package util

import (
	"sort"
	"strings"

	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/util/sets"

	workv1alpha2 "github.com/karmada-io/karmada/pkg/apis/work/v1alpha2"
)

// GetLabelValue retrieves the value via 'labelKey' if exist, otherwise returns an empty string.
func GetLabelValue(labels map[string]string, labelKey string) string {
	if labels == nil {
		return ""
	}

	return labels[labelKey]
}

// RetainLabels merges the labels that added by controllers running
// in member cluster to avoid overwriting.
// Following keys will be ignored if :
//   - the keys were previous propagated to member clusters(that are tracked
//     by "resourcetemplate.karmada.io/managed-lables" annotation in observed)
//     but have been removed from Karmada control plane(don't exist in desired anymore).
//   - the keys that exist in both desired and observed even those been accidentally modified
//     in member clusters.
func RetainLabels(desired *unstructured.Unstructured, observed *unstructured.Unstructured) {
	labels := desired.GetLabels()
	if labels == nil {
		labels = make(map[string]string, 0)
	}
	deletedLabelKeys := getDeletedLabelKeys(desired, observed)
	for key, value := range observed.GetLabels() {
		if deletedLabelKeys.Has(key) {
			continue
		}
		if _, exist := labels[key]; exist {
			continue
		}
		labels[key] = value
	}
	if len(labels) > 0 {
		desired.SetLabels(labels)
	}
}

// MergeLabel adds label for the given object.
func MergeLabel(obj *unstructured.Unstructured, labelKey string, labelValue string) {
	labels := obj.GetLabels()
	if labels == nil {
		labels = make(map[string]string, 1)
	}
	labels[labelKey] = labelValue
	obj.SetLabels(labels)
}

// RemoveLabel removes the label from the given object.
func RemoveLabel(obj *unstructured.Unstructured, labelKey string) {
	labels := obj.GetLabels()
	delete(labels, labelKey)
	obj.SetLabels(labels)
}

// DedupeAndMergeLabels merges the new labels into exist labels.
func DedupeAndMergeLabels(existLabel, newLabel map[string]string) map[string]string {
	if existLabel == nil {
		return newLabel
	}

	for k, v := range newLabel {
		existLabel[k] = v
	}
	return existLabel
}

func getDeletedLabelKeys(desired, observed *unstructured.Unstructured) sets.Set[string] {
	recordKeys := sets.New[string](strings.Split(observed.GetAnnotations()[workv1alpha2.ManagedLabels], ",")...)
	for key := range desired.GetLabels() {
		recordKeys.Delete(key)
	}
	return recordKeys
}

// RecordManagedLabels sets or updates the annotation(resourcetemplate.karmada.io/managed-labels)
// to record the label keys.
func RecordManagedLabels(object *unstructured.Unstructured) {
	annotations := object.GetAnnotations()
	if annotations == nil {
		annotations = make(map[string]string, 1)
	}
	var managedKeys []string
	// record labels.
	labels := object.GetLabels()
	for key := range labels {
		managedKeys = append(managedKeys, key)
	}
	sort.Strings(managedKeys)
	annotations[workv1alpha2.ManagedLabels] = strings.Join(managedKeys, ",")
	object.SetAnnotations(annotations)
}