/*
 * DOM Filter Copyright (C) 2024 Thedro Neely
 * Licence: AGPL | https://www.gnu.org/licenses/agpl-3.0.txt
*/

(function () {
  type millisecond = number;
  const timeout: millisecond = 300;

  const state = "on";
  const key = "config.navigation.fast";

  function fetch(url, method, callback) {
    const http = new XMLHttpRequest();
    http.onreadystatechange = function () {
      if (callback && http.readyState === 4) {
        if (http.status === 200) callback(http);
        else {
          console.error("ERROR: Unable to navigate", http);
          self.location.href = url;
        }
      }
    };
    http.open(method, url);
    http.timeout = timeout;
    http.send();
    return http;
  }

  function styles(node) {
    return (node.nodeName === "LINK") && node.rel && node.rel.includes("stylesheet");
  }

  function scripts(node) {
    return (node.nodeName === "SCRIPT") && node.hasAttribute("src");
  }

  function filter(url, http) {
    let live = document;
    let node = live.head.childNodes.length;
    let next = (new DOMParser()).parseFromString(http.responseText, "text/html");

    if (next.doctype === null || !http.getResponseHeader("content-type").includes("text/html")) return false;

    while (node--) {
      if (styles(live.head.childNodes[node]) || scripts(live.head.childNodes[node])) {
        // console.log("INFO: Persist:", live.head.childNodes[node]);
      } else {
        live.head.removeChild(live.head.childNodes[node]);
      }
    }

    while (next.head.firstChild) {
      if (styles(next.head.firstChild) || scripts(next.head.firstChild)) {
        next.head.removeChild(next.head.firstChild);
      } else {
        live.head.appendChild(next.head.firstChild);
      }
    }

    while (live.documentElement.attributes.length > 0) {
      live.documentElement.removeAttribute(
        live.documentElement.attributes[live.documentElement.attributes.length - 1].name,
      );
    }

    while (next.documentElement.attributes.length > 0) {
      live.documentElement.setAttribute(
        next.documentElement.attributes[next.documentElement.attributes.length - 1].name,
        next.documentElement.attributes[next.documentElement.attributes.length - 1].value,
      );
      next.documentElement.removeAttribute(
        next.documentElement.attributes[next.documentElement.attributes.length - 1].name,
      );
    }

    live.body.parentElement.replaceChild(next.body, live.body);
  }

  function persist() {
    let persist = document.createElement("link");
    persist.rel = "location";
    persist.target = JSON.stringify(self.location);
    document.head.appendChild(persist);
  }

  self.addEventListener("DOMContentLoaded", function () {
    if (localStorage[key] !== state) return;
    persist();
  });

  self.addEventListener("popstate", function (event) {
    if (localStorage[key] !== state) return;
    const link = JSON.parse(document.querySelector('link[rel="location"]').target);
    const url = event.target.location;
    const hashed = link.pathname === url.pathname;
    if (hashed) return;
    fetch(url, "GET", function (http) {
      if (filter(url, http) === false) return self.location.href = url;
      persist();
      self.document.dispatchEvent(new CustomEvent("URLChangedCustomEvent", { bubbles: true }));
    });
  });

  self.addEventListener("click", function (event) {
    if (localStorage[key] !== state) return;
    const links = document.querySelectorAll("a");
    for (let i = 0; i < links.length; i++) {
      const active = links[i].contains(event.target);
      const change = self.location.href !== links[i].href;
      const view = links[i].attributes.hasOwnProperty("download") === false;
      const local = self.location.origin === links[i].origin && links[i].target !== "_self";
      const hashed =  self.location.pathname === links[i].pathname && links[i].href.includes("#");
      if (active && local && change && view && (hashed === false)) {
        event.preventDefault();
        const url = links[i].href;
        links[i].style.cursor = "wait";
        fetch(url, "GET", function (http) {
          links[i].removeAttribute("style")
          if (filter(url, http) === false) return self.location.href = url;
          history.pushState({}, "", links[i].href);
          persist();
          self.document.dispatchEvent(new CustomEvent("URLChangedCustomEvent", { bubbles: true }));
        });
      }
    }
  });
})();

/*
  * Copyright (C) 2024 Thedro Neely
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU Affero General Public License for more details.
  *
  * You should have received a copy of the GNU Affero General Public License
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/