/*
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"
	"time"

	"github.com/go-logr/logr"
	"github.com/google/go-github/v29/github"
	"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"
)

const (
	containerName = "runner"
)

type RegistrationToken struct {
	Token     string `json:"token"`
	ExpiresAt string `json:"expires_at"`
}

// 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

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)
	}

	if !runner.IsRegisterable() {
		reg, err := r.newRegistration(ctx, runner.Spec.Repository)
		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 = reg

		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
		}

		if pod.Spec.Containers[0].Image != newPod.Spec.Containers[0].Image {
			restart = true
		}
		if !reflect.DeepEqual(pod.Spec.Containers[0].Env, newPod.Spec.Containers[0].Env) {
			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) newRegistration(ctx context.Context, repo string) (v1alpha1.RunnerStatusRegistration, error) {
	var reg v1alpha1.RunnerStatusRegistration

	rt, err := r.getRegistrationToken(ctx, repo)
	if err != nil {
		return reg, err
	}

	expiresAt, err := time.Parse(time.RFC3339, rt.ExpiresAt)
	if err != nil {
		return reg, err
	}

	reg.Repository = repo
	reg.Token = rt.Token
	reg.ExpiresAt = metav1.NewTime(expiresAt)

	return reg, err
}

func (r *RunnerReconciler) getRegistrationToken(ctx context.Context, repo string) (RegistrationToken, error) {
	var regToken RegistrationToken

	req, err := r.GitHubClient.NewRequest("POST", fmt.Sprintf("/repos/%s/actions/runners/registration-token", repo), nil)
	if err != nil {
		return regToken, err
	}

	res, err := r.GitHubClient.Do(ctx, req, &regToken)
	if err != nil {
		return regToken, err
	}

	if res.StatusCode != 201 {
		return regToken, fmt.Errorf("unexpected status: %d", res.StatusCode)
	}

	return regToken, 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
	}

	pod := corev1.Pod{
		ObjectMeta: metav1.ObjectMeta{
			Name:      runner.Name,
			Namespace: runner.Namespace,
		},
		Spec: corev1.PodSpec{
			RestartPolicy: "OnFailure",
			Containers: []corev1.Container{
				{
					Name:            containerName,
					Image:           runnerImage,
					ImagePullPolicy: "Always",
					Env: []corev1.EnvVar{
						{
							Name:  "RUNNER_NAME",
							Value: runner.Name,
						},
						{
							Name:  "RUNNER_REPO",
							Value: runner.Spec.Repository,
						},
						{
							Name:  "RUNNER_TOKEN",
							Value: runner.Status.Registration.Token,
						},
					},
					VolumeMounts: []corev1.VolumeMount{
						{
							Name:      "docker",
							MountPath: "/var/run",
						},
					},
					SecurityContext: &corev1.SecurityContext{
						RunAsGroup: &group,
					},
				},
				{
					Name:  "docker",
					Image: r.DockerImage,
					VolumeMounts: []corev1.VolumeMount{
						{
							Name:      "docker",
							MountPath: "/var/run",
						},
					},
					SecurityContext: &corev1.SecurityContext{
						Privileged: &privileged,
					},
				},
			},
			Volumes: []corev1.Volume{
				corev1.Volume{
					Name: "docker",
					VolumeSource: corev1.VolumeSource{
						EmptyDir: &corev1.EmptyDirVolumeSource{},
					},
				},
			},
		},
	}

	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)
}