import { Logger } from '@nestjs/common';
import { ConfigService } from '@nestjs/config';
import { AxiosInstance, AxiosRequestConfig } from 'axios';
import { AuthenticationModuleOptions } from '../authentication';
import { InternalExternalUrl } from './base-urls';
/**
 * BaseHttpService
 *
 * A structured, type-safe abstraction over Axios that standardizes outbound HTTP requests
 * to other internal or external microservices.
 *
 * ### Key Principles:
 * - **Controlled Configuration:** Rather than subclassing Axios (which creates prototype issues),
 *   this class wraps Axios to maintain predictable behavior across environments.
 * - **Environment-Aware Routing:** Selects internal vs. external base URLs automatically based on environment.
 * - **Secure Communication:** Injects a Kubernetes service token into every outbound request header.
 * - **Operational Transparency:** Implements structured logging for observability of inter-service communication.
 */
export declare abstract class BaseHttpService {
    private readonly serviceName;
    private readonly baseUrls;
    private readonly authenticationOptions;
    private readonly configService;
    readonly httpClient: AxiosInstance;
    protected readonly logger: Logger;
    protected readonly isProduction: boolean;
    /**
     * Constructs a base HTTP service instance configured for a downstream microservice.
     *
     * @param {string} serviceName - Name of the downstream service (used for contextualized logs).
     * @param {InternalExternalUrl} baseUrls - Tuple `[internalUrl, externalUrl]`. In production, internal URLs are preferred for security and speed.
     * @param {AuthenticationModuleOptions} authenticationOptions - Configuration containing Kubernetes token.
     * @param {ConfigService} configService - NestJS configuration provider.
     */
    constructor(serviceName: string, baseUrls: InternalExternalUrl, authenticationOptions: AuthenticationModuleOptions, configService: ConfigService);
    /**
     * Converts an Axios error into a structured and consistent error format.
     *
     * This allows downstream callers to rely on predictable error shapes,
     * regardless of how the target service responds.
     *
     * @param {any} error - Raw Axios error object from a failed request.
     * @returns {{ status: number; data: string | Record<string, any>; message: string }}
     */
    protected parseError(error: any): {
        status: number;
        data: string | Record<string, any>;
        message: string;
    };
    /**
     * Retrieves a single resource from the downstream service.
     *
     * Why this abstraction matters:
     * - Prevents unhandled promise rejections by returning `undefined` on failure.
     * - Allows optional per-request configuration without mutating the shared Axios instance.
     *
     * @template T
     * @param {string} endpoint - Relative path (e.g., `"/users/42"`).
     * @param {AxiosRequestConfig} [config={}] - Optional request overrides (headers, params, etc.).
     * @returns {Promise<T | undefined>} - The fetched resource, or `undefined` if the request fails.
     */
    protected fetchResource<T>(endpoint: string, config?: AxiosRequestConfig): Promise<T | undefined>;
    /**
     * Retrieves a collection of resources from the downstream service.
     *
     * Handles cases where large sets of IDs need to be split into chunks
     * to avoid exceeding query parameter length limits.
     *
     * @template T
     * @param {string} endpoint - Relative API path.
     * @param {AxiosRequestConfig} [config={}] - Optional request customization.
     * @returns {Promise<T[]>} - Array of resources, or an empty array if all attempts fail.
     */
    protected fetchResourceCollection<T>(endpoint: string, config?: AxiosRequestConfig): Promise<T[]>;
    /**
     * Helper for fetching a batch (or full collection) of resources in a single request.
     *
     * Encapsulated separately to isolate retry/fallback behavior and keep
     * the main collection method simpler.
     *
     * @template T
     * @param {string} endpoint - Target API path.
     * @param {AxiosRequestConfig} [config={}] - Optional request customization.
     * @returns {Promise<T[]>} - List of retrieved resources or an empty array if failed.
     */
    private fetchResourceCollectionBatch;
}