/**
 * @license
 * Copyright 2025 Google LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
import { BackendType } from './public-types';
/**
 * Abstract base class representing the configuration for an AI service backend.
 * This class should not be instantiated directly. Use its subclasses; {@link GoogleAIBackend} for
 * the Gemini Developer API (via {@link https://ai.google/ | Google AI}), and
 * {@link VertexAIBackend} for the Vertex AI Gemini API.
 *
 * @public
 */
export declare abstract class Backend {
    /**
     * Specifies the backend type.
     */
    readonly backendType: BackendType;
    /**
     * Protected constructor for use by subclasses.
     * @param type - The backend type.
     */
    protected constructor(type: BackendType);
}
/**
 * Configuration class for the Gemini Developer API.
 *
 * Use this with {@link AIOptions} when initializing the AI service via
 * {@link getAI | getAI()} to specify the Gemini Developer API as the backend.
 *
 * @public
 */
export declare class GoogleAIBackend extends Backend {
    /**
     * Creates a configuration object for the Gemini Developer API backend.
     */
    constructor();
}
/**
 * Configuration class for the Vertex AI Gemini API.
 *
 * Use this with {@link AIOptions} when initializing the AI service via
 * {@link getAI | getAI()} to specify the Vertex AI Gemini API as the backend.
 *
 * @public
 */
export declare class VertexAIBackend extends Backend {
    /**
     * The region identifier.
     * See {@link https://firebase.google.com/docs/vertex-ai/locations#available-locations | Vertex AI locations}
     * for a list of supported locations.
     */
    readonly location: string;
    /**
     * Creates a configuration object for the Vertex AI backend.
     *
     * @param location - The region identifier, defaulting to `us-central1`;
     * see {@link https://firebase.google.com/docs/vertex-ai/locations#available-locations | Vertex AI locations}
     * for a list of supported locations.
     */
    constructor(location?: string);
}