feat: adjust pagination for schemas endpoints

closes #44

pkg/schemas/handlers.go

@@ -52,7 +52,7 @@ func (a *API) handleList(w http.ResponseWriter, r *http.Request) {
 
 	pagination := types.ParsePagination(r.URL.Query())
 
-	schemas, err := a.service.ListSchemas(r.Context(), pagination.Page, pagination.Size)
+	schemas, err := a.service.ListSchemas(r.Context(), pagination.Size, pagination.PageToken)
 
 	if err != nil {
 		rr := a.error(schemas.Error)
@@ -63,6 +63,11 @@ func (a *API) handleList(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	// TODO @shipperizer improve on this, see if better to stick with link headers
+	pagination.Next = schemas.Tokens.Next
+	pagination.Prev = schemas.Tokens.Prev
+	pagination.First = schemas.Tokens.First
+
 	w.WriteHeader(http.StatusOK)
 	json.NewEncoder(w).Encode(
 		types.Response{

pkg/schemas/handlers_test.go

@@ -28,7 +28,7 @@ import (
 //go:generate mockgen -build_flags=--mod=mod -package schemas -destination ./mock_monitor.go -source=../../internal/monitoring/interfaces.go
 //go:generate mockgen -build_flags=--mod=mod -package schemas -destination ./mock_tracing.go go.opentelemetry.io/otel/trace Tracer
 //go:generate mockgen -build_flags=--mod=mod -package schemas -destination ./mock_corev1.go k8s.io/client-go/kubernetes/typed/core/v1 CoreV1Interface,ConfigMapInterface
-//go:generate mockgen -build_flags=--mod=mod -package schemas -destination ./mock_kratos.go github.com/ory/kratos-client-go IdentityApi
+//go:generate mockgen -build_flags=--mod=mod -package schemas -destination ./mock_kratos.go github.com/ory/kratos-client-go IdentityAPI
 
 func TestHandleListSuccess(t *testing.T) {
 	ctrl := gomock.NewController(t)
@@ -102,11 +102,16 @@ func TestHandleListSuccess(t *testing.T) {
 				Schema: v1Schema,
 			},
 		},
+		Tokens: PaginationTokens{
+			Next:  "eyJvZmZzZXQiOiIyNTAiLCJ2IjoyfQ",
+			First: "eyJvZmZzZXQiOiIwIiwidiI6Mn0",
+			Prev:  "eyJvZmZzZXQiOiItMjUwIiwidiI6Mn0",
+		},
 	}
 
 	req := httptest.NewRequest(http.MethodGet, "/api/v0/schemas", nil)
 
-	mockService.EXPECT().ListSchemas(gomock.Any(), int64(1), int64(100)).Return(&schemas, nil)
+	mockService.EXPECT().ListSchemas(gomock.Any(), int64(100), "").Return(&schemas, nil)
 
 	w := httptest.NewRecorder()
 	mux := chi.NewMux()
@@ -161,7 +166,7 @@ func TestHandleListFails(t *testing.T) {
 	gerr.SetMessage("teapot error")
 	gerr.SetReason("teapot is broken")
 
-	mockService.EXPECT().ListSchemas(gomock.Any(), int64(1), int64(100)).Return(&IdentitySchemaData{IdentitySchemas: make([]kClient.IdentitySchemaContainer, 0), Error: gerr}, fmt.Errorf("error"))
+	mockService.EXPECT().ListSchemas(gomock.Any(), int64(100), "").Return(&IdentitySchemaData{IdentitySchemas: make([]kClient.IdentitySchemaContainer, 0), Error: gerr}, fmt.Errorf("error"))
 
 	w := httptest.NewRecorder()
 	mux := chi.NewMux()

pkg/schemas/interfaces.go

@@ -10,7 +10,7 @@ import (
 )
 
 type ServiceInterface interface {
-	ListSchemas(context.Context, int64, int64) (*IdentitySchemaData, error)
+	ListSchemas(context.Context, int64, string) (*IdentitySchemaData, error)
 	GetSchema(context.Context, string) (*IdentitySchemaData, error)
 	EditSchema(context.Context, string, *kClient.IdentitySchemaContainer) (*IdentitySchemaData, error)
 	CreateSchema(context.Context, *kClient.IdentitySchemaContainer) (*IdentitySchemaData, error)

pkg/schemas/service.go

@@ -9,9 +9,11 @@ import (
 	"fmt"
 	"io"
 	"net/http"
+	"net/url"
 
 	"github.com/google/uuid"
 	kClient "github.com/ory/kratos-client-go"
+	"github.com/tomnomnom/linkheader"
 	"go.opentelemetry.io/otel/trace"
 	metaV1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	coreV1 "k8s.io/client-go/kubernetes/typed/core/v1"
@@ -26,11 +28,19 @@ type Config struct {
 	Name      string
 	Namespace string
 	K8s       coreV1.CoreV1Interface
-	Kratos    kClient.IdentityApi
+	Kratos    kClient.IdentityAPI
+}
+
+// TODO @shipperizer worth offloading to a different place as it's going to be reused
+type PaginationTokens struct {
+	First string
+	Prev  string
+	Next  string
 }
 
 type IdentitySchemaData struct {
 	IdentitySchemas []kClient.IdentitySchemaContainer
+	Tokens          PaginationTokens
 	Error           *kClient.GenericError
 }
 
@@ -48,15 +58,45 @@ type Service struct {
 	cmNamespace string
 
 	k8s    coreV1.CoreV1Interface
-	kratos kClient.IdentityApi
+	kratos kClient.IdentityAPI
 
 	tracer  trace.Tracer
 	monitor monitoring.MonitorInterface
 	logger  logging.LoggerInterface
 }
 
+func (s *Service) parseLinkURL(linkURL string) string {
+	u, err := url.Parse(linkURL)
+
+	if err != nil {
+		s.logger.Errorf("failed to parse link header successfully: %s", err)
+		return ""
+	}
+
+	return u.Query().Get("page_token")
+}
+
+func (s *Service) parsePagination(r *http.Response) PaginationTokens {
+	links := linkheader.Parse(r.Header.Get("Link"))
+
+	pagination := PaginationTokens{}
+
+	for _, link := range links {
+		switch link.Rel {
+		case "first":
+			pagination.First = s.parseLinkURL(link.URL)
+		case "next":
+			pagination.Next = s.parseLinkURL(link.URL)
+		case "prev":
+			pagination.Prev = s.parseLinkURL(link.URL)
+		}
+	}
+
+	return pagination
+}
+
 func (s *Service) parseError(ctx context.Context, r *http.Response) *kClient.GenericError {
-	ctx, span := s.tracer.Start(ctx, "schemas.Service.parseError")
+	_, span := s.tracer.Start(ctx, "schemas.Service.parseError")
 	defer span.End()
 
 	gerr := KratosError{Error: kClient.NewGenericErrorWithDefaults()}
@@ -72,12 +112,12 @@ func (s *Service) parseError(ctx context.Context, r *http.Response) *kClient.Gen
 	return gerr.Error
 }
 
-func (s *Service) ListSchemas(ctx context.Context, page, size int64) (*IdentitySchemaData, error) {
+func (s *Service) ListSchemas(ctx context.Context, size int64, token string) (*IdentitySchemaData, error) {
 	ctx, span := s.tracer.Start(ctx, "schemas.Service.ListSchemas")
 	defer span.End()
 
 	schemas, rr, err := s.kratos.ListIdentitySchemasExecute(
-		s.kratos.ListIdentitySchemas(ctx).Page(page).PerPage(size),
+		s.kratos.ListIdentitySchemas(ctx).PageToken(token).PageSize(size),
 	)
 
 	data := new(IdentitySchemaData)
@@ -87,6 +127,7 @@ func (s *Service) ListSchemas(ctx context.Context, page, size int64) (*IdentityS
 		data.Error = s.parseError(ctx, rr)
 	}
 
+	data.Tokens = s.parsePagination(rr)
 	data.IdentitySchemas = schemas
 
 	// TODO @shipperizer check if schemas is defaulting to empty slice inside kratos-client