var Swap = (() => {
    "use strict";
    var loaders = {}, unloaders = {};
    register_links();
    new MutationObserver(dom_changes).observe(document.querySelector("html"), { childList: true, subtree: true });
    window.addEventListener("popstate", () => update(location.href, "[swap-history-restore]", false, "body"));
    window.addEventListener("DOMContentLoaded", dom_load);
    function update(href, target, pushstate, fallback = null) {
        fetch(href, { headers: new Headers({"swap-target": target}) }).then(r => r.text()).then(html => {
            var tmp = document.createElement('html');
            tmp.innerHTML = html;
            (document.querySelector(target) ?? document.querySelector(fallback)).outerHTML = (tmp.querySelector(target) ?? tmp.querySelector(fallback)).outerHTML;
            if (pushstate)
                history.pushState({}, "", href);
            register_links();  
        });
    }
    function register_links() {
        for (const elt of document.querySelectorAll('*[swap-target]'))
            elt.onclick = e => {
                update(elt.getAttribute('href'), elt.getAttribute('swap-target'), elt.getAttribute('swap-history'));
                e.preventDefault();
            }
    }
    function dom_changes(mutations) {
        for (var selector in unloaders)
            for (var m of mutations)
                for (var n of m.removedNodes)
                    if (n.matches && n.querySelector && (n.matches(selector) || n.querySelector(selector))) {
                        unloaders[selector]();
                        delete unloaders[selector];
                    }
        for (var selector in loaders)
            for (var m of mutations)
                for (var n of m.addedNodes) 
                    if (n.matches && n.querySelector && (n.matches(selector) || n.querySelector(selector)))
                            unloaders[selector] = loaders[selector]();
    }
    function dom_load() {
        for (var selector in loaders)
            if (document.querySelector(selector))
                    unloaders[selector] = loaders[selector]();
    }
    return {loaders: loaders};
})();