package reconcile

import (
	"context"
	"errors"

	"edge-infra.dev/pkg/k8s/meta/status"
	"edge-infra.dev/pkg/k8s/object"
	"edge-infra.dev/pkg/k8s/runtime/conditions"
	"edge-infra.dev/pkg/k8s/runtime/patch"
)

// Progressing updates the Reconciling condition for an object that is progressing
// through a reconciler. If specific reconciliation states are detected, that
// Reconciling condition is immediately patched so that it is reflected in the
// K8s control plane to provide feedback to users:
//
//   - If the object's ObservedGeneration does not match the object's current
//     generation, a contextual progressing reason is used.
//   - For objects that embed [ReconcileRequestStatus], if [ReconcileRequestAnnotation]
//     is present and it differs from the last handled reconcile request value
//
// The progressing condition is not perrsisted immediately because reconcilers
// which always requeue on some interval would thrash on their Ready status when
// reconciliation _should_ arrive to the same result if the object generation
// has not changed. This behavior is intended to make a trade-off between
// keeping the K8s API up to date with the latest object state as quickly as
// possible vs status churning.
func Progressing(ctx context.Context,
	obj conditions.Setter,
	patcher *patch.SerialPatcher,
	patchOpts ...patch.Option) error {
	conditions.Progressing(obj, status.ProgressingReason, "Reconciliation in progress")

	obsGen, err := object.GetStatusObservedGeneration(obj)
	switch {
	case err != nil && !errors.Is(err, object.ErrObservedGenerationNotFound):
		return err
	case err == nil:
		if obsGen != obj.GetGeneration() {
			conditions.Progressing(obj, status.ProgressingReason,
				"processing object: new generation %d -> %d", obsGen, obj.GetGeneration())
			return patcher.Patch(ctx, obj, patchOpts...)
		}
	}

	var recAtVal string
	if v, ok := GetAnnotation(obj.GetAnnotations()); ok {
		recAtVal = v
	}
	lastRecHandledAtVal, err := GetStatusLastHandledReconcileAt(obj)
	switch {
	case !errors.Is(err, ErrLastHandledReconcileAtNotFound):
		return err
	case err != nil && recAtVal != lastRecHandledAtVal:
		return patcher.Patch(ctx, obj, patchOpts...)
	}

	return nil
}