/*
Copyright 2019 The Knative 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 common

import (
	"encoding/json"
	"fmt"

	"k8s.io/apimachinery/pkg/util/sets"
	"knative.dev/operator/pkg/apis/operator/v1alpha1"
)

// FinalizerRemovalPatch generates a patch for removing the given finalizer.
func FinalizerRemovalPatch(obj v1alpha1.KComponent, toRemove string) ([]byte, error) {
	finalizers := sets.NewString(obj.GetFinalizers()...)

	if !finalizers.Has(toRemove) {
		// Nothing to do.
		return nil, nil
	}

	// Remove the finalizer
	finalizers.Delete(toRemove)

	mergePatch := map[string]interface{}{
		"metadata": map[string]interface{}{
			"finalizers":      finalizers.List(),
			"resourceVersion": obj.GetResourceVersion(),
		},
	}

	patch, err := json.Marshal(mergePatch)
	if err != nil {
		return nil, fmt.Errorf("failed to construct finalizer patch: %w", err)
	}
	return patch, nil
}
