import { ConfigService } from '@nestjs/config';
import { INotification } from '../interfaces';
import { INotificationTransport } from './interfaces';
export declare class AppSyncEventsService implements INotificationTransport {
    private readonly config;
    private readonly logger;
    private readonly url;
    private readonly namespace;
    private readonly signer;
    constructor(config: ConfigService);
    /**
     * Publish INotification to an AppSync Events channel via IAM SigV4.
     *
     * Channel structure (max 5 segments, seg 1 = namespace):
     *   /{namespace}/{tenantCode}/{action}/{sanitizedId}
     *
     * Client subscription options (wildcard /* catches all sub-channels):
     *   /{namespace}/{tenantCode}/*                  — all events for tenant
     *   /{namespace}/{tenantCode}/{action}/*          — filtered by action
     *   /{namespace}/{tenantCode}/{action}/{id}       — specific command
     *
     * Requires: Lambda execution role must have appsync:EventPublish permission.
     */
    sendMessage(notification: INotification): Promise<void>;
    /**
     * Resolves the most specific channel path for a notification.
     * Non-alphanumeric characters (e.g. #, @) are sanitized to dashes
     * since AppSync Events channel segments only allow [a-zA-Z0-9-].
     */
    resolveChannel(notification: INotification): string;
    /**
     * Formats a string to comply with AppSync Events API channel segment rules:
     * 1. Only alphanumeric characters and dashes.
     * 2. Cannot start or end with a dash.
     * 3. Maximum length of 50 characters.
     */
    private sanitizeSegment;
    private postToChannel;
    /**
     * Builds and signs an HttpRequest for the given channel and notification.
     * Separating signing from the fetch call makes each step independently testable.
     */
    private signRequest;
}