1 files changed, 238 insertions, 0 deletions
diff --git a/Run/Que/Server.hs b/Run/Que/Server.hs
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+++ b/Run/Que/Server.hs
@@ -0,0 +1,238 @@
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE GeneralizedNewtypeDeriving #-}
+{-# LANGUAGE OverloadedStrings #-}
+{-# LANGUAGE LambdaCase #-}
+
+{- | Interprocess communication
+-}
+module Run.Que.Server
+  ( main
+  )
+where
+
+import           Com.Simatime.Alpha      hiding ( Text
+                                                , get
+                                                , gets
+                                                , modify
+                                                , poll
+                                                )
+import qualified Com.Simatime.Go               as Go
+import qualified Control.Concurrent.STM        as STM
+import qualified Control.Exception             as Exception
+import           Control.Monad.Reader           ( MonadTrans )
+import qualified Data.ByteString               as BS
+import qualified Data.ByteString.Builder.Extra as Builder
+import qualified Data.ByteString.Lazy          as BSL
+import           Data.HashMap.Lazy              ( HashMap )
+import qualified Data.HashMap.Lazy             as HashMap
+import qualified Data.Text.Encoding            as Encoding
+import           Data.Text.Lazy                 ( Text
+                                                , fromStrict
+                                                )
+import qualified Data.Text.Lazy                as Text
+import qualified Network.HTTP.Types.Status     as Http
+import qualified Network.Socket                as Socket
+import qualified Network.Wai                   as Wai
+import qualified Network.Wai.Handler.Warp      as Warp
+import           Network.Wai.Middleware.RequestLogger
+                                                ( logStdoutDev )
+import qualified System.Console.GetOpt         as Opt
+import qualified System.Environment            as Environment
+import qualified Web.Scotty.Trans              as Scotty
+
+main :: IO ()
+main = Exception.bracket startup shutdown run
+ where
+  run (p, waiapp) =
+    putText ("que-server starting on port " <> show p) >> Warp.run p waiapp
+  startup = do
+    opts <- Environment.getArgs /> getOpts
+    sync <- STM.newTVarIO opts
+    let runActionToIO m = runReaderT (runApp m) sync
+    waiapp <- Scotty.scottyAppT runActionToIO routes
+    return (port opts, waiapp)
+  shutdown :: a -> IO a
+  shutdown = pure . identity
+  getOpts args = case Opt.getOpt Opt.Permute options args of
+    ([]  , [], _) -> Exception.throw ErrorParsingOptions
+    (opts, _ , _) -> smoosh initialAppState opts
+  options =
+    [ Opt.Option
+        ['p']
+        ["port"]
+        (Opt.ReqArg (\n m -> m { port = read n :: Warp.Port }) "PORT")
+        "port to run on "
+    ]
+
+data Error = ErrorParsingOptions
+  deriving (Show)
+
+instance Exception.Exception Error
+
+-- | Only allow my IP or local to access some route.
+guardIP :: Wai.Request -> Scotty.ActionT Text App ()
+guardIP r = case Wai.remoteHost r of
+  Socket.SockAddrInet _ ip | ip `elem` allowed -> Scotty.status Http.ok200
+  _ -> Scotty.status Http.methodNotAllowed405
+ where
+  allowed = Socket.tupleToHostAddress </ [(72, 222, 221, 62), (127, 0, 0, 1)]
+
+routes :: Scotty.ScottyT Text App ()
+routes = do
+  Scotty.middleware logStdoutDev
+
+  let quepath = "^/([[:alnum:]_]*)/([[:alnum:]._/]*)$"
+  let index   = "^(/|/index.html)$"
+
+  Scotty.get (Scotty.regex index) <| do
+    let (ns, qp) = ("_", ["index"])
+    app . modify <| upsertNamespace ns
+    q <- app <| que ns qp
+    r <- liftIO <| takeQue q
+    Scotty.html <| fromStrict <| Encoding.decodeUtf8 r
+
+  Scotty.post (Scotty.regex index) <| do
+    r <- Scotty.request
+    guardIP r
+    let (ns, qp) = ("_", ["index"])
+    app . modify <| upsertNamespace ns
+    q     <- app <| que ns qp
+    qdata <- Scotty.body
+    liftIO <| pushQue (BSL.toStrict qdata) q
+    return ()
+
+  Scotty.matchAny (Scotty.regex "^/([[:alnum:]_]*)/?$") <| do
+    -- matches '/ns' and '/ns/' but not '/ns/path'
+    Scotty.status Http.notImplemented501
+    Scotty.text "namespace management coming soon"
+
+  -- | Receive a value from a que. Blocks until a value is received,
+  -- then returns. If 'poll=true', then stream data from the Que to the
+  -- client.
+  Scotty.get (Scotty.regex quepath) <| do
+    (ns, qp) <- extract
+    -- ensure namespace exists
+    app . modify <| upsertNamespace ns
+    q    <- app <| que ns qp
+    poll <- Scotty.param "poll" !: (pure . const False)
+    case poll of
+      True -> Scotty.stream $ streamQue q
+      _    -> do
+        r <- liftIO <| takeQue q
+        Scotty.html <| fromStrict <| Encoding.decodeUtf8 r
+
+  -- | Put a value on a que. Returns immediately.
+  Scotty.post (Scotty.regex quepath) <| do
+    r <- Scotty.request
+    when (BS.isPrefixOf "/_" <| Wai.rawPathInfo r) $ guardIP r
+    (ns, qp) <- extract
+    -- ensure namespace exists
+    app . modify <| upsertNamespace ns
+    q     <- app <| que ns qp
+    qdata <- Scotty.body
+    liftIO <| pushQue (BSL.toStrict qdata) q
+    return ()
+
+-- | recover from a scotty-thrown exception.
+(!:)
+  :: Scotty.ActionT Text App a -- ^ action that might throw
+  -> (Text -> Scotty.ActionT Text App a) -- ^ a function providing a default response instead
+  -> Scotty.ActionT Text App a
+(!:) = Scotty.rescue
+
+-- | Forever write the data from 'Que' to 'Wai.StreamingBody'.
+streamQue :: Que -> Wai.StreamingBody
+streamQue q write _ = Go.mult q >>= loop
+ where
+  loop c =
+    Go.tap c
+      >>= (write . Builder.byteStringInsert)
+      >>  (write <| Builder.byteStringInsert "\n")
+      >>  loop c
+
+-- | Gets the thing from the Hashmap. Call's 'error' if key doesn't exist.
+grab :: (Eq k, Hashable k) => k -> HashMap k v -> v
+grab = flip (HashMap.!)
+
+-- | Inserts the namespace in 'AppState' if it doesn't exist.
+upsertNamespace :: Namespace -> AppState -> AppState
+upsertNamespace ns as = if HashMap.member ns (ques as)
+  then as
+  else as { ques = HashMap.insert ns mempty (ques as) }
+
+-- | Inserts the que at the proper 'Namespace' and 'Quepath'.
+insertQue :: Namespace -> Quepath -> Que -> AppState -> AppState
+insertQue ns qp q as = as { ques = newQues }
+ where
+  newQues  = HashMap.insert ns newQbase (ques as)
+  newQbase = HashMap.insert qp q <| grab ns <| ques as
+
+extract :: Scotty.ActionT Text App (Namespace, Quepath)
+extract = do
+  ns   <- Scotty.param "0"
+  path <- Scotty.param "1"
+  let p = Text.split (== '/') path |> filter (not . Text.null)
+  return (ns, p)
+
+newtype App a = App
+  { runApp :: ReaderT (STM.TVar AppState) IO a
+  }
+  deriving (Applicative, Functor, Monad, MonadIO, MonadReader
+    (STM.TVar AppState))
+
+data AppState = AppState
+  { ques :: HashMap Namespace Quebase
+  , port :: Warp.Port
+  }
+
+initialAppState :: AppState
+initialAppState = AppState { port = 80, ques = mempty }
+
+-- | Resolve a list of 'AppState' transitions into one.
+smoosh
+  :: AppState -- ^ Initial app state to start with
+  -> [AppState -> AppState] -- ^ List of functions to apply in order
+  -> AppState
+smoosh = foldr identity
+-- there's gotta be a standard name for this
+
+-- | A synonym for 'lift' in order to be explicit about when we are
+-- operating at the 'App' layer.
+app :: MonadTrans t => App a -> t App a
+app = lift
+
+-- | Get something from the app state
+gets :: (AppState -> b) -> App b
+gets f = ask >>= liftIO . STM.readTVarIO >>= return . f
+
+-- | Apply a function to the app state
+modify :: (AppState -> AppState) -> App ()
+modify f = ask >>= liftIO . atomically . flip STM.modifyTVar' f
+
+type Namespace = Text -- ^ housing for a set of que paths
+type Que = Go.Channel Quedata -- ^ a que is just a channel of bytes
+type Quepath = [Text] -- ^ any path can serve as an identifier for a que
+type Quedata = ByteString -- ^ any opaque data
+type Quebase = HashMap Quepath Que -- ^ a collection of ques
+
+-- | Lookup or create a que
+que :: Namespace -> Quepath -> App Que
+que ns qp = do
+  _ques <- gets ques
+  let qbase     = grab ns _ques
+      queExists = HashMap.member qp qbase
+  if queExists
+    then return <| grab qp qbase
+    else do
+      c <- liftIO Go.chan
+      modify (insertQue ns qp c)
+      gets ques /> grab ns /> grab qp
+
+-- | Put data on the que.
+pushQue :: Quedata -> Que -> IO ()
+pushQue = flip Go.write
+
+-- | Tap and read from the Que. Tap first because a Que is actually a
+-- broadcast channel. This allows for multiconsumer Ques.
+takeQue :: Que -> IO Quedata
+takeQue ch = Go.mult ch >>= Go.tap