vervis/src/Vervis/Foundation.hs

{- This file is part of Vervis.
 -
 - Written in 2016, 2018, 2019 by fr33domlover <fr33domlover@riseup.net>.
 -
 - ♡ Copying is an act of love. Please copy, reuse and share.
 -
 - The author(s) have dedicated all copyright and related and neighboring
 - rights to this software to the public domain worldwide. This software is
 - distributed without any warranty.
 -
 - You should have received a copy of the CC0 Public Domain Dedication along
 - with this software. If not, see
 - <http://creativecommons.org/publicdomain/zero/1.0/>.
 -}

module Vervis.Foundation where

import Prelude (init, last)

import Control.Concurrent.MVar (MVar, newEmptyMVar)
import Control.Concurrent.STM.TVar
import Control.Monad.Logger.CallStack (logWarn)
import Control.Monad.STM (atomically)
import Control.Monad.Trans.Except
import Control.Monad.Trans.Maybe
import Crypto.Error (CryptoFailable (..))
import Crypto.PubKey.Ed25519 (PublicKey, publicKey, signature, verify)
import Data.Either (isRight)
import Data.HashMap.Strict (HashMap)
import Data.Maybe (fromJust)
import Data.PEM (pemContent)
import Data.Text.Encoding (decodeUtf8')
import Data.Time.Interval (TimeInterval, fromTimeUnit, toTimeUnit)
import Data.Time.Units (Second, Minute, Day)
import Database.Persist.Sql (ConnectionPool, runSqlPool)
import Graphics.SVGFonts.ReadFont (PreparedFont)
import Network.HTTP.Client (Manager, HttpException, requestFromURI, responseBody)
import Network.HTTP.Simple (httpJSONEither, setRequestManager, addRequestHeader)
import Network.HTTP.Types.Header (hHost)
import Network.URI (URI, uriAuthority, uriFragment, uriRegName, parseURI)
import Text.Shakespeare.Text (textFile)
import Text.Hamlet          (hamletFile)
--import Text.Jasmine         (minifym)
import UnliftIO.MVar (withMVar)
import Yesod.Auth.Account
import Yesod.Auth.Account.Message (AccountMsg (MsgUsernameExists))
import Yesod.Auth.Message   (AuthMessage (IdentifierNotFound))
import Yesod.Core.Types     (Logger)
import Yesod.Default.Util   (addStaticContentExternal)

import qualified Data.ByteString.Char8 as BC (unpack)
import qualified Data.ByteString.Lazy as BL (ByteString)
import qualified Data.HashMap.Strict as M (lookup, insert)
import qualified Yesod.Core.Unsafe as Unsafe
--import qualified Data.CaseInsensitive as CI
import Data.Text as T (pack, intercalate, concat)
--import qualified Data.Text.Encoding as TE

import Network.HTTP.Signature hiding (Algorithm (..))
import Yesod.Auth.Unverified
import Yesod.Auth.Unverified.Creds
import Yesod.HttpSignature (YesodHttpSig (..))
import Yesod.Mail.Send

import qualified Network.HTTP.Signature as S (Algorithm (..))

import Network.FedURI
import Web.ActivityPub hiding (PublicKey)

import Text.Email.Local
import Text.Jasmine.Local (discardm)

import Vervis.Access
import Vervis.ActorKey (ActorKey)
import Vervis.Import.NoFoundation hiding (Handler, Day, last, init, logWarn)
import Vervis.Model.Group
import Vervis.Model.Ident
import Vervis.Model.Role
import Vervis.Widget (breadcrumbsW, revisionW)

-- | The foundation datatype for your application. This can be a good place to
-- keep settings and values requiring initialization before your application
-- starts running, such as database connections. Every handler will have
-- access to the data present here.
data App = App
    { appSettings     :: AppSettings
    , appStatic       :: Static -- ^ Settings for static file serving.
    , appConnPool     :: ConnectionPool -- ^ Database connection pool.
    , appHttpManager  :: Manager
    , appLogger       :: Logger
    , appMailQueue    :: Maybe (Chan (MailRecipe App))
    , appSvgFont      :: PreparedFont Double
    , appActorKeys    :: TVar (ActorKey, ActorKey, Bool)
    , appInstanceMutex :: TVar (HashMap Text (MVar ()))
    , appCapSignKey   :: ActorKey
    , appHashidEncode :: Int64 -> Text
    , appHashidDecode :: Text -> Maybe Int64

    , appActivities  :: TVar (Vector (UTCTime, Either String (ByteString, BL.ByteString)))
    }

-- This is where we define all of the routes in our application. For a full
-- explanation of the syntax, please see:
-- http://www.yesodweb.com/book/routing-and-handlers
--
-- Note that this is really half the story; in Application.hs, mkYesodDispatch
-- generates the rest of the code. Please see the following documentation
-- for an explanation for this split:
-- http://www.yesodweb.com/book/scaffolding-and-the-site-template#scaffolding-and-the-site-template_foundation_and_application_modules
--
-- This function also generates the following type synonyms:
-- type Handler = HandlerT App IO
-- type Widget = WidgetT App IO ()
mkYesodData "App" $(parseRoutesFile "config/routes")

-- | A convenient synonym for creating forms.
type Form a = Html -> MForm (HandlerT App IO) (FormResult a, Widget)

type AppDB = YesodDB App

-- Please see the documentation for the Yesod typeclass. There are a number
-- of settings which can be configured by overriding methods here.
instance Yesod App where
    -- Controls the base of generated URLs. For more information on modifying,
    -- see: https://github.com/yesodweb/yesod/wiki/Overriding-approot
    approot = ApprootRequest $ \app req ->
        case appRoot $ appSettings app of
            Nothing -> getApprootText guessApproot app req
            Just root -> root

    -- Store session data on the client in encrypted cookies,
    -- default session idle timeout is 120 minutes
    makeSessionBackend app =
        -- sslOnlySessions $
        let s = appSettings app
            t = fromIntegral (toTimeUnit $ appClientSessionTimeout s :: Minute)
            k = appClientSessionKeyFile s
        in  Just <$> defaultClientSessionBackend t k

    -- Yesod Middleware allows you to run code before and after each handler function.
    -- The defaultYesodMiddleware adds the response header "Vary: Accept, Accept-Language" and performs authorization checks.
    -- The defaultCsrfMiddleware:
    --   a) Sets a cookie with a CSRF token in it.
    --   b) Validates that incoming write requests include that token in either a header or POST parameter.
    -- For details, see the CSRF documentation in the Yesod.Core.Handler module of the yesod-core package.
    yesodMiddleware
        -- sslOnlyMiddleware 120 .
        = defaultCsrfSetCookieMiddleware
        . (\ handler ->
            csrfCheckMiddleware
                handler
                (getCurrentRoute >>= \ mr -> case mr of
                    Nothing                      -> return False
                    Just InboxR                  -> return False
                    Just (GitUploadRequestR _ _) -> return False
                    Just r                       -> isWriteRequest r
                )
                defaultCsrfHeaderName
                defaultCsrfParamName
          )
        . defaultYesodMiddleware

    defaultLayout widget = do
        master <- getYesod
        mmsg <- getMessage
        mperson <- maybeAuthAllowUnverified
        (title, bcs) <- breadcrumbs

        -- We break up the default layout into two components:
        -- default-layout is the contents of the body tag, and
        -- default-layout-wrapper is the entire page. Since the final
        -- value passed to hamletToRepHtml cannot be a widget, this allows
        -- you to use normal widget features in default-layout.

        pc <- widgetToPageContent $ do
            setTitle $ toHtml $
                T.intercalate " → " (map snd bcs) <> " → " <> title
            let instanceHost = appInstanceHost $ appSettings master
            $(widgetFile "default-layout")
        withUrlRenderer $(hamletFile "templates/default-layout-wrapper.hamlet")

    -- The page to be redirected to when authentication is required.
    authRoute _ = Just $ AuthR LoginR

    -- Who can access which pages.
    isAuthorized r w = case (r, w) of
        (AuthR a                   , True)
            | a == resendVerifyR           -> personFromResendForm
        (AuthR (PluginR "account" ["verify", u, _]), False) -> personUnver u

        (OutboxR                   , True) -> personAny

        (GroupsR                   , True) -> personAny
        (GroupNewR                 , _   ) -> personAny
        (GroupMembersR grp         , True) -> groupAdmin grp
        (GroupMemberNewR grp       , _   ) -> groupAdmin grp
        (GroupMemberR grp _memb    , True) -> groupAdmin grp

        (KeysR                     , _   ) -> personAny
        (KeyR _key                 , _   ) -> personAny
        (KeyNewR                   , _   ) -> personAny

        (ClaimRequestsPersonR      , _   ) -> personAny

        (ProjectRolesR shr         , _   ) -> personOrGroupAdmin shr
        (ProjectRoleNewR shr       , _   ) -> personOrGroupAdmin shr
        (ProjectRoleR shr _rl      , _   ) -> personOrGroupAdmin shr
        (ProjectRoleOpsR shr _rl   , _   ) -> personOrGroupAdmin shr
        (ProjectRoleOpNewR shr _rl , _   ) -> personOrGroupAdmin shr

        (ReposR shr                , True) -> personOrGroupAdmin shr
        (RepoNewR shr              , _   ) -> personOrGroupAdmin shr
        (RepoR shar _              , True) -> person shar
        (RepoEditR shr _rp         , _   ) -> person shr
        (RepoDevsR shr _rp         , _   ) -> person shr
        (RepoDevNewR shr _rp       , _   ) -> person shr
        (RepoDevR shr _rp _dev     , _   ) -> person shr

        (ProjectsR shr             , True) -> personOrGroupAdmin shr
        (ProjectNewR shr           , _   ) -> personOrGroupAdmin shr
        (ProjectR shr _prj         , True) -> person shr
        (ProjectEditR shr _prj     , _   ) -> person shr
        (ProjectDevsR shr _prj     , _   ) -> person shr
        (ProjectDevNewR shr _prj   , _   ) -> person shr
        (ProjectDevR shr _prj _dev , _   ) -> person shr

--      (GlobalWorkflowsR          , _   ) -> serverAdmin
--      (GlobalWorkflowNewR        , _   ) -> serverAdmin
--      (GlobalWorkflowR _wfl      , _   ) -> serverAdmin

        (WorkflowsR shr            , _   ) -> personOrGroupAdmin shr
        (WorkflowNewR shr          , _   ) -> personOrGroupAdmin shr
        (WorkflowR shr _wfl        , _   ) -> personOrGroupAdmin shr
        (WorkflowFieldsR shr _     , _   ) -> personOrGroupAdmin shr
        (WorkflowFieldNewR shr _   , _   ) -> personOrGroupAdmin shr
        (WorkflowFieldR shr _ _    , _   ) -> personOrGroupAdmin shr
        (WorkflowEnumsR shr _      , _   ) -> personOrGroupAdmin shr
        (WorkflowEnumNewR shr _    , _   ) -> personOrGroupAdmin shr
        (WorkflowEnumR shr _ _     , _   ) -> personOrGroupAdmin shr
        (WorkflowEnumCtorsR shr _ _   , _   ) -> personOrGroupAdmin shr
        (WorkflowEnumCtorNewR shr _ _ , _   ) -> personOrGroupAdmin shr
        (WorkflowEnumCtorR shr _ _ _  , _   ) -> personOrGroupAdmin shr

        (TicketsR s j              , True) -> projOp ProjOpOpenTicket s j
        (TicketNewR s j            , _   ) -> projOp ProjOpOpenTicket s j
        (TicketR user _ _          , True) -> person user
        (TicketEditR user _ _      , _   ) -> person user
        (TicketAcceptR s j _       , _   ) -> projOp ProjOpAcceptTicket s j
        (TicketCloseR s j _        , _   ) -> projOp ProjOpCloseTicket s j
        (TicketOpenR s j _         , _   ) -> projOp ProjOpReopenTicket s j
        (TicketClaimR s j _        , _   ) -> projOp ProjOpClaimTicket s j
        (TicketUnclaimR s j _      , _   ) -> projOp ProjOpUnclaimTicket s j
        (TicketAssignR s j _       , _   ) -> projOp ProjOpAssignTicket s j
        (TicketUnassignR s j _     , _   ) -> projOp ProjOpUnassignTicket s j
        (ClaimRequestsTicketR s j _, True) -> projOp ProjOpRequestTicket s j
        (ClaimRequestNewR s j _    , _   ) -> projOp ProjOpRequestTicket s j
        (TicketDiscussionR _ _ _   , True) -> personAny
        (TicketMessageR _ _ _ _    , True) -> personAny
        (TicketTopReplyR _ _ _     , _   ) -> personAny
        (TicketReplyR _ _ _ _      , _   ) -> personAny
        (TicketDepsR s j _         , True) -> projOp ProjOpAddTicketDep s j
        (TicketDepNewR s j _       , _   ) -> projOp ProjOpAddTicketDep s j
        (TicketDepR s j _ _        , True) -> projOp ProjOpRemoveTicketDep s j
        _                                  -> return Authorized
        where
        nobody :: Handler AuthResult
        nobody = return $ Unauthorized "This operation is currently disabled"

        serverAdmin :: Handler AuthResult
        serverAdmin = nobody

        personAnd
            :: (Entity Person -> Handler AuthResult) -> Handler AuthResult
        personAnd f = do
            mp <- maybeAuth
            case mp of
                Nothing -> return AuthenticationRequired
                Just p  -> f p

        personUnverifiedAnd
            :: (Entity Person -> Handler AuthResult) -> Handler AuthResult
        personUnverifiedAnd f = do
            mp <- maybeUnverifiedAuth
            case mp of
                Nothing -> return AuthenticationRequired
                Just p  -> f p

        personAny :: Handler AuthResult
        personAny = personAnd $ \ _p -> return Authorized

        person :: ShrIdent -> Handler AuthResult
        person ident = personAnd $ \ (Entity _ p) -> do
            let sid = personIdent p
            sharer <- runDB $ getJust sid
            return $ if ident == sharerIdent sharer
                then Authorized
                else Unauthorized "No access to this operation"

        personUnver :: Text -> Handler AuthResult
        personUnver uname = personUnverifiedAnd $ \ p ->
            if username p == uname
                then return Authorized
                else do
                    logWarn $ T.concat
                        [ "User ", username p, " tried to verify user ", uname
                        ]
                    return $ Unauthorized "You can't verify other users"

        personFromResendForm :: Handler AuthResult
        personFromResendForm = personUnverifiedAnd $ \ p -> do
            ((result, _), _) <-
                runFormPost $ renderDivs $ resendVerifyEmailForm ""
            case result of
                FormSuccess uname ->
                    if username p == uname
                        then return Authorized
                        else do
                            logWarn $ T.concat
                                [ "User ", username p, " tried to POST to \
                                 \verification email resend for user ", uname
                                ]
                            return $
                                Unauthorized
                                    "You can't do that for other users"
                _ -> do
                    logWarn $ T.concat
                        [ "User ", username p, " tried to POST to \
                         \verification email resend for invalid username"
                        ]
                    return $
                        Unauthorized "Requesting resend for invalid username"

        groupRole :: (GroupRole -> Bool) -> ShrIdent -> Handler AuthResult
        groupRole role grp = personAnd $ \ (Entity pid _p) -> runDB $ do
            Entity sid _s <- getBy404 $ UniqueSharer grp
            Entity gid _g <- getBy404 $ UniqueGroup sid
            mem <- getBy $ UniqueGroupMember pid gid
            let mrole = groupMemberRole . entityVal <$> mem
            return $ case mrole of
                Nothing -> Unauthorized "Not a member of the group"
                Just r  ->
                    if role r
                        then Authorized
                        else Unauthorized "Not the expected group role"

        groupAdmin :: ShrIdent -> Handler AuthResult
        groupAdmin = groupRole (== GRAdmin)

        personOrGroupAdmin :: ShrIdent -> Handler AuthResult
        personOrGroupAdmin shr = personAnd $ \ (Entity vpid _vp) -> runDB $ do
            Entity sid _ <- getBy404 $ UniqueSharer shr
            mep <- getBy $ UniquePersonIdent sid
            case mep of
                Just (Entity pid _p) ->
                    return $ if pid == vpid
                        then Authorized
                        else Unauthorized "Can’t access other people’s roles"
                Nothing -> do
                    meg <- getBy $ UniqueGroup sid
                    case meg of
                        Nothing -> do
                            logWarn $
                                "Found non-person non-group sharer: " <>
                                shr2text shr
                            return $ error "Zombie sharer"
                        Just (Entity gid _g) -> do
                            mem <- getBy $ UniqueGroupMember vpid gid
                            return $ case mem of
                                Nothing -> Unauthorized "Not a group member"
                                Just (Entity _mid m) ->
                                    if groupMemberRole m == GRAdmin
                                        then Authorized
                                        else Unauthorized "Not a group admin"

        projOp
            :: ProjectOperation -> ShrIdent -> PrjIdent -> Handler AuthResult
        projOp op shr prj = do
            mpid <- maybeAuthId
            oas <- runDB $ checkProjectAccess mpid op shr prj
            return $
                case oas of
                    ObjectAccessAllowed -> Authorized
                    _ ->
                        Unauthorized
                        "You need a project role with that operation enabled"

    -- This function creates static content files in the static folder
    -- and names them based on a hash of their content. This allows
    -- expiration dates to be set far in the future without worry of
    -- users receiving stale content.
    addStaticContent ext mime content = do
        master <- getYesod
        let staticDir = appStaticDir $ appSettings master
        addStaticContentExternal
            discardm
            genFileName
            staticDir
            (StaticR . flip StaticRoute [])
            ext
            mime
            content
      where
        -- Generate a unique filename based on the content itself
        genFileName lbs = "autogen-" ++ base64md5 lbs

    -- What messages should be logged. The following includes all messages when
    -- in development, and warnings and errors in production.
    shouldLogIO app _source level = pure $
        appShouldLogAll (appSettings app)
            || level == LevelWarn
            || level == LevelError

    makeLogger = return . appLogger

-- How to run database actions.
instance YesodPersist App where
    type YesodPersistBackend App = SqlBackend
    runDB action = do
        master <- getYesod
        runSqlPool action $ appConnPool master
instance YesodPersistRunner App where
    getDBRunner = defaultGetDBRunner appConnPool

instance YesodMailSend App where
    data MailMessage App
        = MailVerifyAccount (Route App)
        | MailResetPassphrase (Route App)
    formatMailMessage _reply _mname msg =
        case msg of
            MailVerifyAccount url ->
                ( "Verify your Vervis account"
                , $(textFile "templates/person/email/verify-account.md")
                )
            MailResetPassphrase url ->
                ( "Reset your Vervis passphrase"
                , $(textFile "templates/person/email/reset-passphrase.md")
                )
    getMailSettings = getsYesod $ appMail . appSettings
    getSubmitMail = do
        mchan <- getsYesod appMailQueue
        case mchan of
            Nothing   -> return Nothing
            Just chan -> return $ Just $ liftIO . writeChan chan

instance YesodAuth App where
    type AuthId App = PersonId

    -- Where to send a user after successful login
    loginDest _ = HomeR
    -- Where to send a user after logout
    logoutDest _ = HomeR
    -- Override the above two destinations when a Referer: header is present
    redirectToReferer _ = True

    authenticate creds = liftHandler $ do
        let ident = credsIdent creds
        mpid <- runDB $ getBy $ UniquePersonLogin $ credsIdent creds
        return $ case mpid of
            Nothing             -> UserError $ IdentifierNotFound ident
            Just (Entity pid _) -> Authenticated pid

    -- You can add other plugins like BrowserID, email or OAuth here
    authPlugins _ = [accountPlugin]

    authHttpManager = error "authHttpManager"

    onLogout = clearUnverifiedCreds False

instance YesodAuthPersist App

newtype AccountPersistDB' a = AccountPersistDB'
    { unAccountPersistDB' :: Handler a
    }
    deriving (Functor, Applicative, Monad, MonadIO)

morphAPDB :: AccountPersistDB App Person a -> AccountPersistDB' a
morphAPDB = AccountPersistDB' . runAccountPersistDB

instance AccountDB AccountPersistDB' where
    type UserAccount AccountPersistDB' = Entity Person

    loadUser               = morphAPDB . loadUser
    loadUserByEmailAddress = morphAPDB . loadUserByEmailAddress

    addNewUser name email key pwd = AccountPersistDB' $ runDB $ do
        now <- liftIO getCurrentTime
        let sharer = Sharer
                { sharerIdent   = text2shr name
                , sharerName    = Nothing
                , sharerCreated = now
                }
        msid <- insertBy sharer
        case msid of
            Left _ -> do
                mr <- getMessageRender
                return $ Left $ mr $ MsgUsernameExists name
            Right sid -> do
                let defTime = UTCTime (ModifiedJulianDay 0) 0
                    person = Person
                        { personIdent               = sid
                        , personLogin               = name
                        , personPassphraseHash      = pwd
                        , personEmail               = email
                        , personVerified            = False
                        , personVerifiedKey         = key
                        , personVerifiedKeyCreated  = now
                        , personResetPassKey        = ""
                        , personResetPassKeyCreated = defTime
                        , personAbout               = ""
                        }
                pid <- insert person
                return $ Right $ Entity pid person

    verifyAccount          = morphAPDB . verifyAccount
    setVerifyKey           = (morphAPDB .) . setVerifyKey
    setNewPasswordKey      = (morphAPDB .) . setNewPasswordKey
    setNewPassword         = (morphAPDB .) . setNewPassword

instance AccountSendEmail App where
    sendVerifyEmail uname email url = do
        sent <- sendMail (Address (Just uname) email) (MailVerifyAccount url)
        unless sent $ do
            setMessage "Mail sending disabled, please contact admin"
            ur <- getUrlRender
            logWarn $ T.concat
                [ "Verification email NOT SENT for user "
                , uname, " <", emailText email, ">: "
                , ur url
                ]
    sendNewPasswordEmail uname email url = do
        sent <- sendMail (Address (Just uname) email) (MailResetPassphrase url)
        unless sent $ do
            setMessage "Mail sending disabled, please contact admin"
            ur <- getUrlRender
            logWarn $ T.concat
                ["Password reset email NOT SENT for user "
                , uname, " <", emailText email, ">: "
                , ur url
                ]

instance YesodAuthVerify App where
    verificationRoute _ = ResendVerifyEmailR

instance YesodAuthAccount AccountPersistDB' App where
    requireEmailVerification     = appEmailVerification . appSettings
    emailVerifyKeyDuration _     = Just $ fromTimeUnit (1 :: Day)
    passphraseResetKeyDuration _ = Just $ fromTimeUnit (1 :: Day)
    allowLoginByEmailAddress _   = True
    runAccountDB                 = unAccountPersistDB'

    unregisteredLogin u = do
        setUnverifiedCreds True $ Creds "account" (username u) []
        return mempty
    registrationAllowed = do
        settings <- getsYesod appSettings
        if appRegister settings
            then do
                room <- case appAccounts settings of
                    Nothing -> return True
                    Just cap -> do
                        current <- runDB $ count ([] :: [Filter Person])
                        return $ current < cap
                return $
                    if room
                        then Nothing
                        else Just $ setMessage "Maximal number of registered users reached"
            else return $ Just $ setMessage "User registration disabled"

-- This instance is required to use forms. You can modify renderMessage to
-- achieve customized and internationalized form validation messages.
instance RenderMessage App FormMessage where
    renderMessage _ _ = defaultFormMessage

-- Useful when writing code that is re-usable outside of the Handler context.
-- An example is background jobs that send email.
-- This can also be useful for writing code that works across multiple Yesod
-- applications.
--instance HasHttpManager App where
--    getHttpManager = appHttpManager

unsafeHandler :: App -> Handler a -> IO a
unsafeHandler = Unsafe.fakeHandlerGetLogger appLogger

-- Note: Some functionality previously present in the scaffolding has been
-- moved to documentation in the Wiki. Following are some hopefully helpful
-- links:
--
-- https://github.com/yesodweb/yesod/wiki/Sending-email
-- https://github.com/yesodweb/yesod/wiki/Serve-static-files-from-a-separate-domain
-- https://github.com/yesodweb/yesod/wiki/i18n-messages-in-the-scaffolding

-- TODO this is copied from stm-2.5, remove when we upgrade LTS
stateTVar :: TVar s -> (s -> (a, s)) -> STM a
stateTVar var f = do
    s <- readTVar var
    let (a, s') = f s -- since we destructure this, we are strict in f
    writeTVar var s'
    return a

withHostLock :: Text -> Handler a -> Handler a
withHostLock host action = do
    tvar <- getsYesod appInstanceMutex
    mvar <- liftIO $ do
        existing <- M.lookup host <$> readTVarIO tvar
        case existing of
            Just v -> return v
            Nothing -> do
                v <- newEmptyMVar
                atomically $ stateTVar tvar $ \ m ->
                    case M.lookup host m of
                        Just v' -> (v', m)
                        Nothing -> (v, M.insert host v m)
    withMVar mvar $ const action

sumUpTo :: Int -> AppDB Int -> AppDB Int -> AppDB Bool
sumUpTo limit action1 action2 = do
    n <- action1
    if n <= limit
        then do
            m <- action2
            return $ n + m <= limit
        else return False

-- | Grab instance and remote sharer IDs from the DB, inserting new ones if
-- they can't be found in the DB. The @Maybe Bool@ indicates whether the IDs
-- are newly inserted record: 'Nothing' means they're both new. @Just True@
-- means the instance record existed but the remote sharer is new. @Just False@
-- means both the instance and remote sharer existed in the DB.
instanceAndActor
    :: Text
    -> LocalURI
    -> LocalURI
    -> AppDB (InstanceId, RemoteSharerId, Maybe Bool)
instanceAndActor host luActor luInbox = do
    (iid, inew) <- idAndNew <$> insertBy (Instance host)
    let rs = RemoteSharer luActor iid luInbox
    if inew
        then do
            rsid <- insert rs
            return (iid, rsid, Nothing)
        else do
            (rsid, rsnew) <- idAndNew <$> insertBy rs
            return (iid, rsid, Just rsnew)
    where
    idAndNew (Left (Entity iid _)) = (iid, False)
    idAndNew (Right iid)           = (iid, True)

actorRoom :: Int -> RemoteSharerId -> AppDB Bool
actorRoom limit rsid = do
    sumUpTo limit
        (count [VerifKeySharedUsageUser ==. rsid])
        (count [VerifKeySharer ==. Just rsid])

getOldUsageId rsid = fmap entityKey . listToMaybe <$> selectList [VerifKeySharedUsageUser ==. rsid] [Asc VerifKeySharedUsageId, LimitTo 1]

getOldPersonalKeyId rsid = fmap entityKey . listToMaybe <$> selectList [VerifKeySharer ==. Just rsid] [Asc VerifKeyExpires, Asc VerifKeyId, LimitTo 1]

makeActorRoomByPersonal limit rsid vkid = do
    room <-
        if limit <= 1
            then return False
            else (< limit-1) <$> count [VerifKeySharer ==. Just rsid, VerifKeyId !=. vkid]
    unless room $ delete vkid

makeActorRoomByUsage limit rsid suid = do
    room <-
        if limit <= 1
            then return False
            else
                sumUpTo (limit-1)
                    (count [VerifKeySharedUsageUser ==. rsid, VerifKeySharedUsageId !=. suid])
                    (count [VerifKeySharer ==. Just rsid])
    unless room $ delete suid

-- | Checks whether the given actor has room left for a new shared key usage
-- record, and if not, deletes a record to make room for a new one. It prefers
-- to delete a usage record if any exist; otherwise it deletes a personal key.
--
-- The first parameter is the actor key storage limit, and it must be above
-- zero.
makeActorRoomForUsage :: Int -> RemoteSharerId -> AppDB ()
makeActorRoomForUsage limit rsid = do
    msuid <- getOldUsageId rsid
    case msuid of
        Nothing -> do
            mvkid <- getOldPersonalKeyId rsid
            case mvkid of
                Nothing -> return ()
                Just vkid -> makeActorRoomByPersonal limit rsid vkid
        Just suid -> makeActorRoomByUsage limit rsid suid

-- | Checks whether the given actor has room left for a new personal key
-- record, and if not, deletes a record to make room for a new one. It prefers
-- to delete a personal key if any exist; otherwise it deletes a usage record.
--
-- The first parameter is the actor key storage limit, and it must be above
-- zero.
makeActorRoomForPersonalKey :: Int -> RemoteSharerId -> AppDB ()
makeActorRoomForPersonalKey limit rsid = do
    mvkid <- getOldPersonalKeyId rsid
    case mvkid of
        Nothing -> do
            msuid <- getOldUsageId rsid
            case msuid of
                Nothing -> return ()
                Just suid -> makeActorRoomByUsage limit rsid suid
        Just vkid -> makeActorRoomByPersonal limit rsid vkid

-- | Checks whether the given instance has room left for a new shared key
-- record, and if not, deletes a record to make room for a new one.
--
-- The first parameter is the actor key storage limit, and it must be above
-- zero.
makeInstanceRoom :: Int -> InstanceId -> AppDB ()
makeInstanceRoom limit iid = do
    mvk <- listToMaybe <$> selectList [VerifKeyInstance ==. iid, VerifKeySharer ==. Nothing] [Asc VerifKeyExpires, Asc VerifKeyId, LimitTo 1]
    case mvk of
        Nothing -> return ()
        Just (Entity vkid _) -> do
            room <-
                if limit <= 1
                    then return False
                    else (< limit-1) <$> count [VerifKeyInstance ==. iid, VerifKeySharer ==. Nothing, VerifKeyId !=. vkid]
            unless room $ delete vkid

data RoomModeDB
    = RoomModeNoLimit
    | RoomModeLimit Int

data RoomMode
    = RoomModeInstant
    | RoomModeCached RoomModeDB

roomModeFromLimit :: Maybe Int -> RoomMode
roomModeFromLimit Nothing      = RoomModeCached $ RoomModeNoLimit
roomModeFromLimit (Just limit) =
    if limit <= 0
        then RoomModeInstant
        else RoomModeCached $ RoomModeLimit limit

actorRoomMode :: AppSettings -> RoomMode
actorRoomMode = roomModeFromLimit . appMaxActorKeys

instanceRoomMode :: AppSettings -> RoomMode
instanceRoomMode = roomModeFromLimit . appMaxInstanceKeys

-- | Given a shared key we have in our DB, verify that the given actor lists
-- this key, and update the DB accordingly.
--
--   * If the storage limit on actor keys is zero:
--       - If we're supposed to reject signatures when there's no room, raise
--         an error! We can't store anything with a limit of 0
--       - Otherwise, fetch the actor, store in DB if we don't have it, verify
--         usage via actor JSON. Usage isn't stored in the DB.
--   * If there's no storage limit, or it's above zero:
--     - If we know the actor and we have a record that it lists the key,
--       return success, no other action
--     - If we know the actor but we don't have a record of usage, fetch the
--       actor and verify usage. If the actor already has the maximal number of
--       keys: If we're supposed to reject signatures when there's no room,
--       raise an error. Otherwise, delete an old key/usage and store the new
--       usage in the DB.
--     - If we don't know the actor, fetch actor, verify usage, store actor and
--       usage in DB.
--
-- If we get success, that means the actor lists the key, and both the actor
-- and the usage exist in our DB now (if the storage limit isn't zero).
keyListedByActorShared
    :: Manager
    -> InstanceId
    -> VerifKeyId
    -> Text
    -> LocalURI
    -> LocalURI
    -> ExceptT String Handler ()
keyListedByActorShared manager iid vkid host luKey luActor = do
    (reject, roomMode) <- do
        s <- getsYesod appSettings
        return (appRejectOnMaxKeys s, actorRoomMode s)
    case roomMode of
        RoomModeInstant -> do
            when reject $ throwE "Actor key storage limit is 0 and set to reject"
            luInbox <- actorInbox <$> ExceptT (keyListedByActor manager host luKey luActor)
            _ <- lift $ runDB $ insertUnique $ RemoteSharer luActor iid luInbox
            return ()
        RoomModeCached m -> do
            mresult <- do
                ments <- lift $ runDB $ do
                    mrs <- getBy $ UniqueRemoteSharer iid luActor
                    for mrs $ \ (Entity rsid _) ->
                        (rsid,) . isJust <$>
                            getBy (UniqueVerifKeySharedUsage vkid rsid)
                return $
                    case ments of
                        Nothing -> Just Nothing
                        Just (rsid, used) ->
                            if used
                                then Nothing
                                else Just $ Just rsid
            for_ mresult $ \ mrsid -> do
                luInbox <- actorInbox <$> ExceptT (keyListedByActor manager host luKey luActor)
                ExceptT $ runDB $ do
                    vkExists <- isJust <$> get vkid
                    case mrsid of
                        Nothing -> do
                            rsid <- insert $ RemoteSharer luActor iid luInbox
                            when vkExists $ insert_ $ VerifKeySharedUsage vkid rsid
                            return $ Right ()
                        Just rsid -> runExceptT $ when vkExists $ do
                            case m of
                                RoomModeNoLimit -> return ()
                                RoomModeLimit limit -> do
                                    if reject
                                        then do
                                            room <- lift $ actorRoom limit rsid
                                            unless room $ throwE "Actor key storage limit reached"
                                        else lift $ makeActorRoomForUsage limit rsid
                            lift $ insert_ $ VerifKeySharedUsage vkid rsid

data VerifKeyDetail = VerifKeyDetail
    { vkdKeyId     :: LocalURI
    , vkdKey       :: PublicKey
    , vkdExpires   :: Maybe UTCTime
    , vkdActorId   :: LocalURI
    , vkdShared    :: Bool
    }

instance YesodHttpSig App where
    data HttpSigVerResult App = HttpSigVerResult (Either String FedURI)
    httpSigVerHeaders = const [hRequestTarget, hHost, hActivityPubActor]
    httpSigVerSeconds =
        fromIntegral . toSeconds . appHttpSigTimeLimit . appSettings
        where
        toSeconds :: TimeInterval -> Second
        toSeconds = toTimeUnit
    httpVerifySig (Verification malgo (KeyId keyid) input (Signature sig)) = fmap HttpSigVerResult $ runExceptT $ do
        verifySigAlgo malgo
        (host, luKey) <- f2l <$> parseKeyId keyid
        signature <- parseSig sig
        mluActorHeader <- getActorHeader host
        let sigAlgo = isJust malgo
        manager <- getsYesod appHttpManager
        (inboxOrVkid, vkd) <- do
            ments <- lift $ runDB $ do
                mvk <- runMaybeT $ do
                    Entity iid _ <- MaybeT $ getBy $ UniqueInstance host
                    MaybeT $ getBy $ UniqueVerifKey iid luKey
                for mvk $ \ vk@(Entity _ verifkey) -> do
                    mremote <- traverse getJust $ verifKeySharer verifkey
                    return (vk, mremote)
            case ments of
                Just (Entity vkid vk, mremote) -> do
                    (ua, s) <-
                        case mremote of
                            Just remote -> do
                                let sharer = remoteSharerIdent remote
                                for_ mluActorHeader $ \ u ->
                                    if sharer == u
                                        then return ()
                                        else throwE "Key's owner doesn't match actor header"
                                return (sharer, False)
                            Nothing -> do
                                ua <- case mluActorHeader of
                                    Nothing -> throwE "Got a sig with an instance key, but actor header not specified!"
                                    Just u -> return u
                                manager <- getsYesod appHttpManager
                                let iid = verifKeyInstance vk
                                withHostLock' host $ keyListedByActorShared manager iid vkid host luKey ua
                                return (ua, True)
                    return
                        ( Right (verifKeyInstance vk, vkid)
                        , VerifKeyDetail
                            { vkdKeyId     = luKey
                            , vkdKey       = verifKeyPublic vk
                            , vkdExpires   = verifKeyExpires vk
                            , vkdActorId   = ua
                            , vkdShared    = s
                            }
                        )
                Nothing -> fetched2vkd luKey <$> fetchUnknownKey manager sigAlgo host mluActorHeader luKey
        let verify' k = verify k input signature
            errSig1 = throwE "Fetched fresh key; Ed25519 sig verification says not valid"
            errSig2 = throwE "Used key from DB; Ed25519 sig verification says not valid; fetched fresh key; still not valid"
            errTime = throwE "Key expired"
        now <- liftIO getCurrentTime
        let stillValid Nothing        = True
            stillValid (Just expires) = expires > now

        if verify' (vkdKey vkd) && stillValid (vkdExpires vkd)
            then case inboxOrVkid of
                Left uinb -> ExceptT $ withHostLock host $ runDB $ addVerifKey host uinb vkd
                Right _ids -> return ()
            else case inboxOrVkid of
                Left _uinb ->
                    if stillValid $ vkdExpires vkd
                        then errSig1
                        else errTime
                Right (iid, vkid) -> do
                    let ua = vkdActorId vkd
                        listed = withHostLock' host $ keyListedByActorShared manager iid vkid host luKey ua
                    (newKey, newExp) <-
                        if vkdShared vkd
                            then fetchKnownSharedKey manager listed sigAlgo host ua luKey
                            else fetchKnownPersonalKey manager sigAlgo host ua luKey
                    if stillValid newExp
                        then return ()
                        else errTime
                    if verify' newKey
                        then lift $ runDB $ updateVerifKey vkid vkd
                                { vkdKey     = newKey
                                , vkdExpires = newExp
                                }
                        else errSig2

        return $ l2f host $ vkdActorId vkd
        where
        verifySigAlgo = traverse_ $ \ algo ->
            case algo of
                S.AlgorithmEd25519 -> return ()
                S.AlgorithmOther _ -> throwE "Unsupported algo in Sig header"
        parseKeyId k =
            case parseFedURI =<< (first displayException . decodeUtf8') k of
                Left e -> throwE $ "keyId in Sig header isn't a valid FedURI: " ++ e
                Right u -> return u
        parseSig b =
            case signature b of
                CryptoPassed s -> return s
                CryptoFailed e -> throwE "Parsing Ed25519 signature failed"
        getActorHeader host = do
            bs <- lookupHeaders hActivityPubActor
            case bs of
                [] -> return Nothing
                [b] -> fmap Just . ExceptT . pure $ do
                    t <- first displayException $ decodeUtf8' b
                    (h, lu) <- f2l <$> parseFedURI t
                    if h == host
                        then Right ()
                        else Left "Key and actor have different hosts"
                    Right lu
                _ -> throwE "Multiple ActivityPub-Actor headers"
        fetched2vkd uk (Fetched k mexp ua uinb s) =
            ( Left uinb
            , VerifKeyDetail
                { vkdKeyId     = uk
                , vkdKey       = k
                , vkdExpires   = mexp
                , vkdActorId   = ua
                , vkdShared    = s
                }
            )
        addVerifKey h uinb vkd =
            if vkdShared vkd
                then addSharedKey h uinb vkd
                else addPersonalKey h uinb vkd
            where
            addSharedKey host luInbox (VerifKeyDetail luKey key mexpires luActor _) = runExceptT $ do
                (reject, roomModeA, roomModeI) <- do
                    s <- getsYesod appSettings
                    return (appRejectOnMaxKeys s, actorRoomMode s, instanceRoomMode s)
                (iid, rsid, inew) <- lift $ instanceAndActor host luActor luInbox
                case roomModeI of
                    RoomModeInstant ->
                        when reject $ throwE "Instance key storage limit is 0 and set to reject"
                    RoomModeCached m -> do
                        case m of
                            RoomModeNoLimit -> return ()
                            RoomModeLimit limit ->
                                if reject
                                    then when (isJust inew) $ do
                                        room <- lift $ instanceRoom limit iid
                                        unless room $ throwE "Instance key storage limit reached"
                                    else when (isJust inew) $ lift $ makeInstanceRoom limit iid
                        vkid <- lift $ insert $ VerifKey luKey iid mexpires key Nothing
                        case roomModeA of
                            RoomModeInstant ->
                                when reject $ throwE "Actor key storage limit is 0 and set to reject"
                            RoomModeCached m -> do
                                case m of
                                    RoomModeNoLimit -> return ()
                                    RoomModeLimit limit ->
                                        if reject
                                            then when (inew == Just False) $ do
                                                room <- lift $ actorRoom limit rsid
                                                unless room $ throwE "Actor key storage limit reached"
                                            else when (inew == Just False) $ lift $ makeActorRoomForUsage limit rsid
                                lift $ insert_ $ VerifKeySharedUsage vkid rsid
                where
                instanceRoom n iid =
                    (< n) <$> count [VerifKeyInstance ==. iid, VerifKeySharer ==. Nothing]
            addPersonalKey host luInbox (VerifKeyDetail luKey key mexpires luActor _) = runExceptT $ do
                (reject, roomMode) <- do
                    s <- getsYesod appSettings
                    return (appRejectOnMaxKeys s, actorRoomMode s)
                (iid, rsid, inew) <- lift $ instanceAndActor host luActor luInbox
                case roomMode of
                    RoomModeInstant ->
                        when reject $ throwE "Actor key storage limit is 0 and set to reject"
                    RoomModeCached m -> do
                        case m of
                            RoomModeNoLimit -> return ()
                            RoomModeLimit limit ->
                                if reject
                                    then when (inew == Just False) $ do
                                        room <- lift $ actorRoom limit rsid
                                        unless room $ throwE "Actor key storage limit reached"
                                    else when (inew == Just False) $ lift $ makeActorRoomForPersonalKey limit rsid
                        lift $ insert_ $ VerifKey luKey iid mexpires key (Just rsid)
        updateVerifKey vkid vkd =
            update vkid [VerifKeyExpires =. vkdExpires vkd, VerifKeyPublic =. vkdKey vkd]
        withHostLock' h = ExceptT . withHostLock h . runExceptT

instance YesodBreadcrumbs App where
    breadcrumb route = return $ case route of
        StaticR _                        -> ("", Nothing)
        FaviconR                         -> ("", Nothing)
        RobotsR                          -> ("", Nothing)

        InboxR                           -> ("Inbox", Nothing)
        OutboxR                          -> ("Outbox", Nothing)
        ActorKey1R                       -> ("Actor Key 1", Nothing)
        ActorKey2R                       -> ("Actor Key 2", Nothing)

        HomeR                            -> ("Home", Nothing)
        ResendVerifyEmailR               -> ( "Resend verification email"
                                            , Nothing
                                            )
        AuthR _                          -> ("Auth", Nothing)

        SharersR                         -> ("Sharers", Just HomeR)
        SharerR shar                     -> (shr2text shar, Just SharersR)

        PeopleR                          -> ("People", Just HomeR)

        GroupsR                          -> ("Groups", Just HomeR)
        GroupNewR                        -> ("New", Just GroupsR)
        GroupMembersR shar               -> ("Members", Just $ SharerR shar)
        GroupMemberNewR shar             -> ("New", Just $ GroupMembersR shar)
        GroupMemberR grp memb            -> ( shr2text memb
                                            , Just $ GroupMembersR grp
                                            )

        KeysR                            -> ("Keys", Just HomeR)
        KeyNewR                          -> ("New", Just KeysR)
        KeyR key                         -> (ky2text key, Just KeysR)

        ClaimRequestsPersonR             -> ( "Ticket Claim Requests"
                                            , Just HomeR
                                            )

        ProjectRolesR shr                -> ( "Project Roles"
                                            , Just $ SharerR shr
                                            )
        ProjectRoleNewR shr              -> ("New", Just $ ProjectRolesR shr)
        ProjectRoleR shr rl              -> ( rl2text rl
                                            , Just $ ProjectRolesR shr
                                            )
        ProjectRoleOpsR shr rl           -> ( "Operations"
                                            , Just $ ProjectRoleR shr rl
                                            )
        ProjectRoleOpNewR shr rl         -> ( "New"
                                            , Just $ ProjectRoleOpsR shr rl
                                            )

        ReposR shar                      -> ("Repos", Just $ SharerR shar)
        RepoNewR shar                    -> ("New", Just $ ReposR shar)
        RepoR shar repo                  -> (rp2text repo, Just $ ReposR shar)
        RepoEditR shr rp                 -> ("Edit", Just $ RepoR shr rp)
        RepoSourceR shar repo []         -> ("Files", Just $ RepoR shar repo)
        RepoSourceR shar repo refdir     -> ( last refdir
                                            , Just $
                                              RepoSourceR shar repo $
                                              init refdir
                                            )
        RepoHeadChangesR shar repo       -> ("Changes", Just $ RepoR shar repo)
        RepoChangesR shar repo ref       -> ( ref
                                            , Just $ RepoHeadChangesR shar repo
                                            )
        RepoPatchR shr rp hash           -> ( "Patch " <> hash
                                            , Just $ RepoR shr rp
                                            )
        RepoDevsR shr rp                 -> ( "Collaboratots"
                                            , Just $ RepoR shr rp
                                            )
        RepoDevNewR shr rp               -> ("New", Just $ RepoDevsR shr rp)
        RepoDevR shr rp dev              -> ( shr2text dev
                                            , Just $ RepoDevsR shr rp
                                            )

        DarcsDownloadR _ _ _             -> ("", Nothing)

        GitRefDiscoverR _ _              -> ("", Nothing)
        GitUploadRequestR _ _            -> ("", Nothing)

        ProjectsR shar                   -> ("Projects", Just $ SharerR shar)
        ProjectNewR shar                 -> ("New", Just $ ProjectsR shar)
        ProjectR shar proj               -> ( prj2text proj
                                            , Just $ ProjectsR shar
                                            )
        ProjectEditR shr prj             -> ("Edit", Just $ ProjectR shr prj)
        ProjectDevsR shr prj             -> ( "Collaborators"
                                            , Just $ ProjectR shr prj
                                            )
        ProjectDevNewR shr prj           -> ( "New"
                                            , Just $ ProjectDevsR shr prj
                                            )
        ProjectDevR shr prj dev          -> ( shr2text dev
                                            , Just $ ProjectDevsR shr prj
                                            )

        WorkflowsR shr                   -> ("Workflows", Just $ SharerR shr)
        WorkflowNewR shr                 -> ("New", Just $ WorkflowsR shr)
        WorkflowR shr wfl                -> ( wfl2text wfl
                                            , Just $ WorkflowsR shr
                                            )
        WorkflowFieldsR shr wfl          -> ( "Fields"
                                            , Just $ WorkflowR shr wfl
                                            )
        WorkflowFieldNewR shr wfl        -> ( "New"
                                            , Just $ WorkflowFieldsR shr wfl
                                            )
        WorkflowFieldR shr wfl fld       -> ( fld2text fld
                                            , Just $ WorkflowFieldsR shr wfl
                                            )
        WorkflowEnumsR shr wfl           -> ( "Enums"
                                            , Just $ WorkflowR shr wfl
                                            )
        WorkflowEnumNewR shr wfl         -> ( "New"
                                            , Just $ WorkflowEnumsR shr wfl
                                            )
        WorkflowEnumR shr wfl enm        -> ( enm2text enm
                                            , Just $ WorkflowEnumsR shr wfl
                                            )
        WorkflowEnumCtorsR shr wfl enm   -> ( "Ctors"
                                            , Just $ WorkflowEnumR shr wfl enm
                                            )
        WorkflowEnumCtorNewR shr wfl enm -> ( "New"
                                            , Just $
                                              WorkflowEnumCtorsR shr wfl enm
                                            )
        WorkflowEnumCtorR shr wfl enm c  -> ( c
                                            , Just $
                                              WorkflowEnumCtorsR shr wfl enm
                                            )

        TicketsR shar proj               -> ( "Tickets"
                                            , Just $ ProjectR shar proj
                                            )
        TicketTreeR shr prj              -> ( "Tree", Just $ TicketsR shr prj)
        TicketNewR shar proj             -> ("New", Just $ TicketsR shar proj)
        TicketR shar proj num            -> ( T.pack $ '#' : show num
                                            , Just $ TicketsR shar proj
                                            )
        TicketEditR shar proj num        -> ( "Edit"
                                            , Just $ TicketR shar proj num
                                            )
        TicketAcceptR _shr _prj _num     -> ("", Nothing)
        TicketCloseR _shar _proj _num    -> ("", Nothing)
        TicketOpenR _shar _proj _num     -> ("", Nothing)
        TicketClaimR _shar _proj _num    -> ("", Nothing)
        TicketUnclaimR _shar _proj _num  -> ("", Nothing)
        TicketAssignR shr prj num        -> ( "Assign"
                                            , Just $ TicketR shr prj num
                                            )
        TicketUnassignR _shr _prj _num   -> ("", Nothing)
        ClaimRequestsProjectR shr prj    -> ( "Ticket Claim Requests"
                                            , Just $ ProjectR shr prj
                                            )
        ClaimRequestsTicketR shr prj num -> ( "Ticket Claim Requests"
                                            , Just $ TicketR shr prj num
                                            )
        ClaimRequestNewR shr prj num     -> ( "New"
                                            , Just $
                                              ClaimRequestsTicketR shr prj num
                                            )
        TicketDiscussionR shar proj num  -> ( "Discussion"
                                            , Just $ TicketR shar proj num
                                            )
        TicketMessageR shar proj t c     -> ( T.pack $ '#' : show c
                                            , Just $
                                              TicketDiscussionR shar proj t
                                            )
        TicketTopReplyR shar proj num    -> ( "New topic"
                                            , Just $
                                              TicketDiscussionR shar proj num
                                            )
        TicketReplyR shar proj num cnum  -> ( "Reply"
                                            , Just $
                                              TicketMessageR shar proj num cnum
                                            )
        TicketDepsR shr prj num          -> ( "Dependencies"
                                            , Just $ TicketR shr prj num
                                            )
        TicketDepNewR shr prj num        -> ( "New dependency"
                                            , Just $ TicketDepsR shr prj num
                                            )
        TicketDepR shr prj pnum cnum     -> ( T.pack $ '#' : show cnum
                                            , Just $ TicketDepsR shr prj pnum
                                            )
        TicketReverseDepsR shr prj num   -> ( "Dependants"
                                            , Just $ TicketR shr prj num
                                            )

        WikiPageR shr prj _page          -> ("Wiki", Just $ ProjectR shr prj)