package status

import (
	"sync"
	"time"

	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	clusterv1alpha1 "github.com/karmada-io/karmada/pkg/apis/cluster/v1alpha1"
)

type clusterData struct {
	// readyCondition is the last observed ready condition of the cluster.
	readyCondition metav1.ConditionStatus
	// thresholdStartTime is the time that the ready condition changed.
	thresholdStartTime time.Time
}

type clusterConditionStore struct {
	clusterDataMap sync.Map
	// successThreshold is the duration of successes for the cluster to be considered healthy after recovery.
	successThreshold time.Duration
	// failureThreshold is the duration of failure for the cluster to be considered unhealthy.
	failureThreshold time.Duration
}

func (c *clusterConditionStore) thresholdAdjustedReadyCondition(cluster *clusterv1alpha1.Cluster, observedReadyCondition *metav1.Condition) *metav1.Condition {
	saved := c.get(cluster.Name)
	if saved == nil {
		// the cluster is just joined
		c.update(cluster.Name, &clusterData{
			readyCondition: observedReadyCondition.Status,
		})
		return observedReadyCondition
	}
	curReadyCondition := meta.FindStatusCondition(cluster.Status.Conditions, clusterv1alpha1.ClusterConditionReady)
	if curReadyCondition == nil {
		return observedReadyCondition
	}

	now := time.Now()
	if saved.readyCondition != observedReadyCondition.Status {
		// ready condition status changed, record the threshold start time
		saved = &clusterData{
			readyCondition:     observedReadyCondition.Status,
			thresholdStartTime: now,
		}
		c.update(cluster.Name, saved)
	}

	var threshold time.Duration
	if observedReadyCondition.Status == metav1.ConditionTrue {
		threshold = c.successThreshold
	} else {
		threshold = c.failureThreshold
	}

	// we only care about true/not true
	// for unknown->false, just return the observed ready condition
	if ((observedReadyCondition.Status == metav1.ConditionTrue && curReadyCondition.Status != metav1.ConditionTrue) ||
		(observedReadyCondition.Status != metav1.ConditionTrue && curReadyCondition.Status == metav1.ConditionTrue)) &&
		now.Before(saved.thresholdStartTime.Add(threshold)) {
		// retain old status until threshold exceeded to avoid network unstable problems.
		return curReadyCondition
	}
	return observedReadyCondition
}

func (c *clusterConditionStore) get(cluster string) *clusterData {
	condition, ok := c.clusterDataMap.Load(cluster)
	if !ok {
		return nil
	}
	return condition.(*clusterData)
}

func (c *clusterConditionStore) update(cluster string, data *clusterData) {
	// ready condition status changed, record the threshold start time
	c.clusterDataMap.Store(cluster, data)
}

func (c *clusterConditionStore) delete(cluster string) {
	c.clusterDataMap.Delete(cluster)
}