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Flatten the main function #116

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Sep 27, 2023
Merged

Flatten the main function #116

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95 changes: 47 additions & 48 deletions app/Main.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,15 +2,14 @@

module Main
( main
)
where
) where

import Control.Concurrent ( MVar
, newMVar
, threadDelay
, tryPutMVar
)
import qualified Control.Concurrent.Async as Async
import qualified Control.Concurrent.Async as Async
import Control.Monad ( forever )
import Control.Monad.Log ( defaultBatchingOptions
, renderWithTimestamp
Expand All @@ -20,15 +19,15 @@ import Control.Monad.Log ( defaultBatchingOptio
import Control.Monad.Reader ( runReaderT )
import Control.Monad.Trans ( liftIO )
import Data.FileEmbed ( embedDir )
import Data.Foldable ( traverse_ )
import Data.IORef ( IORef
, readIORef
)
import Data.Time.Format ( defaultTimeLocale
, formatTime
, iso8601DateFormat
)
import Lens.Micro.Platform ( (<&>)
, set
import Lens.Micro.Platform ( set
, view
)
import Network.HTTP.Client.TLS ( newTlsManager )
Expand Down Expand Up @@ -56,63 +55,63 @@ import View ( render )

opts :: [OptDescr (Config -> Config)]
opts =
[ Option [] ["help"] (NoArg (set cHelp True)) "Show usage info"
, Option [] ["port"] (ReqArg (set cPort . read) "PORT") "Port to run on"
[ Option [] ["help"] (NoArg (set cHelp True)) "Show usage info"
, Option [] ["port"] (ReqArg (set cPort . read) "PORT") "Port to run on"
, Option []
["interval"]
(ReqArg (set cInterval . (1000000 *) . read) "INTERVAL (s)")
"Update interval"
]

usage :: IO ()
usage = putStrLn $ usageInfo "mat-chalmers [OPTION...]" opts

main :: IO ()
main =
getArgs
<&> getOpt Permute opts
>>= \case
(_ , _ , _ : _) -> usage
(_ , _ : _, _ ) -> usage
(!confs, _ , _ ) -> do
let config = foldl (flip id) defaultConfig confs
if view cHelp config
then usage
else do
upd <- newMVar () -- putMVar when to update
mgr <- newTlsManager
(viewRef, refreshAction) <- runLoggingT
(runReaderT refresh (ClientContext config mgr))
print
main = (reifyConfig . getOpt Permute opts <$> getArgs) >>= \case
(_ , _ , _ : _) -> usage
(_ , _ : _, _ ) -> usage
(Config { _cHelp = True }, _ , _ ) -> usage
(config , _ , _ ) -> do
upd <- newMVar () -- putMVar when to update
mgr <- newTlsManager
(viewRef, refreshAction) <- runLoggingT
(runReaderT refresh (ClientContext config mgr))
print

-- In the list there are three items running concurrently:
-- 1. Timer that sends a signal to the updater when it's time to update
-- 2. Webserver that serves the menus to the user
-- 3. Updater that fetches new data from the restaurants
Async.runConcurrently $ traverse_
Async.Concurrently
[ timer upd config
, webserver config viewRef upd
, updater mgr upd refreshAction config
]
where
timer upd cfg =
forever $ tryPutMVar upd () >> threadDelay (view cInterval cfg)

Async.concurrently_
(Async.concurrently_
-- timer
(forever $ tryPutMVar upd () >> threadDelay (view cInterval config))
-- webserver
(serve config viewRef upd))
-- updater
(forever
$ withFDHandler defaultBatchingOptions stdout 1.0 80
$ \logCallback ->
runReaderT (refreshAction upd) (ClientContext config mgr)
`runLoggingT` ( logCallback
. renderWithTimestamp
(formatTime
defaultTimeLocale
(iso8601DateFormat
(Just "%H:%M:%S")
)
)
id
))
where usage = putStrLn $ usageInfo "mat-chalmers [OPTION...]" opts
updater mgr upd refreshAction cfg =
forever
$ withFDHandler defaultBatchingOptions stdout 1.0 80
$ \logCallback -> runLoggingT
(runReaderT (refreshAction upd) (ClientContext cfg mgr))
( logCallback
. renderWithTimestamp
(formatTime defaultTimeLocale
(iso8601DateFormat (Just "%H:%M:%S"))
)
id
)

serve
webserver
:: Config
-> IORef View -- ^ View model
-> MVar () -- ^ Update signal
-> IO ()
serve conf viewRef upd = scotty (view cPort conf) $ do
webserver conf viewRef upd = scotty (view cPort conf) $ do
middleware logStdout
middleware (static $(embedDir "static"))
get "/" ((html . render) =<< liftIO (readIORef viewRef))
get "/r" (liftIO (tryPutMVar upd ()) >> redirect "/") -- force update

16 changes: 15 additions & 1 deletion src/Config.hs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,6 +4,7 @@

module Config where

import Data.Foldable ( foldl' )
import Lens.Micro.Platform

-- | Configuration record
Expand All @@ -12,9 +13,22 @@ data Config = Config
, _cNextDayHour :: !Int
, _cInterval :: !Int
, _cPort :: !Int
} deriving (Eq, Show)
}
deriving (Eq, Show)

makeLenses ''Config

defaultConfig :: Config
defaultConfig = Config False 14 (1000000 * 60 * 30) 5007

-- | Create a Config we can touch
--
-- Yes, this function implementation is overly cute. It uses a lens to update
-- the first field of the tuple by using defaultConfig as first argument to
-- every function in the list. The brain needs to turn inside out a couple of
-- times before it makes sense, so if you're in a hurry, look at the types.
--
-- TODO: Feel free to bikeshed the function name.
reifyConfig
:: ([Config -> Config], [String], [String]) -> (Config, [String], [String])
reifyConfig = (& _1 %~ foldl' (flip id) defaultConfig)
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