{-# LANGUAGE OverloadedStrings #-}
{-# LANGUAGE ScopedTypeVariables #-}

-- | A server library for HTTP/3.
module Network.HTTP3.Server (
    -- * Runner
    run,

    -- * Common configration
    Config (..),
    defaultConfig,
    allocSimpleConfig,
    freeSimpleConfig,
    defaultQEncoderConfig,
    ecMaxTableCapacity,
    ecHeaderBlockBufferSize,
    ecInstructionBufferSize,
    defaultQDecoderConfig,
    dcMaxTableCapacity,
    dcHuffmanBufferSize,
    Hooks (..),
    defaultHooks,

    -- * HTTP semantics
    module Network.HTTP.Semantics.Server,

    -- * Internal
    runIO,
    ServerIO (..),
) where

import Control.Concurrent
import Control.Concurrent.Async
import Control.Concurrent.STM
import qualified Control.Exception as E
import Data.IORef
import GHC.Conc.Sync
import Network.HTTP.Semantics
import Network.HTTP.Semantics.Server
import Network.HTTP.Semantics.Server.Internal
import Network.HTTP2.Server.Internal (ServerIO (..))
import Network.QUIC (Connection, ConnectionInfo (..), Stream, getConnectionInfo)
import qualified Network.QUIC as QUIC
import Network.QUIC.Internal (mainDone)
import qualified System.TimeManager as T

import Imports
import Network.HTTP3.Config
import Network.HTTP3.Context
import Network.HTTP3.Error
import Network.HTTP3.Frame
import Network.HTTP3.Recv
import Network.HTTP3.Send
import Network.QPACK
import Network.QPACK.Internal

-- | Running an HTTP\/3 server.
run :: Connection -> Config -> Server -> IO ()
run conn conf server = withContext conn conf $ \ctx -> do
    myThreadId >>= \t -> labelThread t "H3 server: run"
    readerServer ctx $ \strm ->
        forkManagedTimeoutFinally
            ctx
            "H3 server: processRequest"
            (processRequest ctx server strm)
            (closeStream strm)

runIO :: Connection -> Config -> (ServerIO Stream -> IO (IO ())) -> IO ()
runIO conn conf action = withContext conn conf $ \ctx -> do
    info <- getConnectionInfo conn
    reqq <- newTQueueIO
    let sio =
            ServerIO
                { sioMySockAddr = localSockAddr info
                , sioPeerSockAddr = remoteSockAddr info
                , sioReadRequest = atomically $ readTQueue reqq
                , sioWriteResponse = sendResponseIO ctx
                , sioDone = mainDone conn
                }
        put strmreq = atomically $ writeTQueue reqq strmreq
    io <- action sio
    concurrently_ io (readerServer ctx $ processRequestIO ctx put)

readerServer :: Context -> (Stream -> IO ()) -> IO ()
readerServer ctx action = loop
  where
    loop = do
        accept ctx >>= process
        loop
    process strm
        | QUIC.isClientInitiatedUnidirectional sid =
            forkManaged ctx "H3 server: unidirectional handler" $
                unidirectional ctx strm
        | QUIC.isClientInitiatedBidirectional sid = action strm
        | QUIC.isServerInitiatedUnidirectional sid = return () -- error
        | otherwise = return ()
      where
        sid = QUIC.streamId strm

processRequest
    :: Context
    -> Server
    -> Stream
    -> T.Handle
    -> IO ()
processRequest ctx server strm th = E.handle reset $ do
    src <- newSource strm
    mvt <- recvHeader ctx sid src
    case mvt of
        Nothing -> QUIC.resetStream strm H3MessageError
        Just ht -> do
            req <- mkRequest ctx strm src ht
            let aux =
                    defaultAux
                        { auxTimeHandle = th
                        , auxMySockAddr = getMySockAddr ctx
                        , auxPeerSockAddr = getPeerSockAddr ctx
                        }
            server req aux $ sendResponse ctx strm th
  where
    sid = QUIC.streamId strm
    reset se
        | isAsyncException se = E.throwIO se
        | Just (_ :: DecodeError) <- E.fromException se =
            abort ctx QpackDecompressionFailed
        | otherwise = QUIC.resetStream strm H3MessageError

processRequestIO :: Context -> ((Stream, Request) -> IO ()) -> Stream -> IO ()
processRequestIO ctx put strm = E.handle reset $ do
    src <- newSource strm
    mvt <- recvHeader ctx sid src
    case mvt of
        Nothing -> QUIC.resetStream strm H3MessageError
        Just ht -> do
            req <- mkRequest ctx strm src ht
            put (strm, req)
  where
    sid = QUIC.streamId strm
    reset se
        | isAsyncException se = E.throwIO se
        | Just (_ :: DecodeError) <- E.fromException se =
            abort ctx QpackDecompressionFailed
        | otherwise = QUIC.resetStream strm H3MessageError

mkRequest
    :: Context
    -> Stream
    -> Source
    -> (TokenHeaderList, ValueTable)
    -> IO Request
mkRequest ctx strm src ht@(_, vt) = do
    let mMethod = getFieldValue tokenMethod vt
        mScheme = getFieldValue tokenScheme vt
        mAuthority = getFieldValue tokenAuthority vt
        mPath = getFieldValue tokenPath vt
    case (mMethod, mScheme, mAuthority, mPath) of
        (Just "CONNECT", _, Just _, _) -> return ()
        (Just _, Just _, Just _, Just _) -> return ()
        _ -> QUIC.resetStream strm H3MessageError
    -- fixme: Content-Length
    refI <- newIORef IInit
    refH <- newIORef Nothing
    let sid = QUIC.streamId strm
    let readB = recvBody ctx sid src refI refH
        req = Request $ InpObj ht Nothing readB refH
    return req

sendResponse
    :: Context -> Stream -> T.Handle -> Response -> [PushPromise] -> IO ()
sendResponse ctx strm th (Response outobj) _pp = do
    sendHeader ctx strm th $ outObjHeaders outobj
    sendBody ctx strm th outobj
    QUIC.shutdownStream strm

sendResponseIO
    :: Context -> Stream -> Response -> IO ()
sendResponseIO ctx strm (Response outobj) =
    void $ withHandle ctx $ \th -> do
        sendHeader ctx strm th $ outObjHeaders outobj
        sendBody ctx strm th outobj
        QUIC.closeStream strm