import { CanActivate, ExecutionContext } from "@nestjs/common";
import { GarmrOptions } from "../garmr.options";
/**
 * Guard that verifies Svix-standard webhook signatures.
 *
 * Validates the HMAC-SHA256 signature in the `svix-signature` header against
 * the request's raw body using the secret configured in `GarmrOptions.webhook`.
 *
 * Requires `rawBody: true` on the NestJS application factory so that
 * `req.rawBody` is available.
 *
 * @example
 * ```typescript
 * @Post("webhooks/inbound-email")
 * @UseGuards(WebhookSignatureGuard)
 * async handleInboundEmail(@Body() payload: InboundEmailPayload) {
 *   // Guard already verified the signature
 * }
 * ```
 *
 * @throws {Error} If `webhook.secret` is not configured in GarmrModule options
 * (boot-time configuration error).
 * @throws {InternalServerErrorException} If rawBody is unavailable (server
 * misconfiguration).
 * @throws {UnauthorizedException} If headers are missing or signature is invalid.
 */
export declare class WebhookSignatureGuard implements CanActivate {
    private readonly options;
    /**
     * Validates that `webhook.secret` is configured and fails fast during
     * module initialisation if it is missing.
     *
     * @param options - The Garmr module options injected via DI
     * @throws {Error} If `webhook.secret` is not configured in GarmrModule options
     */
    constructor(options: GarmrOptions);
    /**
     * Validates the Svix-standard HMAC-SHA256 signature on the incoming request.
     *
     * @param context - Execution context providing access to the request
     * @returns true if the signature is valid
     * @throws {InternalServerErrorException} If rawBody is not available
     * (server misconfiguration)
     * @throws {UnauthorizedException} If required headers are missing or the
     * signature is invalid
     */
    canActivate(context: ExecutionContext): boolean;
}