package execution

import (
	"context"
	"fmt"

	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/apis/meta/v1/unstructured"
	"k8s.io/apimachinery/pkg/util/errors"
	"k8s.io/client-go/tools/record"
	"k8s.io/client-go/util/retry"
	"k8s.io/klog/v2"
	controllerruntime "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
	"sigs.k8s.io/controller-runtime/pkg/predicate"

	workv1alpha1 "github.com/karmada-io/karmada/pkg/apis/work/v1alpha1"
	"github.com/karmada-io/karmada/pkg/util"
	"github.com/karmada-io/karmada/pkg/util/helper"
	"github.com/karmada-io/karmada/pkg/util/informermanager"
	"github.com/karmada-io/karmada/pkg/util/informermanager/keys"
	"github.com/karmada-io/karmada/pkg/util/names"
	"github.com/karmada-io/karmada/pkg/util/objectwatcher"
)

const (
	// ControllerName is the controller name that will be used when reporting events.
	ControllerName = "execution-controller"
)

// Controller is to sync Work.
type Controller struct {
	client.Client        // used to operate Work resources.
	EventRecorder        record.EventRecorder
	RESTMapper           meta.RESTMapper
	ObjectWatcher        objectwatcher.ObjectWatcher
	PredicateFunc        predicate.Predicate
	InformerManager      informermanager.MultiClusterInformerManager
	ClusterClientSetFunc func(clusterName string, client client.Client) (*util.DynamicClusterClient, error)
}

// Reconcile performs a full reconciliation for the object referred to by the Request.
// The Controller will requeue the Request to be processed again if an error is non-nil or
// Result.Requeue is true, otherwise upon completion it will remove the work from the queue.
func (c *Controller) Reconcile(ctx context.Context, req controllerruntime.Request) (controllerruntime.Result, error) {
	klog.V(4).Infof("Reconciling Work %s", req.NamespacedName.String())

	work := &workv1alpha1.Work{}
	if err := c.Client.Get(context.TODO(), req.NamespacedName, work); err != nil {
		// The resource may no longer exist, in which case we stop processing.
		if apierrors.IsNotFound(err) {
			return controllerruntime.Result{}, nil
		}

		return controllerruntime.Result{Requeue: true}, err
	}

	clusterName, err := names.GetClusterName(work.Namespace)
	if err != nil {
		klog.Errorf("Failed to get member cluster name for work %s/%s", work.Namespace, work.Name)
		return controllerruntime.Result{Requeue: true}, err
	}

	cluster, err := util.GetCluster(c.Client, clusterName)
	if err != nil {
		klog.Errorf("Failed to get the given member cluster %s", clusterName)
		return controllerruntime.Result{Requeue: true}, err
	}

	if !work.DeletionTimestamp.IsZero() {
		// Abort deleting workload if cluster is unready when unjoining cluster, otherwise the unjoin process will be failed.
		if util.IsClusterReady(&cluster.Status) {
			err := c.tryDeleteWorkload(clusterName, work)
			if err != nil {
				klog.Errorf("Failed to delete work %v, namespace is %v, err is %v", work.Name, work.Namespace, err)
				return controllerruntime.Result{Requeue: true}, err
			}
		} else if cluster.DeletionTimestamp.IsZero() { // cluster is unready, but not terminating
			return controllerruntime.Result{Requeue: true}, fmt.Errorf("cluster(%s) not ready", cluster.Name)
		}

		return c.removeFinalizer(work)
	}

	if !util.IsClusterReady(&cluster.Status) {
		klog.Errorf("Stop sync work(%s/%s) for cluster(%s) as cluster not ready.", work.Namespace, work.Name, cluster.Name)
		return controllerruntime.Result{Requeue: true}, fmt.Errorf("cluster(%s) not ready", cluster.Name)
	}

	return c.syncWork(clusterName, work)
}

// SetupWithManager creates a controller and register to controller manager.
func (c *Controller) SetupWithManager(mgr controllerruntime.Manager) error {
	return controllerruntime.NewControllerManagedBy(mgr).
		For(&workv1alpha1.Work{}).
		WithEventFilter(predicate.GenerationChangedPredicate{}).
		WithEventFilter(c.PredicateFunc).
		Complete(c)
}

func (c *Controller) syncWork(clusterName string, work *workv1alpha1.Work) (controllerruntime.Result, error) {
	err := c.syncToClusters(clusterName, work)
	if err != nil {
		msg := fmt.Sprintf("Failed to sync work(%s) to cluster(%s): %v", work.Name, clusterName, err)
		klog.Errorf(msg)
		c.EventRecorder.Event(work, corev1.EventTypeWarning, workv1alpha1.EventReasonSyncWorkFailed, msg)
		return controllerruntime.Result{Requeue: true}, err
	}
	msg := fmt.Sprintf("Sync work (%s) to cluster(%s) successful.", work.Name, clusterName)
	klog.V(4).Infof(msg)
	c.EventRecorder.Event(work, corev1.EventTypeNormal, workv1alpha1.EventReasonSyncWorkSucceed, msg)
	return controllerruntime.Result{}, nil
}

// tryDeleteWorkload tries to delete resource in the given member cluster.
func (c *Controller) tryDeleteWorkload(clusterName string, work *workv1alpha1.Work) error {
	for _, manifest := range work.Spec.Workload.Manifests {
		workload := &unstructured.Unstructured{}
		err := workload.UnmarshalJSON(manifest.Raw)
		if err != nil {
			klog.Errorf("failed to unmarshal workload, error is: %v", err)
			return err
		}

		fedKey, err := keys.FederatedKeyFunc(clusterName, workload)
		if err != nil {
			klog.Errorf("Failed to get FederatedKey %s, error: %v", workload.GetName(), err)
			return err
		}

		clusterObj, err := helper.GetObjectFromCache(c.RESTMapper, c.InformerManager, fedKey, c.Client, c.ClusterClientSetFunc)
		if err != nil {
			if apierrors.IsNotFound(err) {
				return nil
			}
			klog.Errorf("Failed to get resource %v from member cluster, err is %v ", workload.GetName(), err)
			return err
		}

		// Avoid deleting resources that not managed by karmada.
		if util.GetLabelValue(clusterObj.GetLabels(), workv1alpha1.WorkNameLabel) != util.GetLabelValue(workload.GetLabels(), workv1alpha1.WorkNameLabel) {
			klog.Infof("Abort deleting the resource(kind=%s, %s/%s) exists in cluster %v but not managed by karamda", clusterObj.GetKind(), clusterObj.GetNamespace(), clusterObj.GetName(), clusterName)
			return nil
		}

		err = c.ObjectWatcher.Delete(clusterName, workload)
		if err != nil {
			klog.Errorf("Failed to delete resource in the given member cluster %v, err is %v", clusterName, err)
			return err
		}
	}

	return nil
}

// removeFinalizer remove finalizer from the given Work
func (c *Controller) removeFinalizer(work *workv1alpha1.Work) (controllerruntime.Result, error) {
	if !controllerutil.ContainsFinalizer(work, util.ExecutionControllerFinalizer) {
		return controllerruntime.Result{}, nil
	}

	controllerutil.RemoveFinalizer(work, util.ExecutionControllerFinalizer)
	err := c.Client.Update(context.TODO(), work)
	if err != nil {
		return controllerruntime.Result{Requeue: true}, err
	}
	return controllerruntime.Result{}, nil
}

// syncToClusters ensures that the state of the given object is synchronized to member clusters.
func (c *Controller) syncToClusters(clusterName string, work *workv1alpha1.Work) error {
	var errs []error
	syncSucceedNum := 0
	for _, manifest := range work.Spec.Workload.Manifests {
		workload := &unstructured.Unstructured{}
		err := workload.UnmarshalJSON(manifest.Raw)
		if err != nil {
			klog.Errorf("failed to unmarshal workload, error is: %v", err)
			errs = append(errs, err)
			continue
		}

		applied := helper.IsResourceApplied(&work.Status)
		if applied {
			err = c.tryUpdateWorkload(clusterName, workload)
			if err != nil {
				klog.Errorf("Failed to update resource(%v/%v) in the given member cluster %s, err is %v", workload.GetNamespace(), workload.GetName(), clusterName, err)
				errs = append(errs, err)
				continue
			}
		} else {
			err = c.tryCreateWorkload(clusterName, workload)
			if err != nil {
				klog.Errorf("Failed to create resource(%v/%v) in the given member cluster %s, err is %v", workload.GetNamespace(), workload.GetName(), clusterName, err)
				errs = append(errs, err)
				continue
			}
		}
		syncSucceedNum++
	}

	if len(errs) > 0 {
		total := len(work.Spec.Workload.Manifests)
		message := fmt.Sprintf("Failed to apply all manifests (%v/%v): %v", syncSucceedNum, total, errors.NewAggregate(errs).Error())
		err := c.updateAppliedCondition(work, metav1.ConditionFalse, "AppliedFailed", message)
		if err != nil {
			klog.Errorf("Failed to update applied status for given work %v, namespace is %v, err is %v", work.Name, work.Namespace, err)
			errs = append(errs, err)
		}
		return errors.NewAggregate(errs)
	}

	err := c.updateAppliedCondition(work, metav1.ConditionTrue, "AppliedSuccessful", "Manifest has been successfully applied")
	if err != nil {
		klog.Errorf("Failed to update applied status for given work %v, namespace is %v, err is %v", work.Name, work.Namespace, err)
		return err
	}

	return nil
}

func (c *Controller) tryUpdateWorkload(clusterName string, workload *unstructured.Unstructured) error {
	fedKey, err := keys.FederatedKeyFunc(clusterName, workload)
	if err != nil {
		klog.Errorf("Failed to get FederatedKey %s, error: %v", workload.GetName(), err)
		return err
	}

	clusterObj, err := helper.GetObjectFromCache(c.RESTMapper, c.InformerManager, fedKey, c.Client, c.ClusterClientSetFunc)
	if err != nil {
		if !apierrors.IsNotFound(err) {
			klog.Errorf("Failed to get resource %v from member cluster, err is %v ", workload.GetName(), err)
			return err
		}
		err = c.tryCreateWorkload(clusterName, workload)
		if err != nil {
			klog.Errorf("Failed to create resource(%v/%v) in the given member cluster %s, err is %v", workload.GetNamespace(), workload.GetName(), clusterName, err)
			return err
		}
		return nil
	}

	err = c.ObjectWatcher.Update(clusterName, workload, clusterObj)
	if err != nil {
		klog.Errorf("Failed to update resource in the given member cluster %s, err is %v", clusterName, err)
		return err
	}
	return nil
}

func (c *Controller) tryCreateWorkload(clusterName string, workload *unstructured.Unstructured) error {
	return c.ObjectWatcher.Create(clusterName, workload)
}

// updateAppliedCondition update the Applied condition for the given Work
func (c *Controller) updateAppliedCondition(work *workv1alpha1.Work, status metav1.ConditionStatus, reason, message string) error {
	newWorkAppliedCondition := metav1.Condition{
		Type:               workv1alpha1.WorkApplied,
		Status:             status,
		Reason:             reason,
		Message:            message,
		LastTransitionTime: metav1.Now(),
	}

	return retry.RetryOnConflict(retry.DefaultBackoff, func() (err error) {
		if err = c.Get(context.TODO(), client.ObjectKey{Namespace: work.Namespace, Name: work.Name}, work); err != nil {
			return err
		}
		meta.SetStatusCondition(&work.Status.Conditions, newWorkAppliedCondition)
		return c.Status().Update(context.TODO(), work)
	})
}