memind/wechat-voice-reco.mjs

import crypto from 'node:crypto';
import { spawn } from 'node:child_process';
import fs from 'node:fs/promises';
import os from 'node:os';
import path from 'node:path';

export const DEFAULT_WECHAT_VOICE_RECO_API_BASE = 'https://api.weixin.qq.com';
export const DEFAULT_WECHAT_VOICE_RECO_LANG = 'zh_CN';
export const WECHAT_VOICE_RECO_MAX_MP3_BYTES = 1024 * 1024;
export const WECHAT_VOICE_RECO_DEFAULT_POLL_INTERVAL_MS = 300;
export const WECHAT_VOICE_RECO_DEFAULT_POLL_TIMEOUT_MS = 8000;

export function buildWechatVoiceRecoVoiceId({ msgId = '', mediaId = '' } = {}) {
  const raw = String(msgId || mediaId || '').trim();
  if (raw) return raw.slice(0, 64);
  return crypto.randomUUID().replace(/-/g, '');
}

function resolveFfmpegPath(explicitPath = '') {
  const configured = String(explicitPath ?? process.env.H5_FFMPEG_PATH ?? '').trim();
  return configured || 'ffmpeg';
}

function runFfmpeg(ffmpegPath, args) {
  return new Promise((resolve, reject) => {
    const proc = spawn(ffmpegPath, args, { stdio: ['ignore', 'ignore', 'pipe'] });
    let stderr = '';
    proc.stderr.on('data', (chunk) => {
      stderr += chunk;
    });
    proc.on('error', reject);
    proc.on('close', (code) => {
      if (code === 0) {
        resolve(undefined);
        return;
      }
      reject(new Error(stderr.trim() || `ffmpeg exit ${code}`));
    });
  });
}

export async function convertWechatVoiceToMp3(
  buffer,
  {
    format = 'amr',
    ffmpegPath = resolveFfmpegPath(),
  } = {},
) {
  if (!Buffer.isBuffer(buffer) || buffer.length === 0) return null;

  const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'memind-wechat-voice-'));
  const extension = String(format ?? '').trim().toLowerCase() || 'amr';
  const inputPath = path.join(tmpDir, `input.${extension}`);
  const outputPath = path.join(tmpDir, 'output.mp3');

  try {
    await fs.writeFile(inputPath, buffer);
    await runFfmpeg(ffmpegPath, [
      '-y',
      '-i',
      inputPath,
      '-ar',
      '16000',
      '-ac',
      '1',
      '-f',
      'mp3',
      outputPath,
    ]);
    const mp3Buffer = await fs.readFile(outputPath);
    if (!mp3Buffer.length || mp3Buffer.length > WECHAT_VOICE_RECO_MAX_MP3_BYTES) {
      return null;
    }
    return mp3Buffer;
  } catch {
    return null;
  } finally {
    await fs.rm(tmpDir, { recursive: true, force: true }).catch(() => {});
  }
}

async function readWechatApiPayload(response) {
  const text = await response.text();
  if (!text) return { payload: null, text: '' };
  try {
    return { payload: JSON.parse(text), text };
  } catch {
    return { payload: null, text };
  }
}

function assertWechatApiOk(payload, fallbackText, httpStatus) {
  const errcode = Number(payload?.errcode ?? 0);
  if (errcode !== 0) {
    throw new Error(String(payload?.errmsg ?? fallbackText ?? `WeChat API error ${errcode}`));
  }
  if (!httpStatus || httpStatus < 200 || httpStatus >= 300) {
    throw new Error(fallbackText || `WeChat HTTP ${httpStatus}`);
  }
}

export function isRetryableWechatVoiceRecoQueryError(payload) {
  const errcode = Number(payload?.errcode ?? 0);
  return errcode === -1 || errcode === 87009;
}

async function queryWechatVoiceRecoResultOnce({
  apiBase = DEFAULT_WECHAT_VOICE_RECO_API_BASE,
  accessToken,
  voiceId,
  lang = DEFAULT_WECHAT_VOICE_RECO_LANG,
  wechatFetch,
}) {
  if (!accessToken) throw new Error('缺少微信 access_token');
  if (!voiceId) throw new Error('缺少 voice_id');

  const url = new URL('/cgi-bin/media/voice/queryrecoresultfortext', apiBase);
  url.searchParams.set('access_token', accessToken);
  url.searchParams.set('voice_id', voiceId);
  url.searchParams.set('lang', lang);

  const response = await wechatFetch(url.toString(), { method: 'POST' });
  const { payload, text } = await readWechatApiPayload(response);
  if (isRetryableWechatVoiceRecoQueryError(payload)) {
    return '';
  }
  assertWechatApiOk(payload, text, response.status);
  return String(payload?.result ?? '').trim();
}

export async function uploadWechatVoiceForReco({
  apiBase = DEFAULT_WECHAT_VOICE_RECO_API_BASE,
  accessToken,
  voiceId,
  mp3Buffer,
  lang = DEFAULT_WECHAT_VOICE_RECO_LANG,
  wechatFetch,
}) {
  if (!accessToken) throw new Error('缺少微信 access_token');
  if (!voiceId) throw new Error('缺少 voice_id');
  if (!Buffer.isBuffer(mp3Buffer) || !mp3Buffer.length) {
    throw new Error('语音内容为空');
  }

  const url = new URL('/cgi-bin/media/voice/addvoicetorecofortext', apiBase);
  url.searchParams.set('access_token', accessToken);
  url.searchParams.set('format', 'mp3');
  url.searchParams.set('voice_id', voiceId);
  url.searchParams.set('lang', lang);

  const form = new FormData();
  form.append('media', new Blob([mp3Buffer], { type: 'audio/mpeg' }), 'voice.mp3');

  const response = await wechatFetch(url.toString(), { method: 'POST', body: form });
  const { payload, text } = await readWechatApiPayload(response);
  assertWechatApiOk(payload, text, response.status);
  return payload;
}

export async function queryWechatVoiceRecoResult(options) {
  return queryWechatVoiceRecoResultOnce(options);
}

function sleep(ms) {
  return new Promise((resolve) => {
    setTimeout(resolve, ms);
  });
}

export async function transcribeWechatVoiceViaRecoApi({
  accessToken,
  voiceBuffer,
  format = 'amr',
  voiceId,
  lang = DEFAULT_WECHAT_VOICE_RECO_LANG,
  apiBase = DEFAULT_WECHAT_VOICE_RECO_API_BASE,
  wechatFetch,
  pollIntervalMs = WECHAT_VOICE_RECO_DEFAULT_POLL_INTERVAL_MS,
  pollTimeoutMs = WECHAT_VOICE_RECO_DEFAULT_POLL_TIMEOUT_MS,
  convertToMp3 = convertWechatVoiceToMp3,
  now = Date.now,
}) {
  const mp3Buffer = await convertToMp3(voiceBuffer, { format });
  if (!mp3Buffer?.length) return '';

  await uploadWechatVoiceForReco({
    apiBase,
    accessToken,
    voiceId,
    mp3Buffer,
    lang,
    wechatFetch,
  });

  const deadline = now() + Math.max(0, pollTimeoutMs);
  while (now() < deadline) {
    const result = await queryWechatVoiceRecoResultOnce({
      apiBase,
      accessToken,
      voiceId,
      lang,
      wechatFetch,
    });
    if (result) return result;
    await sleep(Math.max(1, pollIntervalMs));
  }

  return '';
}