-- HaRP pattern translator produces following warnings:
{-# OPTIONS_GHC -fno-warn-name-shadowing -fno-warn-incomplete-patterns #-}
module Darcs2RDF where

import Prelude hiding (elem)
import Text.XML.HaXml hiding (attr)
import Data.Maybe
import System.Environment (getArgs)

data Patch = Patch { patchHash :: String, patchName :: String,
                     patchDate :: String, patchAuthor :: String } deriving Show

patches (Document _ _ (Elem "changelog" _ c) _) = map patch (elems c) where
    patch el@(Elem "patch" _ _) = 
        Patch (fromJust $ attr "hash" el) (fromJust $ elem "name" el)
              (fromJust $ attr "date" el) (fromJust $ attr "author" el)
        
triples :: String -> Patch -> String
triples repo (Patch hash name date author) =
    "<"++repo++"> <" ++ seeAlso ++ "> <"++month++">.\n" ++
    "<"++month++"> <" ++ seeAlso ++ "> <"++day++">.\n" ++
    "<"++month++"> <" ++ label ++ "> " ++ show (take 7 date') ++ ".\n" ++
    "<"++day++"> <" ++ seeAlso ++ "> "++uri++".\n" ++
    "<"++day++"> <" ++ label ++ "> " ++ show (take 10 date') ++ ".\n" ++
    uri++" <"++label++"> " ++
        ""++show name++".\n" ++
    uri++" <foaf:author> "++authorURI ++ ".\n" ++
    (if not $ null authorName
        then authorURI++" <foaf:name> "++show authorName ++ ".\n" else "") ++    
    authorURI++" <foaf:mbox> <mailto:"++authorMail ++ ">.\n" ++
    uri++ " <dc:date> \""++date'++ "\"^^<xsd:dateTime>.\n"    
    where uri = "<darcs:"++hash++">"
          -- the following uses HaRP patterns
          [/ (/ authorName*, ' '*, '<', authorMail*, '>' /)
           | authorMail* /] = author
          authorURI = "<byemail:"++authorMail++">"
          [/ y@(/_,_,_,_/),m@(/_,_/),d@(/_,_/),h@(/_,_/),mi@(/_,_/),s@(/_,_/) /] = date
          date' = y++"-"++m++"-"++d++"T"++h++":"++mi++":"++s++"+0000"
          month = "ex:patches:" ++ take 7 date' ++ ":" ++ repo
          day = "ex:patches:" ++ take 10 date' ++ ":" ++ repo
          seeAlso = "http://www.w3.org/2000/01/rdf-schema#seeAlso"
          label = "http://www.w3.org/2000/01/rdf-schema#label"

elems :: [Content] -> [Element]
elems (CElem e : cs) = e : elems cs
elems (_ : cs)       = elems cs
elems []             = []

attr :: String -> Element -> Maybe String
attr name (Elem _ attrs _) = fmap getValue (lookup name attrs) where
    getValue (AttValue l) = concatMap getValue' l
    getValue' (Left s) = s
    getValue' (Right ref) = [unref ref]
    
elem :: String -> Element -> Maybe String
elem name (Elem _ _ cs) = findElem (elems cs) where
    findElem (Elem n _ c : _) | n == name = Just (text c)
    findElem (_ : cs') = findElem cs'
    findElem [] = Nothing
    
unref :: Reference -> Char
unref (RefChar c) = toEnum c
unref (RefEntity "apos") = '\''
unref (RefEntity "quot") = '"'
unref (RefEntity "lt") = '<'
unref (RefEntity "gt") = '>'
unref (RefEntity "amp") = '&'
unref _ = error "unimplemented reference thingie"
    
text :: [Content] -> String
text (CString _ s : cs) = s ++ text cs
text (CRef r : cs) = unref r : text cs
text (_ : _) = error "unimplemented content thingie"
text [] = ""


main = do [repo] <- getArgs
          xml <- getContents
          putStr $ concatMap (triples repo) $ patches $ xmlParse "stdin" xml