chore(storage): parse out project number if available (#6671)

The JSON API has a dedicated `ProjectNumber uint64` field used to populate the same field on `BucketAttrs`. The gRPC API has a `string project` field that can contain either a project *number* or a project *identifier* (alphanumeric). Parse out the *project number* if it is present in the returned `Bucket`, otherwise leave it as `0`.

storage/bucket.go

@@ -775,6 +775,7 @@ func newBucketFromProto(b *storagepb.Bucket) *BucketAttrs {
 		LocationType:             b.GetLocationType(),
 		RPO:                      toRPOFromProto(b),
 		CustomPlacementConfig:    customPlacementFromProto(b.GetCustomPlacementConfig()),
+		ProjectNumber:            parseProjectNumber(b.GetProject()), // this can return 0 the project resource name is ID based
 	}
 }
 

storage/storage.go

@@ -33,6 +33,7 @@ import (
 	"reflect"
 	"regexp"
 	"sort"
+	"strconv"
 	"strings"
 	"time"
 	"unicode/utf8"
@@ -2002,6 +2003,24 @@ func parseBucketName(b string) string {
 	return b[sep+1:]
 }
 
+// parseProjectNumber consume the given resource name and parses out the project
+// number if one is present i.e. it is not a project ID.
+func parseProjectNumber(r string) uint64 {
+	projectID := regexp.MustCompile(`projects\/([0-9]+)\/?`)
+	if matches := projectID.FindStringSubmatch(r); len(matches) > 0 {
+		// Capture group follows the matched segment. For example:
+		// input: projects/123/bars/456
+		// output: [projects/123/, 123]
+		number, err := strconv.ParseUint(matches[1], 10, 64)
+		if err != nil {
+			return 0
+		}
+		return number
+	}
+
+	return 0
+}
+
 // toProjectResource accepts a project ID and formats it as a Project resource
 // name.
 func toProjectResource(project string) string {

storage/storage_test.go

@@ -2341,6 +2341,24 @@ func TestSignedURLOptionsClone(t *testing.T) {
 	}
 }
 
+func TestParseProjectNumber(t *testing.T) {
+	for _, tst := range []struct {
+		input string
+		want  uint64
+	}{
+		{"projects/123", 123},
+		{"projects/123/foos/456", 123},
+		{"projects/abc-123/foos/456", 0},
+		{"projects/abc-123", 0},
+		{"projects/abc", 0},
+		{"projects/abc/foos", 0},
+	} {
+		if got := parseProjectNumber(tst.input); got != tst.want {
+			t.Errorf("For %q: got %v, expected %v", tst.input, got, tst.want)
+		}
+	}
+}
+
 // isZeroValue reports whether v is the zero value for its type
 // It errors if the argument is unknown
 func isZeroValue(v reflect.Value) (bool, error) {