import axios from 'axios';

/**
 * Unwraps known link shims (Gmail, Outlook, etc.) and follows redirects
 * to find the final destination URL.
 */
export async function resolveUrl(url: string): Promise<string> {
    let currentUrl = url;

    try {
        const parsedUrl = new URL(url);

        // 1. Unwrap known shims

        // Google/Gmail Shim
        if (/google\.[a-z.]*$/.test(parsedUrl.hostname) &&
            parsedUrl.pathname === '/url' &&
            parsedUrl.searchParams.has('q')) {
            currentUrl = parsedUrl.searchParams.get('q') || currentUrl;
        }

        // Outlook Safelinks
        if (parsedUrl.hostname.includes('safelinks.protection.outlook.com') &&
            parsedUrl.searchParams.has('url')) {
            currentUrl = parsedUrl.searchParams.get('url') || currentUrl;
        }

        // LinkedIn Shim
        if (parsedUrl.hostname === 'lnkd.in' || (parsedUrl.hostname === 'www.linkedin.com' && parsedUrl.pathname.startsWith('/Check/'))) {
            // These are harder to unwrap without following
        }

        // 2. Follow redirects (optional, but good for bit.ly etc.)
        // We only follow if it's a known shortener or if we want to be thorough.
        const shorteners = ['bit.ly', 't.co', 'goo.gl', 'tinyurl.com', 'is.gd', 'buff.ly', 'adf.ly', 'lnkd.in'];
        const isShortener = shorteners.some(s => parsedUrl.hostname.includes(s));

        if (isShortener) {
            const response = await axios.head(currentUrl, {
                maxRedirects: 5,
                validateStatus: (status) => status >= 200 && status < 400
            });
            if (response.request.res.responseUrl) {
                currentUrl = response.request.res.responseUrl;
            }
        }

        return currentUrl;
    } catch (error) {
        console.error('Error resolving URL:', error);
        return url; // Return original if error
    }
}