Start working on multiple data backends

- Closes #28

.gitignore

@@ -1,2 +1,6 @@
 dist/
 config/config.dhall
+/ctags
+/TAGS
+/result*
+/backend/config

backend/ChangeLog.md

@@ -0,0 +1,5 @@
+# Revision history for backend
+
+## 0.1.0.0 -- YYYY-mm-dd
+
+* First version. Released on an unsuspecting world.

backend/LICENSE

@@ -0,0 +1,30 @@
+Copyright (c) 2018, Mats Rauhala
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Mats Rauhala nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

backend/Setup.hs

@@ -0,0 +1,2 @@
+import Distribution.Simple
+main = defaultMain

backend/backend.cabal

@@ -1,7 +1,7 @@
--- Initial ebook-manager.cabal generated by cabal init.  For further
+-- Initial backend.cabal generated by cabal init.  For further
 -- documentation, see http://haskell.org/cabal/users-guide/
 
-name:                ebook-manager
+name:                backend
 version:             0.1.0.0
 -- synopsis:
 -- description:
@@ -15,7 +15,7 @@ build-type:          Simple
 extra-source-files:  ChangeLog.md
 cabal-version:       >=1.10
 
-executable ebook-manager
+executable backend
   main-is:             Main.hs
   other-modules:       Devel.Main
                      , API
@@ -23,8 +23,6 @@ executable ebook-manager
                      , API.Catalogue
                      , API.Channels
                      , API.Users
-                     , Configuration
-                     , Data.Versioned
                      , Database
                      , Database.Book
                      , Database.Channel
@@ -38,7 +36,10 @@ executable ebook-manager
                      , Types
                      , View
   -- other-extensions:
-  build-depends:       base >=4.10 && <4.11
+  build-depends:       base >=4.10
+                     , exceptions
+                     , monad-control
+                     , common
                      , aeson
                      , asn1-data
                      , asn1-types
@@ -80,8 +81,8 @@ executable ebook-manager
                      , xml-conduit
                      , xml-hamlet
   hs-source-dirs:      src
+  default-language:    Haskell2010
   default-extensions:  DeriveGeneric
                      , NoImplicitPrelude
                      , OverloadedStrings
                      , RecordWildCards
-  default-language:    Haskell2010

backend/src/API.hs

@@ -27,8 +27,8 @@ data Index = Index
 
 type API = Get '[HTML] (AppView Index)
       :<|> Users.API
-      :<|> "api" :> Channels.API
-      :<|> "api" :> Books.API
+      :<|> "api" :> "current" :> Channels.API
+      :<|> "api" :> "current" :> Books.API
       :<|> "api" :> "1" :> Catalogue.VersionedAPI 1
       :<|> "api" :> "current" :> Catalogue.VersionedAPI 1
 

backend/src/API/Books.hs

@@ -15,18 +15,19 @@
 {-# Language NamedFieldPuns #-}
 module API.Books where
 
-import Servant hiding (contentType)
-import Types
 import           ClassyPrelude
-import Server.Auth
-import Servant.Auth as SA
+import           Control.Lens
+import           Control.Monad.Catch (throwM, MonadThrow)
 import           Data.Aeson
+import           Data.Generics.Product
+import           Database
 import           Database.Book
 import           Database.Channel
 import           Database.Tag
-import Database
-import Control.Lens
-import Data.Generics.Product
+import           Servant hiding (contentType)
+import           Servant.Auth as SA
+import           Server.Auth
+import           Types
 
 import           Control.Monad.Trans.Maybe
 
@@ -36,14 +37,14 @@ import Crypto.Hash (digestFromByteString)
 
 data JsonBook = JsonBook { identifier :: BookID
                          , contentType :: Text
-                         , title :: Maybe Text
+                         , title :: Text
                          , description :: Maybe Text
                          , channels :: [Text]
                          , tags :: [Text] }
               deriving (Generic, Show)
 
 data PostBook = PostBook { contentType :: Text
-                         , title :: Maybe Text
+                         , title :: Text
                          , description :: Maybe Text
                          , channels :: [Text]
                          , tags :: [Text] }
@@ -61,7 +62,9 @@ type BaseAPI = "books" :> Get '[JSON] [JsonBook]
        :<|> "books" :> ReqBody '[JSON] PostBook :> Post '[JSON] JsonBook
        :<|> "books" :> Capture "book_id" BookID :> "meta" :> ReqBody '[JSON] JsonBook :> Put '[JSON] JsonBook
        :<|> "books" :> Capture "book_id" BookID :> ReqBody '[OctetStream] ByteString :> Put '[JSON] NoContent
-       :<|> "books" :> Capture "book_id" BookID :> Get '[OctetStream] ByteString
+       :<|> GetBook
+
+type GetBook = "books" :> Capture "book_id" BookID :> Get '[OctetStream] ByteString
 
 handler :: ServerT API AppM
 handler user = listBooksHandler user

backend/src/API/Catalogue.hs

@@ -16,15 +16,17 @@
 {-# Language ScopedTypeVariables #-}
 module API.Catalogue (VersionedAPI, handler) where
 
-import Types
-import Servant
+import qualified API.Books
 import           ClassyPrelude
+import           Database
+import           Database.Book (Book(..))
+import qualified Database.Channel as Channel
 import           GHC.TypeLits
-import Server.Auth
+import           Servant hiding (contentType)
 import           Servant.Auth as SA
 import           Servant.XML
-import qualified Database.Channel as Channel
-import Database
+import           Server.Auth
+import           Types
 
 -- This is my first try on going to versioned apis, things might change
 -- I think my rule of thumb is that you can add new things as you want, but
@@ -96,15 +98,40 @@ instance ToNode (Catalog 1) where
 
 class Monad m => VersionedCatalog m (v :: Nat) where
   getChannels :: SafeUser -> m (Catalog v)
+  getBooks :: Channel.ChannelID -> SafeUser -> m (Catalog v)
 
 instance VersionedCatalog AppM 1 where
-  getChannels SafeUser{username} = do
+  getChannels = getChannelsV1
+  getBooks = getBooksV1
+
+relUrl :: Link -> Rel
+relUrl x = Rel ("/api/current/" <> (pack . uriPath . linkURI $ x))
+
+getBooksV1 :: Channel.ChannelID -> SafeUser -> AppM (Catalog 1)
+getBooksV1 channelID SafeUser{username} = do
   updated <- liftIO getCurrentTime
-    let self = Rel ("/api/current/" <> selfUrl)
+  let self = relUrl selfUrl
+      start = relUrl startUrl
+      selfUrl = safeLink (Proxy @(BaseAPI 1)) (Proxy @(ChannelCatalog 1)) channelID
+      startUrl = safeLink (Proxy @(BaseAPI 1)) (Proxy @(RootCatalog 1))
+      pagination = Pagination Nothing Nothing
+  entries <- map (toEntry updated) <$> runDB (Channel.channelBooks username channelID)
+  pure CatalogV1{..}
+  where
+    toEntry updated Book{description,title,identifier=bookId} =
+      let content = fromMaybe "no content" description
+          identifier = pack . show $ bookId
+          link = Right (Acquisition (relUrl (safeLink (Proxy @API.Books.BaseAPI) (Proxy @API.Books.GetBook) bookId)))
+      in EntryV1{..}
+
+getChannelsV1 :: SafeUser -> AppM (Catalog 1)
+getChannelsV1 SafeUser{username} = do
+  updated <- liftIO getCurrentTime
+  let self = relUrl selfUrl
       -- I'm not sure if this safe link approach is really useable with this
       -- api hierarchy since I can't access the topmost api from here. Also
       -- authentication would bring a little bit of extra effort as well
-        selfUrl = pack . uriPath . linkURI $ safeLink (Proxy @(BaseAPI 1)) (Proxy @(RootCatalog 1))
+      selfUrl = safeLink (Proxy @(BaseAPI 1)) (Proxy @(RootCatalog 1))
       start = self
       pagination = Pagination Nothing Nothing
   entries <- map (fromChannel updated) <$> runDB (Channel.userChannels username)
@@ -112,14 +139,16 @@ instance VersionedCatalog AppM 1 where
   where
     fromChannel :: UTCTime -> Channel.Channel -> Entry 1
     fromChannel updated Channel.Channel{..} =
-        let url = pack . uriPath . linkURI $ safeLink (Proxy @(BaseAPI 1)) (Proxy @(ChannelCatalog 1)) identifier
-            self = Rel ("/api/current/" <> url)
+      let url = safeLink (Proxy @(BaseAPI 1)) (Proxy @(ChannelCatalog 1)) identifier
+          self = relUrl url
       in EntryV1 channel channel updated channel (Left $ SubSection self)
 
 type VersionedAPI (v :: Nat) = Auth '[SA.BasicAuth, SA.JWT] SafeUser :> BaseAPI v
 
-type RootCatalog (v :: Nat) = "catalog" :> Get '[XML] (Catalog v)
-type ChannelCatalog (v :: Nat) = "catalog" :> "channel" :> Capture "channel_id" Channel.ChannelID :> Get '[XML] (Catalog v)
+type CatalogContent = '[XML, OPDS]
+
+type RootCatalog (v :: Nat) = "catalog" :> Get CatalogContent (Catalog v)
+type ChannelCatalog (v :: Nat) = "catalog" :> "channel" :> Capture "channel_id" Channel.ChannelID :> Get CatalogContent (Catalog v)
 type BaseAPI (v :: Nat) = RootCatalog v
                     :<|> ChannelCatalog v
 
@@ -127,6 +156,8 @@ handler :: forall v. VersionedCatalog AppM v => ServerT (VersionedAPI v) AppM
 handler auth = catalogRoot :<|> catalogChannels
   where
     catalogChannels :: Channel.ChannelID -> AppM (Catalog v)
-    catalogChannels _ = throwM err403{errBody="Not implemented"}
+    -- Channel specific catalog returns tags inside the catalog
+    catalogChannels identifier = flip requireLoggedIn auth (getBooks identifier)
     catalogRoot :: AppM (Catalog v)
+    -- catalog root returns channels
     catalogRoot = flip requireLoggedIn auth getChannels

backend/src/API/Channels.hs

@@ -0,0 +1,76 @@
+{-# Language DataKinds #-}
+{-# Language TypeFamilies #-}
+{-# Language TypeOperators #-}
+{-# Language NoImplicitPrelude #-}
+{-# Language MultiParamTypeClasses #-}
+{-# Language OverloadedStrings #-}
+{-# Language TemplateHaskell #-}
+{-# Language QuasiQuotes #-}
+{-# Language RecordWildCards #-}
+{-# Language DeriveGeneric #-}
+{-# Language FlexibleInstances #-}
+{-# Language TypeApplications #-}
+{-# Language DataKinds #-}
+{-# Language DuplicateRecordFields #-}
+{-# Language NamedFieldPuns #-}
+module API.Channels (API, handler, JsonChannel(..)) where
+
+import ClassyPrelude
+import Control.Lens
+import Control.Monad.Catch (throwM, MonadThrow)
+import Control.Monad.Logger
+import Data.Aeson
+import Data.Generics.Product
+import Database
+import Database.Channel
+import Servant
+import Servant.Auth as SA
+import Server.Auth
+import Types
+
+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] UpdateChannel
+          :<|> "channels" :> Capture "channel_id" ChannelID :> ReqBody '[JSON] UpdateChannel :> Put '[JSON] UpdateChannel
+          :<|> "channels" :> Get '[JSON] [JsonChannel]
+
+handler :: ServerT API AppM
+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 ->
+  -- I could use the super thing from generic-lens, but then I would need to
+  -- use the 'channel' accessor somehow or export it
+  fmap (\Channel{..} -> JsonChannel{..}) <$> runDB (userChannels (view (field @"username") user))
+
+newChannelHandler :: AuthResult SafeUser -> JsonChannel -> AppM UpdateChannel
+newChannelHandler auth JsonChannel{..} = flip requireLoggedIn auth $ \user -> do
+  $logInfo $ "Creating channel for user " <> pack (show user)
+  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{..}

backend/src/API/Users.hs

@@ -7,17 +7,18 @@
 {-# Language TypeApplications #-}
 module API.Users  where
 
-import Servant
 import ClassyPrelude
-import Types
+import Control.Monad.Catch (throwM, MonadThrow)
 import Data.Aeson
-import Web.FormUrlEncoded
 import Database (runDB)
-import Database.User
 import Database.Schema
-import Server.Auth
-import Servant.Auth.Server as SAS
+import Database.User
+import Servant
 import Servant.Auth as SA
+import Servant.Auth.Server as SAS
+import Server.Auth
+import Types
+import Web.FormUrlEncoded
 
 
 data RegisterForm = RegisterForm { username :: Username

backend/src/Database.hs

@@ -15,15 +15,17 @@ module Database
   , SeldaT )
   where
 
-import Data.Generics.Product
-import Control.Lens (view)
-import Data.Pool (Pool, withResource)
-import Database.Selda.Backend (SeldaConnection, runSeldaT, SeldaT)
-import Database.Selda (query, select, transaction)
-import Database.Selda.Generic (gen, fromRel, fromRels, toRel)
 import ClassyPrelude
+import Control.Lens (view)
+import Control.Monad.Catch (MonadMask)
+import Control.Monad.Trans.Control (MonadBaseControl)
+import Data.Generics.Product
+import Data.Pool (Pool, withResource)
+import Database.Selda (query, select, transaction)
+import Database.Selda.Backend (SeldaConnection, runSeldaT, SeldaT)
+import Database.Selda.Generic (gen, fromRel, fromRels, toRel)
 
-type DBLike r m = (MonadIO m, MonadReader r m, MonadBaseControl IO m, MonadMask m, HasField' "database" r (Pool SeldaConnection))
+type DBLike r m = (MonadBaseControl IO m, MonadIO m, MonadReader r m, HasField "database" r r (Pool SeldaConnection) (Pool SeldaConnection), MonadMask m)
 
 runDB :: DBLike r m => SeldaT m a -> m a
 runDB q = do

backend/src/Database/Book.hs

@@ -18,18 +18,17 @@ module Database.Book
   , BookID) where
 
 import ClassyPrelude
-import Database.Schema (books, users, Username, Book(..), BookID(..), UserID, HashDigest(..))
+import Control.Lens (view)
+import Control.Monad.Catch (MonadCatch)
+import Data.Generics.Product
 import Database
+import Database.Channel (booksChannels, attachChannel, clearChannels)
+import Database.Schema (books, users, Username, Book(..), BookID(..), UserID, HashDigest(..))
 import Database.Selda
 import Database.Selda.Generic
-
-import Control.Lens (view)
-import Data.Generics.Product
-
 import Database.Tag (booksTags, attachTag, clearTags)
-import Database.Channel (booksChannels, attachChannel, clearChannels)
 
-usersBooks :: (MonadSelda m, MonadMask m, MonadIO m) => Username -> m [Book]
+usersBooks :: (MonadSelda m, MonadIO m) => Username -> m [Book]
 usersBooks username = fromRels <$> query q
   where
     q = do
@@ -41,7 +40,7 @@ usersBooks username = fromRels <$> query q
       return book
 
 
-getBook :: (MonadSelda m, MonadMask m, MonadIO m) => BookID -> Username -> m (Maybe Book)
+getBook :: (MonadSelda m, MonadIO m) => BookID -> Username -> m (Maybe Book)
 getBook identifier owner = listToMaybe . fromRels <$> query q
   where
     q = do
@@ -51,12 +50,12 @@ getBook identifier owner = listToMaybe . fromRels <$> query q
       return book
 
 data InsertBook = InsertBook { contentType :: Text
-                             , title :: Maybe Text
+                             , title :: Text
                              , description :: Maybe Text
                              , owner :: Username }
 
 -- Always inserts
-insertBook :: (MonadSelda m, MonadMask m, MonadIO m) => InsertBook -> m (Maybe BookID)
+insertBook :: (MonadSelda m, MonadIO m) => InsertBook -> m (Maybe BookID)
 insertBook InsertBook{..} = do
   mUserId <- query $ do
     userId :*: _ :*: username' :*: _ <- select (gen users)
@@ -68,14 +67,14 @@ insertBook InsertBook{..} = do
 
 data UpdateBook = UpdateBook { identifier :: BookID
                              , contentType :: Text
-                             , title :: Maybe Text
+                             , title :: Text
                              , description :: Maybe Text
                              , owner :: Username
                              , tags :: [Text]
                              , channels :: [Text] }
                 deriving (Show, Generic)
 
-bookExists :: (MonadSelda m, MonadMask m, MonadIO m) => BookID -> m Bool
+bookExists :: (MonadSelda m, MonadIO m) => BookID -> m Bool
 bookExists identifier = not . null <$> query q
   where
     q = do
@@ -83,7 +82,7 @@ bookExists identifier = not . null <$> query q
       restrict (bookId .== literal identifier)
       return bookId
 
-isBookOwner :: (MonadSelda m, MonadIO m, MonadThrow m) => BookID -> Username -> m Bool
+isBookOwner :: (MonadSelda m, MonadIO m) => BookID -> Username -> m Bool
 isBookOwner identifier username = not . null <$> query (bookOwner' identifier username)
 
 bookOwner' :: BookID -> Username -> Query s (Col s UserID :*: Col s BookID)
@@ -95,7 +94,7 @@ bookOwner' identifier username = do
   restrict (bookId .== literal identifier)
   return (userId :*: bookId)
 
-updateBook :: (MonadSelda m, MonadMask m, MonadIO m) => UpdateBook -> m (Maybe UpdateBook)
+updateBook :: (MonadCatch m, MonadSelda m, MonadIO m) => UpdateBook -> m (Maybe UpdateBook)
 updateBook UpdateBook{..} = do
   clearTags identifier >> connectTags
   clearChannels identifier >> connectChannels
@@ -114,7 +113,7 @@ updateBook UpdateBook{..} = do
     predicate (bookId :*: _) = bookId .== literal identifier
 
 
-getUpdateBook :: (MonadMask m, MonadIO m, MonadSelda m) => BookID -> Username -> m (Maybe UpdateBook)
+getUpdateBook :: (MonadIO m, MonadSelda m) => BookID -> Username -> m (Maybe UpdateBook)
 getUpdateBook bookId username = do
   mBook <- getBook bookId username
   forM mBook $ \Book{..} -> do
@@ -122,7 +121,7 @@ getUpdateBook bookId username = do
     tags <- map (view (field @"tag")) <$> booksTags bookId
     return UpdateBook{owner=username,..}
 
-setContent :: (MonadSelda m, MonadMask m, MonadIO m) => BookID -> Username -> HashDigest -> m ()
+setContent :: (MonadSelda m, MonadIO m) => BookID -> Username -> HashDigest -> m ()
 setContent identifier owner digest = do
   mOwner <- query (bookOwner' identifier owner)
   void $ forM (listToMaybe mOwner) $ \_ ->

backend/src/Database/Channel.hs

@@ -0,0 +1,128 @@
+{-# Language TypeApplications #-}
+{-# Language DataKinds #-}
+{-# Language NamedFieldPuns #-}
+module Database.Channel
+  ( userChannels
+  , insertChannel
+  , channelExists
+  , isChannelOwner
+  , updateChannelPrivacy
+  , attachChannel
+  , Visibility(..)
+  , clearChannels
+  , booksChannels
+  , channelBooks
+  , Channel(..)
+  , ChannelID(..) )
+  where
+
+import ClassyPrelude
+import Control.Monad.Catch (MonadMask)
+import Database
+import Database.Schema
+import Database.Selda
+import Database.Selda.Generic
+
+import Control.Monad.Trans.Maybe
+
+getChannel :: (MonadSelda m, MonadIO m) => ChannelID -> m (Maybe Channel)
+getChannel identifier = listToMaybe . fromRels <$> query q
+  where
+    q = do
+      ch@(channelId :*: _) <- select (gen channels)
+      restrict (channelId .== literal identifier)
+      return ch
+
+channelExists :: (MonadSelda m, MonadIO m) => ChannelID -> m Bool
+channelExists identifier = not . null <$> getChannel identifier
+
+isChannelOwner :: (MonadSelda m, MonadIO 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
+    q = do
+      userId :*: _ :*: username' :*: _ <- select (gen users)
+      channel@(_ :*: _ :*: owner :*: _) <- select (gen channels)
+      restrict (owner .== userId)
+      restrict (username' .== literal username)
+      return channel
+
+updateChannelPrivacy :: (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)
+      restrict (user .== literal username)
+      return userId
+
+channelBooks :: (MonadSelda m, MonadIO m) => Username -> ChannelID -> m [Book]
+channelBooks username identifier = fromRels <$> query q
+  where
+    q = do
+      channelId :*: bookId' <- select (gen bookChannels)
+      channelId' :*: _ :*: owner :*: _ <- select (gen channels)
+      userId :*: _ :*: username' :*: _ <- select (gen users)
+      book@(bookId :*: _) <- select (gen books)
+      restrict (username' .== literal username .&& owner .== userId)
+      restrict (channelId .== literal identifier .&& channelId .== channelId')
+      restrict (bookId .== bookId')
+      return book
+
+booksChannels :: (MonadSelda m, MonadIO m) => BookID -> m [Channel]
+booksChannels bookId = fromRels <$> query q
+  where
+    q = do
+      channelId :*: bookId' <- select (gen bookChannels)
+      ch@(channelId' :*: _) <- select (gen channels)
+      restrict (channelId .== channelId')
+      restrict (bookId' .== literal bookId)
+      return ch
+
+attachChannel :: (MonadIO m, MonadSelda m) => Username -> BookID -> Text -> m ()
+attachChannel username bookId channel = do
+  mCh <- fromRels <$> query channelQ
+  forM_ mCh $ \Channel{identifier} ->
+    whenM (null <$> query (attachQ identifier)) $
+      void $ insertGen bookChannels [BookChannel identifier bookId]
+  where
+    attachQ channelId = do
+      (channelId' :*: bookId') <- select (gen bookChannels)
+      restrict (channelId' .== literal channelId .&& bookId' .== literal bookId)
+      return channelId'
+    channelQ = do
+      userId :*: _ :*: username' :*: _ <- select (gen users)
+      ch@(_ :*: channel' :*: owner :*: _) <- select (gen channels)
+      restrict (username' .== literal username)
+      restrict (owner .== userId)
+      restrict (channel' .== literal channel)
+      return ch
+
+clearChannels :: (MonadIO m, MonadSelda m) => BookID -> m Int
+clearChannels bookId = deleteFrom (gen bookChannels) (\(_ :*: bookId') -> bookId' .== literal bookId)

backend/src/Database/Schema.hs

@@ -42,9 +42,9 @@ instance SqlType Username where
 
 newtype UserID = UserID {unUserID :: Int} deriving (Show)
 
-newtype BookID = BookID {unBookID :: Int} deriving (Show, ToJSON, FromJSON, FromHttpApiData, Eq, Ord)
+newtype BookID = BookID {unBookID :: Int} deriving (Show, ToJSON, FromJSON, FromHttpApiData, Eq, Ord, ToHttpApiData)
 
-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)
 
@@ -101,7 +101,7 @@ newtype HashDigest = HashDigest { unHex :: ByteString } deriving Show
 data Book = Book { identifier :: BookID
                  , contentHash :: Maybe HashDigest
                  , contentType :: Text
-                 , title :: Maybe Text
+                 , title :: Text
                  , description :: Maybe Text
                  , owner :: UserID }
           deriving (Show, Generic)
@@ -124,9 +124,22 @@ data Tag = Tag { identifier :: TagID
                , owner :: UserID }
          deriving (Show, Generic)
 
+data Visibility = Public | Private | Followers
+                deriving (Show, Read, Generic)
+
+instance ToJSON Visibility
+instance FromJSON Visibility
+
+instance SqlType Visibility where
+  mkLit = LCustom . LText . pack . show
+  fromSql (SqlString x) = fromMaybe (error "fromSql: Not a valid visibility token") . readMay . unpack $ x
+  fromSql _             = error "fromSql: Not a valid visibility token"
+  defaultValue = mkLit Private
+
 data Channel = Channel { identifier :: ChannelID
                        , channel :: Text
-                       , owner :: UserID }
+                       , owner :: UserID
+                       , visibility :: Visibility }
              deriving (Show, Generic)
 
 tags :: GenTable Tag

backend/src/Database/Tag.hs

@@ -12,13 +12,14 @@ module Database.Tag
   , Tag(..) ) where
 
 import ClassyPrelude
-import Database.Schema
+import Control.Monad.Catch (MonadCatch)
+import Control.Monad.Trans.Maybe
 import Database
+import Database.Schema
 import Database.Selda
 import Database.Selda.Generic
-import Control.Monad.Trans.Maybe
 
-upsertTag :: (MonadMask m, MonadIO m, MonadSelda m) => Username -> Text -> m (Maybe Tag)
+upsertTag :: (MonadCatch m, MonadIO m, MonadSelda m) => Username -> Text -> m (Maybe Tag)
 upsertTag username tag = runMaybeT $ do
   userId <- MaybeT (listToMaybe <$> query userQ)
   void $ lift $ upsert (gen tags) (predicate userId) id [toRel (Tag def tag userId)]
@@ -34,7 +35,7 @@ upsertTag username tag = runMaybeT $ do
       restrict (username' .== literal username)
       return userId
 
-booksTags :: (MonadMask m, MonadIO m, MonadSelda m) => BookID -> m [Tag]
+booksTags :: (MonadIO m, MonadSelda m) => BookID -> m [Tag]
 booksTags bookId = fromRels <$> query q
   where
     q = do
@@ -44,7 +45,7 @@ booksTags bookId = fromRels <$> query q
       restrict (bookId' .== literal bookId)
       return tag
 
-attachTag :: (MonadMask m, MonadIO m, MonadSelda m) => Username -> BookID -> Text -> m ()
+attachTag :: (MonadCatch m, MonadIO m, MonadSelda m) => Username -> BookID -> Text -> m ()
 attachTag username bookId tag = do
   maybeT <- upsertTag username tag
   forM_ maybeT $ \Tag{identifier} -> do
@@ -56,6 +57,6 @@ attachTag username bookId tag = do
       restrict (tagId' .== literal tagId .&& bookId' .== literal bookId)
       return tagId'
 
-clearTags :: (MonadMask m, MonadIO m, MonadSelda m) => BookID -> m Int
+clearTags :: (MonadIO m, MonadSelda m) => BookID -> m Int
 clearTags bookId = deleteFrom (gen bookTags) (\(_ :*: bookId') -> bookId' .== literal bookId)
 

backend/src/Database/User.hs

@@ -5,20 +5,21 @@
 module Database.User where
 
 import ClassyPrelude
+import Control.Lens (view, over, _Just)
+import Control.Monad (mfilter)
+import Control.Monad.Catch (MonadMask)
+import Control.Monad.Logger
+import Crypto.KDF.BCrypt
+import Crypto.Random.Types (MonadRandom)
+import Data.Generics.Product
 import Database
 import Database.Schema
 import Database.Selda
-import Control.Lens (view, over, _Just)
-import Data.Generics.Product
-import Crypto.KDF.BCrypt
-import Crypto.Random.Types (MonadRandom)
-import Control.Monad.Logger
-import Control.Monad (mfilter)
 
 data UserExistsError = UserExistsError
 
 
-insertUser :: (MonadLogger m, MonadIO m, MonadMask m, MonadRandom m) => Username -> Email -> PlainPassword -> SeldaT m (Either UserExistsError (User NoPassword))
+insertUser :: (MonadMask m, MonadLogger m, MonadIO m, MonadRandom m) => Username -> Email -> PlainPassword -> SeldaT m (Either UserExistsError (User NoPassword))
 insertUser username email (PlainPassword password) =
   getUser' username >>= maybe insert' (const (return $ Left UserExistsError))
   where

backend/src/Datastore.hs

@@ -5,6 +5,7 @@
 {-# Language FlexibleContexts #-}
 {-# Language TypeSynonymInstances #-}
 {-# Language FlexibleInstances #-}
+{-# Language ScopedTypeVariables #-}
 module Datastore where
 
 import ClassyPrelude
@@ -28,26 +29,26 @@ instance MonadDS AppM where
   get = getLocal
 
 putLocal :: ( MonadIO m
-            , HasField' "config" r config
-            , HasField' "store" config store
-            , HasField' "path" store Text
+            , HasField "config" r r config config
+            , HasField "store" config config store store
+            , HasType Text store
             , MonadReader r m)
             => ByteString -> m (Digest SHA256)
 putLocal bs = do
-  store <- unpack <$> view (field @"config" . field @"store" . field @"path")
+  store :: FilePath <- unpack <$> view (field @"config" . field @"store" . typed @Text)
   liftIO $ createDirectoryIfMissing True store
   let key = hashWith SHA256 bs
   writeFile (store </> show key) bs
   return key
 
 getLocal :: ( MonadIO m
-            , HasField' "config" r config
-            , HasField' "store" config store
-            , HasField' "path" store Text
+            , HasField "config" r r config config
+            , HasField "store" config config store store
+            , HasType Text store
             , MonadReader r m)
             => Digest SHA256 -> m (Maybe ByteString)
 getLocal key = do
-  store <- unpack <$> view (field @"config" . field @"store" . field @"path")
+  store <- unpack <$> view (field @"config" . field @"store" . typed @Text)
   liftIO $ createDirectoryIfMissing True store
   let file = store </> show key
   exists <- liftIO $ doesFileExist file

backend/src/Devel/Main.hs

@@ -3,19 +3,18 @@
 {-# Language FlexibleContexts #-}
 module Devel.Main where
 
-import Prelude
-import Control.Monad.Trans.Reader (runReaderT)
-import Main (withApp, defaultMain)
 import Control.Concurrent
 import Control.Monad (void)
+import Control.Monad.Trans.Reader (runReaderT)
 import Data.IORef (IORef, newIORef, readIORef, writeIORef)
-import Foreign.Store (Store(..), lookupStore, readStore, storeAction, withStore)
-import GHC.Word (Word32)
-import Dhall (input, auto)
-
+import Database
 import Database.Schema
 import Database.Selda (tryCreateTable)
-import Database
+import Dhall (input, auto)
+import Foreign.Store (Store(..), lookupStore, readStore, storeAction, withStore)
+import GHC.Word (Word32)
+import Main (withApp, defaultMain)
+import Prelude
 
 update :: IO ()
 update = do
@@ -37,7 +36,7 @@ update = do
 
 develMain :: IO ()
 develMain = do
-  conf <- input auto "./config/devel.dhall"
+  conf <- input auto "../config/devel.dhall"
   withApp conf $ \app -> do
     void $ runReaderT (runDB migrate) app
     defaultMain app

backend/src/Main.hs

@@ -25,6 +25,7 @@ withApp :: Config -> (App -> IO ()) -> IO ()
 withApp config f = do
   let pgHost = view (field @"database" . field @"host") config
       pgPort = 5432
+      pgSchema = Nothing
       pgDatabase = view (field @"database" . field @"database") config
       pgUsername = Just (view (field @"database" . field @"username") config)
       pgPassword = Just (view (field @"database" . field @"password") config)

backend/src/Servant/XML.hs

@@ -1,9 +1,11 @@
 {-# Language OverloadedStrings #-}
 {-# Language FlexibleInstances #-}
 {-# Language MultiParamTypeClasses #-}
+{-# Language TypeApplications #-}
 module Servant.XML
   ( ToNode(..)
   , XML
+  , OPDS
   , Text.Hamlet.XML.xml
   , iso8601 )
   where
@@ -16,14 +18,22 @@ import Network.HTTP.Media.MediaType
 
 data XML
 
+data OPDS
+
 instance (ToNode a) => MimeRender XML a where
   mimeRender _ a =
     let [NodeElement root] = toNode a
     in renderLBS def (Document (Prologue [] Nothing []) root [])
 
+instance (ToNode a) => MimeRender OPDS a where
+  mimeRender _ a = mimeRender (Proxy @XML) a
+
 instance Accept XML where
   contentType _ = "application" // "xml" /: ("charset", "utf-8")
 
+instance Accept OPDS where
+  contentType _ = "application" // "atom+xml" /: ("charset", "utf-8") /: ("profile", "opds-catalog")
+
 iso8601 :: UTCTime -> Text
 iso8601 = pack . formatTime defaultTimeLocale "%Y-%m-%dT%H:%M:%SZ"
 

backend/src/Server.hs

@@ -10,6 +10,7 @@
 {-# Language DeriveGeneric #-}
 {-# Language FlexibleInstances #-}
 {-# Language TypeApplications #-}
+{-# Language ScopedTypeVariables #-}
 module Server where
 
 import qualified API as API
@@ -22,19 +23,21 @@ import Control.Monad.Except
 import Servant.Auth.Server as SAS
 import Control.Lens
 import Data.Generics.Product
+import Server.Auth (SafeUser)
 
 type API = API.API :<|> "static" :> Raw
 
+type Ctx = '[BasicAuthData -> IO (AuthResult SafeUser), CookieSettings, JWTSettings]
 
 server :: App -> Application
-server app = serveWithContext api cfg (enter server' API.handler :<|> serveDirectoryFileServer "static")
+server app = serveWithContext api cfg (hoistServerWithContext (Proxy @ API.API) (Proxy @ Ctx) server' API.handler :<|> serveDirectoryFileServer "static")
   where
     myKey = view (field @"jwk") app
     jwtCfg = defaultJWTSettings myKey
     authCfg = authCheck app
     cookieSettings = SAS.defaultCookieSettings{cookieIsSecure=SAS.NotSecure}
     cfg = jwtCfg :. cookieSettings :. authCfg :. EmptyContext
-    server' :: AppM :~> Servant.Handler
-    server' = NT (Handler . ExceptT . try . (`runReaderT` app) . (runFileLoggingT "logs/server.log"))
+    server' :: AppM a -> Servant.Handler a
+    server' = Handler . ExceptT . try . (`runReaderT` app) . (runFileLoggingT "logs/server.log")
     api :: Proxy API
     api = Proxy

backend/src/Server/Auth.hs

@@ -14,16 +14,17 @@ module Server.Auth
   where
 
 import ClassyPrelude
-import Servant.Auth.Server as SAS
+import Control.Lens (view)
+import Control.Monad.Logger
+import Control.Monad.Catch (throwM, MonadThrow)
 import Data.Aeson
+import Data.Generics.Product
+import Database
 import Database.Schema
 import Database.User
-import Database
-import Types
-import Control.Lens (view)
-import Data.Generics.Product
 import Servant (err401)
-import Control.Monad.Logger
+import Servant.Auth.Server as SAS
+import Types
 
 -- generic-lens can convert similar types to this
 -- I'm trying out servant-auth-server which uses a jwt style login. IIRC anyone
@@ -53,6 +54,6 @@ authCheck app (BasicAuthData username password) = flip runReaderT app $
     password' = PlainPassword $ decodeUtf8 password
     authenticated = SAS.Authenticated . view (super @SafeUser)
 
-requireLoggedIn :: (MonadLogger m, MonadThrow m, Monad m) => (SafeUser -> m a) -> AuthResult SafeUser -> m a
+requireLoggedIn :: (MonadThrow m, MonadLogger m, Monad m) => (SafeUser -> m a) -> AuthResult SafeUser -> m a
 requireLoggedIn f (Authenticated user) = f user
 requireLoggedIn _ u = $logError (pack (show u)) >> throwM err401

common/LICENSE

@@ -0,0 +1,30 @@
+Copyright (c) 2018, Mats Rauhala
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright
+      notice, this list of conditions and the following disclaimer.
+
+    * Redistributions in binary form must reproduce the above
+      copyright notice, this list of conditions and the following
+      disclaimer in the documentation and/or other materials provided
+      with the distribution.
+
+    * Neither the name of Mats Rauhala nor the names of other
+      contributors may be used to endorse or promote products derived
+      from this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

common/common.cabal

@@ -0,0 +1,33 @@
+name:                common
+version:             0.1.0.0
+-- synopsis:
+-- description:
+license:             BSD3
+license-file:        LICENSE
+author:              Mats Rauhala
+maintainer:          mats.rauhala@iki.fi
+-- copyright:
+category:            Web
+build-type:          Simple
+extra-source-files:  ChangeLog.md
+cabal-version:       >=1.10
+
+library
+  exposed-modules:     Configuration
+                     , Data.Versioned
+  -- other-extensions:
+  build-depends:       base >=4.10
+                     , classy-prelude
+                     , dhall
+                     , foreign-store
+                     , generic-lens
+                     , lens
+                     , mtl
+                     , text
+                     , transformers
+  hs-source-dirs:      src
+  default-extensions:  DeriveGeneric
+                     , NoImplicitPrelude
+                     , OverloadedStrings
+                     , RecordWildCards
+  default-language:    Haskell2010

common/src/Configuration.hs

@@ -12,7 +12,9 @@ data Pg = Pg { username :: Text
              , database :: Text }
         deriving (Show, Generic)
 
-newtype Store = Store { path :: Text } deriving (Show, Generic)
+data Store = Filestore { path :: Text }
+           | IPFS { common :: Text }
+           deriving (Show, Generic)
 
 data Config = Config { database :: Pg
                      , store :: Store }

default.nix

@@ -1,10 +1,15 @@
-{ mkDerivation, base, stdenv }:
-mkDerivation {
-  pname = "ebook-manager";
-  version = "0.1.0.0";
-  src = ./.;
-  isLibrary = false;
-  isExecutable = true;
-  executableHaskellDepends = [ base ];
-  license = stdenv.lib.licenses.bsd3;
+{ nixpkgs, haskellPackages }:
+
+(import ./project.nix nixpkgs) {
+  packages = {
+    common = ./common;
+    backend = ./backend;
+  };
+  overrides = self: super: {
+    generic-lens = nixpkgs.haskell.lib.dontCheck super.generic-lens;
+  };
+  tools = with haskellPackages; [
+    ghcid
+    hasktags
+  ];
 }

migrations/V1.1__Channel_visibility.sql

@@ -0,0 +1 @@
+alter table channels add column visibility text NOT NULL default 'Private';

nixpkgs-version.json

@@ -1,7 +1,7 @@
 {
   "url": "https://github.com/nixos/nixpkgs.git",
-  "rev": "83a5765b1fea2472ec9cf9d179d3efd18b45c77e",
+  "rev": "e0d250e5cf6d179e1ccc775472d89718f61fcfd1",
   "date": "2018-01-08T11:52:28+01:00",
-  "sha256": "01rb61dkbzjbwnb3p8lgs03a94f4584199dlr0cwdmqzaxnp506h",
+  "sha256": "1iqpjz4czcpghbv924a5h4jvfmj6c8q6sl3b1z7blz3mi740aivs",
   "fetchSubmodules": true
 }

project.nix

@@ -0,0 +1,39 @@
+nixpkgs:
+
+let
+
+  inherit (nixpkgs.lib) mapAttrs mapAttrsToList escapeShellArg optionalString concatStringsSep concatMapStringsSep;
+
+in
+
+{ packages
+, overrides ? _ : _ : {}
+, tools ? []
+}:
+
+let
+
+  overrides' = nixpkgs.lib.foldr nixpkgs.lib.composeExtensions (_: _: {}) [
+    (self: super: mapAttrs (name: path: self.callCabal2nix name path {}) packages)
+    overrides
+  ];
+  haskellPackages = nixpkgs.haskellPackages.override { overrides = overrides'; };
+  packages' = mapAttrs (name: _: haskellPackages."${name}") packages;
+  mkShell = name: pkg:
+  let
+    n =  "${name}-shell";
+    deps = haskellPackages.ghcWithHoogle (pkgs: pkg.buildInputs ++ pkg.propagatedBuildInputs);
+  in
+  {
+    name = "${n}";
+    value = nixpkgs.buildEnv {
+      name = "${n}";
+      paths = tools;
+      buildInputs = tools ++ [deps];
+    };
+  };
+  shells = nixpkgs.lib.listToAttrs (mapAttrsToList mkShell packages');
+
+in
+
+packages' // shells

release.nix

@@ -0,0 +1,15 @@
+{ nixpkgs ? import <nixpkgs> {} }:
+
+let
+
+  pinnedVersion = nixpkgs.lib.importJSON ./nixpkgs-version.json;
+  pinnedPkgs = import (nixpkgs.fetchFromGitHub {
+    owner = "NixOS";
+    repo = "nixpkgs";
+    inherit (pinnedVersion) rev sha256;
+  }) {};
+  inherit (pinnedPkgs) pkgs;
+
+  in
+
+import ./default.nix { nixpkgs = pinnedPkgs; haskellPackages = pinnedPkgs.haskellPackages; }

src/API/Channels.hs

@@ -1,51 +0,0 @@
-{-# Language DataKinds #-}
-{-# Language TypeFamilies #-}
-{-# Language TypeOperators #-}
-{-# Language NoImplicitPrelude #-}
-{-# Language MultiParamTypeClasses #-}
-{-# Language OverloadedStrings #-}
-{-# Language TemplateHaskell #-}
-{-# Language QuasiQuotes #-}
-{-# Language RecordWildCards #-}
-{-# Language DeriveGeneric #-}
-{-# Language FlexibleInstances #-}
-{-# Language TypeApplications #-}
-{-# Language DataKinds #-}
-module API.Channels (API, handler, JsonChannel(..)) where
-
-import Servant
-import Types
-import ClassyPrelude
-import Server.Auth
-import Servant.Auth as SA
-import Control.Monad.Logger
-import Database
-import Database.Channel
-import Data.Aeson
-import Control.Lens
-import Data.Generics.Product
-
-data JsonChannel = JsonChannel { channel :: Text } deriving (Show, Generic)
-
-instance ToJSON JsonChannel
-instance FromJSON JsonChannel
-
-type API = Auth '[SA.BasicAuth, SA.Cookie, SA.JWT] SafeUser :> BaseAPI
-
-type BaseAPI = "channels" :> ReqBody '[JSON] JsonChannel :> Put '[JSON] JsonChannel
-          :<|> "channels" :> Get '[JSON] [JsonChannel]
-
-handler :: ServerT API AppM
-handler user = newChannelHandler user :<|> listChannelsHandler user
-
-listChannelsHandler :: AuthResult SafeUser -> AppM [JsonChannel]
-listChannelsHandler = requireLoggedIn $ \user ->
-  -- I could use the super thing from generic-lens, but then I would need to
-  -- 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
-  $logInfo $ "Creating channel for user " <> pack (show user)
-  runDB (insertChannel (view (field @"username") user) channel)
-  return ch

src/Database/Channel.hs

@@ -1,72 +0,0 @@
-{-# Language TypeApplications #-}
-{-# Language DataKinds #-}
-{-# Language NamedFieldPuns #-}
-module Database.Channel
-  ( userChannels
-  , insertChannel
-  , attachChannel
-  , clearChannels
-  , booksChannels
-  , Channel(..)
-  , ChannelID )
-  where
-
-import ClassyPrelude
-import Database.Schema
-import Database
-import Database.Selda
-import Database.Selda.Generic
-
-userChannels :: (MonadMask m, MonadIO m) => Username -> SeldaT m [Channel]
-userChannels username = fromRels <$> query q
-  where
-    q = do
-      userId :*: _ :*: username' :*: _ <- select (gen users)
-      channel@(_ :*: _ :*: owner) <- select (gen channels)
-      restrict (owner .== userId)
-      restrict (username' .== literal username)
-      return channel
-
-insertChannel :: (MonadMask m, MonadIO m) => Username -> Text -> SeldaT m ()
-insertChannel username channel = do
-  mUserId <- listToMaybe <$> getUser
-  void $ forM mUserId $ \userId ->
-    insertUnless (gen channels) (doesNotExist userId) [ def :*: channel :*: userId ]
-  where
-    doesNotExist userId (_ :*: channel' :*: userId') = channel' .== literal channel .&& userId' .== literal userId
-    getUser = query $ do
-      userId :*: _ :*: user :*: _ <- select (gen users)
-      restrict (user .== literal username)
-      return userId
-
-booksChannels :: (MonadSelda m, MonadMask m, MonadIO m) => BookID -> m [Channel]
-booksChannels bookId = fromRels <$> query q
-  where
-    q = do
-      channelId :*: bookId' <- select (gen bookChannels)
-      ch@(channelId' :*: _) <- select (gen channels)
-      restrict (channelId .== channelId')
-      restrict (bookId' .== literal bookId)
-      return ch
-
-attachChannel :: (MonadMask m, MonadIO m, MonadSelda m) => Username -> BookID -> Text -> m ()
-attachChannel username bookId channel = do
-  mCh <- fromRels <$> query channelQ
-  forM_ mCh $ \Channel{identifier} ->
-    whenM (null <$> query (attachQ identifier)) $
-      void $ insertGen bookChannels [BookChannel identifier bookId]
-  where
-    attachQ channelId = do
-      (channelId' :*: bookId') <- select (gen bookChannels)
-      restrict (channelId' .== literal channelId .&& bookId' .== literal bookId)
-      return channelId'
-    channelQ = do
-      userId :*: _ :*: username' :*: _ <- select (gen users)
-      ch@(_ :*: channel' :*: owner) <- select (gen channels)
-      restrict (username' .== literal username)
-      restrict (owner .== userId)
-      restrict (channel' .== literal channel)
-      return ch
-
-clearChannels :: (MonadMask m, MonadIO m, MonadSelda m) => BookID -> m Int
-clearChannels bookId = deleteFrom (gen bookChannels) (\(_ :*: bookId') -> bookId' .== literal bookId)