Text to Speech for Newsletters and Email Content

// webhook.js: Express route called by Beehiiv (or any newsletter platform)
// on each new post publication. Generates an MP3 and uploads to S3.
import express from "express";
import { S3Client, PutObjectCommand } from "@aws-sdk/client-s3";

const app = express();
app.use(express.json());

const s3 = new S3Client({ region: "eu-central-1" });

app.post("/hooks/newsletter-publish", async (req, res) => {
  const { slug, body_text, lang = "en" } = req.body;

  // Generate audio edition
  const ttsRes = await fetch("https://audexum.com/api/synthesize", {
    method: "POST",
    headers: {
      Authorization: `Bearer ${process.env.AUDEXUM_API_KEY}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({ text: body_text, voice: "F1", lang, format: "mp3" }),
  });

  if (!ttsRes.ok) {
    return res.status(502).json({ error: await ttsRes.text() });
  }

  const audioBuffer = Buffer.from(await ttsRes.arrayBuffer());

  // Upload to S3, serve via signed URL or CDN
  await s3.send(new PutObjectCommand({
    Bucket: process.env.AUDIO_BUCKET,
    Key: `newsletters/${slug}.mp3`,
    Body: audioBuffer,
    ContentType: "audio/mpeg",
  }));

  res.json({ ok: true, key: `newsletters/${slug}.mp3` });
});

app.listen(3000);