implement backend components for push notifications

go/internal/network/reader.go

@@ -16,6 +16,9 @@ type Reader interface {
 	ListForHuman(ctx context.Context, humanId string) ([]*Network, error)
 	// IsMember returns ErrInvalidHumanId if humanId is empty.
 	IsMember(ctx context.Context, networkID, humanId string) (bool, error)
+	// ListMembers returns all human IDs belonging to the network.
+  // Returns an empty slice if the network doesn't exist.
+	ListMembers(ctx context.Context, networkID string) ([]string, error)
 	// ListAll returns all networks with their members
 	ListAll(ctx context.Context) ([]*Network, error)
 	// ListAllMemberships returns humanId -> networkIds for every human with at
@@ -69,6 +72,12 @@ func (r *readerImpl) IsMember(ctx context.Context, networkID, humanId string) (b
 	return r.repo.isMember(ctx, networkID, humanId)
 }
 
+func (r *readerImpl) ListMembers(ctx context.Context, networkID string) ([]string, error) {
+	// Admin is guaranteed to be in network_members: Create() calls AddMembers
+	// for the admin, and RemoveMemberFromNetwork rejects admin removal.
+	return r.repo.getMemberHumanIds(ctx, networkID)
+}
+
 func (r *readerImpl) ListAll(ctx context.Context) ([]*Network, error) {
 	return r.repo.listAll(ctx)
 }