t") . lines) .
        filter (=~ "^number\t[1-9][0-9]*$") . splitOn "\n\n"

listing :: ([String] -> [String]) -> String -> String
listing f xs = "<table cellpadding=\"10\">" ++
               concat (f $ items xs) ++ "</table>"

main :: IO ()
main = do x <- readFile "praxis.info"
          putStrLn $ listing id x
          putStrLn $ listing reverse x