* blog is now running off acid-state (this thing is *fast*)

src/BlogDB.hs

@@ -0,0 +1,208 @@
+{-# LANGUAGE DeriveDataTypeable, GeneralizedNewtypeDeriving, RecordWildCards, 
+TemplateHaskell, TypeFamilies, OverloadedStrings, ScopedTypeVariables, BangPatterns #-}
+
+module BlogDB where
+
+import Control.Monad.Reader (ask)
+import Control.Monad.State  (get, put)
+import Data.Acid
+import Data.Acid.Advanced 
+import Data.Acid.Local
+import Data.ByteString      (ByteString)
+import Data.Data            (Data, Typeable)
+import Data.IxSet           (Indexable(..), IxSet(..), (@=), Proxy(..), getOne, ixFun, ixSet)
+import Data.List 			(insert)
+import Data.SafeCopy        (SafeCopy, base, deriveSafeCopy)
+import Data.Text            (Text, pack)
+import Data.Text.Lazy       (toStrict)
+import Data.Time
+import Happstack.Server 	(ServerPart)
+
+import qualified Crypto.Hash.SHA512 as SHA (hash)
+import qualified Data.ByteString.Char8 as B
+import qualified Data.ByteString.Base64 as B64 (encode)
+import qualified Data.IxSet as IxSet
+import qualified Data.Text  as Text
+
+
+newtype EntryId = EntryId { unEntryId :: Integer }
+    deriving (Eq, Ord, Data, Enum, Typeable, SafeCopy)
+
+instance Show EntryId where
+  show = show . unEntryId
+
+data BlogLang = EN | DE 
+    deriving (Eq, Ord, Data, Typeable)
+
+instance Show BlogLang where
+    show DE = "de"
+    show EN = "en"
+
+$(deriveSafeCopy 0 'base ''BlogLang)
+
+data Comment = Comment { 
+    cauthor :: Text,
+    ctext   :: Text,
+    cdate   :: UTCTime
+} deriving (Eq, Ord, Show, Data, Typeable)
+
+$(deriveSafeCopy 0 'base ''Comment)
+
+data Entry = Entry {
+    entryId :: EntryId,
+    lang   :: BlogLang,
+    author :: Text,
+    title  :: Text,
+    btext  :: Text, 
+    mtext  :: Text,
+    edate  :: UTCTime,
+    tags   :: [Text],
+    comments :: [Comment]
+} deriving (Eq, Ord, Show, Data, Typeable)
+
+$(deriveSafeCopy 0 'base ''Entry)
+
+-- ixSet requires different datatypes for field indexes, so let's define some
+newtype Author = Author Text   deriving (Eq, Ord, Data, Typeable, SafeCopy)
+newtype Title  = Title Text    deriving (Eq, Ord, Data, Typeable, SafeCopy)
+newtype BText  = BText Text    deriving (Eq, Ord, Data, Typeable, SafeCopy) -- standard text
+newtype MText  = MText Text    deriving (Eq, Ord, Data, Typeable, SafeCopy) -- "read more" text
+newtype Tag    = Tag Text      deriving (Eq, Ord, Data, Typeable, SafeCopy)
+newtype EDate  = EDate UTCTime deriving (Eq, Ord, Data, Typeable, SafeCopy)
+newtype SDate  = SDate UTCTime   deriving (Eq, Ord, Data, Typeable, SafeCopy)
+newtype Username = Username Text deriving (Eq, Ord, Data, Typeable, SafeCopy)
+newtype SessionID = SessionID Text deriving (Eq, Ord, Data, Typeable, SafeCopy)
+
+instance Indexable Entry where 
+    empty = ixSet [ ixFun $ \e -> [ entryId e]
+                  , ixFun $ (:[]) . lang
+                  , ixFun $ \e -> [ Author $ author e ]
+                  , ixFun $ \e -> [ Title $ title e]
+                  , ixFun $ \e -> [ BText $ btext e]
+                  , ixFun $ \e -> [ MText $ mtext e]
+                  , ixFun $ \e -> [ EDate $ edate e]
+                  , ixFun $ \e -> map Tag (tags e)
+                  , ixFun $ comments
+                  ]
+
+data User = User {
+    username :: Text,
+    password :: ByteString
+} deriving (Eq, Ord, Data, Typeable)
+
+$(deriveSafeCopy 0 'base ''User)
+
+data Session = Session {
+    sessionID :: Text,
+    user      :: User,
+    sdate     :: UTCTime
+} deriving (Eq, Ord, Data, Typeable)
+
+$(deriveSafeCopy 0 'base ''Session)
+
+instance Indexable User where
+    empty = ixSet [ ixFun $ \u -> [Username $ username u]
+                  , ixFun $ (:[]) . password 
+                  ]
+
+instance Indexable Session where
+    empty = ixSet [ ixFun $ \s -> [SessionID $ sessionID s]
+                  , ixFun $ (:[]) . user
+                  , ixFun $ \s -> [SDate $ sdate s]
+                  ]
+
+data Blog = Blog {
+    blogSessions :: IxSet Session,
+    blogUsers    :: IxSet User,
+    blogEntries  :: IxSet Entry
+} deriving (Data, Typeable)
+
+$(deriveSafeCopy 0 'base ''Blog)
+
+initialBlogState :: Blog 
+initialBlogState = 
+    Blog { blogSessions = empty
+         , blogUsers = empty
+         , blogEntries = empty }
+
+-- acid-state database functions (purity is necessary!)
+
+insertEntry :: Entry -> Update Blog Entry
+insertEntry e = 
+    do b@Blog{..} <- get
+       put $ b { blogEntries = IxSet.insert e blogEntries }
+       return e
+
+addComment :: EntryId -> Comment -> Update Blog Entry
+addComment eId c =
+	do b@Blog{..} <- get
+	   let (Just e) = getOne $ blogEntries @= eId
+	   let newEntry = e { comments = insert c $ comments e }
+	   put $ b { blogEntries = IxSet.updateIx eId newEntry blogEntries }
+	   return newEntry
+
+updateEntry :: Entry -> Update Blog Entry
+updateEntry e = 
+    do b@Blog{..} <- get
+       put $ b { blogEntries = IxSet.updateIx (entryId e) e blogEntries}
+       return e
+
+getEntry :: EntryId -> Query Blog (Maybe Entry)
+getEntry eId =
+    do b@Blog{..} <- ask
+       return $ getOne $ blogEntries @= eId
+
+latestEntries :: BlogLang -> Query Blog [Entry]
+latestEntries lang =
+    do b@Blog{..} <- ask
+       return $ IxSet.toDescList (Proxy :: Proxy EDate) $ blogEntries @= lang
+
+addSession :: Text -> User -> UTCTime -> Update Blog Session
+addSession sId u t =
+    do b@Blog{..} <- get
+       let s = Session sId u t
+       put $ b { blogSessions = IxSet.insert s blogSessions}
+       return s
+
+getSession :: SessionID -> Query Blog (Maybe Session)
+getSession sId =
+  do b@Blog{..} <- ask
+     return $ getOne $ blogSessions @= sId
+
+addUser :: Text -> String -> Update Blog User
+addUser un pw =
+    do b@Blog{..} <- get
+       let u = User un $ hashString pw
+       put $ b { blogUsers = IxSet.insert u blogUsers}
+       return u
+
+getUser :: Username -> Query Blog (Maybe User)
+getUser uN =
+  do b@Blog{..} <- ask
+     return $ getOne $ blogUsers @= uN
+
+checkUser :: Username -> String -> Query Blog (Bool)
+checkUser uN pw =
+  do b@Blog{..} <- ask
+     let user = getOne $ blogUsers @= uN
+     case user of
+       Nothing  -> return False
+       (Just u) -> return $ (password u) == hashString pw
+
+-- various functions
+hashString :: String -> ByteString
+hashString = B64.encode .  SHA.hash . B.pack
+
+$(makeAcidic ''Blog
+    [ 'insertEntry
+    , 'addComment
+    , 'updateEntry
+    , 'getEntry
+    , 'latestEntries
+    , 'addSession
+    , 'getSession
+    , 'addUser
+    , 'getUser
+    , 'checkUser
+    ])
+