lib/flow-api/WebauthnManager.ts

import {
  CredentialRequestOptionsJSON,
  CredentialCreationOptionsJSON,
  PublicKeyCredentialWithAssertionJSON,
  PublicKeyCredentialWithAttestationJSON,
  create,
  get,
} from "@github/webauthn-json";

/**
 * Manages WebAuthn credential operations as a singleton, ensuring only one active request at a time.
 * Uses an internal AbortController to cancel previous requests when a new one is initiated.
 */
class WebauthnManager {
  private static instance: WebauthnManager | null = null;
  private abortController = new AbortController();
  // eslint-disable-next-line no-useless-constructor,require-jsdoc
  private constructor() {}

  /**
   * Gets the singleton instance of WebauthnManager.
   * Creates a new instance if one doesn't exist, otherwise returns the existing one.
   * @returns {WebauthnManager} The singleton instance
   */
  public static getInstance(): WebauthnManager {
    if (!WebauthnManager.instance) {
      WebauthnManager.instance = new WebauthnManager();
    }
    return WebauthnManager.instance;
  }

  /**
   * Creates a new abort signal, aborting any ongoing WebAuthn request.
   * @private
   * @returns {AbortSignal} The new abort signal
   */
  private createAbortSignal(): AbortSignal {
    this.abortController.abort(); // Cancel any ongoing request
    this.abortController = new AbortController();
    return this.abortController.signal;
  }

  /**
   * Retrieves a WebAuthn credential using the provided options.
   * Aborts any previous request before starting a new one.
   * @param {CredentialRequestOptionsJSON} options - The options for credential retrieval
   * @returns {Promise<PublicKeyCredentialWithAssertionJSON>} A promise resolving to the retrieved credential
   * @throws {DOMException} If the WebAuthn request fails (e.g., aborted, not allowed)
   */
  public async getWebauthnCredential(
    options: CredentialRequestOptionsJSON,
  ): Promise<PublicKeyCredentialWithAssertionJSON> {
    return await get({
      ...options,
      signal: this.createAbortSignal(),
    });
  }

  /**
   * Retrieves a WebAuthn credential with conditional UI mediation.
   * Aborts any previous request before starting a new one.
   * @param {CredentialRequestOptionsJSON} publicKey - The public key options for conditional retrieval
   * @returns {Promise<PublicKeyCredentialWithAssertionJSON>} A promise resolving to the retrieved credential
   * @throws {DOMException} If the WebAuthn request fails (e.g., aborted, not allowed)
   */
  public async getConditionalWebauthnCredential(
    publicKey: CredentialRequestOptionsJSON["publicKey"],
  ): Promise<PublicKeyCredentialWithAssertionJSON> {
    return await get({
      publicKey,
      mediation: "conditional" as CredentialMediationRequirement,
      signal: this.createAbortSignal(),
    });
  }

  /**
   * Creates a new WebAuthn credential using the provided options.
   * Aborts any previous request before starting a new one.
   * @param {CredentialCreationOptionsJSON} options - The options for credential creation
   * @returns {Promise<PublicKeyCredentialWithAttestationJSON>} A promise resolving to the created credential
   * @throws {DOMException} If the WebAuthn request fails (e.g., aborted, not allowed)
   */
  public async createWebauthnCredential(
    options: CredentialCreationOptionsJSON,
  ): Promise<PublicKeyCredentialWithAttestationJSON> {
    return await create({
      ...options,
      signal: this.createAbortSignal(),
    });
  }
}

export default WebauthnManager;