import GRPCClient from "./GRPCClient";
import IClientHealth from "../../../interfaces/Client/IClientHealth";
/**
 * gRPC-based health check building block implementation.
 *
 * Provides health status monitoring for the Dapr sidecar.
 * Uses the metadata endpoint as a proxy for sidecar health (gRPC has no dedicated health endpoint).
 *
 * @implements {IClientHealth}
 * @see {@link https://docs.dapr.io/reference/api/health_api/} Dapr Health API
 * @see {@link DaprClient.health} for unified API
 *
 * @internal
 */
export default class GRPCClientHealth implements IClientHealth {
    /**
     * Reference to the underlying gRPC client.
     */
    client: GRPCClient;
    /**
     * Creates a gRPC health check building block.
     *
     * @param client - The gRPC client instance
     */
    constructor(client: GRPCClient);
    /**
     * Checks if the Dapr sidecar is healthy and responding.
     *
     * Attempts to fetch sidecar metadata. Returns true if successful, false on any error.
     * Note: gRPC protocol does not have a dedicated health endpoint, so metadata is used as a proxy.
     *
     * @returns Promise resolving to true if sidecar is healthy, false otherwise
     *
     * @example
     * ```typescript
     * const isHealthy = await client.health.isHealthy();
     * if (isHealthy) {
     *   console.log("Sidecar is responsive");
     * } else {
     *   console.log("Sidecar is not responding");
     * }
     * ```
     *
     * @see {@link https://docs.dapr.io/reference/api/health_api/#checking-sidecar-health}
     */
    isHealthy(): Promise<boolean>;
}