// NewClient creates a new PubSub client.
func NewClient(ctx context.Context, projectID string, opts ...cloud.ClientOption) (*Client, error) {
	var o []cloud.ClientOption
	// Environment variables for gcloud emulator:
	// https://cloud.google.com/sdk/gcloud/reference/beta/emulators/pubsub/
	if addr := os.Getenv("PUBSUB_EMULATOR_HOST"); addr != "" {
		o = []cloud.ClientOption{
			cloud.WithEndpoint("http://" + addr + "/"),
			cloud.WithBaseHTTP(http.DefaultClient),
		}
	} else {
		o = []cloud.ClientOption{
			cloud.WithEndpoint(prodAddr),
			cloud.WithScopes(raw.PubsubScope, raw.CloudPlatformScope),
			cloud.WithUserAgent(userAgent),
		}
	}
	o = append(o, opts...)
	httpClient, endpoint, err := transport.NewHTTPClient(ctx, o...)
	if err != nil {
		return nil, fmt.Errorf("dialing: %v", err)
	}

	s, err := newPubSubService(httpClient, endpoint)
	if err != nil {
		return nil, fmt.Errorf("constructing pubsub client: %v", err)
	}

	c := &Client{
		projectID: projectID,
		s:         s,
	}

	return c, nil
}

// NewClient returns a new log client, logging to the named log in the
// provided project.
//
// The exported fields on the returned client may be modified before
// the client is used for logging. Once log entries are in flight,
// the fields must not be modified.
func NewClient(ctx context.Context, projectID, logName string, opts ...cloud.ClientOption) (*Client, error) {
	httpClient, endpoint, err := transport.NewHTTPClient(ctx, append([]cloud.ClientOption{
		cloud.WithEndpoint(prodAddr),
		cloud.WithScopes(Scope),
		cloud.WithUserAgent(userAgent),
	}, opts...)...)
	if err != nil {
		return nil, err
	}
	svc, err := api.New(httpClient)
	if err != nil {
		return nil, err
	}
	svc.BasePath = endpoint
	c := &Client{
		svc:     svc,
		logs:    api.NewProjectsLogsEntriesService(svc),
		logName: logName,
		projID:  projectID,
	}
	for i := range c.writer {
		level := Level(i)
		c.writer[level] = levelWriter{level, c}
		c.logger[level] = log.New(c.writer[level], "", 0)
	}
	return c, nil
}

// NewClient creates a new Client for a given dataset.
func NewClient(ctx context.Context, projectID string, opts ...cloud.ClientOption) (*Client, error) {
	o := []cloud.ClientOption{
		cloud.WithEndpoint(prodAddr),
		cloud.WithScopes(ScopeDatastore, ScopeUserEmail),
		cloud.WithUserAgent(userAgent),
	}
	o = append(o, opts...)
	client, err := transport.NewProtoClient(ctx, o...)
	if err != nil {
		return nil, fmt.Errorf("dialing: %v", err)
	}
	return &Client{
		client:  client,
		dataset: projectID,
	}, nil

}

// NewClusterAdminClient creates a new ClusterAdminClient for a given project.
func NewClusterAdminClient(ctx context.Context, project string, opts ...cloud.ClientOption) (*ClusterAdminClient, error) {
	o := []cloud.ClientOption{
		cloud.WithEndpoint(clusterAdminAddr),
		cloud.WithScopes(ClusterAdminScope),
	}
	o = append(o, opts...)
	conn, err := cloud.DialGRPC(ctx, o...)
	if err != nil {
		return nil, fmt.Errorf("dialing: %v", err)
	}
	return &ClusterAdminClient{
		conn:    conn,
		cClient: btcspb.NewBigtableClusterServiceClient(conn),

		project: project,
	}, nil
}

// DefaultClientOptions returns the default client options to use for the
// client's gRPC connection.
func DefaultClientOptions(endpoint, scope, userAgent string) ([]cloud.ClientOption, error) {
	var o []cloud.ClientOption
	// Check the environment variables for the bigtable emulator.
	// Dial it directly and don't pass any credentials.
	if addr := os.Getenv("BIGTABLE_EMULATOR_HOST"); addr != "" {
		conn, err := grpc.Dial(addr, grpc.WithInsecure())
		if err != nil {
			return nil, fmt.Errorf("emulator grpc.Dial: %v", err)
		}
		o = []cloud.ClientOption{cloud.WithBaseGRPC(conn)}
	} else {
		o = []cloud.ClientOption{
			cloud.WithEndpoint(endpoint),
			cloud.WithScopes(scope),
			cloud.WithUserAgent(userAgent),
		}
	}
	return o, nil
}

// NewAdminClient creates a new AdminClient for a given project, zone and cluster.
func NewAdminClient(ctx context.Context, project, zone, cluster string, opts ...cloud.ClientOption) (*AdminClient, error) {
	o := []cloud.ClientOption{
		cloud.WithEndpoint(adminAddr),
		cloud.WithScopes(AdminScope),
	}
	o = append(o, opts...)
	conn, err := cloud.DialGRPC(ctx, o...)
	if err != nil {
		return nil, fmt.Errorf("dialing: %v", err)
	}
	return &AdminClient{
		conn:    conn,
		tClient: bttspb.NewBigtableTableServiceClient(conn),

		project: project,
		zone:    zone,
		cluster: cluster,
	}, nil
}

// NewClient creates a new Client for a given dataset.
// If the project ID is empty, it is derived from the DATASTORE_PROJECT_ID environment variable.
// If the DATASTORE_EMULATOR_HOST environment variable is set, client will use its value
// to connect to a locally-running datastore emulator.
func NewClient(ctx context.Context, projectID string, opts ...cloud.ClientOption) (*Client, error) {
	var o []cloud.ClientOption
	// Environment variables for gcd emulator:
	// https://cloud.google.com/datastore/docs/tools/datastore-emulator
	// If the emulator is available, dial it directly (and don't pass any credentials).
	if addr := os.Getenv("DATASTORE_EMULATOR_HOST"); addr != "" {
		conn, err := grpc.Dial(addr, grpc.WithInsecure())
		if err != nil {
			return nil, fmt.Errorf("grpc.Dial: %v", err)
		}
		o = []cloud.ClientOption{cloud.WithBaseGRPC(conn)}
	} else {
		o = []cloud.ClientOption{
			cloud.WithEndpoint(prodAddr),
			cloud.WithScopes(ScopeDatastore),
			cloud.WithUserAgent(userAgent),
		}
	}
	// Warn if we see the legacy emulator environment variables.
	if os.Getenv("DATASTORE_HOST") != "" && os.Getenv("DATASTORE_EMULATOR_HOST") == "" {
		log.Print("WARNING: legacy environment variable DATASTORE_HOST is ignored. Use DATASTORE_EMULATOR_HOST instead.")
	}
	if os.Getenv("DATASTORE_DATASET") != "" && os.Getenv("DATASTORE_PROJECT_ID") == "" {
		log.Print("WARNING: legacy environment variable DATASTORE_DATASET is ignored. Use DATASTORE_PROJECT_ID instead.")
	}
	if projectID == "" {
		projectID = os.Getenv("DATASTORE_PROJECT_ID")
	}
	if projectID == "" {
		return nil, errors.New("datastore: missing project/dataset id")
	}
	o = append(o, opts...)
	conn, err := transport.DialGRPC(ctx, o...)
	if err != nil {
		return nil, fmt.Errorf("dialing: %v", err)
	}
	return &Client{
		conn:    conn,
		client:  pb.NewDatastoreClient(conn),
		dataset: projectID,
	}, nil

}

// CreateGooglePubSubClient returns client communicate with google Pub/Sub service
func CreateGooglePubSubClient() (*pubsub.Client, error) {
	envValue := os.Getenv(NDGooglePubSubURL)
	if envValue != "" {
		googlePubSubURL = envValue
	}

	envValue = os.Getenv(NDGoogleProjectID)
	if envValue != "" {
		googleProjectID = envValue
	}

	ctx := cloud.NewContext(googleProjectID, http.DefaultClient)
	o := []cloud.ClientOption{
		cloud.WithBaseHTTP(http.DefaultClient),
		cloud.WithEndpoint(googleDatastoreURL),
	}
	client, _ := pubsub.NewClient(ctx, googleProjectID, o...)
	return client, nil
}

// NewClient creates a new Client for a given project, zone and cluster.
func NewClient(ctx context.Context, project, zone, cluster string, opts ...cloud.ClientOption) (*Client, error) {
	o := []cloud.ClientOption{
		cloud.WithEndpoint(prodAddr),
		cloud.WithScopes(Scope),
		cloud.WithUserAgent(clientUserAgent),
	}
	o = append(o, opts...)
	conn, err := transport.DialGRPC(ctx, o...)
	if err != nil {
		return nil, fmt.Errorf("dialing: %v", err)
	}
	return &Client{
		conn:   conn,
		client: btspb.NewBigtableServiceClient(conn),

		project: project,
		zone:    zone,
		cluster: cluster,
	}, nil
}

// NewClient create a new PubSub client.
func NewClient(ctx context.Context, projectID string, opts ...cloud.ClientOption) (*Client, error) {
	o := []cloud.ClientOption{
		cloud.WithEndpoint(prodAddr),
		cloud.WithScopes(raw.PubsubScope, raw.CloudPlatformScope),
		cloud.WithUserAgent(userAgent),
	}
	o = append(o, opts...)
	httpClient, endpoint, err := transport.NewHTTPClient(ctx, o...)
	if err != nil {
		return nil, fmt.Errorf("dialing: %v", err)
	}

	s, err := newPubSubService(httpClient, endpoint)

	c := &Client{
		projectID: projectID,
		s:         s,
	}

	return c, nil
}

func newLogTest(t *testing.T) *logTest {
	handlerc := make(chan http.Handler, 1)
	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		select {
		case h := <-handlerc:
			h.ServeHTTP(w, r)
		default:
			slurp, _ := ioutil.ReadAll(r.Body)
			t.Errorf("Unexpected HTTP request received: %s", slurp)
			w.WriteHeader(500)
			io.WriteString(w, "unexpected HTTP request")
		}
	}))
	c, err := NewClient(context.Background(), "PROJ-ID", "LOG-NAME",
		cloud.WithEndpoint(ts.URL),
		cloud.WithTokenSource(dummyTokenSource{}), // prevent DefaultTokenSource
	)
	if err != nil {
		t.Fatal(err)
	}
	var clock struct {
		sync.Mutex
		now time.Time
	}
	c.timeNow = func() time.Time {
		clock.Lock()
		defer clock.Unlock()
		if clock.now.IsZero() {
			clock.now = time.Unix(0, 0)
		}
		clock.now = clock.now.Add(1 * time.Second)
		return clock.now
	}
	return &logTest{
		t:        t,
		ts:       ts,
		c:        c,
		handlerc: handlerc,
	}
}

// NewClient constructs a new Client which can perform BigQuery operations.
// Operations performed via the client are billed to the specified GCP project.
func NewClient(ctx context.Context, projectID string, opts ...cloud.ClientOption) (*Client, error) {
	o := []cloud.ClientOption{
		cloud.WithEndpoint(prodAddr),
		cloud.WithScopes(Scope),
		cloud.WithUserAgent(userAgent),
	}
	o = append(o, opts...)
	httpClient, endpoint, err := transport.NewHTTPClient(ctx, o...)
	if err != nil {
		return nil, fmt.Errorf("dialing: %v", err)
	}

	s, err := newBigqueryService(httpClient, endpoint)
	if err != nil {
		return nil, fmt.Errorf("constructing bigquery client: %v", err)
	}

	c := &Client{
		service:   s,
		projectID: projectID,
	}
	return c, nil
}

// CreateGoogleDatastoreClient create client to communicate to google Datastore service
func CreateGoogleDatastoreClient() (*datastore.Client, error) {
	envValue := os.Getenv(NDGoogleDatastoreURL)
	if envValue != "" {
		googleDatastoreURL = envValue
	}

	envValue = os.Getenv(NDGoogleProjectID)
	if envValue != "" {
		googleProjectID = envValue
	}

	ctx := cloud.NewContext(googleProjectID, http.DefaultClient)
	o := []cloud.ClientOption{
		cloud.WithBaseHTTP(http.DefaultClient),
		cloud.WithEndpoint(googleDatastoreURL),
	}
	client, err := datastore.NewClient(ctx, googleProjectID, o...)
	if err != nil {
		return nil, err
	}

	return client, nil
}