/**
 * @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 { ReactNativeFirebase } from '@react-native-firebase/app';
import type { Auth } from '@react-native-firebase/auth';
import type { AppCheck } from '@react-native-firebase/app-check';
import { Backend } from './backend';

export * from './types';
export { Backend };

/**
 * An instance of the Firebase AI SDK.
 *
 * Do not create this instance directly. Instead, use {@link getAI | getAI()}.
 *
 * @public
 */
export interface AI {
  /**
   * The {@link @firebase/app!FirebaseApp} this {@link AI} instance is associated with.
   */
  app: ReactNativeFirebase.FirebaseApp;
  appCheck?: AppCheck | null;
  auth?: Auth | null;
  /**
   * A {@link Backend} instance that specifies the configuration for the target backend,
   * either the Gemini Developer API (using {@link GoogleAIBackend}) or the
   * Agent Platform Gemini API (using {@link AgentPlatformBackend}).
   */
  backend: Backend;
  /**
   * Options applied to this {@link AI} instance.
   */
  options?: AIOptions;
  /**
   * @deprecated use `AI.backend.location` instead.
   *
   * The location configured for this AI service instance, relevant for
   * Agent Platform Gemini API backends.
   */
  location: string;
}

/**
 * An enum-like object containing constants that represent the supported backends
 * for the Firebase AI SDK.
 * This determines which backend service (Gemini Developer API or Agent Platform Gemini API)
 * the SDK will communicate with.
 *
 * These values are assigned to the `backendType` property within the specific backend
 * configuration objects ({@link GoogleAIBackend} or {@link AgentPlatformBackend}) to identify
 * which service to target.
 *
 * @public
 */
export const BackendType = {
  /**
   * Identifies the backend service for the Agent Platform Gemini API provided through Google Cloud.
   * Use this constant when creating a {@link AgentPlatformBackend} configuration.
   */
  AGENT_PLATFORM: 'AGENT_PLATFORM',

  /**
   * Identifies the backend service for the Agent Platform Gemini API
   * (formerly known as Vertex AI Gemini API) provided through Google Cloud.
   * Use this constant when creating a {@link VertexAIBackend} configuration.
   * @deprecated Use {@link AgentPlatformBackend} instead.
   */
  VERTEX_AI: 'VERTEX_AI',

  /**
   * Identifies the backend service for the Gemini Developer API ({@link https://ai.google/ | Google AI}).
   * Use this constant when creating a {@link GoogleAIBackend} configuration.
   */
  GOOGLE_AI: 'GOOGLE_AI',
} as const; // Using 'as const' makes the string values literal types

/**
 * Type alias representing valid backend types.
 * It should be either `'AGENT_PLATFORM'` or `'GOOGLE_AI'` (`'VERTEX_AI'` is deprecated).
 *
 * @public
 */
export type BackendType = (typeof BackendType)[keyof typeof BackendType];

/**
 * Options for initializing the AI service using {@link getAI | getAI()}.
 * This allows specifying which backend to use (Gemini Developer API or Agent Platform Gemini API)
 * and configuring its specific options (like location for Agent Platform).
 *
 * @public
 */
export interface AIOptions {
  /**
   * The backend configuration to use for the AI service instance.
   * Defaults to the Gemini Developer API backend ({@link GoogleAIBackend}).
   */
  backend?: Backend;
  /**
   * Whether to use App Check limited use tokens. Defaults to false.
   */
  useLimitedUseAppCheckTokens?: boolean;
  appCheck?: AppCheck | null;
  auth?: Auth | null;
}