script.js

/*
 * This program is licensed under the GNU GPL 3.0.
 * You may redistribute and modify it under the terms of the license.
 * See <https://www.gnu.org/licenses/gpl-3.0.html> for details.
 */


let isInvalid = false;
const inputField = document.getElementById('extensionInput');

// Handle form submission to download the extension
document.getElementById('extensionForm').addEventListener('submit', function (event) {
    event.preventDefault();
    downloadExtension();
});

// Update download options and focus on the input when browser selection changes
document.querySelectorAll('.browser-input').forEach(input => {
    input.addEventListener('change', function () {
        updateDownloadOptions();
        inputField.focus();
    });
});

// Keyboard shortcut '/' to focus on the input
document.addEventListener('keydown', function (event) {
    if (event.key === '/' && event.target.tagName !== 'INPUT') {
        event.preventDefault();
        inputField.focus();
    }
});

// Update download options based on the selected browser
function updateDownloadOptions() {
    const browser = document.querySelector('input[name="browser"]:checked').value;
    const downloadType = document.getElementById('downloadType');

    const options = {
        chrome: ['crx', 'zip'],
        firefox: ['xpi', 'zip'],
        opera: ['crx', 'zip'],
        edge: ['crx', 'zip']
    };

    downloadType.innerHTML = "";
    options[browser].forEach(format => {
        const option = document.createElement("option");
        option.value = format;
        option.textContent = `Download as ${format.toUpperCase()}`;
        downloadType.appendChild(option);
    });
}
updateDownloadOptions();

// Detect browser from input URL and update the browser selection
inputField.addEventListener("input", function () {
    detectBrowserFromUrl(this.value.trim());
});

function detectBrowserFromUrl(input) {
    const urlPatterns = {
        chrome: [
            /chrome\.google\.com\/webstore\/detail\//,
            /chromewebstore\.google\.com\/detail\//
        ],
        edge: [/microsoftedge\.microsoft\.com\/addons\/detail\//],
        opera: [/addons\.opera\.com\/.*extensions\/details\//],
        firefox: [
            /addons\.mozilla\.org\/.*addon\//,
            /addons\.allizom\.org\/.*addon\//,
            /addons-dev\.allizom\.org\/.*addon\//,
            /addons\.thunderbird\.net\/.*addon\//
        ]
    };

    for (const [browser, patterns] of Object.entries(urlPatterns)) {
        if (patterns.some(pattern => pattern.test(input))) {
            document.getElementById(browser).checked = true;
            updateDownloadOptions();
            break;
        }
    }
}

// Reset the border color in case of invalid input
inputField.addEventListener('input', function () {
    if (isInvalid) {
        inputField.style.borderColor = '';
        isInvalid = false;
    }
});

// Handle extension download logic
function downloadExtension() {
    const input = inputField.value.trim();
    const browserElement = document.querySelector('input[name="browser"]:checked');
    const browser = browserElement.value;
    const downloadType = document.getElementById('downloadType').value;
    let extensionId = extractExtensionId(input, browser);
    const downloadUrl = getDownloadUrl(browser, extensionId);

    if (!input) return;

    if (!extensionId) {
        inputField.style.borderColor = '#cc0f16';

        alert("Please enter a valid Extension ID or URL.");
        isInvalid = true;
        return;
    }

    if (downloadType === "zip") {
        if (browser === "firefox") {
            convertXpiToZip(downloadUrl, extensionId);
            return;
        }
        convertURLToZip(downloadUrl, extensionId);
        return;
    }

    window.location.href = downloadUrl;
}

// Extract extension ID from the URL based on the browser type
function extractExtensionId(input, browser) {
    const patterns = {
        chrome: /([a-z]{32})/,
        edge: /([a-z]{32})/,
        firefox: /addons(?:-dev)?\.(?:mozilla\.org|allizom\.org|thunderbird\.net)\/[^\/]+\/(?:firefox|thunderbird)\/addon\/([^\/?]+)/,
        opera: /(?:addons.opera.com\/.*?\/extensions\/details\/)([a-zA-Z0-9_-]+)(?=\/|$)/
    };

    // If input is already an extension ID, return it directly
    if ((browser === "firefox" || browser === "opera") && /^[a-zA-Z0-9_-]+$/.test(input)) {
        return input;
    }

    const match = patterns[browser]?.exec(input);

    return match ? match[1] : null;
}

// Get the base download URL for each browser
function getDownloadUrl(browser, extensionId) {
    const baseUrls = {
        chrome: `https://clients2.google.com/service/update2/crx?response=redirect&os=win&arch=x86-64&os_arch=x86-64&nacl_arch=x86-64&prod=chromiumcrx&prodchannel=unknown&prodversion=132.0.0.0&acceptformat=crx2,crx3&x=id%3D${extensionId}%26uc`,
        edge: `https://edge.microsoft.com/extensionwebstorebase/v1/crx?response=redirect&x=id%3D${extensionId}%26installsource%3Dondemand%26uc`,
        opera: `https://addons.opera.com/extensions/download/${extensionId}`,
    };

    const inputUrl = inputField.value.trim();
    if (browser === "firefox") {
        if (inputUrl.includes("addons.allizom.org")) {
            return `https://addons.allizom.org/firefox/downloads/latest/${extensionId}/platform:5/${extensionId}.xpi`;
        }
        if (inputUrl.includes("addons-dev.allizom.org")) {
            return `https://addons-dev.allizom.org/firefox/downloads/latest/${extensionId}/platform:5/${extensionId}.xpi`;
        }
        if (inputUrl.includes("addons.thunderbird.net")) {
            return `https://addons.thunderbird.net/firefox/downloads/latest/${extensionId}/platform:5/${extensionId}.xpi`;
        }
        else {
            return `https://addons.mozilla.org/firefox/downloads/latest/${extensionId}/platform:5/${extensionId}.xpi`;
        }
    }

    return baseUrls[browser];
}

// CRX to ZIP
function ArrayBufferToBlob(arraybuffer) {
    var buf = new Uint8Array(arraybuffer);
    var publicKeyLength, signatureLength, zipStartOffset;

    if (buf[4] === 2) {
        publicKeyLength = buf[8] + (buf[9] << 8) + (buf[10] << 16) + (buf[11] << 24);
        signatureLength = buf[12] + (buf[13] << 8) + (buf[14] << 16) + (buf[15] << 24);
        zipStartOffset = 16 + publicKeyLength + signatureLength;
    } else {
        publicKeyLength = buf[8] + (buf[9] << 8) + (buf[10] << 16) + (buf[11] << 24 >>> 0);
        zipStartOffset = 12 + publicKeyLength;
    }

    return new Blob([new Uint8Array(arraybuffer, zipStartOffset)], { type: 'application/zip' });
}

function convertURLToZip(url, extensionId) {
    fetch(url)
        .then(response => response.arrayBuffer())
        .then(arrayBuffer => {
            const zipBlob = ArrayBufferToBlob(arrayBuffer);
            const link = document.createElement("a");
            link.href = URL.createObjectURL(zipBlob);
            link.download = `${extensionId}.zip`;
            link.click();
        })
        .catch((error) => {
            console.error("Error converting CRX to ZIP:", error);
            alert(`Please ensure that the Extension ID or URL and browser are correct.\n\nIf it is, the request has been blocked due to the CORS policy.`);
        });
}

function convertCRXFileToZip(file, callback) {
    var reader = new FileReader();
    reader.onload = function (event) {
        var arrayBuffer = event.target.result;
        var zipBlob = ArrayBufferToBlob(arrayBuffer);
        callback(zipBlob);
    };
    reader.readAsArrayBuffer(file);
}

// XPI to ZIP
function convertXpiToZip(url, extensionId) {
    fetch(url)
        .then(response => response.arrayBuffer())
        .then(arrayBuffer => {
            var blob = new Blob([arrayBuffer], { type: "application/zip" });
            var zipUrl = URL.createObjectURL(blob);
            var link = document.createElement("a");
            link.href = zipUrl;
            link.download = extensionId + ".zip";
            document.body.appendChild(link);
            link.click();
            document.body.removeChild(link);
        })
        .catch((error) => {
            console.error("Error converting XPI to ZIP:", error);
            alert(`Please ensure that the Extension ID or URL and browser are correct.\n\nIf it is, the request has been blocked due to the CORS policy.\nSelect 'Download as XPI' and manually rename the file extension to .zip after downloading.`);
        });
}