import { AbstractTTSClient } from "../core/abstract-tts";
import type { SpeakOptions, TTSCredentials, UnifiedVoice } from "../types";
/**
 * WitAI TTS Client Credentials
 */
export interface WitAITTSCredentials extends TTSCredentials {
    token: string;
}
/**
 * WitAI TTS Client
 */
export declare class WitAITTSClient extends AbstractTTSClient {
    private token;
    private baseUrl;
    private apiVersion;
    private headers;
    protected sampleRate: number;
    /**
     * Create a new WitAI TTS client
     * @param credentials WitAI credentials object with token
     */
    constructor(credentials: WitAITTSCredentials);
    /**
     * Check if credentials are valid
     * @returns Promise resolving to true if credentials are valid
     */
    checkCredentials(): Promise<boolean>;
    /**
     * Get the list of required credential types for this engine
     * @returns Array of required credential field names
     */
    protected getRequiredCredentials(): string[];
    /**
     * Get raw voices from WitAI
     * @returns Promise resolving to an array of unified voice objects
     */
    protected _getVoices(): Promise<any[]>;
    /**
     * Map WitAI voice objects to unified format
     * @param rawVoices Array of WitAI voice objects
     * @returns Promise resolving to an array of unified voice objects
     */
    protected _mapVoicesToUnified(rawVoices: any[]): Promise<UnifiedVoice[]>;
    /**
     * Prepare text/SSML for synthesis
     * @param text Text or SSML to prepare
     * @param options Synthesis options
     * @returns Prepared text or SSML
     */
    private prepareText;
    /**
     * Get the appropriate Accept header based on the format option
     * @param format Format option from WitAITTSOptions
     * @returns MIME type string
     */
    private getAcceptHeader;
    /**
     * Synthesize text to audio bytes
     * @param text Text to synthesize
     * @param options Synthesis options
     * @returns Promise resolving to audio bytes
     */
    synthToBytes(text: string, options?: SpeakOptions): Promise<Uint8Array>;
    /**
     * Synthesize text to a byte stream with word boundary information
     * @param text Text to synthesize
     * @param options Synthesis options
     * @returns Promise resolving to an object containing the audio stream and word boundary information
     */
    synthToBytestream(text: string, options?: SpeakOptions): Promise<{
        audioStream: ReadableStream<Uint8Array>;
        wordBoundaries: Array<{
            text: string;
            offset: number;
            duration: number;
        }>;
    }>;
    /**
     * Set the voice to use for synthesis
     * @param voiceId Voice ID to use
     * @param lang Language code (not used in WitAI)
     */
    setVoice(voiceId: string, lang?: string): void;
}
/**
 * Extended options for WitAI TTS
 */
export interface WitAITTSOptions extends SpeakOptions {
    format?: "mp3" | "wav" | "pcm";
}