// WatchControllers begins watching for new, changed, or deleted controllers.
func (r *Registry) WatchControllers(ctx api.Context, label labels.Selector, field fields.Selector, resourceVersion string) (watch.Interface, error) {
	if !field.Empty() {
		return nil, fmt.Errorf("field selectors are not supported on replication controllers")
	}
	version, err := tools.ParseWatchResourceVersion(resourceVersion, "replicationControllers")
	if err != nil {
		return nil, err
	}
	key := makeControllerListKey(ctx)
	return r.WatchList(key, version, func(obj runtime.Object) bool {
		controller, ok := obj.(*api.ReplicationController)
		if !ok {
			// Must be an error: return true to propagate to upper level.
			return true
		}
		match := label.Matches(labels.Set(controller.Labels))
		if match {
			pods, err := r.pods.ListPods(ctx, labels.Set(controller.Spec.Selector).AsSelector())
			if err != nil {
				glog.Warningf("Error listing pods: %v", err)
				// No object that's useable so drop it on the floor
				return false
			}
			if pods == nil {
				glog.Warningf("Pods list is nil.  This should never happen...")
				// No object that's useable so drop it on the floor
				return false
			}
			controller.Status.Replicas = len(pods.Items)
		}
		return match
	})
}

// WatchPredicate starts a watch for the items that m matches.
func (e *Etcd) WatchPredicate(ctx api.Context, m generic.Matcher, resourceVersion string) (watch.Interface, error) {
	version, err := tools.ParseWatchResourceVersion(resourceVersion, e.EndpointName)
	if err != nil {
		return nil, err
	}

	filterFunc := func(obj runtime.Object) bool {
		matches, err := m.Matches(obj)
		if err != nil {
			glog.Errorf("unable to match watch: %v", err)
			return false
		}
		if matches && e.Decorator != nil {
			if err := e.Decorator(obj); err != nil {
				glog.Errorf("unable to decorate watch: %v", err)
				return false
			}
		}
		return matches
	}

	if name, ok := m.MatchesSingle(); ok {
		key, err := e.KeyFunc(ctx, name)
		if err != nil {
			return nil, err
		}
		return e.Helper.Watch(key, version, filterFunc)
	}

	return e.Helper.WatchList(e.KeyRootFunc(ctx), version, filterFunc)
}

// WatchControllers begins watching for new, changed, or deleted controllers.
func (r *Registry) WatchControllers(ctx api.Context, resourceVersion string) (watch.Interface, error) {
	version, err := tools.ParseWatchResourceVersion(resourceVersion, "replicationControllers")
	if err != nil {
		return nil, err
	}
	key := makeControllerListKey(ctx)
	return r.WatchList(key, version, tools.Everything)
}

// Watch starts a watch for the items that m matches.
// TODO: Detect if m references a single object instead of a list.
func (e *Etcd) Watch(ctx api.Context, m generic.Matcher, resourceVersion string) (watch.Interface, error) {
	version, err := tools.ParseWatchResourceVersion(resourceVersion, e.EndpointName)
	if err != nil {
		return nil, err
	}
	return e.Helper.WatchList(e.KeyRootFunc(ctx), version, func(obj runtime.Object) bool {
		matches, err := m.Matches(obj)
		return err == nil && matches
	})
}

func (r *Registry) WatchMinions(ctx api.Context, label labels.Selector, field fields.Selector, resourceVersion string) (watch.Interface, error) {
	version, err := tools.ParseWatchResourceVersion(resourceVersion, "node")
	if err != nil {
		return nil, err
	}
	key := makeNodeListKey()
	return r.WatchList(key, version, func(obj runtime.Object) bool {
		minionObj, ok := obj.(*api.Node)
		if !ok {
			// Must be an error: return true to propagate to upper level.
			return true
		}
		// TODO: Add support for filtering based on field, once NodeStatus is defined.
		return label.Matches(labels.Set(minionObj.Labels))
	})
}

// WatchPods begins watching for new, changed, or deleted pods.
func (r *Registry) WatchPods(ctx api.Context, label, field labels.Selector, resourceVersion string) (watch.Interface, error) {
	version, err := tools.ParseWatchResourceVersion(resourceVersion, "pod")
	if err != nil {
		return nil, err
	}
	key := makePodListKey(ctx)
	return r.WatchList(key, version, func(obj runtime.Object) bool {
		podObj, ok := obj.(*api.Pod)
		if !ok {
			// Must be an error: return true to propagate to upper level.
			return true
		}
		fields := pod.PodToSelectableFields(podObj)
		return label.Matches(labels.Set(podObj.Labels)) && field.Matches(fields)
	})
}

// WatchPods begins watching for new, changed, or deleted pods.
func (r *Registry) WatchPods(ctx api.Context, resourceVersion string, filter func(*api.Pod) bool) (watch.Interface, error) {
	version, err := tools.ParseWatchResourceVersion(resourceVersion, "pod")
	if err != nil {
		return nil, err
	}
	key := makePodListKey(ctx)
	return r.WatchList(key, version, func(obj runtime.Object) bool {
		switch t := obj.(type) {
		case *api.Pod:
			return filter(t)
		default:
			// Must be an error
			return true
		}
	})
}

// WatchBuildConfigs begins watching for new, changed, or deleted BuildConfigs.
func (r *Etcd) WatchBuildConfigs(ctx kapi.Context, label labels.Selector, field fields.Selector, resourceVersion string) (watch.Interface, error) {
	version, err := tools.ParseWatchResourceVersion(resourceVersion, "buildConfig")
	if err != nil {
		return nil, err
	}

	return r.WatchList(makeBuildConfigListKey(ctx), version, func(obj runtime.Object) bool {
		buildConfig, ok := obj.(*api.BuildConfig)
		if !ok {
			glog.Errorf("Unexpected object during %s/%s BuildConfig watch: %#v", buildConfig.Namespace, buildConfig.Name, obj)
			return false
		}
		fields := labels.Set{
			"metadata.name": buildConfig.Name,
		}
		return label.Matches(labels.Set(buildConfig.Labels)) && field.Matches(fields)
	})
}

// WatchEndpoints begins watching for new, changed, or deleted endpoint configurations.
func (r *Registry) WatchEndpoints(ctx api.Context, label labels.Selector, field fields.Selector, resourceVersion string) (watch.Interface, error) {
	version, err := tools.ParseWatchResourceVersion(resourceVersion, "endpoints")
	if err != nil {
		return nil, err
	}
	if !label.Empty() {
		return nil, fmt.Errorf("label selectors are not supported on endpoints")
	}
	if value, found := field.RequiresExactMatch("name"); found {
		key, err := makeServiceEndpointsKey(ctx, value)
		if err != nil {
			return nil, err
		}
		return r.Watch(key, version), nil
	}
	if field.Empty() {
		return r.WatchList(makeServiceEndpointsListKey(ctx), version, tools.Everything)
	}
	return nil, fmt.Errorf("only the 'ID' and default (everything) field selectors are supported")
}

// WatchBuilds begins watching for new, changed, or deleted Builds.
func (r *Etcd) WatchBuilds(ctx kapi.Context, label labels.Selector, field fields.Selector, resourceVersion string) (watch.Interface, error) {
	version, err := tools.ParseWatchResourceVersion(resourceVersion, "build")
	if err != nil {
		return nil, err
	}

	return r.WatchList(makeBuildListKey(ctx), version, func(obj runtime.Object) bool {
		build, ok := obj.(*api.Build)
		setDuration(build)
		if !ok {
			glog.Errorf("Unexpected object during build watch: %#v", obj)
			return false
		}
		fields := labels.Set{
			"metadata.name": build.Name,
			"status":        string(build.Status),
			"podName":       buildutil.GetBuildPodName(build),
		}
		return label.Matches(labels.Set(build.Labels)) && field.Matches(fields)
	})
}

// WatchControllers begins watching for new, changed, or deleted controllers.
func (r *Registry) WatchControllers(ctx api.Context, label, field labels.Selector, resourceVersion string) (watch.Interface, error) {
	if !field.Empty() {
		return nil, fmt.Errorf("field selectors are not supported on replication controllers")
	}
	version, err := tools.ParseWatchResourceVersion(resourceVersion, "replicationControllers")
	if err != nil {
		return nil, err
	}
	key := makeControllerListKey(ctx)
	return r.WatchList(key, version, func(obj runtime.Object) bool {
		controller, ok := obj.(*api.ReplicationController)
		if !ok {
			// Must be an error: return true to propagate to upper level.
			return true
		}
		match := label.Matches(labels.Set(controller.Labels))
		if match {
			pods, _ := r.ListPods(ctx, labels.Set(controller.Spec.Selector).AsSelector())
			controller.Status.Replicas = len(pods.Items)
		}
		return match
	})
}

// WatchRoutes begins watching for new, changed, or deleted route configurations.
func (registry *Etcd) WatchRoutes(ctx kapi.Context, label labels.Selector, field fields.Selector, resourceVersion string) (watch.Interface, error) {
	if !label.Empty() {
		return nil, fmt.Errorf("label selectors are not supported on routes yet")
	}

	version, err := tools.ParseWatchResourceVersion(resourceVersion, "pod")
	if err != nil {
		return nil, err
	}

	if value, found := field.RequiresExactMatch("ID"); found {
		key, err := makeRouteKey(ctx, value)
		if err != nil {
			return nil, err
		}
		return registry.Watch(key, version, tools.Everything)
	}

	if field.Empty() {
		key := kubeetcd.MakeEtcdListKey(ctx, RoutePath)
		return registry.WatchList(key, version, tools.Everything)
	}
	return nil, fmt.Errorf("only the 'ID' and default (everything) field selectors are supported")
}