// ==UserScript==
// @name        Cohost Following list tracker
// @namespace   datagirl.xyz
// @match       https://cohost.org/rc/project/following*
// @grant       GM.getValue
// @grant       GM.setValue
// @version     1.0
// @author      snow flurry <snow@datagirl.xyz>
// @description Puts a dot next to users you follow with unread posts.
// ==/UserScript==

(async () => {
  // Used by GM.getValue/GM.setValue
  const gmvalLastViewed = "lastViewed";
  const notifyDotClass = "__x-notify-dot";
  // Stolen from the notification dot on the "refresh" button :3
  const dotSvgPath = `
      <path d="M29.9375 34.712c-4.5219 1.3518-8.8029 1.9644-12.843
               1.8377-4.0401-.1267-7.50633-1.0808-10.39884-2.8624-2.89253-1.7814-4.8862-4.5046-5.981084-8.1695-1.101144-3.6858-.929664-7.062.514464-10.1285
               1.44415-3.0666 3.82337-5.75117 7.13767-8.05372C11.681 5.03302 15.5992 3.2058 20.1211 1.85394 24.6221.508325 28.8858-.104798 32.9123.014595
               36.9387.133964 40.4019 1.07761 43.3017 2.8455c2.8999 1.76792 4.8972 4.48429 5.9921 8.1491 1.0949 3.6649.9166 7.0374-.5349 10.1176-1.4514
               3.0802-3.826 5.7804-7.1235 8.1008-3.2976 2.3204-7.1969 4.1534-11.6979 5.499Z" fill="currentColor">
      </path>`;
  const dotElem = document.createElementNS("http://www.w3.org/2000/svg", "svg");
  dotElem.setAttribute('fill', 'none');
  dotElem.setAttribute('viewBox', '0 0 50 37');
  dotElem.classList.add("absolute", "-right-1", "-bottom-1", "h-4", "w-4", "text-cherry", "dark:text-mango", notifyDotClass);
  dotElem.setAttribute('style', "z-index: auto;");
  dotElem.innerHTML = dotSvgPath;

  // Handle (re)initialization (e.g., when React attempts to rehydrate)
  // XXX: This might not be necessary anymore? Previous attempts to hook
  // React tended to require fighting the server-side hydration until it
  // gave up. Nowadays it only seems to trigger once.
  const onNeedsInit = (parentEl, callback) => {
    // Sentinel used to check if we're still hooked
    const sentinel = document.createElement("flr");
    sentinel.id = "x-flurry-followpostcount-sentinel";
    sentinel.style.setProperty("display", "none");
    sentinel.ariaHidden = true;

    const appEl = document.getElementById("app");
    const observer = new MutationObserver(async () => {
      if (document.getElementById(sentinel.id) == null) {
        app.appendChild(sentinel);
        await callback(appEl);
      }
    });
    observer.observe(appEl, { subtree: true, childList: true });
  };

  // Gets the React properties for a given DOM element
  const reactProps = (elem) => {
    let propsKey = Object.keys(elem).find((k) => k.startsWith("__reactProps$"));
    // No properties, return nothing
    if (propsKey == null) return {};
    return elem[propsKey].children.props;
  };

  // Keeping latest as a global to avoid race conditions
  // in updateProfileDots
  const latest = await (async () => {
    let str = await GM.getValue(gmvalLastViewed, "{}");
    let latest = JSON.parse(str);
    if (!latest) {
      console.warn(`Couldn't parse ${gmvalLastViewed}! Defaulting to an empty list.`);
      return {};
    }
    return latest;
  })();

  // Wrapper for GM.setValue that validates the output
  const storeLastViewed = async (obj) => {
    if (obj == null) {
      console.warn("Received null parameter. This should not happen!");
    } else {
      await GM.setValue(gmvalLastViewed, JSON.stringify(obj));
    }
  }

  const handleNotifiedClick = async (ev) => {
    const targetProps = reactProps(ev.currentTarget.parentElement);
    const projId = targetProps.project.projectId.toString();
    latest[projId] = {
      id: targetProps.latestPost.postId,
      date: targetProps.latestPost.publishedAt
    };

    // remove the notification dot, if any
    const notifyDot = ev.currentTarget.querySelector(`svg.${notifyDotClass}`);
    if (notifyDot != null) {
      notifyDot.parentElement.removeChild(notifyDot);
    }

    await storeLastViewed(latest);
  }

  const updateProfileDots = async (liList) => {
    for (const li of liList) {
      // the MutationObserver might give us non-li elements.
      // Ignore those ones
      if (li.tagName != "LI") {
        continue;
      }

      const liProps = reactProps(li);
      if (liProps == null || !(liProps.project)) continue;
      const projId = liProps.project.projectId.toString();

      if (!(projId in latest)) {
        // No latest post! We won't show a dot, but will note this
        // for later.
        latest[projId] = {
          id: liProps.latestPost.postId,
          date: liProps.latestPost.publishedAt
        };
      }

      if (li.querySelector(`svg.${notifyDotClass}`) != null) {
        // Dot already exists, we don't need to update it
        continue;
      }

      if (latest[projId].id != liProps.latestPost.postId) {
        // New post? make sure it's *actually* newer before
        // showing a dot
        const newDate = new Date(liProps.latestPost.publishedAt);
        const oldDate = new Date(latest[projId].date);
        if (newDate > oldDate) {
          // Okay, post is (probably) definitely newer.
          // Deploy the dot!
          const liDot = dotElem.cloneNode(true);
          li.querySelector("img").parentElement.appendChild(liDot);
          li.children[0].addEventListener("click", handleNotifiedClick);
        }
      }
    } // for (const li of liList)

    await storeLastViewed(latest);
  };

  const app = document.getElementById("app");

  const findSidebar = () => {
    for (const x of app.querySelectorAll("ul")) {
      if (x.querySelector("button") != null) {
        return x;
      }
    }
    return null;
  };

  // Actual script
  onNeedsInit(app, async (app) => {
    // At time of writing, the following list sidebar is the only
    // <ul/> with buttons. Since :has isn't yet stable in Firefox,
    // we do some querySelector stuff to check for it.
    let sidebar = findSidebar();

    // We should be tied to /rc/project/following, but better safe
    // than sorry
    if (sidebar == null) {
      console.error("Couldn't find following sidebar!");
    }

    const listObserver = new MutationObserver(async (records) => {
      // "+ Load More" button is the last node in the list. Sadly,
      // I'm not aware of a better guessing method.
      if (new Array(...records).find((rec) =>
                                      (rec.nextSibling == null &&
                                      rec.addedNodes.length > 0)
            ) != null)
      {
        // HACK: when refreshing, the "+ Load More" button is
        // removed, and is put back after refreshing is complete.
        // We can use this to determine if a refresh occurred, and
        // perform a full refresh of the ul.
        const sidebar = findSidebar();
        if (sidebar) {
          updateProfileDots(sidebar.children);
        }
      } else {
        // Typically happens when the user clicks "+ Load More"
        for (const record of records) {
          if (record.addedNodes.length > 0) {
            updateProfileDots(record.addedNodes);
          }
        }
      }
    });
    listObserver.observe(sidebar, { childList: true, subtree: true });
    // Iterate all list items, each of which corresponding to a
    // following entry
    updateProfileDots(sidebar.children);
  });
})();