/*
Copyright The Helm 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 action

import (
	"fmt"

	"github.com/pkg/errors"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/meta"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/selection"
	"k8s.io/cli-runtime/pkg/resource"

	"helm.sh/helm/v3/pkg/kube"
)

var (
	managedByReq, _ = labels.NewRequirement("app.kubernetes.io/managed-by", selection.Equals, []string{"Helm"})
	accessor        = meta.NewAccessor()
)

func newReleaseSelector(release string) (labels.Selector, error) {
	releaseReq, err := labels.NewRequirement("app.kubernetes.io/instance", selection.Equals, []string{release})
	if err != nil {
		return nil, err
	}

	return labels.Parse(fmt.Sprintf("%s,%s", releaseReq, managedByReq))
}

func existingResourceConflict(resources kube.ResourceList, release string) (kube.ResourceList, error) {
	sel, err := newReleaseSelector(release)
	if err != nil {
		return nil, err
	}

	requireUpdate := kube.ResourceList{}

	err = resources.Visit(func(info *resource.Info, err error) error {
		if err != nil {
			return err
		}

		helper := resource.NewHelper(info.Client, info.Mapping)
		existing, err := helper.Get(info.Namespace, info.Name, info.Export)
		if err != nil {
			if apierrors.IsNotFound(err) {
				return nil
			}

			return errors.Wrap(err, "could not get information about the resource")
		}

		// Allow adoption of the resource if it already has app.kubernetes.io/instance and app.kubernetes.io/managed-by labels.
		lbls, err := accessor.Labels(existing)
		if err == nil {
			set := labels.Set(lbls)
			if sel.Matches(set) {
				requireUpdate = append(requireUpdate, info)
				return nil
			}
		}

		return fmt.Errorf(
			"existing resource conflict: namespace: %s, name: %s, existing_kind: %s, new_kind: %s",
			info.Namespace, info.Name, existing.GetObjectKind().GroupVersionKind(), info.Mapping.GroupVersionKind)
	})

	return requireUpdate, err
}