/*
Copyright 2020 The actions-runner-controller authors.

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 controllers

import (
	"context"
	"fmt"
	"reflect"
	"strings"

	"github.com/go-logr/logr"
	"k8s.io/apimachinery/pkg/api/errors"
	"k8s.io/apimachinery/pkg/runtime"
	"k8s.io/client-go/tools/record"
	ctrl "sigs.k8s.io/controller-runtime"
	"sigs.k8s.io/controller-runtime/pkg/client"

	corev1 "k8s.io/api/core/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"

	"github.com/summerwind/actions-runner-controller/api/v1alpha1"
	"github.com/summerwind/actions-runner-controller/github"
)

const (
	containerName = "runner"
	finalizerName = "runner.actions.summerwind.dev"
)

// RunnerReconciler reconciles a Runner object
type RunnerReconciler struct {
	client.Client
	Log          logr.Logger
	Recorder     record.EventRecorder
	Scheme       *runtime.Scheme
	GitHubClient *github.Client
	RunnerImage  string
	DockerImage  string
}

// +kubebuilder:rbac:groups=actions.summerwind.dev,resources=runners,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=actions.summerwind.dev,resources=runners/status,verbs=get;update;patch
// +kubebuilder:rbac:groups=core,resources=pods,verbs=get;list;watch;create;update;patch;delete
// +kubebuilder:rbac:groups=core,resources=events,verbs=create;patch

func (r *RunnerReconciler) Reconcile(req ctrl.Request) (ctrl.Result, error) {
	ctx := context.Background()
	log := r.Log.WithValues("runner", req.NamespacedName)

	var runner v1alpha1.Runner
	if err := r.Get(ctx, req.NamespacedName, &runner); err != nil {
		return ctrl.Result{}, client.IgnoreNotFound(err)
	}

	err := runner.Validate()
	if err != nil {
		log.Info("Failed to validate runner spec", "error", err.Error())
		return ctrl.Result{}, nil
	}

	if runner.ObjectMeta.DeletionTimestamp.IsZero() {
		finalizers, added := addFinalizer(runner.ObjectMeta.Finalizers)

		if added {
			newRunner := runner.DeepCopy()
			newRunner.ObjectMeta.Finalizers = finalizers

			if err := r.Update(ctx, newRunner); err != nil {
				log.Error(err, "Failed to update runner")
				return ctrl.Result{}, err
			}

			return ctrl.Result{}, nil
		}
	} else {
		finalizers, removed := removeFinalizer(runner.ObjectMeta.Finalizers)

		if removed {
			if len(runner.Status.Registration.Token) > 0 {
				ok, err := r.unregisterRunner(ctx, runner.Spec.Organization, runner.Spec.Repository, runner.Name)
				if err != nil {
					log.Error(err, "Failed to unregister runner")
					return ctrl.Result{}, err
				}

				if !ok {
					log.V(1).Info("Runner no longer exists on GitHub")
				}
			} else {
				log.V(1).Info("Runner was never registered on GitHub")
			}

			newRunner := runner.DeepCopy()
			newRunner.ObjectMeta.Finalizers = finalizers

			if err := r.Update(ctx, newRunner); err != nil {
				log.Error(err, "Failed to update runner")
				return ctrl.Result{}, err
			}

			log.Info("Removed runner from GitHub", "repository", runner.Spec.Repository, "organization", runner.Spec.Organization)
		}

		return ctrl.Result{}, nil
	}

	if !runner.IsRegisterable() {
		rt, err := r.GitHubClient.GetRegistrationToken(ctx, runner.Spec.Organization, runner.Spec.Repository, runner.Name)
		if err != nil {
			r.Recorder.Event(&runner, corev1.EventTypeWarning, "FailedUpdateRegistrationToken", "Updating registration token failed")
			log.Error(err, "Failed to get new registration token")
			return ctrl.Result{}, err
		}

		updated := runner.DeepCopy()
		updated.Status.Registration = v1alpha1.RunnerStatusRegistration{
			Organization: runner.Spec.Organization,
			Repository:   runner.Spec.Repository,
			Labels:       runner.Spec.Labels,
			Token:        rt.GetToken(),
			ExpiresAt:    metav1.NewTime(rt.GetExpiresAt().Time),
		}

		if err := r.Status().Update(ctx, updated); err != nil {
			log.Error(err, "Failed to update runner status")
			return ctrl.Result{}, err
		}

		r.Recorder.Event(&runner, corev1.EventTypeNormal, "RegistrationTokenUpdated", "Successfully update registration token")
		log.Info("Updated registration token", "repository", runner.Spec.Repository)
		return ctrl.Result{}, nil
	}

	var pod corev1.Pod
	if err := r.Get(ctx, req.NamespacedName, &pod); err != nil {
		if !errors.IsNotFound(err) {
			return ctrl.Result{}, err
		}

		newPod, err := r.newPod(runner)
		if err != nil {
			log.Error(err, "Could not create pod")
			return ctrl.Result{}, err
		}

		if err := r.Create(ctx, &newPod); err != nil {
			log.Error(err, "Failed to create pod resource")
			return ctrl.Result{}, err
		}

		r.Recorder.Event(&runner, corev1.EventTypeNormal, "PodCreated", fmt.Sprintf("Created pod '%s'", newPod.Name))
		log.Info("Created runner pod", "repository", runner.Spec.Repository)
	} else {
		if runner.Status.Phase != string(pod.Status.Phase) {
			updated := runner.DeepCopy()
			updated.Status.Phase = string(pod.Status.Phase)
			updated.Status.Reason = pod.Status.Reason
			updated.Status.Message = pod.Status.Message

			if err := r.Status().Update(ctx, updated); err != nil {
				log.Error(err, "Failed to update runner status")
				return ctrl.Result{}, err
			}

			return ctrl.Result{}, nil
		}

		if !pod.ObjectMeta.DeletionTimestamp.IsZero() {
			return ctrl.Result{}, err
		}

		restart := false

		if pod.Status.Phase == corev1.PodRunning {
			for _, status := range pod.Status.ContainerStatuses {
				if status.Name != containerName {
					continue
				}

				if status.State.Terminated != nil && status.State.Terminated.ExitCode == 0 {
					restart = true
				}
			}
		}

		newPod, err := r.newPod(runner)
		if err != nil {
			log.Error(err, "Could not create pod")
			return ctrl.Result{}, err
		}

		runnerBusy, err := r.isRunnerBusy(ctx, runner.Spec.Organization, runner.Spec.Repository, runner.Name)
		if err != nil {
			log.Error(err, "Failed to check if runner is busy")
			return ctrl.Result{}, nil
		}

		if !runnerBusy && (!reflect.DeepEqual(pod.Spec.Containers[0].Env, newPod.Spec.Containers[0].Env) || pod.Spec.Containers[0].Image != newPod.Spec.Containers[0].Image) {
			restart = true
		}

		if !restart {
			return ctrl.Result{}, err
		}

		if err := r.Delete(ctx, &pod); err != nil {
			log.Error(err, "Failed to delete pod resource")
			return ctrl.Result{}, err
		}

		r.Recorder.Event(&runner, corev1.EventTypeNormal, "PodDeleted", fmt.Sprintf("Deleted pod '%s'", newPod.Name))
		log.Info("Deleted runner pod", "repository", runner.Spec.Repository)
	}

	return ctrl.Result{}, nil
}

func (r *RunnerReconciler) isRunnerBusy(ctx context.Context, org, repo, name string) (bool, error) {
	runners, err := r.GitHubClient.ListRunners(ctx, org, repo)
	if err != nil {
		return false, err
	}

	for _, runner := range runners {
		if runner.GetName() == name {
			return runner.GetBusy(), nil
		}
	}

	return false, fmt.Errorf("runner not found")
}

func (r *RunnerReconciler) unregisterRunner(ctx context.Context, org, repo, name string) (bool, error) {
	runners, err := r.GitHubClient.ListRunners(ctx, org, repo)
	if err != nil {
		return false, err
	}

	id := int64(0)
	for _, runner := range runners {
		if runner.GetName() == name {
			if runner.GetBusy() {
				return false, fmt.Errorf("runner is busy")
			}
			id = runner.GetID()
			break
		}
	}

	if id == int64(0) {
		return false, nil
	}

	if err := r.GitHubClient.RemoveRunner(ctx, org, repo, id); err != nil {
		return false, err
	}

	return true, nil
}

func (r *RunnerReconciler) newPod(runner v1alpha1.Runner) (corev1.Pod, error) {
	var (
		privileged bool  = true
		group      int64 = 0
	)

	runnerImage := runner.Spec.Image
	if runnerImage == "" {
		runnerImage = r.RunnerImage
	}

	runnerImagePullPolicy := runner.Spec.ImagePullPolicy
	if runnerImagePullPolicy == "" {
		runnerImagePullPolicy = corev1.PullAlways
	}

	env := []corev1.EnvVar{
		{
			Name:  "RUNNER_NAME",
			Value: runner.Name,
		},
		{
			Name:  "RUNNER_ORG",
			Value: runner.Spec.Organization,
		},
		{
			Name:  "RUNNER_REPO",
			Value: runner.Spec.Repository,
		},
		{
			Name:  "RUNNER_LABELS",
			Value: strings.Join(runner.Spec.Labels, ","),
		},
		{
			Name:  "RUNNER_TOKEN",
			Value: runner.Status.Registration.Token,
		},
	}

	env = append(env, runner.Spec.Env...)
	pod := corev1.Pod{
		ObjectMeta: metav1.ObjectMeta{
			Name:        runner.Name,
			Namespace:   runner.Namespace,
			Labels:      runner.Labels,
			Annotations: runner.Annotations,
		},
		Spec: corev1.PodSpec{
			RestartPolicy: "OnFailure",
			Containers: []corev1.Container{
				{
					Name:            containerName,
					Image:           runnerImage,
					ImagePullPolicy: runnerImagePullPolicy,
					Env:             env,
					EnvFrom:         runner.Spec.EnvFrom,
					VolumeMounts: []corev1.VolumeMount{
						{
							Name:      "work",
							MountPath: "/runner/_work",
						},
						{
							Name:      "docker",
							MountPath: "/var/run",
						},
					},
					SecurityContext: &corev1.SecurityContext{
						RunAsGroup: &group,
					},
					Resources: runner.Spec.Resources,
				},
				{
					Name:  "docker",
					Image: r.DockerImage,
					VolumeMounts: []corev1.VolumeMount{
						{
							Name:      "work",
							MountPath: "/runner/_work",
						},
						{
							Name:      "docker",
							MountPath: "/var/run",
						},
					},
					SecurityContext: &corev1.SecurityContext{
						Privileged: &privileged,
					},
				},
			},
			Volumes: []corev1.Volume{
				{
					Name: "work",
					VolumeSource: corev1.VolumeSource{
						EmptyDir: &corev1.EmptyDirVolumeSource{},
					},
				},
				{
					Name: "docker",
					VolumeSource: corev1.VolumeSource{
						EmptyDir: &corev1.EmptyDirVolumeSource{},
					},
				},
			},
		},
	}

	if len(runner.Spec.Containers) != 0 {
		pod.Spec.Containers = runner.Spec.Containers
	}

	if len(runner.Spec.VolumeMounts) != 0 {
		pod.Spec.Containers[0].VolumeMounts = append(pod.Spec.Containers[0].VolumeMounts, runner.Spec.VolumeMounts...)
	}

	if len(runner.Spec.Volumes) != 0 {
		pod.Spec.Volumes = append(pod.Spec.Volumes, runner.Spec.Volumes...)
	}
	if len(runner.Spec.InitContainers) != 0 {
		pod.Spec.InitContainers = append(pod.Spec.InitContainers, runner.Spec.InitContainers...)
	}

	if runner.Spec.NodeSelector != nil {
		pod.Spec.NodeSelector = runner.Spec.NodeSelector
	}
	if runner.Spec.ServiceAccountName != "" {
		pod.Spec.ServiceAccountName = runner.Spec.ServiceAccountName
	}
	if runner.Spec.AutomountServiceAccountToken != nil {
		pod.Spec.AutomountServiceAccountToken = runner.Spec.AutomountServiceAccountToken
	}

	if len(runner.Spec.SidecarContainers) != 0 {
		pod.Spec.Containers = append(pod.Spec.Containers, runner.Spec.SidecarContainers...)
	}

	if runner.Spec.SecurityContext != nil {
		pod.Spec.SecurityContext = runner.Spec.SecurityContext
	}

	if len(runner.Spec.ImagePullSecrets) != 0 {
		pod.Spec.ImagePullSecrets = runner.Spec.ImagePullSecrets
	}

	if runner.Spec.Affinity != nil {
		pod.Spec.Affinity = runner.Spec.Affinity
	}

	if len(runner.Spec.Tolerations) != 0 {
		pod.Spec.Tolerations = runner.Spec.Tolerations
	}

	if len(runner.Spec.EphemeralContainers) != 0 {
		pod.Spec.EphemeralContainers = runner.Spec.EphemeralContainers
	}

	if runner.Spec.TerminationGracePeriodSeconds != nil {
		pod.Spec.TerminationGracePeriodSeconds = runner.Spec.TerminationGracePeriodSeconds
	}

	if err := ctrl.SetControllerReference(&runner, &pod, r.Scheme); err != nil {
		return pod, err
	}

	return pod, nil
}

func (r *RunnerReconciler) SetupWithManager(mgr ctrl.Manager) error {
	r.Recorder = mgr.GetEventRecorderFor("runner-controller")

	return ctrl.NewControllerManagedBy(mgr).
		For(&v1alpha1.Runner{}).
		Owns(&corev1.Pod{}).
		Complete(r)
}

func addFinalizer(finalizers []string) ([]string, bool) {
	exists := false
	for _, name := range finalizers {
		if name == finalizerName {
			exists = true
		}
	}

	if exists {
		return finalizers, false
	}

	return append(finalizers, finalizerName), true
}

func removeFinalizer(finalizers []string) ([]string, bool) {
	removed := false
	result := []string{}

	for _, name := range finalizers {
		if name == finalizerName {
			removed = true
			continue
		}
		result = append(result, name)
	}

	return result, removed
}