package notify

import (
	"b612.me/stario"
	"context"
	"io"
	"math"
	"net"
	"sync"
	"sync/atomic"
	"testing"
	"time"
)

func TestStreamRuntimeSeparatesPeerDataIDNamespaces(t *testing.T) {
	clientRuntime := newStreamRuntime("cstrm")
	serverRuntime := newStreamRuntime("sstrm")
	clientID := clientRuntime.nextDataID()
	serverID := serverRuntime.nextDataID()
	if clientID == serverID || clientID%2 != 1 || serverID%2 != 0 {
		t.Fatalf("client/server stream data ids = %d/%d, want disjoint odd/even namespaces", clientID, serverID)
	}
}

func TestStreamRuntimeKeepsLegacyZeroDataIDControlsCompatible(t *testing.T) {
	tests := []struct {
		name       string
		rolePrefix string
		wantParity uint64
	}{
		{name: "client receives server stream", rolePrefix: "cstrm", wantParity: 0},
		{name: "server receives client stream", rolePrefix: "sstrm", wantParity: 1},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			runtime := newStreamRuntime(tt.rolePrefix)
			scope := "legacy-zero"
			stream := newStreamHandle(context.Background(), runtime, scope, StreamOpenRequest{
				StreamID: "legacy-stream",
				DataID:   0,
			}, 0, nil, nil, 0, nil, nil, nil, runtime.configSnapshot())
			if err := runtime.registerInbound(scope, stream); err != nil {
				t.Fatalf("register legacy zero-DataID stream: %v", err)
			}
			defer stream.markReset(io.ErrClosedPipe)
			if dataID := stream.dataIDSnapshot(); dataID == 0 || dataID%2 != tt.wantParity {
				t.Fatalf("legacy assigned DataID = %d, want non-zero parity %d", dataID, tt.wantParity)
			}
			if got, ok := runtime.lookupControl(scope, stream.ID(), 0); !ok || got != stream {
				t.Fatalf("legacy DataID=0 control lookup = %p/%v, want %p/true", got, ok, stream)
			}
		})
	}
}

func TestStreamOpenConcurrentlyFromBothPeers(t *testing.T) {
	server := NewServer().(*ServerCommon)
	if err := UseModernPSKServer(server, integrationSharedSecret, integrationModernPSKOptions()); err != nil {
		t.Fatalf("UseModernPSKServer failed: %v", err)
	}
	serverAccepted := make(chan StreamAcceptInfo, 1)
	server.SetStreamHandler(func(info StreamAcceptInfo) error {
		serverAccepted <- info
		return nil
	})
	if err := server.Listen("tcp", "127.0.0.1:0"); err != nil {
		t.Fatalf("server Listen failed: %v", err)
	}
	defer func() { _ = server.Stop() }()

	client := NewClient().(*ClientCommon)
	if err := UseModernPSKClient(client, integrationSharedSecret, integrationModernPSKOptions()); err != nil {
		t.Fatalf("UseModernPSKClient failed: %v", err)
	}
	clientAccepted := make(chan StreamAcceptInfo, 1)
	client.SetStreamHandler(func(info StreamAcceptInfo) error {
		clientAccepted <- info
		return nil
	})
	if err := client.Connect("tcp", server.listener.Addr().String()); err != nil {
		t.Fatalf("client Connect failed: %v", err)
	}
	defer func() { _ = client.Stop() }()
	logical := waitForTransferControlLogicalConn(t, server, 2*time.Second)

	type openResult struct {
		stream Stream
		err    error
	}
	clientResult := make(chan openResult, 1)
	serverResult := make(chan openResult, 1)
	start := make(chan struct{})
	var ready sync.WaitGroup
	ready.Add(2)
	go func() {
		ready.Done()
		<-start
		stream, err := client.OpenStream(context.Background(), StreamOpenOptions{Channel: StreamDataChannel})
		clientResult <- openResult{stream: stream, err: err}
	}()
	go func() {
		ready.Done()
		<-start
		stream, err := server.OpenStreamLogical(context.Background(), logical, StreamOpenOptions{Channel: StreamDataChannel})
		serverResult <- openResult{stream: stream, err: err}
	}()
	ready.Wait()
	close(start)

	clientOpen := <-clientResult
	serverOpen := <-serverResult
	if clientOpen.err != nil || serverOpen.err != nil {
		t.Fatalf("concurrent stream opens failed: client=%v server=%v", clientOpen.err, serverOpen.err)
	}
	clientInbound := waitAcceptedStream(t, serverAccepted, 2*time.Second)
	serverInbound := waitAcceptedStream(t, clientAccepted, 2*time.Second)
	clientID := clientOpen.stream.(*streamHandle).dataIDSnapshot()
	serverID := serverOpen.stream.(*streamHandle).dataIDSnapshot()
	if clientID%2 != 1 || serverID%2 != 0 {
		t.Fatalf("local stream data ids = %d/%d, want odd/even", clientID, serverID)
	}
	if clientInbound.DataID != clientID || serverInbound.DataID != serverID {
		t.Fatalf("stream data ids differ across peers: client=%d/%d server=%d/%d", clientID, clientInbound.DataID, serverID, serverInbound.DataID)
	}
	if _, err := clientOpen.stream.Write([]byte("client")); err != nil {
		t.Fatalf("client stream write failed: %v", err)
	}
	readStreamExactly(t, clientInbound.Stream, "client", 2*time.Second)
	if _, err := serverOpen.stream.Write([]byte("server")); err != nil {
		t.Fatalf("server stream write failed: %v", err)
	}
	readStreamExactly(t, serverInbound.Stream, "server", 2*time.Second)
	_ = clientOpen.stream.Close()
	_ = clientInbound.Stream.Close()
	_ = serverOpen.stream.Close()
	_ = serverInbound.Stream.Close()
}

func TestStreamHandlerWriteBeforeOpenReplyIsDelivered(t *testing.T) {
	server := NewServer().(*ServerCommon)
	if err := UseModernPSKServer(server, integrationSharedSecret, integrationModernPSKOptions()); err != nil {
		t.Fatalf("UseModernPSKServer failed: %v", err)
	}
	server.SetStreamHandler(func(info StreamAcceptInfo) error {
		_, err := info.Stream.Write([]byte("early"))
		return err
	})
	if err := server.Listen("tcp", "127.0.0.1:0"); err != nil {
		t.Fatalf("server Listen failed: %v", err)
	}
	defer func() { _ = server.Stop() }()

	client := NewClient().(*ClientCommon)
	if err := UseModernPSKClient(client, integrationSharedSecret, integrationModernPSKOptions()); err != nil {
		t.Fatalf("UseModernPSKClient failed: %v", err)
	}
	if err := client.Connect("tcp", server.listener.Addr().String()); err != nil {
		t.Fatalf("client Connect failed: %v", err)
	}
	defer func() { _ = client.Stop() }()

	stream, err := client.OpenStream(context.Background(), StreamOpenOptions{Channel: StreamDataChannel})
	if err != nil {
		t.Fatalf("client OpenStream failed: %v", err)
	}
	readStreamExactly(t, stream, "early", 2*time.Second)
	_ = stream.Close()
}

func TestServerRejectsQueuedStreamOpenFromStaleTransport(t *testing.T) {
	server := NewServer().(*ServerCommon)
	UseLegacySecurityServer(server)
	var handlerCalls atomic.Int32
	server.SetStreamHandler(func(StreamAcceptInfo) error {
		handlerCalls.Add(1)
		return nil
	})

	firstLeft, firstRight := net.Pipe()
	defer firstRight.Close()
	logical := server.bootstrapAcceptedLogical("stale-inbound-stream-open", nil, firstLeft)
	if logical == nil {
		t.Fatal("bootstrapAcceptedLogical should return logical")
	}
	staleTransport := logical.CurrentTransportConn()
	secondLeft, secondRight := net.Pipe()
	defer secondRight.Close()
	if err := logical.attachClientConnSessionTransport(secondLeft); err != nil {
		t.Fatalf("attach replacement transport: %v", err)
	}
	payload, err := encode(StreamOpenRequest{StreamID: "queued-stale-open", DataID: 1})
	if err != nil {
		t.Fatalf("encode StreamOpenRequest: %v", err)
	}
	message := Message{
		NetType:       NET_SERVER,
		LogicalConn:   logical,
		TransportConn: staleTransport,
		TransferMsg: TransferMsg{
			Key:   StreamOpenSignalKey,
			Value: payload,
			Type:  MSG_ASYNC,
		},
	}

	server.handleInboundStreamOpen(&message)
	if got := handlerCalls.Load(); got != 0 {
		t.Fatalf("stale StreamOpen handler calls = %d, want 0", got)
	}
	if stream, ok := server.getStreamRuntime().lookup(serverFileScope(logical), "queued-stale-open"); ok {
		t.Fatalf("stale StreamOpen registered runtime handle: %+v", stream.snapshot())
	}
}

func TestClientRejectsStreamOpenWhenRouteReattachesDuringRegistration(t *testing.T) {
	client := NewClient().(*ClientCommon)
	UseLegacySecurityClient(client)
	var handlerCalls atomic.Int32
	client.SetStreamHandler(func(StreamAcceptInfo) error {
		handlerCalls.Add(1)
		return nil
	})

	stopCtx, stopFn := context.WithCancel(context.Background())
	defer stopFn()
	queue := stario.NewQueueCtx(stopCtx, 4, math.MaxUint32)
	firstLeft, firstRight := net.Pipe()
	defer firstRight.Close()
	epoch := client.beginClientSessionEpoch()
	client.setClientSessionRuntime(newClientSessionRuntime(firstLeft, stopCtx, stopFn, queue, epoch))
	client.markSessionStarted()
	defer client.markSessionStopped("test done", nil)

	payload, err := encode(StreamOpenRequest{StreamID: "client-stale-inbound-open", DataID: 2})
	if err != nil {
		t.Fatalf("encode StreamOpenRequest: %v", err)
	}
	message := Message{
		NetType:     NET_CLIENT,
		ServerConn:  client,
		clientRoute: client.clientSessionRouteSnapshot(),
		TransferMsg: TransferMsg{
			Key:   StreamOpenSignalKey,
			Value: payload,
			Type:  MSG_ASYNC,
		},
	}

	runtime := client.getStreamRuntime()
	runtime.mu.Lock()
	done := make(chan struct{})
	go func() {
		defer close(done)
		client.handleInboundStreamOpen(&message)
	}()
	secondLeft, secondRight := net.Pipe()
	defer secondRight.Close()
	if err := client.attachClientSessionTransport(secondLeft); err != nil {
		runtime.mu.Unlock()
		t.Fatalf("attach client replacement transport: %v", err)
	}
	runtime.mu.Unlock()

	select {
	case <-done:
	case <-time.After(time.Second):
		t.Fatal("client stale StreamOpen handler did not return")
	}
	if got := handlerCalls.Load(); got != 0 {
		t.Fatalf("stale client StreamOpen handler calls = %d, want 0", got)
	}
	if stream, ok := runtime.lookup(clientFileScope(), "client-stale-inbound-open"); ok {
		t.Fatalf("stale client StreamOpen registered runtime handle: %+v", stream.snapshot())
	}
}

func TestClientStaleStreamRouteCannotAffectReplacement(t *testing.T) {
	client := NewClient().(*ClientCommon)
	runtime := client.getStreamRuntime()
	epoch := client.beginClientSessionEpoch()

	staleLeft, staleRight := net.Pipe()
	defer staleLeft.Close()
	defer staleRight.Close()
	currentLeft, currentRight := net.Pipe()
	defer currentLeft.Close()
	defer currentRight.Close()
	staleRoute := clientSessionRoute{binding: newTransportBinding(staleLeft, nil), epoch: epoch}
	currentRoute := clientSessionRoute{binding: newTransportBinding(currentLeft, nil), epoch: epoch}

	stream := newStreamHandle(context.Background(), runtime, clientFileScope(), StreamOpenRequest{
		StreamID: "replacement-stream",
		DataID:   2,
		Channel:  StreamDataChannel,
	}, epoch, nil, nil, 0, nil, nil, nil, runtime.configSnapshot())
	stream.setClientSessionRoute(currentRoute)
	if err := runtime.register(clientFileScope(), stream); err != nil {
		t.Fatalf("register replacement stream: %v", err)
	}

	closePayload, err := encode(StreamCloseRequest{StreamID: stream.ID(), Full: true})
	if err != nil {
		t.Fatalf("encode close request: %v", err)
	}
	client.handleInboundStreamClose(&Message{
		NetType:     NET_CLIENT,
		ServerConn:  client,
		clientRoute: staleRoute,
		TransferMsg: TransferMsg{Key: StreamCloseSignalKey, Value: closePayload, Type: MSG_ASYNC},
	})

	resetPayload, err := encode(StreamResetRequest{StreamID: stream.ID(), DataID: stream.dataIDSnapshot(), Error: "stale reset"})
	if err != nil {
		t.Fatalf("encode reset request: %v", err)
	}
	client.handleInboundStreamReset(&Message{
		NetType:     NET_CLIENT,
		ServerConn:  client,
		clientRoute: staleRoute,
		TransferMsg: TransferMsg{Key: StreamResetSignalKey, Value: resetPayload, Type: MSG_ASYNC},
	})
	mismatchedClose, err := encode(StreamCloseRequest{StreamID: stream.ID(), DataID: stream.dataIDSnapshot() + 2, Full: true})
	if err != nil {
		t.Fatalf("encode mismatched close request: %v", err)
	}
	client.handleInboundStreamClose(&Message{
		NetType:     NET_CLIENT,
		ServerConn:  client,
		clientRoute: currentRoute,
		TransferMsg: TransferMsg{Key: StreamCloseSignalKey, Value: mismatchedClose, Type: MSG_ASYNC},
	})
	mismatchedReset, err := encode(StreamResetRequest{StreamID: stream.ID(), DataID: stream.dataIDSnapshot() + 2, Error: "mismatched reset"})
	if err != nil {
		t.Fatalf("encode mismatched reset request: %v", err)
	}
	client.handleInboundStreamReset(&Message{
		NetType:     NET_CLIENT,
		ServerConn:  client,
		clientRoute: currentRoute,
		TransferMsg: TransferMsg{Key: StreamResetSignalKey, Value: mismatchedReset, Type: MSG_ASYNC},
	})
	client.dispatchStreamEnvelopeAtRoute(staleRoute, newStreamDataEnvelope(stream.ID(), []byte("stale-envelope")))
	client.dispatchFastStreamDataWithOwnerAtRoute(staleRoute, streamFastDataFrame{
		DataID:  stream.dataIDSnapshot(),
		Seq:     1,
		Payload: []byte("stale-fast"),
	}, nil)

	stream.mu.Lock()
	defer stream.mu.Unlock()
	if stream.remoteClosed || stream.peerReadClosed || stream.resetErr != nil || len(stream.readQueue) != 0 || len(stream.readBuf.data) != 0 {
		t.Fatalf("stale route mutated replacement: remoteClosed=%v peerReadClosed=%v reset=%v queued=%d buffered=%d", stream.remoteClosed, stream.peerReadClosed, stream.resetErr, len(stream.readQueue), len(stream.readBuf.data))
	}
}

func TestServerStaleStreamControlsCannotAffectReplacement(t *testing.T) {
	server := NewServer().(*ServerCommon)
	UseLegacySecurityServer(server)

	firstLeft, firstRight := net.Pipe()
	defer firstRight.Close()
	logical := server.bootstrapAcceptedLogical("stale-stream-control", nil, firstLeft)
	if logical == nil {
		t.Fatal("bootstrapAcceptedLogical should return logical")
	}
	staleTransport := logical.CurrentTransportConn()
	secondLeft, secondRight := net.Pipe()
	defer secondRight.Close()
	if err := logical.attachClientConnSessionTransport(secondLeft); err != nil {
		t.Fatalf("attach replacement transport: %v", err)
	}
	currentTransport := logical.CurrentTransportConn()
	if currentTransport == nil || currentTransport == staleTransport {
		t.Fatal("replacement transport should be current")
	}

	runtime := server.getStreamRuntime()
	scope := serverFileScope(logical)
	stream := newStreamHandle(logical.stopContextSnapshot(), runtime, scope, StreamOpenRequest{
		StreamID: "replacement-stream",
		DataID:   1,
		Channel:  StreamDataChannel,
	}, 0, logical, currentTransport, currentTransport.TransportGeneration(), nil, nil, nil, runtime.configSnapshot())
	if err := runtime.register(scope, stream); err != nil {
		t.Fatalf("register replacement stream: %v", err)
	}

	closePayload, err := encode(StreamCloseRequest{StreamID: stream.ID(), Full: true})
	if err != nil {
		t.Fatalf("encode close request: %v", err)
	}
	server.handleInboundStreamClose(&Message{
		NetType:       NET_SERVER,
		LogicalConn:   logical,
		TransportConn: staleTransport,
		TransferMsg:   TransferMsg{Key: StreamCloseSignalKey, Value: closePayload, Type: MSG_ASYNC},
	})

	resetPayload, err := encode(StreamResetRequest{StreamID: stream.ID(), DataID: stream.dataIDSnapshot(), Error: "stale reset"})
	if err != nil {
		t.Fatalf("encode reset request: %v", err)
	}
	server.handleInboundStreamReset(&Message{
		NetType:       NET_SERVER,
		LogicalConn:   logical,
		TransportConn: staleTransport,
		TransferMsg:   TransferMsg{Key: StreamResetSignalKey, Value: resetPayload, Type: MSG_ASYNC},
	})

	stream.mu.Lock()
	defer stream.mu.Unlock()
	if stream.remoteClosed || stream.peerReadClosed || stream.resetErr != nil {
		t.Fatalf("stale controls mutated replacement: remoteClosed=%v peerReadClosed=%v reset=%v", stream.remoteClosed, stream.peerReadClosed, stream.resetErr)
	}
}