PronounsPage/server/express/pronounce.ts

import { Polly } from '@aws-sdk/client-polly';
import { S3, NoSuchKey } from '@aws-sdk/client-s3';
import type { NodeJsClient } from '@smithy/types';
import { Router } from 'express';
import { Base64 } from 'js-base64';
import sha1 from 'sha1';

import { convertPronunciationStringToSsml, handleErrorAsync } from '../../src/helpers.ts';
import { awsConfig, awsParams } from '../aws.ts';

const router = Router();

router.get('/pronounce/:voice/:pronunciation', handleErrorAsync(async (req, res) => {
    const text = Base64.decode(req.params.pronunciation);

    if (!text || text.length > 256) {
        return res.status(404).json({ error: 'Not found' });
    }

    const voice = global.config.pronunciation?.voices?.[req.params.voice];
    if (!voice) {
        return res.status(404).json({ error: 'Not found' });
    }

    const s3 = new S3(awsConfig) as NodeJsClient<S3>;
    const polly = new Polly(awsConfig) as NodeJsClient<Polly>;

    const ssml = convertPronunciationStringToSsml(text);
    const key = `pronunciation/${global.config.locale}-${req.params.voice}/${sha1(ssml)}.mp3`;

    try {
        const s3Response = await s3.getObject({ Key: key, ...awsParams });
        res.set('content-type', s3Response.ContentType);
        return s3Response.Body!.pipe(res);
    } catch (error) {
        if (!(error instanceof NoSuchKey)) {
            throw error;
        }
        const pollyResponse = await polly.synthesizeSpeech({
            TextType: 'ssml',
            Text: ssml,
            OutputFormat: 'mp3',
            LanguageCode: voice.language,
            VoiceId: voice.voice,
            Engine: voice.engine,
        });
        const buffer = await pollyResponse.AudioStream!.transformToByteArray();
        await s3.putObject({
            Key: key,
            Body: buffer,
            ContentType: pollyResponse.ContentType,
            ...awsParams,
        });

        res.set('content-type', pollyResponse.ContentType);
        res.write(buffer);
        return res.end();
    }
}));

export default router;