const urlPatterns = ['*://danbooru.donmai.us/posts/*'];

let pairs;
let tabsLeft = 0;

function saveAs(filename, text) {
    let href = 'data:text/plain;charset=utf-8,' + encodeURIComponent(text);

    let element = document.createElement('a');
    element.href = href;
    element.download = filename;
    element.click();
}

function onResponse(id, url) {
    pairs.push({ id: id, url: url });

    tabsLeft--;

    if (tabsLeft == 0) {
        pairs = pairs.filter(p => p.url != null);

        let urls = pairs.map(p => p.url);
        urls = [...new Set(urls)];
        urlText = urls.join('\n');
        saveAs('urls', urlText);

        let ids = pairs.map(p => p.id);
        chrome.tabs.remove(ids);
    }
}

function getURLs() {
    if (tabsLeft > 0) {
        return;
    }

    chrome.tabs.query({ url: urlPatterns }, tabs => {
        pairs = [];
        tabsLeft = tabs.length;

        for (tab of tabs) {
            let id = tab.id;
            chrome.tabs.sendMessage(tab.id, "", null, url => onResponse(id, url));
        }
    });
}


chrome.browserAction.onClicked.addListener(getURLs);

//TODO: Disable browser action when no booru tab is found