/*
Copyright 2021 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 detector

import (
	"math"

	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/klog/v2"

	policyv1alpha1 "github.com/karmada-io/karmada/pkg/apis/policy/v1alpha1"
	"github.com/karmada-io/karmada/pkg/util"
	"github.com/karmada-io/karmada/pkg/util/fedinformer/keys"
)

func getHighestPriorityPropagationPolicy(policies []*policyv1alpha1.PropagationPolicy, resource *unstructured.Unstructured, objectKey keys.ClusterWideKey) *policyv1alpha1.PropagationPolicy {
	matchedPolicyImplicitPriority := util.PriorityMisMatch
	matchedPolicyExplicitPriority := int32(math.MinInt32)
	var matchedPolicy *policyv1alpha1.PropagationPolicy

	for _, policy := range policies {
		implicitPriority := util.ResourceMatchSelectorsPriority(resource, policy.Spec.ResourceSelectors...)
		if implicitPriority <= util.PriorityMisMatch {
			continue
		}
		explicitPriority := policy.ExplicitPriority()

		if matchedPolicyExplicitPriority < explicitPriority {
			matchedPolicyImplicitPriority = implicitPriority
			matchedPolicyExplicitPriority = explicitPriority
			matchedPolicy = policy
			continue
		}

		if matchedPolicyExplicitPriority == explicitPriority {
			if implicitPriority > matchedPolicyImplicitPriority {
				matchedPolicyImplicitPriority = implicitPriority
				matchedPolicy = policy
			} else if implicitPriority == matchedPolicyImplicitPriority {
				matchedPolicy = getHigherPriorityPropagationPolicy(matchedPolicy, policy)
			}
		}
	}

	if matchedPolicy == nil {
		klog.V(2).Infof("No propagationpolicy match for resource(%s)", objectKey)
		return nil
	}
	klog.V(2).Infof("Matched policy(%s/%s) for resource(%s)", matchedPolicy.Namespace, matchedPolicy.Name, objectKey)
	return matchedPolicy
}

func getHighestPriorityClusterPropagationPolicy(policies []*policyv1alpha1.ClusterPropagationPolicy, resource *unstructured.Unstructured, objectKey keys.ClusterWideKey) *policyv1alpha1.ClusterPropagationPolicy {
	matchedClusterPolicyImplicitPriority := util.PriorityMisMatch
	matchedClusterPolicyExplicitPriority := int32(math.MinInt32)
	var matchedClusterPolicy *policyv1alpha1.ClusterPropagationPolicy

	for _, policy := range policies {
		implicitPriority := util.ResourceMatchSelectorsPriority(resource, policy.Spec.ResourceSelectors...)
		if implicitPriority <= util.PriorityMisMatch {
			continue
		}
		explicitPriority := policy.ExplicitPriority()

		if matchedClusterPolicyExplicitPriority < explicitPriority {
			matchedClusterPolicyImplicitPriority = implicitPriority
			matchedClusterPolicyExplicitPriority = explicitPriority
			matchedClusterPolicy = policy
			continue
		}

		if matchedClusterPolicyExplicitPriority == explicitPriority {
			if implicitPriority > matchedClusterPolicyImplicitPriority {
				matchedClusterPolicyImplicitPriority = implicitPriority
				matchedClusterPolicy = policy
			} else if implicitPriority == matchedClusterPolicyImplicitPriority {
				matchedClusterPolicy = getHigherPriorityClusterPropagationPolicy(matchedClusterPolicy, policy)
			}
		}
	}

	if matchedClusterPolicy == nil {
		klog.V(2).Infof("No clusterpropagationpolicy match for resource(%s)", objectKey)
		return nil
	}
	klog.V(2).Infof("Matched cluster policy(%s) for resource(%s)", matchedClusterPolicy.Name, objectKey)
	return matchedClusterPolicy
}

// getHigherPriorityPropagationPolicy compare two PropagationPolicies with some priority comparison logic
func getHigherPriorityPropagationPolicy(a, b *policyv1alpha1.PropagationPolicy) *policyv1alpha1.PropagationPolicy {
	if a == nil {
		return b
	}
	// logic of priority comparison
	if a.Name < b.Name {
		return a
	}
	return b
}

// getHigherPriorityClusterPropagationPolicy compare two ClusterPropagationPolicies with some priority comparison logic
func getHigherPriorityClusterPropagationPolicy(a, b *policyv1alpha1.ClusterPropagationPolicy) *policyv1alpha1.ClusterPropagationPolicy {
	if a == nil {
		return b
	}
	// logic of priority comparison
	if a.Name < b.Name {
		return a
	}
	return b
}