/*
Copyright the Velero contributors.

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 kube

import (
	"k8s.io/client-go/util/workqueue"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/event"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
)

type MapUpdateFunc func(client.Object) []reconcile.Request

// EnqueueRequestsFromMapUpdateFunc has the same purpose with handler.EnqueueRequestsFromMapFunc.
// MapUpdateFunc is simpler on Update event because mapAndEnqueue is called once with the new object. EnqueueRequestsFromMapFunc is called twice with the old and new object.
func EnqueueRequestsFromMapUpdateFunc(fn MapUpdateFunc) handler.EventHandler {
	return &enqueueRequestsFromMapFunc{
		toRequests: fn,
	}
}

var _ handler.EventHandler = &enqueueRequestsFromMapFunc{}

type enqueueRequestsFromMapFunc struct {
	toRequests MapUpdateFunc
}

// Create implements EventHandler.
func (e *enqueueRequestsFromMapFunc) Create(evt event.CreateEvent, q workqueue.RateLimitingInterface) {
	e.mapAndEnqueue(q, evt.Object)
}

// Update implements EventHandler.
func (e *enqueueRequestsFromMapFunc) Update(evt event.UpdateEvent, q workqueue.RateLimitingInterface) {
	e.mapAndEnqueue(q, evt.ObjectNew)
}

// Delete implements EventHandler.
func (e *enqueueRequestsFromMapFunc) Delete(evt event.DeleteEvent, q workqueue.RateLimitingInterface) {
	e.mapAndEnqueue(q, evt.Object)
}

// Generic implements EventHandler.
func (e *enqueueRequestsFromMapFunc) Generic(evt event.GenericEvent, q workqueue.RateLimitingInterface) {
	e.mapAndEnqueue(q, evt.Object)
}

func (e *enqueueRequestsFromMapFunc) mapAndEnqueue(q workqueue.RateLimitingInterface, object client.Object) {
	reqs := map[reconcile.Request]struct{}{}

	for _, req := range e.toRequests(object) {
		_, ok := reqs[req]
		if !ok {
			q.Add(req)
			reqs[req] = struct{}{}
		}
	}
}