package notify

import (
	"bytes"
	"context"
	"errors"
	"io"
	"sync"
	"sync/atomic"
	"testing"
	"time"
)

func TestRegressionRecordResetSendFailureReleasesNativeStream(t *testing.T) {
	runtime := newStreamRuntime("review-reset")
	sendErr := errors.New("injected reset send failure")
	s := newStreamHandle(context.Background(), runtime, clientFileScope(), StreamOpenRequest{StreamID: "review-reset"}, 0, nil, nil, 0, nil,
		func(context.Context, *streamHandle, string) error { return sendErr }, nil, defaultStreamConfig())
	if err := runtime.register(clientFileScope(), s); err != nil {
		t.Fatal(err)
	}
	t.Cleanup(func() { s.markReset(io.ErrClosedPipe) })
	record, err := WrapStreamAsRecord(s, RecordOpenOptions{})
	if err != nil {
		t.Fatal(err)
	}
	err = record.Reset(errors.New("application aborted"))
	if err != nil && !errors.Is(err, sendErr) {
		t.Fatal(err)
	}
	select {
	case <-s.Context().Done():
	case <-time.After(100 * time.Millisecond):
		_, retained := runtime.lookup(clientFileScope(), s.ID())
		t.Fatalf("Reset returned %v but native context is live, runtime retained=%v", err, retained)
	}
	select {
	case <-record.(*recordStream).readerCh:
	case <-time.After(time.Second):
		t.Fatal("record reader was not released")
	}
}

func TestRegressionRecordHalfCloseKeepsResponseAcknowledgements(t *testing.T) {
	server := NewServer().(*ServerCommon)
	if err := UseModernPSKServer(server, integrationSharedSecret, integrationModernPSKOptions()); err != nil {
		t.Fatal(err)
	}
	accepted := make(chan RecordStream, 1)
	server.SetRecordStreamHandler(func(info RecordAcceptInfo) error { accepted <- info.RecordStream; return nil })
	if err := server.Listen("tcp", "127.0.0.1:0"); err != nil {
		t.Fatal(err)
	}
	defer server.Stop()
	client := NewClient().(*ClientCommon)
	if err := UseModernPSKClient(client, integrationSharedSecret, integrationModernPSKOptions()); err != nil {
		t.Fatal(err)
	}
	if err := client.Connect("tcp", server.listener.Addr().String()); err != nil {
		t.Fatal(err)
	}
	defer client.Stop()
	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Second)
	defer cancel()
	local, err := client.OpenRecordStream(ctx, RecordOpenOptions{})
	if err != nil {
		t.Fatal(err)
	}
	var remote RecordStream
	select {
	case remote = <-accepted:
	case <-ctx.Done():
		t.Fatal(ctx.Err())
	}
	for i := 0; i < 3; i++ {
		if _, err := local.WriteRecord(ctx, []byte{byte(i)}); err != nil {
			t.Fatal(err)
		}
	}
	if err := local.CloseWrite(); err != nil {
		t.Fatal(err)
	}
	for i := 0; i < 3; i++ {
		msg, err := remote.ReadRecord(ctx)
		if err != nil || !bytes.Equal(msg.Payload, []byte{byte(i)}) {
			t.Fatalf("queued request %d: %v %+v", i, err, msg)
		}
		if err := remote.AckRecord(msg.Seq); err != nil {
			t.Fatal(err)
		}
	}
	if _, err := remote.ReadRecord(ctx); !errors.Is(err, io.EOF) {
		t.Fatalf("request half-close EOF: %v", err)
	}
	if _, err := local.BarrierTo(ctx, 3); err != nil {
		t.Fatalf("request ACK after FIN: %v", err)
	}
	seq, err := remote.WriteRecord(ctx, []byte("response after request EOF"))
	if err != nil {
		t.Fatal(err)
	}
	if err := remote.Flush(ctx); err != nil {
		t.Fatal(err)
	}
	msg, err := local.ReadRecord(ctx)
	if err != nil {
		t.Fatal(err)
	}
	if err := local.AckRecord(msg.Seq); err != nil {
		t.Fatal(err)
	}
	if _, err := remote.BarrierTo(ctx, seq); err != nil {
		t.Fatalf("response was received and applied, but its barrier failed after peer CloseWrite: %v", err)
	}
}

func TestRecordHalfCloseNegotiation(t *testing.T) {
	request := advertiseRecordStreamOpenMetadata(StreamMetadata{recordStreamMetadataUseHalfCloseKey: "1"})
	if recordStreamUseHalfClose(request) {
		t.Fatal("request enabled half-close before peer negotiation")
	}
	for _, supported := range []bool{false, true} {
		meta := StreamMetadata{recordStreamMetadataUseHalfCloseKey: "1"}
		if supported {
			meta[recordStreamMetadataCapHalfCloseKey] = "1"
		}
		accepted, response := negotiateRecordStreamOpenMetadata(StreamRecordChannel, meta)
		if recordStreamUseHalfClose(accepted) != supported || recordStreamUseHalfClose(response) != supported {
			t.Fatalf("half-close negotiation with supported=%v: %v %v", supported, accepted, response)
		}
	}
}

func TestRecordLegacyHalfCloseUsesNativeClose(t *testing.T) {
	s := newStreamHandle(context.Background(), newStreamRuntime("legacy-fin"), clientFileScope(), StreamOpenRequest{StreamID: "legacy-fin"}, 0, nil, nil, 0, nil, nil, nil, defaultStreamConfig())
	t.Cleanup(func() { s.markReset(io.ErrClosedPipe) })
	record, err := WrapStreamAsRecord(s, RecordOpenOptions{})
	if err != nil {
		t.Fatal(err)
	}
	if err := record.CloseWrite(); err != nil {
		t.Fatal(err)
	}
	if !s.localClosedSnapshot() {
		t.Fatal("unnegotiated peer received logical FIN instead of native close")
	}
}

func TestRecordInvalidFINAndPostFINDataAbort(t *testing.T) {
	batch, err := encodeRecordBatchFrame([]recordOutboundMessage{{Seq: 1, Payload: []byte("after EOF")}}, 0, false)
	if err != nil {
		t.Fatal(err)
	}
	for _, tc := range []struct {
		name       string
		negotiated bool
		frames     [][]byte
	}{
		{"unnegotiated", false, [][]byte{encodeRecordFINFrame(0)}},
		{"wrong-sequence", true, [][]byte{encodeRecordFINFrame(1)}},
		{"duplicate", true, [][]byte{encodeRecordFINFrame(0), encodeRecordFINFrame(0)}},
		{"data-after-fin", true, [][]byte{encodeRecordFINFrame(0), batch}},
		{"truncated-fin", true, [][]byte{encodeRecordFINFrame(0)[:10]}},
	} {
		t.Run(tc.name, func(t *testing.T) {
			metadata := StreamMetadata{}
			if tc.negotiated {
				metadata[recordStreamMetadataUseHalfCloseKey] = "1"
			}
			s := newStreamHandle(context.Background(), newStreamRuntime("fin"), clientFileScope(), StreamOpenRequest{StreamID: "fin", Metadata: metadata}, 0, nil, nil, 0, nil, nil,
				func(context.Context, *streamHandle, []byte) error { return nil }, defaultStreamConfig())
			t.Cleanup(func() { s.markReset(io.ErrClosedPipe) })
			record, err := WrapStreamAsRecord(s, RecordOpenOptions{})
			if err != nil {
				t.Fatal(err)
			}
			for _, payload := range tc.frames {
				if err := s.pushChunk(buildTransferFrame(payload)); err != nil {
					t.Fatal(err)
				}
			}
			select {
			case <-record.(*recordStream).readerCh:
			case <-time.After(time.Second):
				t.Fatal("invalid FIN reader stuck")
			}
			if s.Context().Err() == nil {
				t.Fatal("protocol failure retained native stream")
			}
			if _, err := record.WriteRecord(context.Background(), []byte("unexpected")); err == nil {
				t.Fatal("protocol failure accepted a new write")
			}
		})
	}
}

func TestRecordFailureNotificationIsBounded(t *testing.T) {
	s := newStreamHandle(context.Background(), newStreamRuntime("blocked-failure"), clientFileScope(), StreamOpenRequest{StreamID: "blocked-failure"}, 0, nil, nil, 0, nil, nil,
		func(_ context.Context, stream *streamHandle, _ []byte) error {
			<-stream.Context().Done()
			return io.ErrClosedPipe
		}, defaultStreamConfig())
	t.Cleanup(func() { s.markReset(io.ErrClosedPipe) })
	record, err := WrapStreamAsRecord(s, RecordOpenOptions{Stream: StreamOpenOptions{WriteTimeout: 30 * time.Millisecond}})
	if err != nil {
		t.Fatal(err)
	}
	started := time.Now()
	if err := record.FailRecord(1, RecordFailure{Message: "apply failed"}); !errors.Is(err, context.DeadlineExceeded) {
		t.Fatalf("bounded failure error: %v", err)
	}
	if elapsed := time.Since(started); elapsed > time.Second {
		t.Fatalf("failure took %v", elapsed)
	}
	if s.Context().Err() == nil {
		t.Fatal("failure retained native stream")
	}
	select {
	case <-record.(*recordStream).readerCh:
	case <-time.After(time.Second):
		t.Fatal("failure retained reader")
	}
}

func TestRecordWriterFailureReleasesNativeStream(t *testing.T) {
	errWrite := errors.New("injected write error")
	s := newStreamHandle(context.Background(), newStreamRuntime("writer-failure"), clientFileScope(), StreamOpenRequest{StreamID: "writer-failure"}, 0, nil, nil, 0, nil, nil,
		func(context.Context, *streamHandle, []byte) error { return errWrite }, defaultStreamConfig())
	t.Cleanup(func() { s.markReset(io.ErrClosedPipe) })
	record, err := WrapStreamAsRecord(s, RecordOpenOptions{MaxBatchRecords: 1})
	if err != nil {
		t.Fatal(err)
	}
	if _, err := record.WriteRecord(context.Background(), []byte("request")); err != nil {
		t.Fatal(err)
	}
	select {
	case <-record.(*recordStream).writerCh:
	case <-time.After(time.Second):
		t.Fatal("writer stuck")
	}
	if s.Context().Err() == nil {
		t.Fatal("writer failure retained native stream")
	}
	select {
	case <-record.(*recordStream).readerCh:
	case <-time.After(time.Second):
		t.Fatal("writer failure retained reader")
	}
}

func TestStreamConcurrentResetLocallyClosesBeforeNotification(t *testing.T) {
	runtime := newStreamRuntime("reset-once")
	var calls atomic.Int32
	s := newStreamHandle(context.Background(), runtime, clientFileScope(), StreamOpenRequest{StreamID: "reset-once"}, 0, nil, nil, 0, nil,
		func(ctx context.Context, stream *streamHandle, _ string) error {
			calls.Add(1)
			if stream.Context().Err() == nil {
				t.Error("notification preceded local teardown")
			}
			if _, retained := runtime.lookup(clientFileScope(), stream.ID()); retained {
				t.Error("runtime retained stream during notification")
			}
			<-ctx.Done()
			return ctx.Err()
		}, nil, defaultStreamConfig())
	if err := runtime.register(clientFileScope(), s); err != nil {
		t.Fatal(err)
	}
	if err := s.SetWriteDeadline(time.Now().Add(30 * time.Millisecond)); err != nil {
		t.Fatal(err)
	}
	var wg sync.WaitGroup
	for i := 0; i < 8; i++ {
		wg.Add(1)
		go func() { defer wg.Done(); _ = s.Reset(io.ErrClosedPipe) }()
	}
	wg.Wait()
	if calls.Load() != 1 {
		t.Fatalf("reset notifications=%d", calls.Load())
	}
}

func TestRecordFailureRejectsOversizedCode(t *testing.T) {
	if _, err := encodeRecordErrorFrame(RecordFailure{FailedSeq: 1, Code: RecordErrorCode(bytes.Repeat([]byte("x"), 1<<16))}); !errors.Is(err, errRecordFrameInvalid) {
		t.Fatalf("oversized failure code: %v", err)
	}
}

func TestRegressionRecordFailRecordWriteFailureIsTerminal(t *testing.T) {
	s := newStreamHandle(context.Background(), newStreamRuntime("review-fail"), clientFileScope(), StreamOpenRequest{StreamID: "review-fail"}, 0, nil, nil, 0, nil, nil,
		func(context.Context, *streamHandle, []byte) error { return io.ErrUnexpectedEOF }, defaultStreamConfig())
	t.Cleanup(func() { s.markReset(io.ErrClosedPipe) })
	record, err := WrapStreamAsRecord(s, RecordOpenOptions{})
	if err != nil {
		t.Fatal(err)
	}
	defer record.Close()
	payload, err := encodeRecordBatchFrame([]recordOutboundMessage{{Seq: 1, Payload: []byte("valid incoming record")}}, 0, false)
	if err != nil {
		t.Fatal(err)
	}
	if err := s.pushChunk(buildTransferFrame(payload)); err != nil {
		t.Fatal(err)
	}
	ctx, cancel := context.WithTimeout(context.Background(), time.Second)
	defer cancel()
	if _, err := record.ReadRecord(ctx); err != nil {
		t.Fatal(err)
	}
	if err := record.FailRecord(1, RecordFailure{FailedSeq: 1, Code: RecordErrorCodeApplyFailed, Message: "disk full"}); !errors.Is(err, io.ErrUnexpectedEOF) {
		t.Fatalf("failure send: %v", err)
	}
	seq, err := record.WriteRecord(context.Background(), []byte("must not admit more records"))
	if err == nil {
		t.Fatalf("failed record stream still accepts data: seq=%d", seq)
	}
}