module Haskell (doHaskell) where

import Regex (mkRegex,matchRegex,Sub,mkSub,doSub)

import Split (Split(..))

import Filter (Filt,DocSubs,filterLine,docSubs,process)

notSymbol :: String
notSymbol = "[^-!#$%&*+./<=>?@\\^|~]"

isolated :: String -> String
isolated s = "(^|" ++ notSymbol ++ ")" ++ s ++ "($|" ++ notSymbol ++ ")"

codeSubs :: [Sub]
codeSubs = map mkSub
    [ (isolated "=>", "\\1&rArr;\\2")
    , (isolated "<=", "\\1&lArr;\\2")
    , (isolated "->", "\\1&rarr;\\2")
    , (isolated "<-", "\\1&larr;\\2")
    ]

libraries :: String
libraries = "http://www.haskell.org/ghc/docs/latest/html/libraries/"

haskellDocSubs :: DocSubs
haskellDocSubs = 
    [ ("lib", "([^` \t]+)[ \t]+`([^` \t]+)`",
        "[`\\3`](" ++ libraries ++ "\\2/\\3.html \"\\3\")")
    ]

undotURL :: String -> String
undotURL line =
    let regex = mkRegex $ "(^.*" ++ libraries ++ ")(.*)(.html .*$)"
        sub   = mkSub ("\\.", "-")
    in  case matchRegex regex line of
        Just [x,y,z] -> x ++ (doSub y sub) ++ z
        _ -> line

codeFilter, docFilter :: Filt
codeFilter = filterLine codeSubs
docFilter = undotURL . (filterLine $ docSubs haskellDocSubs)

doHaskell :: [Split] -> [Split]
doHaskell = process codeFilter docFilter