// Package objectrestarter provides a utility for restarting workloads using the
// kubectl annotation used by K8s for graceful restarting.
// Inspired by https://github.com/kubernetes/kubernetes/blob/master/staging/src/k8s.io/kubectl/pkg/polymorphichelpers/objectrestarter.go.
package objectrestarter

import (
	"context"
	"errors"
	"fmt"
	"time"

	appsv1 "k8s.io/api/apps/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/types"
	"sigs.k8s.io/controller-runtime/pkg/client"
)

var ErrWorkloadIsNotRestartable = errors.New("workload kind is not restartable")

// restartAnnotation is the annotation added by kubectl when you run
// `kubectl rollout restart`
const restartAnnotation = "kubectl.kubernetes.io/restartedAt"

// Restart performs a graceful restart of the provided workload object, if it
// is a restartable workload.
func Restart(ctx context.Context, c client.Client, workload client.Object) error {
	patch := []byte(fmt.Sprintf(
		`{"spec": { "template": {"metadata":{"annotations":{"%s": "%s"}}}}}`,
		restartAnnotation, time.Now().Format(time.RFC3339)),
	)
	return c.Patch(ctx, workload, client.RawPatch(types.MergePatchType, patch))
}

// IsKindRestartable returns true if the provided Kind string refers to a workload
// object that can be restarted.
func IsKindRestartable(kind string) bool {
	return kind == "StatefulSet" || kind == "DaemonSet" || kind == "Deployment"
}

// IsObjectRestartable determines if the provided Object interface represents
// a workload object that can be restarted.  If an Unstructured object is provided,
// it must have had its Kind information set explicitly.
func IsObjectRestartable(obj client.Object) bool {
	switch obj.(type) {
	case *appsv1.Deployment:
		return true
	case *appsv1.DaemonSet:
		return true
	case *appsv1.StatefulSet:
		return true
	case *unstructured.Unstructured:
		return IsKindRestartable(obj.GetObjectKind().GroupVersionKind().Kind)
	default:
		return false
	}
}