// vim: tabstop=4 shiftwidth=4 expandtab

function makeid(length) {
    let result = '';
    const characters = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz';
    const charactersLength = characters.length;
    let counter = 0;
    while (counter < length) {
        result += characters.charAt(Math.floor(Math.random() * charactersLength));
        counter += 1;
    }
    return result;
}

function checkAuth(request) {
    const auth = request.headers.get("Authorization");
    return auth === AUTH_KEY;
}

function getHost(request) {
    return request.headers.get("Host")
}

async function add(host,path,request) {
    if (!request.headers.get("content-type"))
        return new Response("No URL provided", {status:400})
    const data = await request.formData()
    const dest = data.get("u")
    if (!dest) return new Response("No URL provided",{status:400})
    try {
        new URL(dest)
    } catch (e) {
        if (e instanceof TypeError)
            return new Response("No valid URL provided",{status:400});
        else throw e;
    };
    if (!path) return new Response("No path provided",{status:400})
    if (path === "_") {
        var x = 0
        while (true) {
            path = makeid(4)
            const lookup = await KV.get(path)
            if (!lookup) break
            if (x >= 5) return new Response("Failed to generate a unique ID in 5 attempts", {status:500});
            x += 1
        }
    }
    await KV.put(path, dest)
    return new Response(`https://${host}/${path}`, {status:201})
}

async function remove(host,path) {
    if (!path) return new Response("No path provided",{status:400})
    await KV.delete(path)
    return new Response(`DELETE https://${host}/${path}`, {status:200})
}

async function get(host,path,auth) {
    if (!path && auth) {
        const { keys } = await KV.list()
        let paths = ""
        keys.forEach(element => paths += `${element.name}\n`);
        return new Response(paths,{status:200})
    }
    if (!path) return Response.redirect("https://aly-smith.carrd.co",301)
    const dest = await KV.get(path)
    if (dest) return Response.redirect(dest, 302)
    return new Response("Path not found", {status:404})
}

async function handleRequest(request) {
    const host = getHost(request)
    const url = new URL(request.url)
    var path = url.pathname.split("/")[1]
    switch (request.method) {
        case "PUT":
        case "POST":
        case "PATCH":
            if (!checkAuth(request))
                return new Response("Only GET requests allowed to unauthed users", {status:403});
            return add(host,path,request)
        case "DELETE":
            if (!checkAuth(request))
                return new Response("Only GET requests allowed to unauthed users", {status:403});
            return remove(host,path)
        case "HEAD":
        case "GET":
            return get(host,path,checkAuth(request))
        default:
            return new Response("Method not allowed", {status:405})
    }
}

addEventListener('fetch', event => {
    const { request } = event;
    return event.respondWith(handleRequest(request));
});