Add the forge kind open: every open pull request into trunk, so the indexer can drop the rest (issue 1279, ADR 0443)

go/delivery/source.go

@@ -41,8 +41,19 @@ const (
 	ForgePull    = "pull"
 	ForgeMerged  = "merged"
 	ForgeRefused = "refused"
+	ForgeOpen    = "open"
 )
 
+// OpenPull names an open pull request into the trunk: the repository as `<owner>/<name>` and the number.
+type OpenPull struct {
+	Repository string `json:"repository"`
+	Number     int    `json:"number"`
+}
+
+// OpenEvent is the name of an open message: `forge.open`. It names no repository: it says every open pull request of
+// every repository the forge bridge reads (novox/hq ADR 0443 §5).
+func OpenEvent() string { return "forge." + ForgeOpen }
+
 // The actions of a pull message.
 const (
 	PullOpened  = "opened"
@@ -106,18 +117,21 @@ func checkRepository(repository string) error {
 
 func checkForgeKind(kind string) error {
 	switch kind {
-	case ForgePull, ForgeMerged, ForgeRefused:
+	case ForgePull, ForgeMerged, ForgeRefused, ForgeOpen:
 		return nil
 	}
-	return fmt.Errorf("delivery: the forge kind %q is not pull, merged or refused", kind)
+	return fmt.Errorf("delivery: the forge kind %q is not pull, merged, refused or open", kind)
 }
 
 // ForgeEvent is the name of a forge message of the given kind: `forge.<owner>.<name>.<kind>`.
 func ForgeEvent(repository, kind string) (string, error) {
-	if err := checkRepository(repository); err != nil {
+	if err := checkForgeKind(kind); err != nil {
 		return "", err
 	}
-	if err := checkForgeKind(kind); err != nil {
+	if kind == ForgeOpen {
+		return "", fmt.Errorf("delivery: an open message names no repository, its event is %s", OpenEvent())
+	}
+	if err := checkRepository(repository); err != nil {
 		return "", err
 	}
 	owner, name, _ := strings.Cut(repository, "/")
@@ -126,6 +140,9 @@ func ForgeEvent(repository, kind string) (string, error) {
 
 // ParseForgeEvent is the inverse of ForgeEvent.
 func ParseForgeEvent(event string) (repository, kind string, err error) {
+	if event == OpenEvent() {
+		return "", ForgeOpen, nil
+	}
 	parts := strings.Split(event, ".")
 	if len(parts) != 4 || parts[0] != "forge" {
 		return "", "", fmt.Errorf("delivery: %q is not a forge event, forge.<owner>.<name>.<kind>", event)
@@ -259,13 +276,20 @@ type Forge struct {
 	Root       string            `json:"root,omitempty"`
 	Act        string            `json:"act,omitempty"`
 	Words      string            `json:"words,omitempty"`
+	Open       []OpenPull        `json:"open,omitempty"`
 }
 
 func (f Forge) check() error {
-	if err := checkRepository(f.Repository); err != nil {
+	if err := checkForgeKind(f.Kind); err != nil {
 		return err
 	}
-	if err := checkForgeKind(f.Kind); err != nil {
+	if f.Kind == ForgeOpen {
+		return f.checkOpen()
+	}
+	if len(f.Open) > 0 {
+		return fmt.Errorf("delivery: only an open message names open pull requests")
+	}
+	if err := checkRepository(f.Repository); err != nil {
 		return err
 	}
 	switch f.Kind {
@@ -322,6 +346,24 @@ func (f Forge) check() error {
 	return nil
 }
 
+// checkOpen refuses an open message that names a repository, a branch, a head or anything of the other kinds, or
+// an open pull request that is not `<owner>/<name>` and a number.
+func (f Forge) checkOpen() error {
+	if f.Repository != "" || f.Branch != "" || f.Number != 0 || f.Head != "" || f.Action != "" || len(f.Dirs) > 0 || f.DirsKnown ||
+		f.Merge != "" || len(f.Trees) > 0 || f.Root != "" || f.Act != "" || f.Words != "" {
+		return fmt.Errorf("delivery: an open message carries only the open pull requests it names")
+	}
+	for _, p := range f.Open {
+		if err := checkRepository(p.Repository); err != nil {
+			return err
+		}
+		if p.Number <= 0 {
+			return fmt.Errorf("delivery: the open pull request of %s has no number", p.Repository)
+		}
+	}
+	return nil
+}
+
 // EncodeSource is s as JSON at Version; it refuses a source with no repository or an empty head.
 func EncodeSource(s Source) ([]byte, error) {
 	if err := s.check(); err != nil {