/*
Copyright 2022 The Karmada Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package helper

import (
	"time"

	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	clusterv1alpha1 "github.com/karmada-io/karmada/pkg/apis/cluster/v1alpha1"
	policyv1alpha1 "github.com/karmada-io/karmada/pkg/apis/policy/v1alpha1"
)

// TaintExists checks if the given taint exists in list of taints. Returns true if exists false otherwise.
func TaintExists(taints []corev1.Taint, taintToFind *corev1.Taint) bool {
	for _, taint := range taints {
		if taint.MatchTaint(taintToFind) {
			return true
		}
	}
	return false
}

// TolerationExists checks if the given toleration exists in list of tolerations. Returns true if exists false otherwise.
func TolerationExists(tolerations []corev1.Toleration, tolerationToFind *corev1.Toleration) bool {
	for _, toleration := range tolerations {
		if toleration.MatchToleration(tolerationToFind) {
			return true
		}
	}
	return false
}

// SetCurrentClusterTaints sets current cluster taints which need to be updated.
func SetCurrentClusterTaints(taintsToAdd, taintsToRemove []*corev1.Taint, cluster *clusterv1alpha1.Cluster) []corev1.Taint {
	taints := cluster.Spec.Taints

	var clusterTaintsToAdd, clusterTaintsToRemove []corev1.Taint
	// Find which taints need to be added.
	for _, taintToAdd := range taintsToAdd {
		if !TaintExists(taints, taintToAdd) {
			clusterTaintsToAdd = append(clusterTaintsToAdd, *taintToAdd)
		}
	}
	// Find which taints need to be removed.
	for _, taintToRemove := range taintsToRemove {
		if TaintExists(taints, taintToRemove) {
			clusterTaintsToRemove = append(clusterTaintsToRemove, *taintToRemove)
		}
	}
	// If no taints need to be added and removed, just return.
	if len(clusterTaintsToAdd) == 0 && len(clusterTaintsToRemove) == 0 {
		return taints
	}

	taints = make([]corev1.Taint, 0, len(taints)+len(clusterTaintsToAdd)-len(clusterTaintsToRemove))
	// Remove taints which need to be removed.
	for i := range cluster.Spec.Taints {
		if !TaintExists(clusterTaintsToRemove, &cluster.Spec.Taints[i]) {
			taints = append(taints, cluster.Spec.Taints[i])
		}
	}

	// Add taints.
	for _, taintToAdd := range clusterTaintsToAdd {
		now := metav1.Now()
		taintToAdd.TimeAdded = &now
		taints = append(taints, taintToAdd)
	}

	return taints
}

// AddTolerations add some tolerations if not existed.
func AddTolerations(placement *policyv1alpha1.Placement, tolerationsToAdd ...*corev1.Toleration) {
	for _, tolerationToAdd := range tolerationsToAdd {
		if !TolerationExists(placement.ClusterTolerations, tolerationToAdd) {
			placement.ClusterTolerations = append(placement.ClusterTolerations, *tolerationToAdd)
		}
	}
}

// HasNoExecuteTaints check if NoExecute taints exist.
func HasNoExecuteTaints(taints []corev1.Taint) bool {
	for i := range taints {
		if taints[i].Effect == corev1.TaintEffectNoExecute {
			return true
		}
	}
	return false
}

// GetNoExecuteTaints will get all NoExecute taints.
func GetNoExecuteTaints(taints []corev1.Taint) []corev1.Taint {
	var result []corev1.Taint
	for i := range taints {
		if taints[i].Effect == corev1.TaintEffectNoExecute {
			result = append(result, taints[i])
		}
	}
	return result
}

// GetMinTolerationTime returns minimal toleration time from the given slice, or -1 if it's infinite.
func GetMinTolerationTime(noExecuteTaints []corev1.Taint, usedTolerations []corev1.Toleration) time.Duration {
	if len(noExecuteTaints) == 0 {
		return -1
	}
	if len(usedTolerations) == 0 {
		return 0
	}

	// Get all trigger time.
	var triggerTimes []time.Time
	for i := range usedTolerations {
		if usedTolerations[i].TolerationSeconds == nil {
			continue
		}
		tolerationSeconds := *(usedTolerations[i].TolerationSeconds)
		for j := range noExecuteTaints {
			// should not happen
			if noExecuteTaints[j].TimeAdded == nil {
				continue
			}
			timeAdded := *noExecuteTaints[j].TimeAdded
			if usedTolerations[i].ToleratesTaint(&noExecuteTaints[j]) {
				triggerTimes = append(triggerTimes, timeAdded.Add(time.Duration(tolerationSeconds)*time.Second))
			}
		}
	}

	// If triggerTimes is empty, it means all taints would be tolerated forever.
	if len(triggerTimes) == 0 {
		return -1
	}

	// Find the latest trigger time.
	t := triggerTimes[0]
	for i := 1; i < len(triggerTimes); i++ {
		if triggerTimes[i].Before(t) {
			t = triggerTimes[i]
		}
	}

	// If trigger time is up, don't tolerate.
	if t.Before(time.Now()) {
		return 0
	}

	return time.Until(t)
}

// GetMatchingTolerations returns true and list of Tolerations matching all Taints if all are tolerated, or false otherwise.
func GetMatchingTolerations(taints []corev1.Taint, tolerations []corev1.Toleration) (bool, []corev1.Toleration) {
	if len(taints) == 0 {
		return true, []corev1.Toleration{}
	}
	if len(tolerations) == 0 && len(taints) > 0 {
		return false, []corev1.Toleration{}
	}
	var result []corev1.Toleration
	for i := range taints {
		tolerated := false
		for j := range tolerations {
			if tolerations[j].ToleratesTaint(&taints[i]) {
				result = append(result, tolerations[j])
				tolerated = true
				break
			}
		}
		if !tolerated {
			return false, []corev1.Toleration{}
		}
	}
	return true, result
}

// NewNotReadyToleration returns a default not ready toleration.
func NewNotReadyToleration(tolerationSeconds int64) *corev1.Toleration {
	return &corev1.Toleration{
		Key:               clusterv1alpha1.TaintClusterNotReady,
		Operator:          corev1.TolerationOpExists,
		Effect:            corev1.TaintEffectNoExecute,
		TolerationSeconds: &tolerationSeconds,
	}
}

// NewUnreachableToleration returns a default unreachable toleration.
func NewUnreachableToleration(tolerationSeconds int64) *corev1.Toleration {
	return &corev1.Toleration{
		Key:               clusterv1alpha1.TaintClusterUnreachable,
		Operator:          corev1.TolerationOpExists,
		Effect:            corev1.TaintEffectNoExecute,
		TolerationSeconds: &tolerationSeconds,
	}
}