cluster: add recursive RegionIterator to Zone

Signed-off-by: Alejandro Mery <amery@jpi.io>

pkg/cluster/regions.go

@@ -8,8 +8,16 @@ import (
 var (
 	_ MachineIterator = (*Region)(nil)
 	_ ZoneIterator    = (*Region)(nil)
+
+	_ RegionIterator = (*Zone)(nil)
+	_ RegionIterator = (*Cluster)(nil)
 )
 
+// A RegionIterator is a set of Regions we can iterate on
+type RegionIterator interface {
+	ForEachRegion(func(*Region) bool)
+}
+
 // Region represents a group of zones geographically related
 type Region struct {
 	m     *Cluster
@@ -124,6 +132,28 @@ func (m *Cluster) appendRegionRegions(name string, subs ...string) {
 	})
 }
 
+// ForEachRegion calls a function on all regions this zone belongs to.
+func (z *Zone) ForEachRegion(fn func(*Region) bool) {
+	if fn == nil {
+		return
+	}
+
+	z.zones.ForEachRegion(func(r *Region) bool {
+		var match bool
+
+		r.ForEachZone(func(z2 *Zone) bool {
+			match = (z == z2)
+			return match
+		})
+
+		if match && fn(r) {
+			return true
+		}
+
+		return false
+	})
+}
+
 func (z *Zone) appendRegions(regions ...string) error {
 	for _, s := range regions {
 		// TODO: validate
@@ -147,7 +177,7 @@ func (m *Cluster) finishRegion(r *Region) {
 	r.m = m
 	sub := []string{}
 	for _, name := range r.Regions {
-		r2, ok := m.getRegion(name)
+		r2, ok := m.getFinishRegion(name)
 		if !ok {
 			m.warn(nil).WithField("region", name).Print("unknown region")
 			continue
@@ -162,9 +192,7 @@ func (m *Cluster) finishRegion(r *Region) {
 func (m *Cluster) getRegion(name string) (*Region, bool) {
 	for i := range m.Regions {
 		r := &m.Regions[i]
-
 		if name == r.Name {
-			m.finishRegion(r)
 			return r, true
 		}
 	}
@@ -172,6 +200,15 @@ func (m *Cluster) getRegion(name string) (*Region, bool) {
 	return nil, false
 }
 
+func (m *Cluster) getFinishRegion(name string) (*Region, bool) {
+	if r, ok := m.getRegion(name); ok {
+		m.finishRegion(r)
+		return r, true
+	}
+
+	return nil, false
+}
+
 // SyncRegions writes to the file system the regions this [Zone]
 // belongs to.
 func (z *Zone) SyncRegions() error {