export default {
    async fetch(request) {
        const url = new URL(request.url);
        const { hostname, pathname, search } = url;
        if (checkUrl(pathname)) {
            const response = await fetch(new Request("https://github.com" + pathname + search, {
                body: request.body,
                headers: request.headers,
                method: request.method,
                redirect: "follow"
            }));
            const responseText = await response.text();
            const modifiedText = responseText.replace(/github\.com/g, hostname);

            return new Response(modifiedText, {
                status: response.status,
                statusText: response.statusText,
                headers: response.headers
            });
        } else {
            let tip = `GitHub 下载代理，支持 releases、archive、tags、raw 等。\n\n\n\n
使用方法：
将 Github 原链接中的 【github.com】 改为 【${hostname}】。\n
例如：
【https://github.com/a/a/releases】
                  ↓
【https://${hostname}/a/a/releases】`
            return new Response(tip);
        }
    }
};

function checkUrl(u) {
    const exp1 = "/.+?\/.+?\/(?:releases|archive|tags).*"
    const exp2 = "/.+?\/.+?\/raw\/.*"
    for (let ind of [exp1, exp2]) {
        if (u.search(ind) === 0) {
            return true
        }
    }
    return false
}