import { AbstractTTSClient } from "../core/abstract-tts";
import type { SpeakOptions, TTSCredentials, UnifiedVoice } from "../types";
/**
 * SAPI TTS Client Credentials
 */
export interface SAPITTSCredentials extends TTSCredentials {
}
/**
 * SAPI TTS Client for Windows environments
 *
 * This client uses Windows Speech API (SAPI) through PowerShell to provide:
 * - High-quality Windows TTS synthesis
 * - SSML support
 * - Rich voice metadata
 * - Word boundary events
 * - Rate, pitch, and volume controls
 */
export declare class SAPITTSClient extends AbstractTTSClient {
    private static readonly TEMP_PREFIX;
    constructor(credentials?: SAPITTSCredentials);
    /**
     * Validate that we're running on Windows with PowerShell available
     */
    private validateEnvironment;
    /**
     * Get the list of required credential types for this engine
     * @returns Array of required credential field names
     */
    protected getRequiredCredentials(): string[];
    /**
     * SAPI does not require credentials but we validate the environment
     */
    checkCredentials(): Promise<boolean>;
    /**
     * Get available SAPI voices with rich metadata
     */
    getVoices(): Promise<UnifiedVoice[]>;
    /**
     * Get raw voices from SAPI
     */
    protected _getVoices(): Promise<UnifiedVoice[]>;
    /**
     * Run a PowerShell script and return the output
     */
    private runPowerShellScript;
    /**
     * Convert culture code to ISO 639-3 language code
     */
    private convertCultureToISO639;
    /**
     * Get voice name by voice ID for SAPI SelectVoice() method
     * @param voiceId Voice ID to look up
     * @returns Promise resolving to voice name or null if not found
     */
    private getVoiceNameById;
    /**
     * Synthesize text to audio bytes using SAPI
     */
    synthToBytes(text: string, options?: SpeakOptions): Promise<Uint8Array>;
    /**
     * Synthesize text to a byte stream with word boundaries
     */
    synthToBytestream(text: string, options?: SpeakOptions): Promise<{
        audioStream: ReadableStream<Uint8Array>;
        wordBoundaries: Array<{
            text: string;
            offset: number;
            duration: number;
        }>;
    }>;
    /**
     * Convert rate option to SAPI rate format
     * @param rate Rate option (string or number)
     * @returns Rate value for SAPI (-10 to 10)
     */
    private convertRate;
    /**
     * Convert volume option to SAPI volume format
     * @param volume Volume option (string or number)
     * @returns Volume value for SAPI (0 to 100)
     */
    private convertVolume;
    /**
     * Escape a string for use in PowerShell
     * @param str String to escape
     * @returns Escaped string
     */
    private escapePowerShellString;
    /**
     * Strip SSML tags from text (fallback for plain text processing)
     * @param text Text with SSML tags
     * @returns Plain text without SSML tags
     */
    private stripSSML;
    /**
     * Ensure SSML has proper format for SAPI
     * @param text SSML text
     * @returns Properly formatted SSML
     */
    private ensureProperSSML;
}