const SLACK_AUTH_ERROR_RE =
  /account_inactive|invalid_auth|token_revoked|token_expired|not_authed|org_login_required|team_access_not_granted|missing_scope|cannot_find_service|invalid_token/i;

export const SLACK_SOCKET_RECONNECT_POLICY = {
  initialMs: 2_000,
  maxMs: 30_000,
  factor: 1.8,
  jitter: 0.25,
  maxAttempts: 12,
} as const;

export type SlackSocketDisconnectEvent = "disconnect" | "unable_to_socket_mode_start" | "error";

type EmitterLike = {
  on: (event: string, listener: (...args: unknown[]) => void) => unknown;
  off: (event: string, listener: (...args: unknown[]) => void) => unknown;
};

export function getSocketEmitter(app: unknown): EmitterLike | null {
  const receiver = (app as { receiver?: unknown }).receiver;
  const client =
    receiver && typeof receiver === "object"
      ? (receiver as { client?: unknown }).client
      : undefined;
  if (!client || typeof client !== "object") {
    return null;
  }
  const on = (client as { on?: unknown }).on;
  const off = (client as { off?: unknown }).off;
  if (typeof on !== "function" || typeof off !== "function") {
    return null;
  }
  return {
    on: (event, listener) =>
      (
        on as (this: unknown, event: string, listener: (...args: unknown[]) => void) => unknown
      ).call(client, event, listener),
    off: (event, listener) =>
      (
        off as (this: unknown, event: string, listener: (...args: unknown[]) => void) => unknown
      ).call(client, event, listener),
  };
}

export function waitForSlackSocketDisconnect(
  app: unknown,
  abortSignal?: AbortSignal,
): Promise<{
  event: SlackSocketDisconnectEvent;
  error?: unknown;
}> {
  return new Promise((resolve) => {
    const emitter = getSocketEmitter(app);
    if (!emitter) {
      abortSignal?.addEventListener("abort", () => resolve({ event: "disconnect" }), {
        once: true,
      });
      return;
    }

    const disconnectListener = () => resolveOnce({ event: "disconnect" });
    const startFailListener = (error?: unknown) =>
      resolveOnce({ event: "unable_to_socket_mode_start", error });
    const errorListener = (error: unknown) => resolveOnce({ event: "error", error });
    const abortListener = () => resolveOnce({ event: "disconnect" });

    const cleanup = () => {
      emitter.off("disconnected", disconnectListener);
      emitter.off("unable_to_socket_mode_start", startFailListener);
      emitter.off("error", errorListener);
      abortSignal?.removeEventListener("abort", abortListener);
    };

    const resolveOnce = (value: { event: SlackSocketDisconnectEvent; error?: unknown }) => {
      cleanup();
      resolve(value);
    };

    emitter.on("disconnected", disconnectListener);
    emitter.on("unable_to_socket_mode_start", startFailListener);
    emitter.on("error", errorListener);
    abortSignal?.addEventListener("abort", abortListener, { once: true });
  });
}

/**
 * Detect non-recoverable Slack API / auth errors that should NOT be retried.
 * These indicate permanent credential problems (revoked bot, deactivated account, etc.)
 * and retrying will never succeed — continuing to retry blocks the entire gateway.
 */
export function isNonRecoverableSlackAuthError(error: unknown): boolean {
  const msg = error instanceof Error ? error.message : typeof error === "string" ? error : "";
  return SLACK_AUTH_ERROR_RE.test(msg);
}

export function formatUnknownError(error: unknown): string {
  if (error instanceof Error) {
    return error.message;
  }
  if (typeof error === "string") {
    return error;
  }
  try {
    return JSON.stringify(error);
  } catch {
    return "unknown error";
  }
}