/**
 * TTS announcement module — generates announcement WAV files at startup.
 *
 * Engine priority: espeak-ng (formant TTS, fast) → Kokoro neural TTS via
 * proxy-engine → disabled.
 *
 * The generated WAV is left on disk for Rust's audio_player / start_interaction
 * to play during calls. No encoding or RTP playback happens in TypeScript.
 */

import { execSync } from 'node:child_process';
import fs from 'node:fs';
import path from 'node:path';
import { sendProxyCommand, isProxyReady } from './proxybridge.ts';

// ---------------------------------------------------------------------------
// State
// ---------------------------------------------------------------------------

const TTS_DIR = path.join(process.cwd(), '.nogit', 'tts');
const ANNOUNCEMENT_TEXT = "Hello. I'm connecting your call now.";
const CACHE_WAV = path.join(TTS_DIR, 'announcement.wav');

// Kokoro fallback constants.
const KOKORO_MODEL = 'kokoro-v1.0.onnx';
const KOKORO_VOICES = 'voices.bin';
const KOKORO_VOICE = 'af_bella';

// ---------------------------------------------------------------------------
// TTS generators
// ---------------------------------------------------------------------------

/** Check if espeak-ng is available on the system. */
function isEspeakAvailable(): boolean {
  try {
    execSync('which espeak-ng', { stdio: 'pipe' });
    return true;
  } catch {
    return false;
  }
}

/** Generate announcement WAV via espeak-ng (primary engine). */
function generateViaEspeak(wavPath: string, text: string, log: (msg: string) => void): boolean {
  log('[tts] generating announcement audio via espeak-ng...');
  try {
    execSync(
      `espeak-ng -v en-us -s 150 -w "${wavPath}" "${text}"`,
      { timeout: 10000, stdio: 'pipe' },
    );
    log('[tts] espeak-ng WAV generated');
    return true;
  } catch (e: any) {
    log(`[tts] espeak-ng failed: ${e.message}`);
    return false;
  }
}

/** Generate announcement WAV via Kokoro TTS (fallback, runs inside proxy-engine). */
async function generateViaKokoro(wavPath: string, text: string, log: (msg: string) => void): Promise<boolean> {
  const modelPath = path.join(TTS_DIR, KOKORO_MODEL);
  const voicesPath = path.join(TTS_DIR, KOKORO_VOICES);

  if (!fs.existsSync(modelPath) || !fs.existsSync(voicesPath)) {
    log('[tts] Kokoro model/voices not found — Kokoro fallback unavailable');
    return false;
  }

  if (!isProxyReady()) {
    log('[tts] proxy-engine not ready — Kokoro fallback unavailable');
    return false;
  }

  log('[tts] generating announcement audio via Kokoro TTS (fallback)...');
  try {
    await sendProxyCommand('generate_tts', {
      model: modelPath,
      voices: voicesPath,
      voice: KOKORO_VOICE,
      text,
      output: wavPath,
    });
    log('[tts] Kokoro WAV generated (via proxy-engine)');
    return true;
  } catch (e: any) {
    log(`[tts] Kokoro failed: ${e.message}`);
    return false;
  }
}

// ---------------------------------------------------------------------------
// Initialization
// ---------------------------------------------------------------------------

/**
 * Pre-generate the announcement WAV file.
 * Must be called after the proxy engine is initialized.
 *
 * Engine priority: espeak-ng → Kokoro → disabled.
 */
export async function initAnnouncement(log: (msg: string) => void): Promise<boolean> {
  fs.mkdirSync(TTS_DIR, { recursive: true });

  try {
    if (!fs.existsSync(CACHE_WAV)) {
      let generated = false;

      // Try espeak-ng first.
      if (isEspeakAvailable()) {
        generated = generateViaEspeak(CACHE_WAV, ANNOUNCEMENT_TEXT, log);
      } else {
        log('[tts] espeak-ng not installed — trying Kokoro fallback');
      }

      // Fall back to Kokoro (via proxy-engine).
      if (!generated) {
        generated = await generateViaKokoro(CACHE_WAV, ANNOUNCEMENT_TEXT, log);
      }

      if (!generated) {
        log('[tts] no TTS engine available — announcements disabled');
        return false;
      }
    }

    log('[tts] announcement WAV ready');
    return true;
  } catch (e: any) {
    log(`[tts] init error: ${e.message}`);
    return false;
  }
}

/** Get the path to the cached announcement WAV, or null if not generated. */
export function getAnnouncementWavPath(): string | null {
  return fs.existsSync(CACHE_WAV) ? CACHE_WAV : null;
}