// 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
	})
}

// GetPodControllers returns a list of controllers managing a pod. Returns an error only if no matching controllers are found.
func (s *StoreToControllerLister) GetPodControllers(pod *api.Pod) (controllers []api.ReplicationController, err error) {
	var selector labels.Selector
	var rc api.ReplicationController

	if len(pod.Labels) == 0 {
		err = fmt.Errorf("No controllers found for pod %v because it has no labels", pod.Name)
		return
	}

	for _, m := range s.Store.List() {
		rc = *m.(*api.ReplicationController)
		if rc.Namespace != pod.Namespace {
			continue
		}
		labelSet := labels.Set(rc.Spec.Selector)
		selector = labels.Set(rc.Spec.Selector).AsSelector()

		// If an rc with a nil or empty selector creeps in, it should match nothing, not everything.
		if labelSet.AsSelector().Empty() || !selector.Matches(labels.Set(pod.Labels)) {
			continue
		}
		controllers = append(controllers, rc)
	}
	if len(controllers) == 0 {
		err = fmt.Errorf("Could not find controllers for pod %s in namespace %s with labels: %v", pod.Name, pod.Namespace, pod.Labels)
	}
	return
}

// TODO: Move this back to scheduler as a helper function that takes a Store,
// rather than a method of StoreToServiceLister.
func (s *StoreToServiceLister) GetPodServices(pod *api.Pod) (services []api.Service, err error) {
	var selector labels.Selector
	var service api.Service

	for _, m := range s.Store.List() {
		service = *m.(*api.Service)
		// consider only services that are in the same namespace as the pod
		if service.Namespace != pod.Namespace {
			continue
		}
		if service.Spec.Selector == nil {
			// services with nil selectors match nothing, not everything.
			continue
		}
		selector = labels.Set(service.Spec.Selector).AsSelector()
		if selector.Matches(labels.Set(pod.Labels)) {
			services = append(services, service)
		}
	}
	if len(services) == 0 {
		err = fmt.Errorf("Could not find service for pod %s in namespace %s with labels: %v", pod.Name, pod.Namespace, pod.Labels)
	}

	return
}

// List returns []*api.Pod matching a query.
func (f FakePodLister) List(s labels.Selector) (selected []*api.Pod, err error) {
	for _, pod := range f {
		if s.Matches(labels.Set(pod.Labels)) {
			selected = append(selected, pod)
		}
	}
	return selected, nil
}

// MatchPodTemplate returns a generic matcher for a given label and field selector.
func MatchPodTemplate(label labels.Selector, field fields.Selector) generic.Matcher {
	return generic.MatcherFunc(func(obj runtime.Object) (bool, error) {
		podObj, ok := obj.(*api.PodTemplate)
		if !ok {
			return false, fmt.Errorf("not a pod template")
		}
		return label.Matches(labels.Set(podObj.Labels)), nil
	})
}

// MatchPersistentVolume returns a generic matcher for a given label and field selector.
func MatchPersistentVolumes(label labels.Selector, field fields.Selector) generic.Matcher {
	return generic.MatcherFunc(func(obj runtime.Object) (bool, error) {
		persistentvolumeObj, ok := obj.(*api.PersistentVolume)
		if !ok {
			return false, fmt.Errorf("not a persistentvolume")
		}
		fields := PersistentVolumeToSelectableFields(persistentvolumeObj)
		return label.Matches(labels.Set(persistentvolumeObj.Labels)) && field.Matches(fields), nil
	})
}

// MatchNamespace returns a generic matcher for a given label and field selector.
func MatchNamespace(label labels.Selector, field fields.Selector) generic.Matcher {
	return generic.MatcherFunc(func(obj runtime.Object) (bool, error) {
		namespaceObj, ok := obj.(*api.Namespace)
		if !ok {
			return false, fmt.Errorf("not a namespace")
		}
		fields := NamespaceToSelectableFields(namespaceObj)
		return label.Matches(labels.Set(namespaceObj.Labels)) && field.Matches(fields), nil
	})
}

// MatchResourceQuota returns a generic matcher for a given label and field selector.
func MatchResourceQuota(label labels.Selector, field fields.Selector) generic.Matcher {
	return generic.MatcherFunc(func(obj runtime.Object) (bool, error) {
		resourcequotaObj, ok := obj.(*api.ResourceQuota)
		if !ok {
			return false, fmt.Errorf("not a resourcequota")
		}
		fields := ResourceQuotaToSelectableFields(resourcequotaObj)
		return label.Matches(labels.Set(resourcequotaObj.Labels)) && field.Matches(fields), nil
	})
}

// Matcher returns a generic matcher for a given label and field selector.
func Matcher(label labels.Selector, field fields.Selector) generic.Matcher {
	return generic.MatcherFunc(func(obj runtime.Object) (bool, error) {
		sa, ok := obj.(*api.Secret)
		if !ok {
			return false, fmt.Errorf("not a secret")
		}
		fields := SelectableFields(sa)
		return label.Matches(labels.Set(sa.Labels)) && field.Matches(fields), nil
	})
}

// LabelsSelectorParam adds the given selector as a query parameter
func (r *Request) LabelsSelectorParam(s labels.Selector) *Request {
	if r.err != nil {
		return r
	}
	if s == nil {
		return r
	}
	if s.Empty() {
		return r
	}
	return r.setParam(api.LabelSelectorQueryParam(r.apiVersion), s.String())
}

// Please note that selector is filtering among the pods that have gotten into
// the store; there may have been some filtering that already happened before
// that.
func (s storePodsNamespacer) List(selector labels.Selector) (pods api.PodList, err error) {
	list := api.PodList{}
	for _, m := range s.store.List() {
		pod := m.(*api.Pod)
		if s.namespace == api.NamespaceAll || s.namespace == pod.Namespace {
			if selector.Matches(labels.Set(pod.Labels)) {
				list.Items = append(list.Items, *pod)
			}
		}
	}
	return list, nil
}

func (rs *REST) List(ctx api.Context, label labels.Selector, field fields.Selector) (runtime.Object, error) {
	list, err := rs.registry.ListServices(ctx)
	if err != nil {
		return nil, err
	}
	var filtered []api.Service
	for _, service := range list.Items {
		if label.Matches(labels.Set(service.Labels)) {
			filtered = append(filtered, service)
		}
	}
	list.Items = filtered
	return list, err
}

// GetPodServices gets the services that have the selector that match the labels on the given pod
func (f FakeServiceLister) GetPodServices(pod *api.Pod) (services []api.Service, err error) {
	var selector labels.Selector

	for _, service := range f {
		// consider only services that are in the same namespace as the pod
		if service.Namespace != pod.Namespace {
			continue
		}
		selector = labels.Set(service.Spec.Selector).AsSelector()
		if selector.Matches(labels.Set(pod.Labels)) {
			services = append(services, service)
		}
	}
	if len(services) == 0 {
		err = fmt.Errorf("Could not find service for pod %s in namespace %s with labels: %v", pod.Name, pod.Namespace, pod.Labels)
	}

	return
}

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

// CheckServiceAffinity ensures that only the minions that match the specified labels are considered for scheduling.
// The set of labels to be considered are provided to the struct (ServiceAffinity).
// The pod is checked for the labels and any missing labels are then checked in the minion
// that hosts the service pods (peers) for the given pod.
//
// We add an implicit selector requiring some particular value V for label L to a pod, if:
// - L is listed in the ServiceAffinity object that is passed into the function
// - the pod does not have any NodeSelector for L
// - some other pod from the same service is already scheduled onto a minion that has value V for label L
func (s *ServiceAffinity) CheckServiceAffinity(pod *api.Pod, existingPods []*api.Pod, node string) (bool, error) {
	var affinitySelector labels.Selector

	// check if the pod being scheduled has the affinity labels specified in its NodeSelector
	affinityLabels := map[string]string{}
	nodeSelector := labels.Set(pod.Spec.NodeSelector)
	labelsExist := true
	for _, l := range s.labels {
		if nodeSelector.Has(l) {
			affinityLabels[l] = nodeSelector.Get(l)
		} else {
			// the current pod does not specify all the labels, look in the existing service pods
			labelsExist = false
		}
	}

	// skip looking at other pods in the service if the current pod defines all the required affinity labels
	if !labelsExist {
		services, err := s.serviceLister.GetPodServices(pod)
		if err == nil {
			// just use the first service and get the other pods within the service
			// TODO: a separate predicate can be created that tries to handle all services for the pod
			selector := labels.SelectorFromSet(services[0].Spec.Selector)
			servicePods, err := s.podLister.List(selector)
			if err != nil {
				return false, err
			}
			// consider only the pods that belong to the same namespace
			nsServicePods := []*api.Pod{}
			for _, nsPod := range servicePods {
				if nsPod.Namespace == pod.Namespace {
					nsServicePods = append(nsServicePods, nsPod)
				}
			}
			if len(nsServicePods) > 0 {
				// consider any service pod and fetch the minion its hosted on
				otherMinion, err := s.nodeInfo.GetNodeInfo(nsServicePods[0].Spec.NodeName)
				if err != nil {
					return false, err
				}
				for _, l := range s.labels {
					// If the pod being scheduled has the label value specified, do not override it
					if _, exists := affinityLabels[l]; exists {
						continue
					}
					if labels.Set(otherMinion.Labels).Has(l) {
						affinityLabels[l] = labels.Set(otherMinion.Labels).Get(l)
					}
				}
			}
		}
	}

	// if there are no existing pods in the service, consider all minions
	if len(affinityLabels) == 0 {
		affinitySelector = labels.Everything()
	} else {
		affinitySelector = labels.Set(affinityLabels).AsSelector()
	}

	minion, err := s.nodeInfo.GetNodeInfo(node)
	if err != nil {
		return false, err
	}

	// check if the minion matches the selector
	return affinitySelector.Matches(labels.Set(minion.Labels)), nil
}

func (r *PodRegistry) ListPods(ctx api.Context, selector labels.Selector) (*api.PodList, error) {
	return r.ListPodsPredicate(ctx, func(pod *api.Pod) bool {
		return selector.Matches(labels.Set(pod.Labels))
	})
}