index.js

// Imports
import { Zip, ZipDeflate } from "https://esm.sh/fflate@0.8.2";

// Constants
const CORS_PROXY = "https://shcors.uwu.network/"; // TODO: Use my own proxy
const TRACKER_URL = "https://tracker.vendetta.rocks/tracker";
const FILE_NAMES = [
    "base",
    "config.arm64_v8a",
    "config.armeabi_v7a",
    "config.x86_64",
    "config.x86",
    "config.hdpi",
    "config.xxhdpi",
    "config.de",
    "config.en",
];

// Little fetch wrapper
async function mFetch(url, options) {
    const res = await fetch(CORS_PROXY + url, options);
    if (!res.ok) throw new Error("Response gave non-ok status code");

    return res;
}

// Love me some file downloading (I hate this)
function downloadFile(data, fileName) {
    const downloadable = document.createElement("a");
    downloadable.href = URL.createObjectURL(new Blob([data]));
    downloadable.download = fileName;
    downloadable.click();
    downloadable.remove();
}

// Split APK creation logic
const createAPKZip = (version) => new Promise(async (resolve, reject) => {
    const parts = [];

    const zip = new Zip((err, data, done) => {
        if (err) reject(err);
        parts.push(data);

        if (done) {
            const final = new Uint8Array(parts.map((i) => i.length).reduce((a, b) => a + b, 0));
            let offset = 0;

            for (const part of parts) {
                final.set(part, offset);
                offset += part.length;
            }
            
            resolve(final);
        }
    });

    const responses = await Promise.all(FILE_NAMES.map(async (fileName) => [await mFetch(TRACKER_URL + `/download/${version}/${fileName}`), fileName]));

    let done = 0;
    const max = responses.map(([r,]) => r.headers.get("Content-Length")).reduce((a, b) => a + parseInt(b), 0);

    await Promise.all(responses.map(async ([response, fileName]) => {
        const apkFile = new ZipDeflate(`${fileName}.apk`, { level: 9 });
        zip.add(apkFile);

        for await (const chunk of response.body) {
            done += chunk.length;
            apkFile.push(chunk);
            downloadBar.style.width = `${done / max * 100}%`;
        }
        apkFile.push("", true);

        console.log(`downloaded ${fileName}`);
        return apkFile;
    }));

    zip.end();
});

// Get some elements
const versionInput = document.getElementById("version-input");
const versionSelect = document.getElementById("version-select");
const downloadButton = document.getElementById("download-button");
const downloadStatus = document.getElementById("download-status");
const downloadBar = document.getElementById("download-bar");

// Attempt to fetch latest versions
let latestVersions;

try {
    const data = await (await mFetch(TRACKER_URL + "/index")).json();
    latestVersions = data.latest;
} catch {
    alert("failed to fetch latest versions from tracker, try reloading?");
}

// Set the version string textbox to the latest stable if we have it
versionInput.value = latestVersions.stable;

// Add select handlers
versionSelect.addEventListener("change", () => {
    if (!latestVersions) return;

    const versionType = versionSelect.options[versionSelect.selectedIndex].value;
    versionInput.value = latestVersions[versionType];
});

// Download handler
downloadButton.addEventListener("click", async () => {
    const version = versionInput.value;

    downloadButton.disabled = true;
    downloadStatus.innerText = `downloading ${version}...`;
    downloadBar.style.display = "initial";

    createAPKZip(version).then((zip) => {
        downloadFile(zip, `Discord-${version}.zip`);
        downloadStatus.innerText = "success :D";
    }).catch((err) => {
        console.error(err);
        alert("failed - check the console?");
        downloadStatus.innerText = "failed :<";
    }).finally(() => {
        setTimeout(() => {
            downloadStatus.innerText = "download";
            downloadBar.style.width = null;
            downloadBar.style.display = "none";
        }, 2000);
        downloadButton.disabled = false;
    });
});