import { TTS } from '../../agents/providers.js';
import type { GoogleTTSModel } from './models.js';
/** Options for selecting a Google Cloud TTS voice. */
export type GoogleVoiceConfigOptions = {
    /** BCP-47 language code for the voice (e.g. `'en-US'`). Default `'en-US'`. */
    languageCode?: string | null;
    /** Google voice name (e.g. `'en-US-Neural2-F'`). Default `''` (empty). */
    name?: string;
};
declare class GoogleVoiceConfigImpl {
    static readonly displayName = "GoogleVoiceConfig";
    languageCode: string | null;
    name: string;
    language_code: string | null;
    constructor(opts?: GoogleVoiceConfigOptions);
}
/** A resolved Google Cloud TTS voice selection. */
export type GoogleVoiceConfig = GoogleVoiceConfigImpl;
/** Build a Google Cloud TTS voice selection (language code + voice name). */
export declare const GoogleVoiceConfig: (opts?: GoogleVoiceConfigOptions) => GoogleVoiceConfig;
/** Configuration options for the Google Cloud text-to-speech (TTS) provider. */
export type GoogleTTSOptions = {
    /** Google API key. Falls back to the `GOOGLE_API_KEY` environment variable, then `null`. */
    apiKey?: string | null;
    /** Service-account credentials as a JSON string. Default `null`. */
    credentialsJson?: string | null;
    /** Path to a service-account JSON key file. Default `null`. */
    serviceAccountPath?: string | null;
    /** Stream audio from the model. Default `true`. */
    stream?: boolean;
    /** Voice name to synthesize with (e.g. `'en-US-Neural2-F'`). Default `'en-US-Neural2-F'`. */
    voice?: string;
    /** BCP-47 language code. Default `'en-US'`. */
    languageCode?: string;
    /** Voice model family (e.g. `'neural2'`, `'wavenet'`, `'chirp3-hd'`). Must match the voice's family; omit (default `''`) to let the voice decide. Known families: standard, wavenet, neural2, news, polyglot, studio, chirp, chirp-hd, chirp3-hd. */
    model?: GoogleTTSModel | string;
    /** Output audio sample rate in Hz. Default `24000`. */
    sampleRate?: number;
    /** Speaking rate (1.0 = normal). Must be in `[0.25, 4.0]`. Default `null` (provider default). */
    speakingRate?: number | null;
    /** Voice pitch in semitones (0 = normal). Must be in `[-20.0, 20.0]`. Default `null` (provider default). */
    pitch?: number | null;
    /** Voice selection used as a fallback for `voice` and `languageCode` when those are left at their defaults. Default `null`. */
    voiceConfig?: GoogleVoiceConfig | null;
    /** Additional/forward-compatible options. */
    [key: string]: any;
};
declare class GoogleTTSImpl extends TTS {
    static readonly displayName = "GoogleTTS";
    _providerName: string;
    apiKey: string | null;
    voiceId: string;
    voice: string;
    languageCode: string;
    language: string;
    model: string;
    speakingRate: number | null;
    pitch: number | null;
    ttsServiceAccountJson: string | null;
    ttsStream: boolean;
    constructor(opts?: GoogleTTSOptions);
    private static _validateModel;
    private static _coerceToJsonContent;
    private static _resolveServiceAccountJson;
    getRuntimeConfig(): Record<string, any>;
}
/** A configured Google Cloud TTS provider instance. */
export type GoogleTTS = GoogleTTSImpl;
/**
 * Google Cloud text-to-speech (TTS) provider.
 *
 * The `model` family must be consistent with `voice`; mismatches throw, and
 * an unknown family is passed through (routing falls back to the voice name).
 */
export declare const GoogleTTS: (opts?: GoogleTTSOptions) => GoogleTTS;
export {};