    {-
    Copyright (C) 2009 John MacFarlane <jgm@berkeley.edu>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    -}

    {- | Functions for embedding a gitit wiki into a Happstack application.

    The following is a minimal standalone wiki program:

    > import Network.Gitit
    > import Happstack.Server.SimpleHTTP
    >
    > main = do
    >   conf <- getDefaultConfig
    >   createStaticIfMissing conf
    >   createTemplateIfMissing conf
    >   createRepoIfMissing conf
    >   initializeGititState conf
    >   simpleHTTP nullConf{port = 5001} $ wiki conf

    Here is a more complex example, which serves different wikis
    under different paths, and uses a custom authentication scheme:

    > import Network.Gitit
    > import Control.Monad
    > import Text.XHtml hiding (dir)
    > import Happstack.Server.SimpleHTTP
    >
    > type WikiSpec = (String, FileStoreType, PageType)
    >
    > wikis = [ ("markdownWiki", Git, Markdown)
    >         , ("latexWiki", Darcs, LaTeX) ]
    >
    > -- custom authentication
    > myWithUser :: Handler -> Handler
    > myWithUser handler = do
    >   -- replace the following with a function that retrieves
    >   -- the logged in user for your happstack app:
    >   user <- return "testuser"
    >   localRq (setHeader "REMOTE_USER" user) handler
    >
    > myAuthHandler = msum
    >   [ dir "_login"  $ seeOther "/your/login/url"  $ toResponse ()
    >   , dir "_logout" $ seeOther "/your/logout/url" $ toResponse () ]
    >
    > handlerFor :: Config -> WikiSpec -> ServerPart Response
    > handlerFor conf (path', fstype, pagetype) = dir path' $
    >   wiki conf{ repositoryPath = path'
    >            , repositoryType = fstype
    >            , defaultPageType = pagetype}
    >
    > indexPage :: ServerPart Response
    > indexPage = ok $ toResponse $
    >   (p << "Wiki index") +++
    >   ulist << map (\(path', _, _) -> li << hotlink (path' ++ "/") << path') wikis
    >
    > main = do
    >   conf <- getDefaultConfig
    >   let conf' = conf{authHandler = myAuthHandler, withUser = myWithUser}
    >   forM wikis $ \(path', fstype, pagetype) -> do
    >     let conf'' = conf'{ repositoryPath = path'
    >                       , repositoryType = fstype
    >                       , defaultPageType = pagetype
    >                       }
    >     createStaticIfMissing conf''
    >     createRepoIfMissing conf''
    >   createTemplateIfMissing conf'
    >   initializeGititState conf'
    >   simpleHTTP nullConf{port = 5001} $
    >     (nullDir >> indexPage) `mplus` msum (map (handlerFor conf') wikis)

    -}

    module Network.Gitit (
                         -- * Wiki handlers
                           wiki
                         , reloadTemplates
                         , runHandler
                         -- * Initialization
                         , module Network.Gitit.Initialize
                         -- * Configuration
                         , module Network.Gitit.Config
                         , loginUserForm
                         -- * Types
                         , module Network.Gitit.Types
                         -- * Tools for building handlers
                         , module Network.Gitit.Framework
                         , module Network.Gitit.Layout
                         , module Network.Gitit.ContentTransformer
                         , module Network.Gitit.Page
                         , getFileStore
                         , getUser
                         , getConfig
                         , queryGititState
                         , updateGititState
                         )
    where
    import Network.Gitit.Types
    import Network.Gitit.Server
    import Network.Gitit.Framework
    import Network.Gitit.Handlers
    import Network.Gitit.Initialize
    import Network.Gitit.Config
    import Network.Gitit.Layout
    import Network.Gitit.State
            (getFileStore, getUser, getConfig, queryGititState, updateGititState)
    import Network.Gitit.ContentTransformer
    import Network.Gitit.Page
    import Network.Gitit.Authentication (loginUserForm)
    import Paths_gitit (getDataFileName)
    import Control.Monad.Reader
    import Prelude hiding (readFile)
    import qualified Data.ByteString.Char8 as B
    import System.FilePath ((</>))
    import System.Directory (getTemporaryDirectory)
    import Safe

    -- | Happstack handler for a gitit wiki.
    wiki :: Config -> ServerPart Response
    wiki conf = do
      tempDir <- liftIO getTemporaryDirectory
      let maxSize = fromIntegral $ maxUploadSize conf
      decodeBody $ defaultBodyPolicy tempDir maxSize maxSize maxSize
      let static = staticDir conf
      defaultStatic <- liftIO $ getDataFileName $ "data" </> "static"
      -- if file not found in staticDir, we check also in the data/static
      -- directory, which contains defaults
      let staticHandler = withExpiresHeaders $
            serveDirectory' static `mplus` serveDirectory' defaultStatic
      let debugHandler' = msum [debugHandler | debugMode conf]
      let handlers = debugHandler' `mplus` authHandler conf `mplus`
                     authenticate ForRead (msum wikiHandlers)
      let fs = filestoreFromConfig conf
      let ws = WikiState { wikiConfig = conf, wikiFileStore = fs }
      if compressResponses conf
         then compressedResponseFilter
         else return ""
      staticHandler `mplus` runHandler ws (withUser conf handlers)

    -- | Like 'serveDirectory', but if file is not found, fail instead of
    -- returning a 404 error.
    serveDirectory' :: FilePath -> ServerPart Response
    serveDirectory' p = do
      rq <- askRq
      resp' <- serveDirectory EnableBrowsing [] p
      if rsCode resp' == 404 || lastNote "fileServeStrict'" (rqUri rq) == '/'
         then mzero  -- pass through if not found or directory index
         else
           -- turn off compresion filter unless it's text
           case getHeader "Content-Type" resp' of
                Just ct | B.pack "text/" `B.isPrefixOf` ct -> return resp'
                _ -> ignoreFilters >> return resp'

    wikiHandlers :: [Handler]
    wikiHandlers =
      [ -- redirect /wiki -> /wiki/ when gitit is being served at /wiki
        -- so that relative wikilinks on the page will work properly:
        guardBareBase >> getWikiBase >>= \b -> movedPermanently (b ++ "/") (toResponse ())
      , dir "_activity" showActivity
      , dir "_go"       goToPage
      , method GET >> dir "_search"   searchResults
      , dir "_upload"   $  do guard =<< return . uploadsAllowed =<< getConfig
                              msum [ method GET  >> authenticate ForModify uploadForm
                                     , method POST >> authenticate ForModify uploadFile ]
      , dir "_random"   $ method GET  >> randomPage
      , dir "_index"    indexPage
      , dir "_feed"     feedHandler
      , dir "_category" categoryPage
      , dir "_categories" categoryListPage
      , dir "_expire"     expireCache
      , dir "_showraw"  $ msum
          [ showRawPage
          , guardPath isSourceCode >> showFileAsText ]
      , dir "_history"  $ msum
          [ showPageHistory
          , guardPath isSourceCode >> showFileHistory ]
      , dir "_edit" $ authenticate ForModify (unlessNoEdit editPage showPage)
      , dir "_diff" $ msum
          [ showPageDiff
          , guardPath isSourceCode >> showFileDiff ]
      , dir "_discuss" discussPage
      , dir "_delete" $ msum
          [ method GET  >>
              authenticate ForModify (unlessNoDelete confirmDelete showPage)
          , method POST >>
              authenticate ForModify (unlessNoDelete deletePage showPage) ]
      , dir "_preview" preview
      , guardIndex >> indexPage
      , guardCommand "export" >> exportPage
      , method POST >> guardCommand "cancel" >> showPage
      , method POST >> guardCommand "update" >>
          authenticate ForModify (unlessNoEdit updatePage showPage)
      , showPage
      , guardPath isSourceCode >> method GET >> showHighlightedSource
      , handleAny
      , notFound =<< (guardPath isPage >> createPage)
      ]

    -- | Recompiles the gitit templates.
    reloadTemplates :: ServerPart Response
    reloadTemplates = do
      liftIO recompilePageTemplate
      ok $ toResponse "Page templates have been recompiled."

    -- | Converts a gitit Handler into a standard happstack ServerPart.
    runHandler :: WikiState -> Handler -> ServerPart Response
    runHandler = mapServerPartT . unpackReaderT

    unpackReaderT :: s -> UnWebT (ReaderT s IO) a -> UnWebT IO a
    unpackReaderT st uw = runReaderT uw st