package workloads

import (
	"context"
	"errors"
	"fmt"
	"reflect"

	v1 "k8s.io/api/apps/v1"
	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/runtime/schema"
	"k8s.io/apimachinery/pkg/types"
	"sigs.k8s.io/controller-runtime/pkg/client"

	"edge-infra.dev/pkg/k8s/runtime/objectrestarter"
)

// getOwnerReference determines the workload object that owns the input object.
// If a valid workload owner cant be found, an empty metav1.OwnerReference is returned.
func getOwnerReference(m metav1.ObjectMeta) metav1.OwnerReference {
	for i, ref := range m.OwnerReferences {
		// either the kind must be restartable, a descendant of a kind that is
		// restartable (eg, ReplicaSet are owned by Deployments, which are restartable)
		if !objectrestarter.IsKindRestartable(ref.Kind) && ref.Kind != reflect.TypeOf(v1.ReplicaSet{}).Name() {
			continue
		}
		return m.OwnerReferences[i]
	}
	return metav1.OwnerReference{}
}

// getReplicaSetOwnerReference determines the workload object that owns the input replicaSet.
// For pods owned by a ReplicaSet we need to go one level up for the real owning type.
// Technically ReplicaSets could be the highest level owning type, but it would
// be an antipattern since the K8s API docs say they should be managed by
// higher level workload types: https://kubernetes.io/docs/concepts/workloads/controllers/replicaset/#when-to-use-a-replicaset
func getReplicaSetOwnerReference(ctx context.Context, c client.Client, pod corev1.Pod, ownerRef metav1.OwnerReference) (metav1.OwnerReference, error) {
	replicaSet := &v1.ReplicaSet{}
	if err := c.Get(ctx, types.NamespacedName{Name: ownerRef.Name, Namespace: pod.Namespace}, replicaSet); err != nil {
		return metav1.OwnerReference{}, fmt.Errorf("failed to get owning replicaset: %w", err)
	}
	replicaSetOwnerRef := getOwnerReference(replicaSet.ObjectMeta)
	if replicaSetOwnerRef == (metav1.OwnerReference{}) {
		return metav1.OwnerReference{}, errors.New("failed to get owner ref for replicaset")
	}
	return replicaSetOwnerRef, nil
}

// getWorkloadFromOwnerReference returns the workload from the given ownerReference as an unstructured object.
func getWorkloadFromOwnerReference(ctx context.Context, c client.Client, pod corev1.Pod, ownerRef metav1.OwnerReference) (*unstructured.Unstructured, error) {
	gv, err := schema.ParseGroupVersion(ownerRef.APIVersion)
	if err != nil {
		return nil, fmt.Errorf("failed to parse apiVersion for owner ref: %w", err)
	}
	workload := &unstructured.Unstructured{}
	workload.SetGroupVersionKind(gv.WithKind(ownerRef.Kind))
	if err := c.Get(ctx, types.NamespacedName{Name: ownerRef.Name, Namespace: pod.Namespace}, workload); err != nil {
		return nil, fmt.Errorf("failed to get owning workload %s/%s/%s: %w", ownerRef.Kind, pod.Namespace, ownerRef.Name, err)
	}
	return workload, nil
}