iceberg: wire pagination for list namespaces/tables REST APIs (#8275)

* s3api/iceberg: wire list pagination tokens and page size

* fmt

* Update weed/s3api/iceberg/iceberg.go

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

---------

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

weed/s3api/iceberg/iceberg.go

@@ -10,6 +10,7 @@ import (
 	"net/http"
 	"os"
 	"path"
+	"strconv"
 	"strings"
 	"time"
 
@@ -368,6 +369,38 @@ func buildTableBucketARN(bucketName string) string {
 	return arn
 }
 
+const (
+	defaultListPageSize = 1000
+	maxListPageSize     = 1000
+)
+
+func getPaginationQueryParam(r *http.Request, primary, fallback string) string {
+	if v := strings.TrimSpace(r.URL.Query().Get(primary)); v != "" {
+		return v
+	}
+	return strings.TrimSpace(r.URL.Query().Get(fallback))
+}
+
+func parsePagination(r *http.Request) (pageToken string, pageSize int, err error) {
+	pageToken = getPaginationQueryParam(r, "pageToken", "page-token")
+	pageSize = defaultListPageSize
+
+	pageSizeValue := getPaginationQueryParam(r, "pageSize", "page-size")
+	if pageSizeValue == "" {
+		return pageToken, pageSize, nil
+	}
+
+	parsedPageSize, parseErr := strconv.Atoi(pageSizeValue)
+	if parseErr != nil || parsedPageSize <= 0 {
+		return pageToken, 0, fmt.Errorf("invalid pageSize %q: must be a positive integer", pageSizeValue)
+	}
+	if parsedPageSize > maxListPageSize {
+		return pageToken, 0, fmt.Errorf("invalid pageSize %q: must be <= %d", pageSizeValue, maxListPageSize)
+	}
+
+	return pageToken, parsedPageSize, nil
+}
+
 // handleConfig returns catalog configuration.
 func (s *Server) handleConfig(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
@@ -388,14 +421,21 @@ func (s *Server) handleListNamespaces(w http.ResponseWriter, r *http.Request) {
 	// Extract identity from context
 	identityName := s3_constants.GetIdentityNameFromContext(r)
 
+	pageToken, pageSize, err := parsePagination(r)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "BadRequestException", err.Error())
+		return
+	}
+
 	// Use S3 Tables manager to list namespaces
 	var resp s3tables.ListNamespacesResponse
 	req := &s3tables.ListNamespacesRequest{
-		TableBucketARN: bucketARN,
-		MaxNamespaces:  1000,
+		TableBucketARN:    bucketARN,
+		ContinuationToken: pageToken,
+		MaxNamespaces:     pageSize,
 	}
 
-	err := s.filerClient.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
+	err = s.filerClient.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
 		mgrClient := s3tables.NewManagerClient(client)
 		return s.tablesManager.Execute(r.Context(), mgrClient, "ListNamespaces", req, &resp, identityName)
 	})
@@ -413,7 +453,8 @@ func (s *Server) handleListNamespaces(w http.ResponseWriter, r *http.Request) {
 	}
 
 	result := ListNamespacesResponse{
-		Namespaces: namespaces,
+		NextPageToken: resp.ContinuationToken,
+		Namespaces:    namespaces,
 	}
 	writeJSON(w, http.StatusOK, result)
 }
@@ -615,14 +656,21 @@ func (s *Server) handleListTables(w http.ResponseWriter, r *http.Request) {
 	// Extract identity from context
 	identityName := s3_constants.GetIdentityNameFromContext(r)
 
+	pageToken, pageSize, err := parsePagination(r)
+	if err != nil {
+		writeError(w, http.StatusBadRequest, "BadRequestException", err.Error())
+		return
+	}
+
 	listReq := &s3tables.ListTablesRequest{
-		TableBucketARN: bucketARN,
-		Namespace:      namespace,
-		MaxTables:      1000,
+		TableBucketARN:    bucketARN,
+		Namespace:         namespace,
+		ContinuationToken: pageToken,
+		MaxTables:         pageSize,
 	}
 	var listResp s3tables.ListTablesResponse
 
-	err := s.filerClient.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
+	err = s.filerClient.WithFilerClient(false, func(client filer_pb.SeaweedFilerClient) error {
 		mgrClient := s3tables.NewManagerClient(client)
 		return s.tablesManager.Execute(r.Context(), mgrClient, "ListTables", listReq, &listResp, identityName)
 	})
@@ -647,7 +695,8 @@ func (s *Server) handleListTables(w http.ResponseWriter, r *http.Request) {
 	}
 
 	result := ListTablesResponse{
-		Identifiers: identifiers,
+		NextPageToken: listResp.ContinuationToken,
+		Identifiers:   identifiers,
 	}
 	writeJSON(w, http.StatusOK, result)
 }