/*
Copyright 2023 The Kubernetes 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 cacher

import (
	"context"

	"google.golang.org/grpc/metadata"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/fields"
	"k8s.io/apimachinery/pkg/labels"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/watch"
	"k8s.io/apiserver/pkg/storage"
	"k8s.io/client-go/tools/cache"
)

// listerWatcher opaques storage.Interface to expose cache.ListerWatcher.
type listerWatcher struct {
	storage         storage.Interface
	resourcePrefix  string
	newListFunc     func() runtime.Object
	contextMetadata metadata.MD
}

// NewListerWatcher returns a storage.Interface backed ListerWatcher.
func NewListerWatcher(storage storage.Interface, resourcePrefix string, newListFunc func() runtime.Object, contextMetadata metadata.MD) cache.ListerWatcher {
	return &listerWatcher{
		storage:         storage,
		resourcePrefix:  resourcePrefix,
		newListFunc:     newListFunc,
		contextMetadata: contextMetadata,
	}
}

// Implements cache.ListerWatcher interface.
func (lw *listerWatcher) List(options metav1.ListOptions) (runtime.Object, error) {
	list := lw.newListFunc()
	pred := storage.SelectionPredicate{
		Label:    labels.Everything(),
		Field:    fields.Everything(),
		Limit:    options.Limit,
		Continue: options.Continue,
	}

	storageOpts := storage.ListOptions{
		ResourceVersionMatch: options.ResourceVersionMatch,
		Predicate:            pred,
		Recursive:            true,
	}
	ctx := context.Background()
	if lw.contextMetadata != nil {
		ctx = metadata.NewOutgoingContext(ctx, lw.contextMetadata)
	}
	if err := lw.storage.GetList(ctx, lw.resourcePrefix, storageOpts, list); err != nil {
		return nil, err
	}
	return list, nil
}

// Implements cache.ListerWatcher interface.
func (lw *listerWatcher) Watch(options metav1.ListOptions) (watch.Interface, error) {
	opts := storage.ListOptions{
		ResourceVersion: options.ResourceVersion,
		Predicate:       storage.Everything,
		Recursive:       true,
		ProgressNotify:  true,
	}
	ctx := context.Background()
	if lw.contextMetadata != nil {
		ctx = metadata.NewOutgoingContext(ctx, lw.contextMetadata)
	}
	return lw.storage.Watch(ctx, lw.resourcePrefix, opts)
}
