package server

import (
	"context"
	"fmt"
	"slices"

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

	"edge-infra.dev/pkg/sds/lib/containerd"
	"edge-infra.dev/pkg/sds/lib/dbus/systemd"
	"edge-infra.dev/pkg/sds/lib/k8s/manifest"
)

var (
	FNCFlag = "--force-new-cluster=true"
)

// EnterNewClusterMode creates a new etcd cluster with the current node as the only member.
// Always run ExitNewClusterMode after you have finished configuring your new cluster
// after using EnterNewClusterMode. Failure to do so will result in the cluster being reset
// every time the etcd container restarts.
func EnterNewClusterMode(ctx context.Context, m *manifest.Manifest, restarter systemd.Restarter, terminator containerd.Terminator) error {
	return WithRestart(ctx, restarter, terminator, func() error {
		return m.WithUpdate(func(obj runtime.Object) error {
			pod, ok := obj.(*corev1.Pod)
			if !ok {
				return fmt.Errorf("current content of the etcd manifest is not a valid pod")
			}
			return SetFNCFlag(pod)
		})
	})
}

// ExitNewClusterMode prevents the etcd cluster from being restarted when the etcd
// container restarts.
func ExitNewClusterMode(ctx context.Context, m *manifest.Manifest, restarter systemd.Restarter, terminator containerd.Terminator) error {
	return WithRestart(ctx, restarter, terminator, func() error {
		return m.WithUpdate(func(obj runtime.Object) error {
			pod, ok := obj.(*corev1.Pod)
			if !ok {
				return fmt.Errorf("current content of the etcd manifest is not a valid pod")
			}
			return ClearFNCFlag(pod)
		})
	})
}

// WithRestart takes a function and adds functionality to restart the etcd
// container and kubelet service.
func WithRestart(ctx context.Context, restarter systemd.Restarter, terminator containerd.Terminator, fn func() error) error {
	labelFilters := containerd.NewLabelFiltersBuilder().WithContainerName("etcd").WithPodNamespace(metav1.NamespaceSystem).Build()
	err := terminator.WithTerminate(ctx, *labelFilters, func() error {
		return fn()
	})
	if err != nil {
		return err
	}

	return restarter.Restart(ctx, "kubelet.service", systemd.Replace, false)
}

// SetFNCFlag adds the --force-new-cluster=true flag to the etcd container command if
// it does not already exist.
func SetFNCFlag(pod *corev1.Pod) error {
	if len(pod.Spec.Containers) == 0 {
		return fmt.Errorf("etcd container not found in etcd manifest")
	}

	if !slices.Contains(pod.Spec.Containers[0].Command, FNCFlag) {
		pod.Spec.Containers[0].Command = append(pod.Spec.Containers[0].Command, FNCFlag)
	}

	return nil
}

// ClearFNCFlag removes the --force-new-cluster=true flag from the etcd container command
// if it exists.
func ClearFNCFlag(pod *corev1.Pod) error {
	if len(pod.Spec.Containers) == 0 {
		return fmt.Errorf("etcd container not found in etcd manifest")
	}

	updatedCommand := make([]string, 0, len(pod.Spec.Containers[0].Command))
	for _, value := range pod.Spec.Containers[0].Command {
		if value != FNCFlag {
			// Value doesn't match the forceNewClusterFlag, keep it in the updatedCommand array
			updatedCommand = append(updatedCommand, value)
		}
	}
	pod.Spec.Containers[0].Command = updatedCommand

	return nil
}