var base_url = undefined
let formats = ["Atom", "Mrss", "Html"]
let types = {
    'application/rss+xml': "rss",
    'application/atom+xml': "atom",
    'application/rdf+xml': "rdf",
    'application/rss': "rss",
    'application/atom': "atom",
    'application/rdf': "rdf",
    'text/rss+xml': "rss",
    'text/atom+xml': "atom",
    'text/rdf+xml': "rdf",
    'text/rss': "rss",
    'text/atom': "atom",
    'text/rdf': "rdf"
}

function normalize_feed_url(feed_url) {
    if (feed_url.startsWith('/')) {
        let url = window.location.href
        feed_url = url.split('/')[0] + '//' + url.split('/')[2] + feed_url;
    }
    return feed_url
}

function find_links_in_page() {
    let links = document.querySelectorAll('link[type]');
    let feeds = [];
    for (let i = 0; i < links.length; i++) {
        if (links[i].hasAttribute('type') && links[i].getAttribute('type') in types) {
            let title = links[i].getAttribute('title')
            let feed_url = normalize_feed_url(links[i].getAttribute('href'));
            let type = types[links[i].getAttribute('type')]
            let feed = {
                type: `native: ${title || type}`,
                url: feed_url,
            };
            feeds.push(feed);
        }
    }
    return feeds
}

function get_all_types(feed_url) {
    let feeds = [];
    formats.forEach(el => {
        feeds.push({
            type: `rss-bridge: ${el}`,
            url: feed_url + el
        });
    })
    return feeds;
}

async function get_insta(url) {
    let insta_url = url + "?__a=1"
    console.log("fetching")
    let res = await fetch(insta_url);
    let json = await res.json();
    let uid = json.graphql.user.id
    let feed_url = `${base_url}/?action=display&bridge=Instagram&context=Username&u=${uid}&media_type=all&format=`;
    return get_all_types(feed_url)
}

function get_twitter(url) {
    let pattern = /twitter.com\/(\w+).*/
    let match = url.match(pattern);
    if (match) {
        let twitter_handle = match[1]
        let feed_url = `${base_url}/?action=display&bridge=Twitter&context=By+username&u=${twitter_handle}&format=`
        return get_all_types(feed_url)
    }
    return []
}

async function get_youtube(url) {
    // use link to channel if given a video url
    let patternVideo = /youtube.com\/watch\?v=\w+/
    if (url.match(patternVideo)) {
        url = document.querySelector("#channel-name a")["href"]
    }

    let patternUser = /youtube.com\/user\/(\w+).*/
    let matchUser = url.match(patternUser)

    let patternChannel = /youtube.com\/channel\/(\w+).*/
    let matchChannel = url.match(patternChannel)

    let patternPlaylist = /youtube.com\/playlist\?list=(\w+)/
    let matchPlaylist = url.match(patternPlaylist)

    
    if (matchUser) {
        let user = matchUser[1];
        let feed_url = `${base_url}/?action=display&bridge=Youtube&context=By+username&u=${user}&duration_min=&duration_max=&format=`
        return get_all_types(feed_url)
    } else if (matchChannel) {
        let channelId = matchChannel[1]
        let feed_url = `${base_url}/?action=display&bridge=Youtube&context=By+channel+id&c=${channelId}&duration_min=&duration_max=&format=`
        return get_all_types(feed_url)
    } else if (matchPlaylist) {
        let playlistId = matchPlaylist[1]
        let native_url = `https://www.youtube.com/feeds/videos.xml?playlist_id=${playlistId}`
        let feed_url = `${base_url}/?action=display&bridge=Youtube&context=By+playlist+Id&p=${playlistId}&duration_min=&duration_max=&format=`
        let rb_feeds = get_all_types(feed_url)
        return rb_feeds.concat([{ type: `native: Rss`, url: native_url }])
    } 
    return []
}

async function get_feed_urls() {
    let settings = await browser.storage.sync.get("rb");
    base_url = settings.rb;
    let all_feed_urls = []
    let url = window.location.href;
    //url = url.toLowerCase()
    if (url.includes("instagram")) {
        all_feed_urls = all_feed_urls.concat(await get_insta(url))
    } else if (url.includes("twitter")) {
        all_feed_urls = all_feed_urls.concat(get_twitter(url))
    } else if (url.includes("youtube")) {
        all_feed_urls = all_feed_urls.concat(await get_youtube(url))
    }
    all_feed_urls = all_feed_urls.concat(find_links_in_page())
    return all_feed_urls
}

browser.runtime.onMessage.addListener(function (msg, sender) {
    return Promise.resolve(get_feed_urls());
})