import { PatchStrategy } from "@kubernetes/client-node";
import type { KubernetesObject } from "@kubernetes/client-node";
import { LABELS } from "../const";
import { objectApi } from "./k8s";

const FIELD_MANAGER = "kuber";

const ResourceOrder = {
  Namespace: 0,
  GarageBucket: 1,
  GarageKey: 2,
  ServiceAccount: 3,
  ClusterRole: 4,
  Role: 5,
  ClusterRoleBinding: 6,
  RoleBinding: 7,
  StorageClass: 8,
  PersistentVolumeClaim: 9,
  Secret: 10,
  ConfigMap: 11,
  Service: 12,
  Deployment: 13,
  HorizontalPodAutoscaler: 14,
  Ingress: 15,
  IngressRoute: 16,
} as const;

const ManagedResources = [
  { apiVersion: "v1", kind: "PersistentVolumeClaim" },
  { apiVersion: "v1", kind: "Secret" },
  { apiVersion: "v1", kind: "ConfigMap" },
  { apiVersion: "v1", kind: "Service" },
  { apiVersion: "apps/v1", kind: "Deployment" },
  { apiVersion: "autoscaling/v2", kind: "HorizontalPodAutoscaler" },
  { apiVersion: "networking.k8s.io/v1", kind: "Ingress" },
  { apiVersion: "traefik.io/v1alpha1", kind: "IngressRoute" },
] as const;

const ManagedBySelector = `app.kubernetes.io/managed-by=${LABELS["app.kubernetes.io/managed-by"]}`;
const ManagedByLabel = LABELS["app.kubernetes.io/managed-by"];

function getResourceOrder(resource: KubernetesObject): number {
  return ResourceOrder[resource.kind as keyof typeof ResourceOrder] ?? 999;
}

export function sortResources<T extends KubernetesObject>(resources: T[]): T[] {
  return [...resources].sort(
    (left, right) => getResourceOrder(left) - getResourceOrder(right),
  );
}

export function getResourceKey(resource: KubernetesObject): string {
  return `${resource.kind}:${resource.metadata?.namespace ?? ""}:${resource.metadata?.name ?? ""}`;
}

export async function getNamespaceManagementStatus(
  namespace: string,
): Promise<"missing" | "managed" | "external"> {
  try {
    const existing = await objectApi.read({
      apiVersion: "v1",
      kind: "Namespace",
      metadata: { name: namespace },
    });

    return existing.metadata?.labels?.["app.kubernetes.io/managed-by"] ===
      ManagedByLabel
      ? "managed"
      : "external";
  } catch (error) {
    if (
      error &&
      typeof error === "object" &&
      "code" in error &&
      error.code === 404
    ) {
      return "missing";
    }

    throw error;
  }
}

export async function assertManagedNamespace(namespace: string): Promise<void> {
  const status = await getNamespaceManagementStatus(namespace);
  if (status === "external") {
    throw new Error(
      `Namespace ${namespace} is not managed by kuber. Refusing to mutate it.`,
    );
  }
}

export async function applyResource<T extends KubernetesObject>(
  resource: T,
): Promise<T> {
  return objectApi.patch(
    resource,
    undefined,
    undefined,
    FIELD_MANAGER,
    true,
    PatchStrategy.ServerSideApply,
  );
}

export async function applyResources<T extends KubernetesObject>(
  resources: T[],
): Promise<T[]> {
  const applied: T[] = [];

  for (const resource of sortResources(resources)) {
    applied.push(await applyResource(resource));
  }

  return applied;
}

export async function deleteResource(
  resource: KubernetesObject,
): Promise<void> {
  await objectApi.delete(resource);
}

export async function deleteResources(
  resources: KubernetesObject[],
): Promise<void> {
  for (const resource of sortResources(resources).reverse()) {
    await deleteResource(resource);
  }
}

export async function listManagedResources(
  namespace: string,
): Promise<KubernetesObject[]> {
  const resources = await Promise.all(
    ManagedResources.map(async ({ apiVersion, kind }) => {
      const list = await objectApi.list(
        apiVersion,
        kind,
        namespace,
        undefined,
        undefined,
        undefined,
        undefined,
        ManagedBySelector,
      );

      return list.items.map((item) => ({
        ...item,
        apiVersion: item.apiVersion ?? apiVersion,
        kind: item.kind ?? kind,
        metadata: {
          ...item.metadata,
          namespace: item.metadata?.namespace ?? namespace,
        },
      }));
    }),
  );

  return resources.flat();
}

export async function getStaleResources(
  namespace: string,
  desiredResources: KubernetesObject[],
): Promise<KubernetesObject[]> {
  const desired = new Set(
    desiredResources
      .filter((resource) => resource.kind !== "Namespace")
      .map(getResourceKey),
  );

  const existing = await listManagedResources(namespace);
  return existing.filter((resource) => !desired.has(getResourceKey(resource)));
}