package utils

import (
	"context"
	"errors"
	"time"

	"k8s.io/apimachinery/pkg/fields"
	"k8s.io/apimachinery/pkg/runtime"
	kwatch "k8s.io/apimachinery/pkg/watch"
	"sigs.k8s.io/controller-runtime/pkg/client"
)

var (
	ErrWatchTimeout = errors.New("timeout getting data")
	ErrNotAMatch    = errors.New("updated object is not a match")
)

// MatchFn return nil when matching, ErrNotAMatch when not matching, will stop watching for any other errors
type MatchFn func(obj runtime.Object) error

func Watch(cl client.WithWatch, list client.ObjectList, objectKey client.ObjectKey, timeout time.Duration, matches MatchFn) error {
	ctx, cancel := context.WithTimeout(context.Background(), timeout)
	defer cancel()
	watch, err := cl.Watch(ctx, list, &client.ListOptions{
		FieldSelector: fields.OneTermEqualSelector("metadata.name", objectKey.Name),
		Namespace:     objectKey.Namespace,
	})
	if err != nil {
		return err
	}
	defer watch.Stop()

	watchChannel := watch.ResultChan()
	for {
		select {
		case event := <-watchChannel:
			switch event.Type {
			case kwatch.Added, kwatch.Modified, kwatch.Deleted:
				err = matches(event.Object)
				if err == nil { // when there is a match no error is return
					return nil
				}
				if !errors.Is(err, ErrNotAMatch) { // stop watch for any other errors
					return err
				}
			}
		case <-ctx.Done():
			return ErrWatchTimeout
		}
	}
}