postinstall.js

import fs from 'fs';
import path from 'path';
import os from 'os';
import https from 'https';
import yauzl from 'yauzl';
import { fileURLToPath } from 'url';

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);

const URL = "https://alphacephei.com/vosk/models/vosk-model-small-en-us-0.15.zip";
const MODEL_DIR = path.resolve(__dirname, "model");

async function main() {
    if (!fs.existsSync(MODEL_DIR)) {
        fs.mkdirSync(MODEL_DIR, { recursive: true });
    }

    if (fs.existsSync(path.resolve(MODEL_DIR, "DONE"))) {
        console.log("Model already downloaded");
        return;
    }

    const zip = path.resolve(os.tmpdir(), path.basename(URL));
    await download(URL, zip);
    console.log("Downloaded model to", zip);

    await unzip(zip, MODEL_DIR);
    fs.unlinkSync(zip);
}

function download(url, to, redirect = 0) {
    if (redirect === 0) {
        console.log(`Downloading ${url} to ${to}`);
    } else {
        console.log(`Redirecting to ${url}`);
    }

    return new Promise((resolve, reject) => {
        if (!fs.existsSync(path.dirname(to))) {
            fs.mkdirSync(path.dirname(to), { recursive: true });
        }

        let done = true;
        const file = fs.createWriteStream(to);
        const request = https.get(url, (res) => {
            if (res.statusCode === 302 && res.headers.location !== undefined) {
                done = false;
                file.close();
                resolve(download(res.headers.location, to, redirect + 1));
                return;
            }
            res.pipe(file);
        });

        file.on("finish", () => {
            if (done) {
                resolve(to);
            }
        });

        request.on("error", (err) => {
            fs.unlink(to, () => reject(err));
        });

        file.on("error", (err) => {
            fs.unlink(to, () => reject(err));
        });

        request.end();
    });
}

function unzip(zip, dest) {
    const dir = path.basename(zip, ".zip");
    return new Promise((resolve, reject) => {
        yauzl.open(zip, { lazyEntries: true }, (err, zipfile) => {
            if (err) {
                reject(err);
            }
            zipfile.readEntry();
            zipfile
                .on("entry", (entry) => {
                    if (/\/$/.test(entry.fileName)) {
                        zipfile.readEntry();
                    } else {
                        zipfile.openReadStream(entry, (err, stream) => {
                            if (err) {
                                reject(err);
                            }
                            const f = path.resolve(dest, entry.fileName.replace(`${dir}/`, ""));
                            if (!fs.existsSync(path.dirname(f))) {
                                fs.mkdirSync(path.dirname(f), { recursive: true });
                                console.log("Created directory", path.dirname(f));
                            }
                            stream.pipe(fs.createWriteStream(f));
                            stream
                                .on("end", () => {
                                    console.log("Extracted", f);
                                    zipfile.readEntry();
                                })
                                .on("error", (err) => {
                                    reject(err);
                                });
                        });
                    }
                })
                .on("error", (err) => {
                    reject(err);
                })
                .on("end", () => {
                    console.log("Extracted all files");
                    fs.writeFileSync(path.resolve(dest, "DONE"), "");
                })
                .on("close", () => {
                    resolve();
                });
        });
    });
}

main().catch(console.error);