Updating channels (visibility)

src/API/Channels.hs

@@ -11,6 +11,8 @@
 {-# Language FlexibleInstances #-}
 {-# Language TypeApplications #-}
 {-# Language DataKinds #-}
+{-# Language DuplicateRecordFields #-}
+{-# Language NamedFieldPuns #-}
 module API.Channels (API, handler, JsonChannel(..)) where
 
 import Servant
@@ -28,17 +30,34 @@ import Data.Generics.Product
 data JsonChannel = JsonChannel { channel :: Text
                                , visibility :: Visibility }
                  deriving (Show, Generic)
+data UpdateChannel = UpdateChannel { identifier :: ChannelID
+                                   , channel :: Text
+                                   , visibility :: Visibility }
+                 deriving (Show, Generic)
 
 instance ToJSON JsonChannel
 instance FromJSON JsonChannel
+instance ToJSON UpdateChannel
+instance FromJSON UpdateChannel
 
 type API = Auth '[SA.BasicAuth, SA.Cookie, SA.JWT] SafeUser :> BaseAPI
 
-type BaseAPI = "channels" :> ReqBody '[JSON] JsonChannel :> Post '[JSON] JsonChannel
+type BaseAPI = "channels" :> ReqBody '[JSON] JsonChannel :> Post '[JSON] UpdateChannel
+          :<|> "channels" :> Capture "channel_id" ChannelID :> ReqBody '[JSON] UpdateChannel :> Put '[JSON] UpdateChannel
           :<|> "channels" :> Get '[JSON] [JsonChannel]
 
 handler :: ServerT API AppM
-handler user = newChannelHandler user :<|> listChannelsHandler user
+handler user = newChannelHandler user :<|> updateChannelHandler user :<|> listChannelsHandler user
+
+requireChannelOwner :: AuthResult SafeUser -> ChannelID -> (SafeUser -> AppM a) -> AppM a
+requireChannelOwner auth channelId f = flip requireLoggedIn auth $ \u@SafeUser{username} -> do
+  unlessM (runDB . channelExists $ channelId) $ throwM err404
+  runDB (isChannelOwner channelId username) >>= \o -> if o then f u else throwM err403
+
+updateChannelHandler :: AuthResult SafeUser -> ChannelID -> UpdateChannel -> AppM UpdateChannel
+updateChannelHandler auth channelId UpdateChannel{visibility} = requireChannelOwner auth channelId $ \_ -> do
+  mChannel <- fmap toChannel <$> runDB (updateChannelPrivacy channelId visibility)
+  maybe (throwM err403) return mChannel
 
 listChannelsHandler :: AuthResult SafeUser -> AppM [JsonChannel]
 listChannelsHandler = requireLoggedIn $ \user ->
@@ -46,8 +65,11 @@ listChannelsHandler = requireLoggedIn $ \user ->
   -- use the 'channel' accessor somehow or export it
   fmap (\Channel{..} -> JsonChannel{..}) <$> runDB (userChannels (view (field @"username") user))
 
-newChannelHandler :: AuthResult SafeUser -> JsonChannel -> AppM JsonChannel
-newChannelHandler auth ch@JsonChannel{..} = flip requireLoggedIn auth $ \user -> do
+newChannelHandler :: AuthResult SafeUser -> JsonChannel -> AppM UpdateChannel
+newChannelHandler auth JsonChannel{..} = flip requireLoggedIn auth $ \user -> do
   $logInfo $ "Creating channel for user " <> pack (show user)
-  runDB (insertChannel (view (field @"username") user) channel visibility)
-  return ch
+  mChannel <- fmap toChannel <$> runDB (insertChannel (view (field @"username") user) channel visibility)
+  maybe (throwM err403{errBody="Could not create the channel"}) return mChannel
+
+toChannel :: Channel -> UpdateChannel
+toChannel Channel{..} = UpdateChannel{..}

src/Database/Channel.hs

@@ -4,6 +4,9 @@
 module Database.Channel
   ( userChannels
   , insertChannel
+  , channelExists
+  , isChannelOwner
+  , updateChannelPrivacy
   , attachChannel
   , Visibility(..)
   , clearChannels
@@ -18,6 +21,30 @@ import Database
 import Database.Selda
 import Database.Selda.Generic
 
+import Control.Monad.Trans.Maybe
+
+getChannel :: (MonadSelda m, MonadMask m, MonadIO m) => ChannelID -> m (Maybe Channel)
+getChannel identifier = listToMaybe . fromRels <$> query q
+  where
+    q = do
+      ch@(channelId :*: _) <- select (gen channels)
+      restrict (channelId .== literal identifier)
+      return ch
+
+channelExists :: (MonadSelda m, MonadMask m, MonadIO m) => ChannelID -> m Bool
+channelExists identifier = not . null <$> getChannel identifier
+
+isChannelOwner :: (MonadSelda m, MonadIO m, MonadMask m) => ChannelID -> Username -> m Bool
+isChannelOwner identifier username = not . null <$> query q
+  where
+    q = do
+      userId :*: _ :*: username' :*: _ <- select (gen users)
+      channelId :*: _ :*: channelOwner :*: _ <- select (gen channels)
+      restrict (userId .== channelOwner)
+      restrict (username' .== literal username)
+      restrict (channelId .== literal identifier)
+      return channelId
+
 userChannels :: (MonadMask m, MonadIO m) => Username -> SeldaT m [Channel]
 userChannels username = fromRels <$> query q
   where
@@ -28,12 +55,25 @@ userChannels username = fromRels <$> query q
       restrict (username' .== literal username)
       return channel
 
-insertChannel :: (MonadMask m, MonadIO m) => Username -> Text -> Visibility -> SeldaT m ()
-insertChannel username channel visibility = do
-  mUserId <- listToMaybe <$> getUser
-  void $ forM mUserId $ \userId ->
-    insertUnless (gen channels) (doesNotExist userId) [ def :*: channel :*: userId :*: visibility ]
+updateChannelPrivacy :: (MonadMask m, MonadIO m, MonadSelda m) => ChannelID -> Visibility -> m (Maybe Channel)
+updateChannelPrivacy channelId visibility = do
+  void $ update (gen channels) predicate (\channel -> channel `with` [pVis := literal visibility])
+  getChannel channelId
   where
+    predicate (channelId' :*: _) = channelId' .== literal channelId
+    _ :*: _ :*: _ :*: pVis = selectors (gen channels)
+
+insertChannel :: (MonadMask m, MonadIO m, MonadSelda m) => Username -> Text -> Visibility -> m (Maybe Channel)
+insertChannel username channel visibility = runMaybeT $ do
+  userId <- MaybeT (listToMaybe <$> getUser)
+  channelId <- toChannelId <$> MaybeT (insertUnless (gen channels) (doesNotExist userId) [ def :*: channel :*: userId :*: visibility ])
+  MaybeT (listToMaybe . fromRels <$> query (q channelId))
+  where
+    q channelId = do
+      ch@(channelId' :*: _) <- select (gen channels)
+      restrict (channelId' .== literal channelId)
+      return ch
+    toChannelId = ChannelID . fromRowId
     doesNotExist userId (_ :*: channel' :*: userId' :*: _) = channel' .== literal channel .&& userId' .== literal userId
     getUser = query $ do
       userId :*: _ :*: user :*: _ <- select (gen users)

src/Database/Schema.hs

@@ -44,7 +44,7 @@ newtype UserID = UserID {unUserID :: Int} deriving (Show)
 
 newtype BookID = BookID {unBookID :: Int} deriving (Show, ToJSON, FromJSON, FromHttpApiData, Eq, Ord)
 
-newtype ChannelID = ChannelID {unChannelID :: Int} deriving (Show, ToHttpApiData, FromHttpApiData)
+newtype ChannelID = ChannelID {unChannelID :: Int} deriving (Show, ToHttpApiData, FromHttpApiData, ToJSON, FromJSON)
 
 newtype TagID = TagID {unTagID :: Int} deriving (Show)