Update creating pagination info

* Add test.
* Validate input arguments.

rpc/v2_endpoints.go

@@ -6,6 +6,7 @@ import (
 	"encoding/hex"
 	"github.com/cockroachdb/pebble"
 	"github.com/qubic/go-archiver/validator/tick"
+	"log"
 	"slices"
 
 	"github.com/pkg/errors"
@@ -370,15 +371,33 @@ func (s *Server) GetIdentityTransfersInTickRangeV2(ctx context.Context, req *pro
 		totalTransactions = append(totalTransactions, transfers)
 	}
 
+	pagination, err := getPaginationInformation(totalCount, pageNumber+1, int(pageSize))
+	if err != nil {
+		log.Printf("Error creating pagination info: %s", err.Error())
+		return nil, status.Error(codes.Internal, "creating pagination info")
+	}
+
 	return &protobuff.GetIdentityTransfersInTickRangeResponseV2{
-		Pagination:   getPaginationInformation(totalCount, pageNumber+1, int(pageSize)),
+		Pagination:   pagination,
 		Transactions: totalTransactions,
 	}, nil
 
 }
 
 // ATTENTION: first page has pageNumber == 1 as API starts with index 1
-func getPaginationInformation(totalRecords, pageNumber, pageSize int) *protobuff.Pagination {
+func getPaginationInformation(totalRecords, pageNumber, pageSize int) (*protobuff.Pagination, error) {
+
+	if pageNumber < 1 {
+		return nil, errors.Errorf("invalid page number [%d]", pageNumber)
+	}
+
+	if pageSize < 1 {
+		return nil, errors.Errorf("invalid page size [%d]", pageSize)
+	}
+
+	if totalRecords < 0 {
+		return nil, errors.Errorf("invalid number of total records [%d]", totalRecords)
+	}
 
 	totalPages := totalRecords / pageSize // rounds down
 	if totalRecords%pageSize != 0 {
@@ -402,10 +421,10 @@ func getPaginationInformation(totalRecords, pageNumber, pageSize int) *protobuff
 		CurrentPage:  int32(min(totalRecords, pageNumber)), // 0 if there are no records
 		TotalPages:   int32(totalPages),                    // 0 if there are no records
 		PageSize:     int32(pageSize),
-		NextPage:     int32(nextPage),     // -1 if there is none
-		PreviousPage: int32(previousPage), // -1 if there is none
+		NextPage:     int32(nextPage),                      // -1 if there is none
+		PreviousPage: int32(min(totalPages, previousPage)), // -1 if there is none, do not exceed total pages
 	}
-	return &pagination
+	return &pagination, nil
 }
 
 func (s *Server) GetEmptyTickListV2(ctx context.Context, req *protobuff.GetEmptyTickListRequestV2) (*protobuff.GetEmptyTickListResponseV2, error) {

rpc/v2_endpoints_test.go

@@ -0,0 +1,67 @@
+package rpc
+
+import (
+	"github.com/qubic/go-archiver/protobuff"
+	"github.com/stretchr/testify/assert"
+	"testing"
+)
+
+func Test_V2Endpoints_createPaginationInfo(t *testing.T) {
+
+	pagination, err := getPaginationInformation(0, 1, 100)
+	assert.NoError(t, err)
+	verify(t, pagination,
+		0, 0, 100, 0, -1, -1)
+
+	pagination, err = getPaginationInformation(1, 1, 100)
+	assert.NoError(t, err)
+	verify(t, pagination,
+		1, 1, 100, 1, -1, -1)
+
+	pagination, err = getPaginationInformation(12345, 1, 100)
+	assert.NoError(t, err)
+	verify(t, pagination,
+		12345, 1, 100, 124, -1, 2)
+
+	pagination, err = getPaginationInformation(12345, 10, 100)
+	assert.NoError(t, err)
+	verify(t, pagination,
+		12345, 10, 100, 124, 9, 11)
+
+	pagination, err = getPaginationInformation(12345, 124, 100)
+	assert.NoError(t, err)
+	verify(t, pagination,
+		12345, 124, 100, 124, 123, -1)
+
+	pagination, err = getPaginationInformation(12345, 125, 100)
+	assert.NoError(t, err)
+	verify(t, pagination,
+		12345, 125, 100, 124, 124, -1)
+
+	pagination, err = getPaginationInformation(12345, 999, 100)
+	assert.NoError(t, err)
+	verify(t, pagination,
+		12345, 999, 100, 124, 124, -1)
+
+}
+
+func Test_V2Endpoints_createPaginationInfo_givenInvalidArguments_thenError(t *testing.T) {
+	_, err := getPaginationInformation(12345, 0, 100)
+	assert.Error(t, err)
+
+	_, err = getPaginationInformation(-1, 1, 100)
+	assert.Error(t, err)
+
+	_, err = getPaginationInformation(12345, 1, 0)
+	assert.Error(t, err)
+}
+
+func verify(t *testing.T, pagination *protobuff.Pagination, totalRecords, pageNumber, pageSize, totalPages, previousPage, nextPage int) {
+	assert.NotNil(t, pagination)
+	assert.Equal(t, int32(totalRecords), pagination.TotalRecords, "unexpected number of total records")
+	assert.Equal(t, int32(pageNumber), pagination.CurrentPage, "unexpected current page number")
+	assert.Equal(t, int32(pageSize), pagination.PageSize, "unexpected page size")
+	assert.Equal(t, int32(totalPages), pagination.TotalPages, "unexpected number of total pages")
+	assert.Equal(t, int32(previousPage), pagination.PreviousPage, "unexpected previous page number")
+	assert.Equal(t, int32(nextPage), pagination.NextPage, "unexpected next page number")
+}