import { WebSocket } from 'ws';

const VIBEVOICE_HOST = process.env.VIBEVOICE_HOST || 'localhost:3001';
const VOICE = process.env.VIBEVOICE_VOICE || 'en-Emma_woman';
const MAX_BUSY_RETRIES = 30;
const BUSY_RETRY_DELAY_MS = 1000;

export async function synthesize(text: string): Promise<Buffer> {
  for (let attempt = 0; attempt <= MAX_BUSY_RETRIES; attempt++) {
    try {
      return await _synthesizeOnce(text);
    } catch (err: any) {
      if (err.message === 'VibeVoice: server busy' && attempt < MAX_BUSY_RETRIES) {
        await new Promise(r => setTimeout(r, BUSY_RETRY_DELAY_MS));
        continue;
      }
      throw err;
    }
  }
  throw new Error('VibeVoice: server busy after max retries');
}

function _synthesizeOnce(text: string): Promise<Buffer> {
  const params = new URLSearchParams({ text, voice: VOICE, cfg: '1.5' });
  const wsUrl = `ws://${VIBEVOICE_HOST}/stream?${params}`;

  return new Promise((resolve, reject) => {
    const ws = new WebSocket(wsUrl);
    const chunks: Buffer[] = [];
    let done = false;

    const finish = (err?: Error) => {
      if (done) return;
      done = true;
      ws.terminate();
      if (err) {
        reject(err);
      } else {
        resolve(Buffer.concat(chunks));
      }
    };

    ws.on('message', (data: Buffer, isBinary: boolean) => {
      if (isBinary) {
        chunks.push(Buffer.from(data));
      } else {
        try {
          const msg = JSON.parse(data.toString());
          if (msg.event === 'backend_stream_complete') {
            finish();
          } else if (msg.event === 'backend_error') {
            finish(new Error(`VibeVoice: ${msg.data?.message || 'generation error'}`));
          } else if (msg.event === 'backend_busy') {
            finish(new Error('VibeVoice: server busy'));
          }
        } catch {}
      }
    });

    ws.on('error', (err) => finish(new Error(`VibeVoice WebSocket: ${err.message}`)));

    ws.on('close', () => {
      if (!done) {
        if (chunks.length > 0) finish();
        else finish(new Error('VibeVoice: closed without audio'));
      }
    });

    setTimeout(() => {
      if (!done) finish(new Error('VibeVoice: timeout (60s)'));
    }, 60000);
  });
}