// Prioritizes the minions by running the individual priority functions sequentially.
// Each priority function is expected to set a score of 0-10
// 0 is the lowest priority score (least preferred minion) and 10 is the highest
// Each priority function can also have its own weight
// The minion scores returned by the priority function are multiplied by the weights to get weighted scores
// All scores are finally combined (added) to get the total weighted scores of all minions
func PrioritizeNodes(pod *api.Pod, podLister algorithm.PodLister, priorityConfigs []algorithm.PriorityConfig, minionLister algorithm.MinionLister, cloud cloudprovider.Interface) (api.HostPriorityList, error) {
	result := api.HostPriorityList{}

	// If no priority configs are provided, then the EqualPriority function is applied
	// This is required to generate the priority list in the required format
	if len(priorityConfigs) == 0 {
		return EqualPriority(pod, podLister, minionLister)
	}

	combinedScores := map[string]int{}
	for _, priorityConfig := range priorityConfigs {
		weight := priorityConfig.Weight
		// skip the priority function if the weight is specified as 0
		if weight == 0 {
			continue
		}
		priorityFunc := priorityConfig.Function
		prioritizedList, err := priorityFunc(pod, podLister, minionLister)
		if err != nil {
			return api.HostPriorityList{}, err
		}
		for _, hostEntry := range prioritizedList {
			combinedScores[hostEntry.Host] += hostEntry.Score * weight
		}
	}

	if cloud != nil {
		ext, supported := cloud.SchedulerExtension()
		if supported {
			nodes, err := minionLister.List()
			if err != nil {
				return api.HostPriorityList{}, err
			}

			prioritizedList, err := ext.Prioritize(pod, &nodes)
			if err != nil {
				return api.HostPriorityList{}, err
			}

			for _, hostEntry := range *prioritizedList {
				combinedScores[hostEntry.Host] += hostEntry.Score
			}
		}
	}

	for host, score := range combinedScores {
		glog.V(10).Infof("Host %s Score %d", host, score)
		result = append(result, api.HostPriority{Host: host, Score: score})
	}
	return result, nil
}

func getInstanceIPFromCloud(cloud cloudprovider.Interface, host string) string {
	if cloud == nil {
		return ""
	}
	instances, ok := cloud.Instances()
	if instances == nil || !ok {
		return ""
	}
	addr, err := instances.IPAddress(host)
	if err != nil {
		glog.Errorf("Error getting instance IP for %q: %v", host, err)
		return ""
	}
	return addr.String()
}

func getInstanceIP(cloud cloudprovider.Interface, host string) string {
	if cloud == nil {
		return ""
	}
	instances, ok := cloud.Instances()
	if instances == nil || !ok {
		return ""
	}
	ix := strings.Index(host, ".")
	if ix != -1 {
		host = host[:ix]
	}
	addr, err := instances.IPAddress(host)
	if err != nil {
		glog.Errorf("Error getting instance IP: %#v", err)
		return ""
	}
	return addr.String()
}

// Filters the minions to find the ones that fit based on the given predicate functions
// Each minion is passed through the predicate functions to determine if it is a fit
func findNodesThatFit(pod *api.Pod, podLister algorithm.PodLister, predicateFuncs map[string]algorithm.FitPredicate, nodes api.NodeList, cloud cloudprovider.Interface) (api.NodeList, FailedPredicateMap, error) {
	filtered := []api.Node{}
	machineToPods, err := predicates.MapPodsToMachines(podLister)
	failedPredicateMap := FailedPredicateMap{}
	if err != nil {
		return api.NodeList{}, FailedPredicateMap{}, err
	}
	for _, node := range nodes.Items {
		fits := true
		for name, predicate := range predicateFuncs {
			fit, err := predicate(pod, machineToPods[node.Name], node.Name)
			if err != nil {
				return api.NodeList{}, FailedPredicateMap{}, err
			}
			if !fit {
				fits = false
				if _, found := failedPredicateMap[node.Name]; !found {
					failedPredicateMap[node.Name] = util.StringSet{}
				}
				failedPredicateMap[node.Name].Insert(name)
				break
			}
		}
		if fits {
			filtered = append(filtered, node)
		}
	}

	if cloud != nil {
		ext, supported := cloud.SchedulerExtension()
		if supported {
			filteredList, err := ext.Filter(pod, &api.NodeList{Items: filtered})
			if err != nil {
				return api.NodeList{}, FailedPredicateMap{}, err
			}
			filtered = filteredList.Items
		}
	}

	return api.NodeList{Items: filtered}, failedPredicateMap, nil
}