Application.hs

{-# OPTIONS_GHC -fno-warn-orphans #-}
module Application
    ( getApplicationDev
    , appMain
    , develMain
    , makeFoundation
    -- * for DevelMain
    , getApplicationRepl
    , shutdownApp
    -- * for GHCI
    , handler
    , db
    ) where

import Control.Monad.Logger                 (liftLoc, runLoggingT)
import Database.Persist.Postgresql          (createPostgresqlPool, pgConnStr,
                                             pgPoolSize, runSqlPool)
import Import                               hiding (Request, requestHeaders, sendResponse)
import Language.Haskell.TH.Syntax           (qLocation)
import Network.Wai
import Network.Wai.Handler.Warp             (Settings, defaultSettings,
                                             defaultShouldDisplayException,
                                             runSettings, setHost,
                                             setOnException, setPort, getPort)
import Network.Wai.Middleware.RequestLogger (Destination (Logger),
                                             IPAddrSource (..),
                                             OutputFormat (..), destination,
                                             mkRequestLogger, outputFormat)
import System.Log.FastLogger                (defaultBufSize, newStdoutLoggerSet,
                                             toLogStr)
import Helpers.Request (siteCors)

-- Import all relevant handler modules here.
-- Don't forget to add new modules to your cabal file!
import Handler.All

-- This line actually creates our YesodDispatch instance. It is the second half
-- of the call to mkYesodData which occurs in Foundation.hs. Please see the
-- comments there for more details.
mkYesodDispatch "App" resourcesApp

-- | This function allocates resources (such as a database connection pool),
-- performs initialization and return a foundation datatype value. This is also
-- the place to put your migrate statements to have automatic database
-- migrations handled by Yesod.
makeFoundation :: AppSettings -> IO App
makeFoundation appSettings = do
    -- Some basic initializations: HTTP connection manager and logger.
    appHttpManager <- newManager
    appLogger <- newStdoutLoggerSet defaultBufSize >>= makeYesodLogger

    -- We need a log function to create a connection pool. We need a connection
    -- pool to create our foundation. And we need our foundation to get a
    -- logging function. To get out of this loop, we initially create a
    -- temporary foundation without a real connection pool, get a log function
    -- from there, and then create the real foundation.
    let mkFoundation appConnPool = App {..}
        -- The App {..} syntax is an example of record wild cards. For more
        -- information, see:
        -- https://ocharles.org.uk/blog/posts/2014-12-04-record-wildcards.html
        tempFoundation = mkFoundation $ error "connPool forced in tempFoundation"
        logFunc = messageLoggerSource tempFoundation appLogger

    -- Create the database connection pool
    pool <- flip runLoggingT logFunc $ createPostgresqlPool
        (pgConnStr  $ appDatabaseConf appSettings)
        (pgPoolSize $ appDatabaseConf appSettings)

    -- Perform database migration using our application's logging settings.
    runLoggingT (runSqlPool (runMigration migrateAll) pool) logFunc

    -- Return the foundation
    return $ mkFoundation pool

-- | Convert our foundation to a WAI Application by calling @toWaiAppPlain@ and
-- applyng some additional middlewares.
makeApplication :: App -> IO Application
makeApplication foundation = do
    logWare <- mkRequestLogger def
        { outputFormat =
            if appDetailedRequestLogging $ appSettings foundation
                then Detailed True
                else Apache
                        (if appIpFromHeader $ appSettings foundation
                            then FromFallback
                            else FromSocket)
        , destination = Logger $ loggerSet $ appLogger foundation
        }

    -- Create the WAI application and apply middlewares
    appPlain <- toWaiAppPlain foundation
    return $ forceSSL $ siteCors $ logWare $ defaultMiddlewaresNoLogging appPlain

forceSSL :: Middleware
forceSSL = ifRequest ((shouldForceSSL &&) . not . appearsSecure) return500
    where
        shouldForceSSL = appForceSSL compileTimeAppSettings
        return500 _ _ sendResponse = sendResponse resp
        resp = responseBuilder status500 [] mempty

appearsSecure :: Request -> Bool
appearsSecure request = isSecure request || matchHeader "X-Forwarded-Proto" (== "https")
    where
        matchHeader h f = maybe False f $ lookup h $ requestHeaders request

-- | Warp settings for the given foundation value.
warpSettings :: App -> Settings
warpSettings foundation =
      setPort (appPort $ appSettings foundation)
    $ setHost (appHost $ appSettings foundation)
    $ setOnException (\_req e ->
        when (defaultShouldDisplayException e) $ messageLoggerSource
            foundation
            (appLogger foundation)
            $(qLocation >>= liftLoc)
            "yesod"
            LevelError
            (toLogStr $ "Exception from Warp: " ++ show e))
      defaultSettings

-- | For yesod devel, return the Warp settings and WAI Application.
getApplicationDev :: IO (Settings, Application)
getApplicationDev = do
    settings <- getAppSettings
    foundation <- makeFoundation settings
    wsettings <- getDevSettings $ warpSettings foundation
    app <- makeApplication foundation
    return (wsettings, app)

getAppSettings :: IO AppSettings
getAppSettings = loadAppSettings [configSettingsYml] [] useEnv

-- | main function for use by yesod devel
develMain :: IO ()
develMain = develMainHelper getApplicationDev

-- | The @main@ function for an executable running this site.
appMain :: IO ()
appMain = do
    -- Get the settings from all relevant sources
    settings <- loadAppSettingsArgs
        -- fall back to compile-time values, set to [] to require values at runtime
        [configSettingsYmlValue]

        -- allow environment variables to override
        useEnv

    -- Generate the foundation from the settings
    foundation <- makeFoundation settings

    -- Generate a WAI Application from the foundation
    app <- makeApplication foundation

    -- Run the application with Warp
    runSettings (warpSettings foundation) app


--------------------------------------------------------------
-- Functions for DevelMain.hs (a way to run the app from GHCi)
--------------------------------------------------------------
getApplicationRepl :: IO (Int, App, Application)
getApplicationRepl = do
    settings <- getAppSettings
    foundation <- makeFoundation settings
    wsettings <- getDevSettings $ warpSettings foundation
    app1 <- makeApplication foundation
    return (getPort wsettings, foundation, app1)

shutdownApp :: App -> IO ()
shutdownApp _ = return ()


---------------------------------------------
-- Functions for use in development with GHCi
---------------------------------------------

-- | Run a handler
handler :: Handler a -> IO a
handler h = getAppSettings >>= makeFoundation >>= flip unsafeHandler h

-- | Run DB queries
db :: ReaderT SqlBackend (HandlerT App IO) a -> IO a
db = handler . runDB