/**
 * Resume + destroy lifecycle helpers for Kubernetes sandbox leases.
 *
 * Resume semantics: a lease is resumable only while its workload resource
 * (Sandbox CR or Job) still exists and its pod is Running/Ready (or becomes
 * Ready within a short bounded wait). Unlike Daytona — where a stopped sandbox
 * can be started again by ID — Kubernetes pods are NOT restartable: once the
 * pod backing a lease is gone or terminally failed, the lease can never be
 * revived in place. That asymmetry is intentional; the plugin reports the
 * lease as expired and the server falls back to a fresh acquireLease, which
 * provisions a new pod.
 *
 * Destroy semantics: the forced cleanup path. Deletes every resource
 * acquireLease created (Sandbox CR / Job, its pod, the per-run Secret),
 * treating 404s as success so it is idempotent and safe to call against
 * half-deleted leases.
 */

import type { KubeClients } from "./kube-client.js";
import { deleteJob, findPodForJob, getJobStatus } from "./job-orchestrator.js";
import {
  deleteSandboxCr,
  findPodForSandbox,
  waitForSandboxReady,
} from "./sandbox-cr-orchestrator.js";

/** True when a Kubernetes API error means "resource not found" (HTTP 404). */
export function isKubeNotFoundError(err: unknown): boolean {
  const code = (err as { code?: number; statusCode?: number }).code
    ?? (err as { code?: number; statusCode?: number }).statusCode;
  return code === 404;
}

async function ignoreNotFound(promise: Promise<unknown>): Promise<void> {
  try {
    await promise;
  } catch (err) {
    if (!isKubeNotFoundError(err)) throw err;
  }
}

export type ResumeCheckResult =
  | { resumable: true; podName: string | null; phase: "Pending" | "Running" }
  | { resumable: false; reason: string };

export interface ResumeCheckInput {
  namespace: string;
  /** Workload resource name (Sandbox CR name or Job name) == providerLeaseId. */
  name: string;
  backend: "sandbox-cr" | "job";
  /** Bounded wait for an existing Sandbox pod to report Ready. */
  readyTimeoutMs?: number;
  pollMs?: number;
}

/**
 * Check whether the workload behind a lease is still alive and exec-able.
 * Returns `resumable: false` (never throws "expected" states) when the
 * resource is gone (404), terminally failed, terminating, or doesn't become
 * Ready within the bounded wait — all of which mean the caller should fall
 * back to a fresh acquireLease.
 */
export async function checkLeaseResumable(
  clients: KubeClients,
  input: ResumeCheckInput,
): Promise<ResumeCheckResult> {
  if (input.backend === "sandbox-cr") {
    // Bounded wait for the Sandbox to report Ready. waitForSandboxReady fails
    // fast on Failed/Terminating; a timeout means the pod never came up. None
    // of those states are resumable — k8s pods cannot be restarted in place.
    try {
      await waitForSandboxReady(clients, input.namespace, input.name, {
        timeoutMs: input.readyTimeoutMs ?? 30_000,
        pollMs: input.pollMs ?? 1_000,
      });
    } catch (err) {
      if (isKubeNotFoundError(err)) {
        return { resumable: false, reason: "Sandbox CR no longer exists" };
      }
      return {
        resumable: false,
        reason: err instanceof Error ? err.message : String(err),
      };
    }

    let podName: string | null;
    try {
      podName = await findPodForSandbox(clients, input.namespace, input.name);
    } catch (err) {
      // CR deleted between the readiness check and the pod lookup.
      if (isKubeNotFoundError(err)) {
        return { resumable: false, reason: "Sandbox CR no longer exists" };
      }
      throw err;
    }
    if (!podName) {
      return {
        resumable: false,
        reason: "Sandbox is Ready but no backing pod was found",
      };
    }

    // Confirm the pod itself is Running and not being torn down — the CR
    // status can lag pod deletion.
    let pod: { metadata?: { deletionTimestamp?: unknown }; status?: { phase?: string } };
    try {
      pod = await clients.core.readNamespacedPod({
        namespace: input.namespace,
        name: podName,
      }) as typeof pod;
    } catch (err) {
      if (isKubeNotFoundError(err)) {
        return { resumable: false, reason: `Pod ${podName} no longer exists` };
      }
      throw err;
    }
    const podPhase = pod.status?.phase;
    const terminating = Boolean(pod.metadata?.deletionTimestamp);
    if (podPhase !== "Running" || terminating) {
      return {
        resumable: false,
        reason: `Pod ${podName} is ${terminating ? "terminating" : podPhase ?? "in an unknown phase"}`,
      };
    }
    return { resumable: true, podName, phase: "Running" };
  }

  // ── Job backend ───────────────────────────────────────────────────────────
  let status;
  try {
    status = await getJobStatus(clients, input.namespace, input.name);
  } catch (err) {
    if (isKubeNotFoundError(err)) {
      return { resumable: false, reason: "Job no longer exists" };
    }
    throw err;
  }
  if (status.phase === "Succeeded" || status.phase === "Failed") {
    // Terminal Jobs cannot be re-run in place.
    return { resumable: false, reason: `Job is ${status.phase}` };
  }
  // Pending/Running Jobs are resumable: execute() waits for completion
  // itself, so a not-yet-scheduled pod (podName null) is fine here.
  const podName = await findPodForJob(clients, input.namespace, input.name);
  return {
    resumable: true,
    podName,
    phase: status.phase === "Running" ? "Running" : "Pending",
  };
}

export interface DestroyLeaseInput {
  namespace: string;
  /** Workload resource name (Sandbox CR name or Job name) == providerLeaseId. */
  name: string;
  backend: "sandbox-cr" | "job";
  podName: string | null;
  secretName: string | null;
}

/**
 * Forcibly delete every resource acquireLease created for this lease.
 * Workload first (its deletion cascades to the pod and, via ownerReferences,
 * the per-run Secret in the normal case); then the pod and Secret explicitly
 * so a wedged controller or broken ownerRef cannot strand them. Every delete
 * treats 404 as success — destroy is idempotent.
 */
export async function destroyLeaseResources(
  clients: KubeClients,
  input: DestroyLeaseInput,
): Promise<void> {
  if (input.backend === "sandbox-cr") {
    await ignoreNotFound(deleteSandboxCr(clients, input.namespace, input.name));
  } else {
    await ignoreNotFound(deleteJob(clients, input.namespace, input.name));
  }
  if (input.podName) {
    await ignoreNotFound(
      clients.core.deleteNamespacedPod({
        namespace: input.namespace,
        name: input.podName,
      }),
    );
  }
  if (input.secretName) {
    await ignoreNotFound(
      clients.core.deleteNamespacedSecret({
        namespace: input.namespace,
        name: input.secretName,
      }),
    );
  }
}