package osupgrade

import (
	"context"
	"fmt"
	"os"
	"sync/atomic"

	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/klog/v2"

	monov1alpha1 "example.com/monok8s/pkg/apis/monok8s/v1alpha1"
	"example.com/monok8s/pkg/buildinfo"
	"example.com/monok8s/pkg/catalog"
	"example.com/monok8s/pkg/controller/osimage"
	"example.com/monok8s/pkg/kube"
	"example.com/monok8s/pkg/node/uboot"
)

type UpgradeRunner struct {
	running   atomic.Bool
	rebooting atomic.Bool
}

var r UpgradeRunner

func (r *UpgradeRunner) Run(fn func() error) error {
	if r.rebooting.Load() {
		return nil
	}

	if !r.running.CompareAndSwap(false, true) {
		return nil
	}
	defer r.running.Store(false)

	if r.rebooting.Load() {
		return nil
	}

	return fn()
}

func HandleOSUpgrade(ctx context.Context, clients *kube.Clients,
	namespace string, nodeName string,
	osu *monov1alpha1.OSUpgrade,
) error {
	return r.Run(func() error {
		return handleOSUpgradeLocked(ctx, clients, namespace, nodeName, osu)
	})
}

func handleOSUpgradeLocked(ctx context.Context, clients *kube.Clients,
	namespace string, nodeName string,
	osu *monov1alpha1.OSUpgrade,
) error {
	osup, err := ensureProgressHeartbeat(ctx, clients, namespace, nodeName, osu)
	if err != nil {
		return err
	}

	klog.InfoS("handling osupgrade",
		"name", osu.Name,
		"node", nodeName,
		"desiredVersion", osu.Spec.DesiredVersion,
	)

	kata, err := catalog.ResolveCatalog(ctx, clients.Kubernetes, namespace, osu.Spec.Catalog)
	if err != nil {
		return failProgress(ctx, clients, osup, "resolve catalog", err)
	}

	plan, err := PlanUpgrade(buildinfo.KubeVersion, osu, kata)
	if err != nil {
		return failProgress(ctx, clients, osup, "plan upgrade", err)
	}

	if len(plan.Path) == 0 {
		osup.Status.CurrentVersion = buildinfo.KubeVersion
		osup.Status.TargetVersion = buildinfo.KubeVersion
		if err := markProgressCompleted(ctx, clients, osup, "already at target version"); err != nil {
			return err
		}
		klog.InfoS("osupgrade already satisfied",
			"name", osu.Name,
			"node", nodeName,
			"target", plan.ResolvedTarget,
		)
		return nil
	}

	first := plan.Path[0]

	updated, err := updateProgressRobust(ctx, clients, osup.Namespace, osup.Name, func(cur *monov1alpha1.OSUpgradeProgress) {
		now := metav1.Now()
		cur.Status.CurrentVersion = buildinfo.KubeVersion
		cur.Status.TargetVersion = plan.ResolvedTarget
		cur.Status.Phase = monov1alpha1.OSUpgradeProgressPhaseDownloading
		cur.Status.Message = fmt.Sprintf("downloading image: %s", first.URL)
		cur.Status.LastUpdatedAt = &now
	})
	if updated != nil {
		osup = updated
	}
	if err != nil {
		return fmt.Errorf("update progress status: %w", err)
	}

	klog.InfoS("planned osupgrade",
		"name", osu.Name,
		"node", nodeName,
		"resolvedTarget", plan.ResolvedTarget,
		"steps", len(plan.Path),
		"currentVersion", buildinfo.KubeVersion,
		"firstVersion", first.Version,
		"firstURL", first.URL,
		"size", first.Size,
	)

	imageSHA, err := first.SHA256()
	if err != nil {
		return failProgress(ctx, clients, osup, "apply image", err)
	}

	pLogger := osimage.NewProgressLogger(2, 25)
	statusUpdater := osimage.NewTimeBasedUpdater(15)

	imageOptions := osimage.ApplyOptions{
		URL:               first.URL,
		TargetPath:        monov1alpha1.AltPartDeviceLink,
		ExpectedRawSHA256: imageSHA,
		ExpectedRawSize:   first.Size,
		BufferSize:        6 * 1024 * 1024,
		Progress: func(p osimage.Progress) {
			pLogger.Log(p)

			if err := statusUpdater.Run(func() error {

				klog.Infof("%s: %d%%", p.Stage, osimage.PercentOf(p.BytesComplete, p.BytesTotal))

				updated, err := updateProgressRobust(ctx, clients, osup.Namespace, osup.Name, func(cur *monov1alpha1.OSUpgradeProgress) {
					now := metav1.Now()

					switch p.Stage {
					case "flash":
						cur.Status.Phase = monov1alpha1.OSUpgradeProgressPhaseWriting
					case "verify":
						cur.Status.Phase = monov1alpha1.OSUpgradeProgressPhaseVerifying
					}

					cur.Status.TargetVersion = plan.ResolvedTarget
					cur.Status.LastUpdatedAt = &now
					cur.Status.Message = fmt.Sprintf(
						"%s: %d%%",
						p.Stage,
						osimage.PercentOf(p.BytesComplete, p.BytesTotal),
					)
				})
				if updated != nil {
					osup = updated
				}
				if err != nil {
					return fmt.Errorf("update progress status: %w", err)
				}
				return nil
			}); err != nil {
				klog.ErrorS(err, "throttled progress update failed")
			}
		},
	}

	result, err := osimage.ApplyImageStreamed(ctx, imageOptions)
	if err != nil {
		return failProgress(ctx, clients, osup, "apply image", err)
	}

	klog.Info(result)

	cfgPath := os.Getenv("FW_ENV_CONFIG_FILE")
	if err := uboot.ConfigureNextBoot(ctx, cfgPath); err != nil {
		return failProgress(ctx, clients, osup, "set boot env", err)
	}

	updated, err = updateProgressRobust(ctx, clients, osup.Namespace, osup.Name, func(cur *monov1alpha1.OSUpgradeProgress) {
		now := metav1.Now()
		cur.Status.TargetVersion = plan.ResolvedTarget
		cur.Status.Message = "image applied, verified, and next boot environment updated"
		cur.Status.Phase = monov1alpha1.OSUpgradeProgressPhaseRebooting
		cur.Status.LastUpdatedAt = &now
	})
	if updated != nil {
		osup = updated
	}
	if err != nil {
		return fmt.Errorf("update progress status: %w", err)
	}

	// TODO: Drain the node here
	// Get all running pods outta here!
	// kubectl.Run()
	// Wait for the node to be drained
	// kubectl.Wait()

	r.rebooting.Store(true)
	if err := triggerReboot(); err != nil {
		r.rebooting.Store(false)
		return fmt.Errorf("trigger reboot: %w", err)
	}
	select {}
}

func triggerReboot() error {
	_ = os.WriteFile("/proc/sysrq-trigger", []byte("s\n"), 0)
	_ = os.WriteFile("/proc/sysrq-trigger", []byte("u\n"), 0)
	return os.WriteFile("/proc/sysrq-trigger", []byte("b\n"), 0)
}