package backupcontroller

import (
	"context"
	"fmt"
	"net/http"

	corev1 "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/meta"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/dynamic"
	"k8s.io/client-go/rest"
	"k8s.io/client-go/tools/record"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/client/apiutil"
	"sigs.k8s.io/controller-runtime/pkg/log"

	strategyv1alpha1 "github.com/cozystack/cozystack/api/backups/strategy/v1alpha1"
	backupsv1alpha1 "github.com/cozystack/cozystack/api/backups/v1alpha1"
)

// RestoreJobReconciler reconciles RestoreJob objects.
// It routes RestoreJobs to strategy-specific handlers based on the strategy
// referenced in the Backup that the RestoreJob is restoring from.
type RestoreJobReconciler struct {
	client.Client
	dynamic.Interface
	meta.RESTMapper
	Scheme   *runtime.Scheme
	Recorder record.EventRecorder
}

func (r *RestoreJobReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	logger := log.FromContext(ctx)
	logger.Info("reconciling RestoreJob", "namespace", req.Namespace, "name", req.Name)

	restoreJob := &backupsv1alpha1.RestoreJob{}
	err := r.Get(ctx, types.NamespacedName{Namespace: req.Namespace, Name: req.Name}, restoreJob)
	if err != nil {
		if apierrors.IsNotFound(err) {
			logger.V(1).Info("RestoreJob not found, skipping")
			return ctrl.Result{}, nil
		}
		logger.Error(err, "failed to get RestoreJob")
		return ctrl.Result{}, err
	}

	// If already completed, no need to reconcile
	if restoreJob.Status.Phase == backupsv1alpha1.RestoreJobPhaseSucceeded ||
		restoreJob.Status.Phase == backupsv1alpha1.RestoreJobPhaseFailed {
		logger.V(1).Info("RestoreJob already completed, skipping", "phase", restoreJob.Status.Phase)
		return ctrl.Result{}, nil
	}

	// Step 1: Fetch the referenced Backup
	backup := &backupsv1alpha1.Backup{}
	backupKey := types.NamespacedName{Namespace: req.Namespace, Name: restoreJob.Spec.BackupRef.Name}
	if err := r.Get(ctx, backupKey, backup); err != nil {
		return r.markRestoreJobFailed(ctx, restoreJob, fmt.Sprintf("failed to get Backup: %v", err))
	}

	// Step 2: Determine effective strategy from backup.spec.strategyRef
	if backup.Spec.StrategyRef.APIGroup == nil {
		return r.markRestoreJobFailed(ctx, restoreJob, "Backup has nil StrategyRef.APIGroup")
	}

	if *backup.Spec.StrategyRef.APIGroup != strategyv1alpha1.GroupVersion.Group {
		return r.markRestoreJobFailed(ctx, restoreJob,
			fmt.Sprintf("StrategyRef.APIGroup doesn't match: %s", *backup.Spec.StrategyRef.APIGroup))
	}

	logger.Info("processing RestoreJob", "restorejob", restoreJob.Name, "backup", backup.Name, "strategyKind", backup.Spec.StrategyRef.Kind)
	switch backup.Spec.StrategyRef.Kind {
	case strategyv1alpha1.JobStrategyKind:
		return r.reconcileJobRestore(ctx, restoreJob, backup)
	case strategyv1alpha1.VeleroStrategyKind:
		return r.reconcileVeleroRestore(ctx, restoreJob, backup)
	default:
		return r.markRestoreJobFailed(ctx, restoreJob, fmt.Sprintf("StrategyRef.Kind not supported: %s", backup.Spec.StrategyRef.Kind))
	}
}

// SetupWithManager registers our controller with the Manager and sets up watches.
func (r *RestoreJobReconciler) SetupWithManager(mgr ctrl.Manager) error {
	cfg := mgr.GetConfig()
	var err error
	if r.Interface, err = dynamic.NewForConfig(cfg); err != nil {
		return err
	}
	var h *http.Client
	if h, err = rest.HTTPClientFor(cfg); err != nil {
		return err
	}
	if r.RESTMapper, err = apiutil.NewDynamicRESTMapper(cfg, h); err != nil {
		return err
	}
	return ctrl.NewControllerManagedBy(mgr).
		For(&backupsv1alpha1.RestoreJob{}).
		Complete(r)
}

// getTargetApplicationRef determines the effective target application reference.
// According to DESIGN.md, if spec.targetApplicationRef is omitted, drivers SHOULD
// restore into backup.spec.applicationRef.
// The returned reference is normalized to ensure APIGroup has a default value.
func (r *RestoreJobReconciler) getTargetApplicationRef(restoreJob *backupsv1alpha1.RestoreJob, backup *backupsv1alpha1.Backup) corev1.TypedLocalObjectReference {
	if restoreJob.Spec.TargetApplicationRef != nil {
		return backupsv1alpha1.NormalizeApplicationRef(*restoreJob.Spec.TargetApplicationRef)
	}
	return backup.Spec.ApplicationRef
}

// markRestoreJobFailed updates the RestoreJob status to Failed with the given message.
func (r *RestoreJobReconciler) markRestoreJobFailed(ctx context.Context, restoreJob *backupsv1alpha1.RestoreJob, message string) (ctrl.Result, error) {
	logger := getLogger(ctx)
	now := metav1.Now()
	restoreJob.Status.CompletedAt = &now
	restoreJob.Status.Phase = backupsv1alpha1.RestoreJobPhaseFailed
	restoreJob.Status.Message = message

	// Add condition
	restoreJob.Status.Conditions = append(restoreJob.Status.Conditions, metav1.Condition{
		Type:               "Ready",
		Status:             metav1.ConditionFalse,
		Reason:             "RestoreFailed",
		Message:            message,
		LastTransitionTime: now,
	})

	if err := r.Status().Update(ctx, restoreJob); err != nil {
		logger.Error(err, "failed to update RestoreJob status to Failed")
		return ctrl.Result{}, err
	}
	logger.Debug("RestoreJob failed", "message", message)
	return ctrl.Result{}, nil
}