package mxgateway

import (
	"context"
	"errors"
	"io"
	"net"
	"testing"
	"time"

	pb "gitea.dohertylan.com/dohertj2/mxaccessgw/clients/go/internal/generated"
	"google.golang.org/grpc"
	"google.golang.org/grpc/metadata"
	"google.golang.org/grpc/test/bufconn"
)

const bufSize = 1024 * 1024

func TestDialAttachesAuthMetadataToUnaryCalls(t *testing.T) {
	fake := &fakeGatewayServer{
		openReply: &pb.OpenSessionReply{
			SessionId:              "session-1",
			GatewayProtocolVersion: GatewayProtocolVersion,
			WorkerProtocolVersion:  WorkerProtocolVersion,
			ProtocolStatus: &pb.ProtocolStatus{
				Code: pb.ProtocolStatusCode_PROTOCOL_STATUS_CODE_OK,
			},
		},
	}
	client, cleanup := newBufconnClient(t, fake)
	defer cleanup()

	_, err := client.OpenSession(context.Background(), OpenSessionOptions{ClientSessionName: "fixture"})
	if err != nil {
		t.Fatalf("OpenSession() error = %v", err)
	}

	if got := fake.openAuth; got != "Bearer test-api-key" {
		t.Fatalf("authorization metadata = %q, want %q", got, "Bearer test-api-key")
	}
}

func TestStreamEventsAttachesAuthMetadataAndClosesOnCancellation(t *testing.T) {
	fake := &fakeGatewayServer{
		streamStarted: make(chan struct{}),
	}
	client, cleanup := newBufconnClient(t, fake)
	defer cleanup()
	session := NewSessionForID(client, "session-1")
	ctx, cancel := context.WithCancel(context.Background())

	events, err := session.Events(ctx)
	if err != nil {
		t.Fatalf("Events() error = %v", err)
	}
	<-fake.streamStarted

	first := <-events
	if first.Err != nil {
		t.Fatalf("first event error = %v", first.Err)
	}
	if first.Event.GetWorkerSequence() != 1 {
		t.Fatalf("worker sequence = %d, want 1", first.Event.GetWorkerSequence())
	}
	if got := fake.streamAuth; got != "Bearer test-api-key" {
		t.Fatalf("stream authorization metadata = %q, want %q", got, "Bearer test-api-key")
	}

	cancel()
	select {
	case _, ok := <-events:
		if ok {
			t.Fatal("events channel produced an extra item after cancellation")
		}
	case <-time.After(2 * time.Second):
		t.Fatal("events channel did not close after cancellation")
	}
}

func TestSessionHelpersBuildCommandsAndExposeRawReply(t *testing.T) {
	fake := &fakeGatewayServer{
		invokeReply: &pb.MxCommandReply{
			SessionId: "session-1",
			Kind:      pb.MxCommandKind_MX_COMMAND_KIND_ADD_ITEM2,
			ProtocolStatus: &pb.ProtocolStatus{
				Code: pb.ProtocolStatusCode_PROTOCOL_STATUS_CODE_OK,
			},
			Payload: &pb.MxCommandReply_AddItem2{
				AddItem2: &pb.AddItem2Reply{ItemHandle: 42},
			},
		},
	}
	client, cleanup := newBufconnClient(t, fake)
	defer cleanup()
	session := NewSessionForID(client, "session-1")

	itemHandle, err := session.AddItem2(context.Background(), 12, "Area001.Pump001.Speed", "runtime")
	if err != nil {
		t.Fatalf("AddItem2() error = %v", err)
	}

	if itemHandle != 42 {
		t.Fatalf("item handle = %d, want 42", itemHandle)
	}
	req := fake.invokeRequest
	if req.GetSessionId() != "session-1" {
		t.Fatalf("session id = %q, want session-1", req.GetSessionId())
	}
	if req.GetClientCorrelationId() == "" {
		t.Fatal("client correlation id is empty")
	}
	if req.GetCommand().GetKind() != pb.MxCommandKind_MX_COMMAND_KIND_ADD_ITEM2 {
		t.Fatalf("command kind = %s", req.GetCommand().GetKind())
	}
	if req.GetCommand().GetAddItem2().GetItemContext() != "runtime" {
		t.Fatalf("item context = %q, want runtime", req.GetCommand().GetAddItem2().GetItemContext())
	}
}

func TestInvokeReturnsTypedMxAccessErrorWithRawReply(t *testing.T) {
	hresult := int32(-2147467259)
	fake := &fakeGatewayServer{
		invokeReply: &pb.MxCommandReply{
			SessionId:         "session-1",
			Kind:              pb.MxCommandKind_MX_COMMAND_KIND_ADVISE,
			Hresult:           &hresult,
			DiagnosticMessage: "native failure",
			ProtocolStatus:    &pb.ProtocolStatus{Code: pb.ProtocolStatusCode_PROTOCOL_STATUS_CODE_MXACCESS_FAILURE, Message: "MXAccess failed"},
			Statuses:          []*pb.MxStatusProxy{{Success: 0, DiagnosticText: "failed"}},
		},
	}
	client, cleanup := newBufconnClient(t, fake)
	defer cleanup()
	session := NewSessionForID(client, "session-1")

	err := session.Advise(context.Background(), 12, 34)

	var mxErr *MxAccessError
	if !errors.As(err, &mxErr) {
		t.Fatalf("error %T does not support errors.As(*MxAccessError)", err)
	}
	if mxErr.Reply.GetHresult() != hresult {
		t.Fatalf("raw reply HRESULT = %d, want %d", mxErr.Reply.GetHresult(), hresult)
	}
	var commandErr *CommandError
	if !errors.As(err, &commandErr) {
		t.Fatalf("error %T does not support errors.As(*CommandError)", err)
	}
	if commandErr.Reply.GetDiagnosticMessage() != "native failure" {
		t.Fatalf("raw diagnostic = %q", commandErr.Reply.GetDiagnosticMessage())
	}
}

func newBufconnClient(t *testing.T, fake *fakeGatewayServer) (*Client, func()) {
	t.Helper()

	listener := bufconn.Listen(bufSize)
	server := grpc.NewServer()
	pb.RegisterMxAccessGatewayServer(server, fake)
	go func() {
		if err := server.Serve(listener); err != nil && !errors.Is(err, grpc.ErrServerStopped) {
			t.Errorf("bufconn server failed: %v", err)
		}
	}()

	dialer := func(ctx context.Context, _ string) (net.Conn, error) {
		return listener.DialContext(ctx)
	}
	client, err := Dial(context.Background(), Options{
		Endpoint:  "bufnet",
		APIKey:    "test-api-key",
		Plaintext: true,
		DialOptions: []grpc.DialOption{
			grpc.WithContextDialer(dialer),
		},
	})
	if err != nil {
		t.Fatalf("Dial() error = %v", err)
	}

	return client, func() {
		client.Close()
		server.Stop()
		listener.Close()
	}
}

type fakeGatewayServer struct {
	pb.UnimplementedMxAccessGatewayServer

	openReply     *pb.OpenSessionReply
	openAuth      string
	streamAuth    string
	streamStarted chan struct{}
	invokeReply   *pb.MxCommandReply
	invokeRequest *pb.MxCommandRequest
}

func (s *fakeGatewayServer) OpenSession(ctx context.Context, req *pb.OpenSessionRequest) (*pb.OpenSessionReply, error) {
	s.openAuth = authorizationFromContext(ctx)
	if s.openReply != nil {
		return s.openReply, nil
	}
	return &pb.OpenSessionReply{
		SessionId: "session-1",
		ProtocolStatus: &pb.ProtocolStatus{
			Code: pb.ProtocolStatusCode_PROTOCOL_STATUS_CODE_OK,
		},
	}, nil
}

func (s *fakeGatewayServer) CloseSession(ctx context.Context, req *pb.CloseSessionRequest) (*pb.CloseSessionReply, error) {
	return &pb.CloseSessionReply{
		SessionId: req.GetSessionId(),
		ProtocolStatus: &pb.ProtocolStatus{
			Code: pb.ProtocolStatusCode_PROTOCOL_STATUS_CODE_OK,
		},
	}, nil
}

func (s *fakeGatewayServer) Invoke(ctx context.Context, req *pb.MxCommandRequest) (*pb.MxCommandReply, error) {
	s.invokeRequest = req
	if s.invokeReply != nil {
		return s.invokeReply, nil
	}
	return &pb.MxCommandReply{
		SessionId: req.GetSessionId(),
		Kind:      req.GetCommand().GetKind(),
		ProtocolStatus: &pb.ProtocolStatus{
			Code: pb.ProtocolStatusCode_PROTOCOL_STATUS_CODE_OK,
		},
	}, nil
}

func (s *fakeGatewayServer) StreamEvents(req *pb.StreamEventsRequest, stream grpc.ServerStreamingServer[pb.MxEvent]) error {
	s.streamAuth = authorizationFromContext(stream.Context())
	if s.streamStarted != nil {
		close(s.streamStarted)
	}
	if err := stream.Send(&pb.MxEvent{
		SessionId:      req.GetSessionId(),
		Family:         pb.MxEventFamily_MX_EVENT_FAMILY_ON_DATA_CHANGE,
		WorkerSequence: 1,
	}); err != nil {
		return err
	}
	<-stream.Context().Done()
	return io.EOF
}

func authorizationFromContext(ctx context.Context) string {
	md, ok := metadata.FromIncomingContext(ctx)
	if !ok {
		return ""
	}
	values := md.Get(authorizationHeader)
	if len(values) == 0 {
		return ""
	}
	return values[0]
}