/*
Copyright 2026.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package controller

import (
	"context"

	"fmt"
	apps "k8s.io/api/apps/v1"
	core "k8s.io/api/core/v1"
	apierrors "k8s.io/apimachinery/pkg/api/errors"
	apiMeta "k8s.io/apimachinery/pkg/api/meta"
	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/apimachinery/pkg/util/intstr"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"
	cu "sigs.k8s.io/controller-runtime/pkg/controller/controllerutil"
	"time"

	labv1alpha1 "cloudlab.training/runner/api/v1alpha1"
)

// RunnerReconciler reconciles a Runner object
type RunnerReconciler struct {
	client.Client
	Scheme *runtime.Scheme
}

// +kubebuilder:rbac:groups=lab.cloudlab.training,resources=runners,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=lab.cloudlab.training,resources=runners/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=lab.cloudlab.training,resources=runners/finalizers,verbs=update
// +kubebuilder:rbac:groups=apps,resources=deployments,verbs=get;list;watch;create;update;delete
// +kubebuilder:rbac:groups="",resources=services,verbs=get;list;watch;create;update;delete

func (r *RunnerReconciler) Reconcile(ctx context.Context, req ctrl.Request) (ctrl.Result, error) {
	var u labv1alpha1.Runner
	done := ctrl.Result{}
	if err := r.Get(ctx, req.NamespacedName, &u); err != nil {
		return done, client.IgnoreNotFound(err)
	}
	const finalizer = "lab.cloudlab.training/children"
	child := meta.ObjectMeta{Name: u.Name, Namespace: u.Namespace}
	d := &apps.Deployment{ObjectMeta: child}
	svc := &core.Service{ObjectMeta: child}
	if !u.DeletionTimestamp.IsZero() {
		if !cu.ContainsFinalizer(&u, finalizer) {
			return done, nil
		}
		waiting := false
		for _, obj := range []client.Object{svc, d} {
			err := r.Get(ctx, req.NamespacedName, obj)
			if apierrors.IsNotFound(err) {
				continue
			}
			if err != nil {
				return done, err
			}
			if !meta.IsControlledBy(obj, &u) {
				continue
			}
			waiting = true
			if obj.GetDeletionTimestamp() == nil {
				uid := obj.GetUID()
				if err = r.Delete(ctx, obj, client.Preconditions{UID: &uid}); client.IgnoreNotFound(err) != nil {
					return done, err
				}
			}
		}
		if waiting {
			return ctrl.Result{RequeueAfter: time.Second}, nil
		}
		cu.RemoveFinalizer(&u, finalizer)
		return done, r.Update(ctx, &u)
	}
	if cu.AddFinalizer(&u, finalizer) {
		return done, r.Update(ctx, &u)
	}
	labels := map[string]string{"cloudlab.training/runner": string(u.UID)}
	own := func(obj client.Object) error {
		if obj.GetUID() != "" && !meta.IsControlledBy(obj, &u) {
			return fmt.Errorf("refusing to adopt %s", obj.GetName())
		}
		return cu.SetControllerReference(&u, obj, r.Scheme)
	}
	_, err := cu.CreateOrUpdate(ctx, r.Client, d, func() error {
		if err := own(d); err != nil {
			return err
		}
		d.Spec.Replicas = &u.Spec.Replicas
		d.Spec.Selector = &meta.LabelSelector{MatchLabels: labels}
		d.Spec.Template.Labels = labels
		if len(d.Spec.Template.Spec.Containers) == 0 {
			d.Spec.Template.Spec.Containers = []core.Container{{Name: "runtime"}}
		}
		c := &d.Spec.Template.Spec.Containers[0]
		c.Image = u.Spec.Image
		c.ImagePullPolicy = core.PullIfNotPresent
		c.ReadinessProbe = &core.Probe{ProbeHandler: core.ProbeHandler{TCPSocket: &core.TCPSocketAction{Port: intstr.FromInt(80)}}, PeriodSeconds: 5, TimeoutSeconds: 1, SuccessThreshold: 1, FailureThreshold: 3}
		return nil
	})
	if err != nil {
		return done, err
	}
	_, err = cu.CreateOrUpdate(ctx, r.Client, svc, func() error {
		if err := own(svc); err != nil {
			return err
		}
		svc.Spec.Selector = labels
		svc.Spec.Ports = []core.ServicePort{{Name: "http", Protocol: core.ProtocolTCP, Port: 80, TargetPort: intstr.FromInt(80)}}
		return nil
	})
	if err != nil {
		return done, err
	}
	ready := meta.ConditionFalse
	if d.Status.ObservedGeneration == d.Generation && d.Status.UpdatedReplicas == u.Spec.Replicas && d.Status.AvailableReplicas == u.Spec.Replicas {
		ready = meta.ConditionTrue
	}
	changed := apiMeta.SetStatusCondition(&u.Status.Conditions, meta.Condition{Type: "Ready", Status: ready, ObservedGeneration: u.Generation, Reason: "DeploymentObserved", Message: "Compared current Deployment revision and available replicas"})
	if changed {
		return done, r.Status().Update(ctx, &u)
	}
	return done, nil
}
func (r *RunnerReconciler) SetupWithManager(mgr ctrl.Manager) error {
	return ctrl.NewControllerManagedBy(mgr).For(&labv1alpha1.Runner{}).Owns(&apps.Deployment{}).Owns(&core.Service{}).Complete(r)
}