package controllers

import (
	"bufio"
	"encoding/json"
	formolv1alpha1 "github.com/desmo999r/formol/api/v1alpha1"
	volumesnapshotv1 "github.com/kubernetes-csi/external-snapshotter/client/v6/apis/volumesnapshot/v1"
	"io"
	corev1 "k8s.io/api/core/v1"
	"k8s.io/apimachinery/pkg/api/errors"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"os"
	"os/exec"
	"sigs.k8s.io/controller-runtime/pkg/client"
)

const (
	SNAPSHOT_PREFIX = "formol-"
)

type BackupResult struct {
	SnapshotId string
	Duration   float64
}

func (r *BackupSessionReconciler) backupPaths(tag string, paths []string) (result BackupResult, err error) {
	if err = r.CheckRepo(); err != nil {
		r.Log.Error(err, "unable to setup repo", "repo", os.Getenv(formolv1alpha1.RESTIC_REPOSITORY))
		return
	}
	r.Log.V(0).Info("backing up paths", "paths", paths)
	cmd := exec.Command(RESTIC_EXEC, append([]string{"backup", "--json", "--tag", tag}, paths...)...)
	stdout, _ := cmd.StdoutPipe()
	stderr, _ := cmd.StderrPipe()
	_ = cmd.Start()

	scanner := bufio.NewScanner(io.MultiReader(stdout, stderr))
	scanner.Split(bufio.ScanLines)
	var data map[string]interface{}
	for scanner.Scan() {
		if err := json.Unmarshal(scanner.Bytes(), &data); err != nil {
			r.Log.Error(err, "unable to unmarshal json", "data", scanner.Text())
			continue
		}
		switch data["message_type"].(string) {
		case "summary":
			result.SnapshotId = data["snapshot_id"].(string)
			result.Duration = data["total_duration"].(float64)
		case "status":
			r.Log.V(0).Info("backup running", "percent done", data["percent_done"].(float64))
		}
	}

	err = cmd.Wait()
	return
}

func (r *BackupSessionReconciler) backupJob(tag string, target formolv1alpha1.Target) (result BackupResult, err error) {
	paths := []string{}
	for _, container := range target.Containers {
		for _, job := range container.Job {
			if err = r.runFunction(*job.Backup); err != nil {
				r.Log.Error(err, "unable to run job")
				return
			}

		}
		addPath := true
		for _, path := range paths {
			if path == container.SharePath {
				addPath = false
			}
		}
		if addPath {
			paths = append(paths, container.SharePath)
		}
	}
	result, err = r.backupPaths(tag, paths)
	return
}

func (r *BackupSessionReconciler) backupSnapshot(target formolv1alpha1.Target) error {
	targetObject, targetPodSpec := formolv1alpha1.GetTargetObjects(target.TargetKind)
	if err := r.Get(r.Context, client.ObjectKey{
		Namespace: r.Namespace,
		Name:      target.TargetName,
	}, targetObject); err != nil {
		r.Log.Error(err, "cannot get target", "target", target.TargetName)
		return err
	}
	for _, container := range targetPodSpec.Containers {
		for _, targetContainer := range target.Containers {
			if targetContainer.Name == container.Name {
				// Now snapshot all the container PVC that support snapshots
				// then create new volumes from the snapshots
				// replace the volumes in the container struct with the snapshot volumes
				// use formolv1alpha1.GetVolumeMounts to get the volume mounts for the Job
				// sidecar := formolv1alpha1.GetSidecar(backupConf, target)
				_, vms := formolv1alpha1.GetVolumeMounts(container, targetContainer)
				if err := r.snapshotVolumes(vms, targetPodSpec); err != nil {
					r.Log.Error(err, "volume snapshot not ready")
					return err
				}

			}
		}
	}
	return nil
}

type NotReadyToUseError struct{}

func (e *NotReadyToUseError) Error() string {
	return "Snapshot is not ready to use"
}

func (r *BackupSessionReconciler) snapshotVolume(volume corev1.Volume) error {
	r.Log.V(0).Info("Preparing snapshot", "volume", volume.Name)
	if volume.VolumeSource.PersistentVolumeClaim != nil {
		pvc := corev1.PersistentVolumeClaim{}
		if err := r.Get(r.Context, client.ObjectKey{
			Namespace: r.Namespace,
			Name:      volume.VolumeSource.PersistentVolumeClaim.ClaimName,
		}, &pvc); err != nil {
			r.Log.Error(err, "unable to get pvc", "volume", volume)
			return err
		}
		pv := corev1.PersistentVolume{}
		if err := r.Get(r.Context, client.ObjectKey{
			Name: pvc.Spec.VolumeName,
		}, &pv); err != nil {
			r.Log.Error(err, "unable to get pv", "volume", pvc.Spec.VolumeName)
			return err
		}
		if pv.Spec.PersistentVolumeSource.CSI != nil {
			// This volume is supported by a CSI driver. Let's see if we can snapshot it.
			volumeSnapshotClassList := volumesnapshotv1.VolumeSnapshotClassList{}
			if err := r.List(r.Context, &volumeSnapshotClassList); err != nil {
				r.Log.Error(err, "unable to get VolumeSnapshotClass list")
				return err
			}
			for _, volumeSnapshotClass := range volumeSnapshotClassList.Items {
				if volumeSnapshotClass.Driver == pv.Spec.PersistentVolumeSource.CSI.Driver {
					// Check if a snapshot exist
					volumeSnapshot := volumesnapshotv1.VolumeSnapshot{}
					if err := r.Get(r.Context, client.ObjectKey{
						Namespace: r.Namespace,
						Name:      SNAPSHOT_PREFIX + pv.Name,
					}, &volumeSnapshot); errors.IsNotFound(err) {
						// No snapshot found. Create a new one.
						// We want to snapshot using this VolumeSnapshotClass
						r.Log.V(0).Info("Create a volume snapshot", "pvc", pvc.Name)
						volumeSnapshot = volumesnapshotv1.VolumeSnapshot{
							ObjectMeta: metav1.ObjectMeta{
								Namespace: r.Namespace,
								Name:      SNAPSHOT_PREFIX + pv.Name,
							},
							Spec: volumesnapshotv1.VolumeSnapshotSpec{
								VolumeSnapshotClassName: &volumeSnapshotClass.Name,
								Source: volumesnapshotv1.VolumeSnapshotSource{
									PersistentVolumeClaimName: &pvc.Name,
								},
							},
						}
						if err := r.Create(r.Context, &volumeSnapshot); err != nil {
							r.Log.Error(err, "unable to create the snapshot", "pvc", pvc.Name)
							return err
						}
						// We just created the snapshot. We have to assume it's not yet ready and reschedule
						return &NotReadyToUseError{}
					} else {
						if err != nil {
							r.Log.Error(err, "Something went very wrong here")
							return err
						}
						// The VolumeSnapshot exists. Is it ReadyToUse?
						if volumeSnapshot.Status == nil || volumeSnapshot.Status.ReadyToUse == nil || *volumeSnapshot.Status.ReadyToUse == false {
							r.Log.V(0).Info("Volume snapshot exists but it is not ready", "volume", volumeSnapshot.Name)
							return &NotReadyToUseError{}
						}
						r.Log.V(0).Info("Volume snapshot is ready to use", "volume", volumeSnapshot.Name)
					}
				}
			}
		}
	}
	return nil
}

func (r *BackupSessionReconciler) snapshotVolumes(vms []corev1.VolumeMount, podSpec *corev1.PodSpec) (err error) {
	// We snapshot/check all the volumes. If at least one of the snapshot is not ready to use. We reschedule.
	for _, vm := range vms {
		for _, volume := range podSpec.Volumes {
			if vm.Name == volume.Name {
				err = r.snapshotVolume(volume)
				if err != nil {
					switch err.(type) {
					case *NotReadyToUseError:
						defer func() {
							err = &NotReadyToUseError{}
						}()
					default:
						return
					}
				}
			}
		}
	}
	return
}

func (r *BackupSessionReconciler) deleteVolumeSnapshots(target formolv1alpha1.Target) error {
	return nil
}