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{-# 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 System.Environment(getEnv)
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 :: Session -> Update Blog Session
addSession nSession =
do b@Blog{..} <- get
put $ b { blogSessions = IxSet.insert nSession blogSessions}
return nSession
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
])
interactiveUserAdd :: IO ()
interactiveUserAdd = do
tbDir <- getEnv "TAZBLOG"
acid <- openLocalStateFrom (tbDir ++ "/BlogState") initialBlogState
putStrLn "Username:"
un <- getLine
putStrLn "Password:"
pw <- getLine
update' acid (AddUser (pack un) pw)
createCheckpointAndClose acid
|
