var base_reader = undefined

function subscribe_link(reader, feed_url){
  if(reader == "ttrss"){
    return `${base_reader}/public.php?op=subscribe&feed_url=${encodeURIComponent(feed_url)}`;
  } else {
    return `${base_reader}/bookmarklet?uri=${encodeURIComponent(feed_url)}`;
  }
}

function insertElementsIntoRow(rowElement, elements){
    let tdElement = document.createElement("td")
    elements.forEach( el => tdElement.append(el))
    rowElement.append(tdElement)
}

function insertElementIntoRow(rowElement, element){
    let tdElement = document.createElement("td")
    tdElement.append(element)
    rowElement.append(tdElement)
}

function wrapInDiv(element){
    let wrapperDiv = document.createElement("div")
    wrapperDiv.append(element)
    return wrapperDiv
}

let itemMap = {
    "updated": "pubDate",
    "summary": "description",
}
function parseCollection(collection, entries){
    for(const child of collection){
        feedEntry = {"link": "", "title": "", "pubDate": "", "description": ""}
        for(const c of child.children){
            if(c.tagName == "link" && c.getAttribute("href")){
                feedEntry["link"] = c.getAttribute("href")
            } else {
                feedEntry[c.tagName] = c.innerHTML
            }
        }
        // Copy keys to normalized version
        for(const key in itemMap){
            if(feedEntry[key]){
                feedEntry[itemMap[key]] = feedEntry[key]
            }
        }
        entries.push(feedEntry)
    }
}

function previewOnclick(item){
    return function(){
        fetch(item.url)
            .then( r => r.text() )
            .then(r => new window.DOMParser().parseFromString(r, "text/xml"))
            .then(p => {
                let entries = []
                parseCollection(p.getElementsByTagName("entry"), entries)
                parseCollection(p.getElementsByTagName("item"), entries)

                let tableEl = document.createElement("table")
                tableEl.classList.add("preview")
                entries.forEach(entry => {
                    let trEl = document.createElement("tr")
                    tableEl.append(trEl)

                    let titleEl = document.createElement("a")
                    titleEl.href = entry["link"]
                    titleEl.innerText = entry["title"]

                    let wrapperDiv2 = document.createElement("div")
                    wrapperDiv2.innerText = entry["pubDate"]

                    insertElementsIntoRow(trEl, [
                        wrapInDiv(titleEl), wrapperDiv2
                    ])

                    let td3El = document.createElement("td")
                    td3El.innerText = entry["description"]
                    trEl.append(td3El)
                })
                feeds.append(tableEl)
            })
    }
}

window.onload = async function () {
    let settings = await browser.storage.sync.get(["rb", "reader", "instance"]);
    base_reader = settings.instance;
    let base_rb = settings.rb;
    let feedsElement = document.getElementById('feeds');
    feedsElement.innerText = "Loading..."
    browser.tabs.query({ active: true, currentWindow: true }, function (tabs) {
        browser.tabs.sendMessage(tabs[0].id, {}).then(
            function (feeds) {
                feedsElement.innerText = ""
                if(!base_rb) {
                    let newSettingsLink = document.createElement("a")
                    newSettingsLink["href"] = "/options.html"
                    newSettingsLink.innerText = "RSS-bridge instance not set! Click here to open options.";
                    let newDiv = document.createElement('div');
                    newDiv.append(newSettingsLink);
                    feedsElement.appendChild(newDiv);

                    let newP = document.createElement('p')
                    newP.innerText = `Found ${feeds.length} feeds`
                    feedsElement.append(newP)
                    return;
                }

                let table = document.createElement("table")
                table.classList.add("feeds")
                feedsElement.append(table)
                feeds.forEach(feed => {
                    let newRow = document.createElement("tr")
                    table.append(newRow)

                    let newLink = document.createElement('a');
                    newLink["href"] = feed.url
                    newLink.innerText = feed.name;
                    insertElementIntoRow(newRow, newLink)

                    let previewLink = document.createElement('a');
                    previewLink["onclick"] = previewOnclick(feed)
                    previewLink["href"] = "#"
                    previewLink.innerText = "preview";

                    let newPreviewData = document.createElement("td")
                    // Preview only works for XML feeds
                    if(
                        feed.type.toLowerCase().includes("rss") ||
                        feed.type.toLowerCase().includes("xml") ||
                        feed.type.toLowerCase().includes("atom")
                    ){
                        newPreviewData.append(previewLink)
                    }
                    newRow.append(newPreviewData)

                    if(base_reader){
                        let subLink = document.createElement('a');
                        subLink["href"] = subscribe_link(settings.reader, feed.url)
                        subLink.innerText = "subscribe";
                        let newSubData = document.createElement("td")
                        newSubData.append(subLink)
                        newRow.append(newSubData)
                    }
                })
                if(feeds.length == 0) {
                    let newP = document.createElement('p')
                    newP.innerText = "No feeds found"
                    feedsElement.append(newP)
                }
            });
    });
}