package binding

import (
	"context"

	apiextensionsv1 "k8s.io/apiextensions-apiserver/pkg/apis/apiextensions/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/api/meta"
	"k8s.io/apimachinery/pkg/types"
	"k8s.io/client-go/dynamic"
	"k8s.io/client-go/tools/record"
	"k8s.io/klog/v2"
	controllerruntime "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	"sigs.k8s.io/controller-runtime/pkg/handler"
	"sigs.k8s.io/controller-runtime/pkg/reconcile"
	"sigs.k8s.io/controller-runtime/pkg/source"

	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/overridemanager"
)

// ClusterResourceBindingControllerName is the controller name that will be used when reporting events.
const ClusterResourceBindingControllerName = "cluster-resource-binding-controller"

// ClusterResourceBindingController is to sync ClusterResourceBinding.
type ClusterResourceBindingController struct {
	client.Client                     // used to operate ClusterResourceBinding resources.
	DynamicClient   dynamic.Interface // used to fetch arbitrary resources.
	EventRecorder   record.EventRecorder
	RESTMapper      meta.RESTMapper
	OverrideManager overridemanager.OverrideManager
}

// 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 *ClusterResourceBindingController) Reconcile(req controllerruntime.Request) (controllerruntime.Result, error) {
	klog.V(4).Infof("Reconciling ClusterResourceBinding %s.", req.NamespacedName.String())

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

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

	if !clusterResourceBinding.DeletionTimestamp.IsZero() {
		// Do nothing, just return as we have added owner reference to Work.
		// Work will be removed automatically by garbage collector.
		return controllerruntime.Result{}, nil
	}

	isReady := helper.IsBindingReady(clusterResourceBinding.Spec.Clusters)
	if !isReady {
		klog.Infof("ClusterResourceBinding %s is not ready to sync", clusterResourceBinding.GetName())
		return controllerruntime.Result{}, nil
	}

	return c.syncBinding(clusterResourceBinding)
}

// syncBinding will sync clusterResourceBinding to Works.
func (c *ClusterResourceBindingController) syncBinding(binding *workv1alpha1.ClusterResourceBinding) (controllerruntime.Result, error) {
	clusterNames := helper.GetBindingClusterNames(binding.Spec.Clusters)
	works, err := helper.FindOrphanWorks(c.Client, "", binding.Name, clusterNames, apiextensionsv1.ClusterScoped)
	if err != nil {
		klog.Errorf("Failed to find orphan works by ClusterResourceBinding(%s). Error: %v.", binding.GetName(), err)
		return controllerruntime.Result{Requeue: true}, err
	}

	err = helper.RemoveOrphanWorks(c.Client, works)
	if err != nil {
		klog.Errorf("Failed to remove orphan works by clusterResourceBinding(%s). Error: %v.", binding.GetName(), err)
		return controllerruntime.Result{Requeue: true}, err
	}

	workload, err := helper.FetchWorkload(c.DynamicClient, c.RESTMapper, binding.Spec.Resource)
	if err != nil {
		klog.Errorf("Failed to fetch workload for clusterResourceBinding(%s). Error: %v.", binding.GetName(), err)
		return controllerruntime.Result{Requeue: true}, err
	}

	err = helper.EnsureWork(c.Client, workload, clusterNames, c.OverrideManager, binding, apiextensionsv1.ClusterScoped)
	if err != nil {
		klog.Errorf("Failed to transform clusterResourceBinding(%s) to works. Error: %v.", binding.GetName(), err)
		return controllerruntime.Result{Requeue: true}, err
	}

	err = helper.AggregateClusterResourceBindingWorkStatus(c.Client, binding, workload)
	if err != nil {
		klog.Errorf("Failed to aggregate workStatuses to clusterResourceBinding(%s). Error: %v.", binding.GetName(), err)
		return controllerruntime.Result{Requeue: true}, err
	}

	return controllerruntime.Result{}, nil
}

// SetupWithManager creates a controller and register to controller manager.
func (c *ClusterResourceBindingController) SetupWithManager(mgr controllerruntime.Manager) error {
	workFn := handler.ToRequestsFunc(
		func(a handler.MapObject) []reconcile.Request {
			var requests []reconcile.Request

			labels := a.Meta.GetLabels()
			namespacesName := types.NamespacedName{
				Name: labels[util.ClusterResourceBindingLabel],
			}

			requests = append(requests, reconcile.Request{NamespacedName: namespacesName})
			return requests
		})

	return controllerruntime.NewControllerManagedBy(mgr).For(&workv1alpha1.ClusterResourceBinding{}).
		Watches(&source.Kind{Type: &workv1alpha1.Work{}}, &handler.EnqueueRequestsFromMapFunc{ToRequests: workFn}, workPredicateFn).
		Complete(c)
}