worker.js

const ITEM_REGEX = /[a-zA-Z0-9]+\.(png|jpe?g|gifv?)/;
const DOMAIN = "cdn.elitedamyth.xyz"
addEventListener('fetch', event => {
    event.respondWith(handleRequest(event));
})

async function handleRequest(event) {
    let resp;
    if (event.request.method == 'POST') {
        let json = await event.request.json();
        resp = json.url.replace("i.imgur.com", DOMAIN)
        return new Response(resp);
    } else {
        const request = event.request;
        const url = new URL(request.url);
        const path = url.pathname.substring(1);

        if (!path) {
            return jsonError('No Filename', 406);
        }

        if (!ITEM_REGEX.test(path)) {
            return jsonError('Not found', 404);
        }
        resp = fetchImgurImage(path, event)
    }
    return resp;
}


async function fetchImgurImage(imageId, event) {
    const lookUpUrl = "http://i.imgur.com/" + imageId;
    const cache = caches.default;
    let response = await cache.match(lookUpUrl);

    if (!response) {
        const imageResponse = await fetch(lookUpUrl, {
            headers: {
                'User-Agent': "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/80.0.3987.149 Safari/537.36",
            }
        });

        const headers = {
            'cache-control': 'public, max-age=31536000',
        };
        const cloned = imageResponse.clone();

        response = new Response(cloned.body, {
            ...cloned,
            headers
        });

        if (imageResponse.status === 200) {
            event.waitUntil(cache.put(lookUpUrl, imageResponse.clone()));
        }
    }

    return response;
}


function jsonError(message, status = 400) {
    return new Response(
        JSON.stringify({
            error: message
        }), {
            status: status,
            headers: {
                'content-type': 'application/json'
            }
        }
    );
}