package notify

import (
	"context"
	"errors"
	"math"
	"net"
	"os"
	"testing"
	"time"

	"b612.me/stario"
)

func newServerBlackholeTransport(t *testing.T, id string) (*ServerCommon, *LogicalConn, *TransportConn, net.Conn, net.Conn) {
	t.Helper()
	server := NewServer().(*ServerCommon)
	UseLegacySecurityServer(server)
	stopCtx, stopFn := context.WithCancel(context.Background())
	server.setServerSessionRuntime(&serverSessionRuntime{
		stopCtx: stopCtx,
		stopFn:  stopFn,
		queue:   stario.NewQueueCtx(stopCtx, 4, math.MaxUint32),
	})
	server.markSessionStarted()
	left, right := net.Pipe()
	logical, _, _ := newRegisteredServerLogicalForTest(t, server, id, left, stopCtx, stopFn)
	logical.applyAttachmentProfile(0, 0, server.defaultMsgEn, server.defaultMsgDe, server.defaultFastStreamEncode, server.defaultFastBulkEncode, server.defaultFastPlainEncode, server.handshakeRsaKey, server.SecretKey)
	transport := logical.CurrentTransportConn()
	if transport == nil {
		t.Fatal("server transport is nil")
	}
	t.Cleanup(func() {
		_ = left.Close()
		_ = right.Close()
		server.markSessionStopped("test done", nil)
	})
	return server, logical, transport, left, right
}

func requireBoundedServerWrite(t *testing.T, timeout time.Duration, write func(context.Context) error) {
	t.Helper()
	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()
	done := make(chan error, 1)
	started := time.Now()
	go func() { done <- write(ctx) }()
	select {
	case err := <-done:
		if err == nil {
			t.Fatal("blackhole server write returned nil")
		}
		if !errors.Is(err, context.DeadlineExceeded) && !errors.Is(err, os.ErrDeadlineExceeded) {
			var netErr net.Error
			if !errors.As(err, &netErr) || !netErr.Timeout() {
				t.Fatalf("blackhole server write error=%v, want deadline error", err)
			}
		}
		if elapsed := time.Since(started); elapsed > 5*timeout {
			t.Fatalf("blackhole server write returned after %v, want bounded by %v", elapsed, timeout)
		}
	case <-time.After(10 * timeout):
		t.Fatalf("blackhole server write ignored its %v context deadline", timeout)
	}
}

func TestServerSharedBulkWriteHonorsContextDeadline(t *testing.T) {
	server, logical, transport, _, _ := newServerBlackholeTransport(t, "shared-bulk-write-context")
	requireBoundedServerWrite(t, 30*time.Millisecond, func(ctx context.Context) error {
		return server.sendFastBulkDataTransport(ctx, logical, transport, 1, 0, []byte("bulk"), bulkFastPathVersionV1)
	})
}

func TestServerSharedStreamWriteHonorsContextDeadline(t *testing.T) {
	server, logical, transport, _, _ := newServerBlackholeTransport(t, "shared-stream-write-context")
	stream := newStreamHandle(context.Background(), nil, serverFileScope(logical), StreamOpenRequest{
		StreamID:        "shared-stream-write-context",
		DataID:          1,
		Channel:         StreamDataChannel,
		FastPathVersion: streamFastPathVersionV1,
	}, 0, logical, transport, transport.TransportGeneration(), nil, nil, nil, defaultStreamConfig())
	requireBoundedServerWrite(t, 30*time.Millisecond, func(ctx context.Context) error {
		return server.sendFastStreamDataTransport(ctx, logical, transport, stream, []byte("stream"))
	})
}

func TestMessageReplyUsesConfiguredDefaultWriteTimeout(t *testing.T) {
	server, logical, transport, left, _ := newServerBlackholeTransport(t, "reply-default-write-timeout")
	server.SetReplyWriteTimeout(35 * time.Millisecond)
	message := Message{
		NetType:       NET_SERVER,
		LogicalConn:   logical,
		TransportConn: transport,
		TransferMsg: TransferMsg{
			ID:   1,
			Key:  "reply-default-write-timeout",
			Type: MSG_SYNC_ASK,
		},
		inboundConn: left,
	}
	started := time.Now()
	err := message.Reply([]byte("reply"))
	if err == nil {
		t.Fatal("blackhole Message.Reply returned nil")
	}
	if elapsed := time.Since(started); elapsed > 250*time.Millisecond {
		t.Fatalf("Message.Reply returned after %v, want configured default write bound", elapsed)
	}
}

func TestMessageReplyCtxUsesEarlierCallerDeadline(t *testing.T) {
	server, logical, transport, left, _ := newServerBlackholeTransport(t, "reply-caller-write-timeout")
	server.SetReplyWriteTimeout(time.Second)
	message := Message{
		NetType:       NET_SERVER,
		LogicalConn:   logical,
		TransportConn: transport,
		TransferMsg: TransferMsg{
			ID:   2,
			Key:  "reply-caller-write-timeout",
			Type: MSG_SYNC_ASK,
		},
		inboundConn: left,
	}
	ctx, cancel := context.WithTimeout(context.Background(), 25*time.Millisecond)
	defer cancel()
	started := time.Now()
	err := message.ReplyCtx(ctx, []byte("reply"))
	if err == nil {
		t.Fatal("blackhole Message.ReplyCtx returned nil")
	}
	if elapsed := time.Since(started); elapsed > 200*time.Millisecond {
		t.Fatalf("Message.ReplyCtx returned after %v, want caller deadline", elapsed)
	}

	canceled, cancelNow := context.WithCancel(context.Background())
	cancelNow()
	if err := message.ReplyObjCtx(canceled, "ok"); !errors.Is(err, context.Canceled) {
		t.Fatalf("Message.ReplyObjCtx canceled error=%v, want context canceled", err)
	}
}

type closeTrackingWriteConn struct {
	closed bool
	writes int
}

func (c *closeTrackingWriteConn) Read([]byte) (int, error)         { return 0, net.ErrClosed }
func (c *closeTrackingWriteConn) Close() error                     { c.closed = true; return nil }
func (c *closeTrackingWriteConn) LocalAddr() net.Addr              { return nil }
func (c *closeTrackingWriteConn) RemoteAddr() net.Addr             { return nil }
func (c *closeTrackingWriteConn) SetDeadline(time.Time) error      { return nil }
func (c *closeTrackingWriteConn) SetReadDeadline(time.Time) error  { return nil }
func (c *closeTrackingWriteConn) SetWriteDeadline(time.Time) error { return nil }
func (c *closeTrackingWriteConn) Write(data []byte) (int, error) {
	c.writes++
	return len(data), nil
}

func TestServerRawWriteGateWaitTimeoutDoesNotCloseConnection(t *testing.T) {
	server, logical, transport, _, _ := newServerBlackholeTransport(t, "raw-write-gate-timeout")
	conn := &closeTrackingWriteConn{}
	gateRef := retainRawConnWriteGate(conn)
	<-gateRef.gate
	t.Cleanup(func() {
		gateRef.gate <- struct{}{}
		releaseRawConnWriteGate(conn, gateRef)
	})

	ctx, cancel := context.WithTimeout(context.Background(), 25*time.Millisecond)
	defer cancel()
	err := server.writeEnvelopePayloadContextTimeout(ctx, logical, transport, conn, []byte("reply"), time.Second)
	if !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("raw write gate wait error=%v, want context deadline exceeded", err)
	}
	if conn.closed {
		t.Fatal("raw write gate wait timeout closed a connection before physical write started")
	}
	if conn.writes != 0 {
		t.Fatalf("raw write gate wait performed %d physical writes", conn.writes)
	}
}

func TestServerUDPWriteGateWaitHonorsWriteTimeout(t *testing.T) {
	server := NewServer().(*ServerCommon)
	stopCtx, stopFn := context.WithCancel(context.Background())
	t.Cleanup(stopFn)
	sender, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: 0})
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = sender.Close() })
	receiver, err := net.ListenUDP("udp", &net.UDPAddr{IP: net.ParseIP("127.0.0.1"), Port: 0})
	if err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { _ = receiver.Close() })
	server.setServerSessionRuntime(&serverSessionRuntime{
		stopCtx:     stopCtx,
		stopFn:      stopFn,
		queue:       stario.NewQueueCtx(stopCtx, 4, math.MaxUint32),
		udpListener: sender,
	})
	logical := newServerLogicalConn(server, "udp-write-gate-timeout", receiver.LocalAddr())
	transport := &TransportConn{logical: logical, remoteAddr: receiver.LocalAddr(), attached: true}

	gateHeld := make(chan struct{})
	releaseGate := make(chan struct{})
	firstDone := make(chan error, 1)
	go func() {
		firstDone <- server.withUDPWriteLock(context.Background(), func() error {
			close(gateHeld)
			<-releaseGate
			return nil
		})
	}()
	select {
	case <-gateHeld:
	case <-time.After(time.Second):
		t.Fatal("first UDP writer did not acquire the write gate")
	}

	started := time.Now()
	writeDone := make(chan error, 1)
	go func() {
		writeDone <- server.writeEnvelopePayloadContextTimeout(context.Background(), logical, transport, nil, []byte("reply"), 30*time.Millisecond)
	}()
	select {
	case err = <-writeDone:
	case <-time.After(200 * time.Millisecond):
		close(releaseGate)
		<-firstDone
		<-writeDone
		t.Fatal("UDP write gate wait ignored the configured write timeout")
	}
	if !errors.Is(err, context.DeadlineExceeded) {
		close(releaseGate)
		<-firstDone
		t.Fatalf("UDP write gate wait error=%v, want context deadline exceeded", err)
	}
	if elapsed := time.Since(started); elapsed > 200*time.Millisecond {
		close(releaseGate)
		<-firstDone
		t.Fatalf("UDP write gate wait returned after %v, want configured write bound", elapsed)
	}
	close(releaseGate)
	if err := <-firstDone; err != nil {
		t.Fatalf("first UDP writer failed: %v", err)
	}
}

func TestTransportWriteGateRegistryReleasesBindingsAndRawWrites(t *testing.T) {
	conn := &serializedWriteTestConn{}
	first := newTransportBinding(conn, stario.NewQueue())
	second := newTransportBinding(conn, stario.NewQueue())
	if first.writeGateSnapshot() != second.writeGateSnapshot() {
		t.Fatal("same physical connection did not share one write gate")
	}
	entry, ok := transportConnWriteGates.Load(conn)
	if !ok {
		t.Fatal("shared write gate was not registered")
	}
	first.stopBackgroundWorkers()
	if current, ok := transportConnWriteGates.Load(conn); !ok || current != entry {
		t.Fatal("stopping one shared binding removed the live write gate")
	}
	second.stopBackgroundWorkers()
	if _, ok := transportConnWriteGates.Load(conn); ok {
		t.Fatal("last binding release retained the historical connection write gate")
	}

	rawConn := &serializedWriteTestConn{}
	if err := writeFullToConn(rawConn, []byte("raw")); err != nil {
		t.Fatalf("raw write failed: %v", err)
	}
	if _, ok := transportConnWriteGates.Load(rawConn); ok {
		t.Fatal("completed raw write retained a temporary write gate reference")
	}
}