// ==UserScript==
// @name         Holotower Thread Status Updater
// @namespace    http://holotower.org/
// @version      1.3
// @author       Anonymous
// @description  Updates Holotower favicon on new replies, accurate post counts, adds deleted post counter, and notifies when post limit is reached
// @icon         https://boards.holotower.org/favicon.gif
// @match        *://boards.holotower.org/*/res/*
// @match        *://holotower.org/*/res/*
// @run-at       document-end
// ==/UserScript==


(function() {
  'use strict';

  // === Settings ===
  const showDeletedCounter = true; // Displays the number of deleted posts since entering or refreshing the thread
  const showDeletedIcon = true; // Displays a trash icon next to deleted posts
  const showArchivedMessage = true; // Displays a message when post limit is reached or the thread 404s
  const notifyNewPost = true; // Displays a white circle in the favicon whenever a new post appears
  const notifyNewYou = true; // Displays a red circle in the favicon whenever a post quotes (You)
  const changeFaviconOnArchive = true; // Changes the favicon to red when the thread is archived
  const showUnreadLine = true; // Displays a red line underneath the last post prior to the auto updater

  const FAVICON_URL = window.location.hostname === 'boards.holotower.org'
    ? 'https://boards.holotower.org/favicon.gif'
    : 'https://holotower.org/favicon.gif';
  let alertState = 'none';

  let lastPostCount = null;
  let lastSeenPostId = 0;
  let lastLine = 0;
  let hasUnreadLine = false;
  let previousStyle = '';

  function setFavicon(url) {
    let link = document.querySelector("link[rel*='icon']") || document.createElement('link');
    link.type = 'image/x-icon';
    link.rel = 'shortcut icon';
    link.href = url;
    if (!link.parentNode) document.head.appendChild(link);
  }

  function updateFavicon(color) {
    if (alertState === 'red' && color === 'white') return;
    if (alertState === color) return;

    const img = new Image();
    img.onload = () => {
      const canvas = document.createElement('canvas');
      canvas.width = img.width;
      canvas.height = img.height;
      const ctx = canvas.getContext('2d');
      ctx.drawImage(img, 0, 0);

      ctx.beginPath();
      ctx.arc(canvas.width - 16, 16, 5, 0, 2 * Math.PI);
      ctx.fillStyle = color;
      ctx.fill();

      setFavicon(canvas.toDataURL('image/x-icon'));
      alertState = color;
    };
    img.src = FAVICON_URL;
  }

  function updateFaviconArchived() {
    if (!changeFaviconOnArchive) return;

    const img = new Image();
    img.onload = () => {
      const canvas = document.createElement('canvas');
      canvas.width = img.width;
      canvas.height = img.height;
      const ctx = canvas.getContext('2d');
      ctx.drawImage(img, 0, 0);

      ctx.globalCompositeOperation = 'source-atop';
      ctx.fillStyle = 'red';
      ctx.fillRect(0, 0, canvas.width, canvas.height);

      setFavicon(canvas.toDataURL('image/x-icon'));
    };
    img.src = FAVICON_URL;
  }

  function revertFavicon() {
    if (alertState !== 'none') {
      setFavicon(FAVICON_URL);
      alertState = 'none';
    }
  }

  function classifyPost(node) {
    if (node.nodeType !== 1) return 'none';
    if (node.classList.contains('post-hover')) return 'none';
    if (node.closest('.inline-quote-container')) return 'none';
    if (node.closest('.post.qp.reply')) return 'none';
    if (node.matches('div.post.reply') && node.textContent.trim() === '') return 'none';

    if (node.matches('div.post.reply.quoting-you') && notifyNewYou) return 'red';
    if (node.matches('div.post.reply') && node.querySelector('.body small')?.textContent.trim() === '(You)' && notifyNewYou) return 'red';
    if (node.matches('div.post.reply') && notifyNewPost) return 'white';

    return 'none';
  }

  new MutationObserver(mutations => {
    for (const mutation of mutations) {
      for (const node of mutation.addedNodes) {
        const result = classifyPost(node);
        if (result === 'red') {
          updateFavicon('red');
          return;
        } else if (result === 'white') {
          updateFavicon('white');
        }
      }
    }
  }).observe(document.body, { childList: true, subtree: true });

  window.addEventListener('scroll', () => {
    if (window.scrollY + window.innerHeight >= document.documentElement.scrollHeight - 2) {
      revertFavicon();
      removeUnreadLine();
    }
  });

  function initializeLastSeenPostId() {
    const posts = document.querySelectorAll('div.post.reply');
    posts.forEach(post => {
      const postId = post.id.split('_')[1];
      if (postId > lastSeenPostId) lastSeenPostId = postId;
        lastLine = postId;
    });
  }

  initializeLastSeenPostId();

  function addUnreadLine() {
    if (!showUnreadLine) return;

    const lastPost = document.querySelector(`#reply_${lastLine}`);
    if (lastPost && !hasUnreadLine) {
      previousStyle = lastPost.getAttribute('style') || '';
      lastPost.style.boxShadow = '0 3px red';
      hasUnreadLine = true;
    }
  }

  function removeUnreadLine() {
    if (!showUnreadLine) return;

    const lastPost = document.querySelector(`#reply_${lastLine}`);
    if (lastPost && hasUnreadLine) {
  if (previousStyle) {
        lastPost.setAttribute('style', previousStyle);
      } else {
        lastPost.removeAttribute('style');
      }
      lastLine = lastSeenPostId;
      hasUnreadLine = false;
    }
  }

  function countPostsFromHTML(htmlText) {
    const parser = new DOMParser();
    const doc = parser.parseFromString(htmlText, "text/html");
    const postCount = doc.querySelectorAll('div.post.reply').length;

    if (postCount > 0) {
      lastPostCount = postCount;
      updateThreadStatsActual();
    }
  }

  function updateThreadStatsActual() {
    if (lastPostCount !== null) {
      const oldElement = document.getElementById('thread_stats_posts');
      if (oldElement) {
        oldElement.style.display = 'none';

        let newElement = document.getElementById('thread_stats_posts_actual');
        if (!newElement) {
          newElement = document.createElement('span');
          newElement.id = 'thread_stats_posts_actual';
          oldElement.parentNode.insertBefore(newElement, oldElement.nextSibling);
        }

        newElement.textContent = lastPostCount;

        const postsDeleted = parseInt(oldElement.textContent) - lastPostCount;

        if (showDeletedCounter) {
          let deletedElement = document.getElementById('thread_stats_posts_deleted');
          if (postsDeleted >= 1) {
            if (!deletedElement) {
              deletedElement = document.createElement('span');
              deletedElement.id = 'thread_stats_posts_deleted';
              const imagesElement = document.getElementById('thread_stats_images');
              if (imagesElement) {
                imagesElement.parentNode.insertBefore(deletedElement, imagesElement);
              }
            }

          deletedElement.textContent = postsDeleted;
          deletedElement.insertAdjacentHTML('beforeend', ' deleted | ');
          } else if (deletedElement) {
            deletedElement.remove();
          }
        }

        if (lastPostCount >= 1500) {
          if (changeFaviconOnArchive) updateFaviconArchived();
          if (showArchivedMessage && !document.getElementById('archived-msg')) {
            addArchivedMessage();
          }
        }
      }
    }
  }

  function addArchivedMessage() {
    const postControlsForm = document.forms["postcontrols"];
    if (!postControlsForm) return;

    const archivedMsg = document.createElement('div');
    archivedMsg.id = 'archived-msg';
    archivedMsg.style.marginTop = '-25px';
    archivedMsg.style.marginBottom = '20px';

    archivedMsg.innerHTML = `
      <strong style="color: red; font-size: 14px;">THREAD ARCHIVED</strong><br>
      <img src="https://i.imgur.com/LQHVLil.png" alt="Archived Image" style="margin-top: 5px; width: 7%;">
    `;

    postControlsForm.parentNode.insertBefore(archivedMsg, postControlsForm.nextSibling);
  }

  (function(open) {
    XMLHttpRequest.prototype.open = function(method, url) {
      const currentThreadId = window.location.pathname.split('/res/')[1].split('.')[0];
      const target = `/res/${currentThreadId}.html`;
      this._monitored = url.includes(target) && url.indexOf(target) + target.length === url.length;
      return open.apply(this, arguments);
    };
  })(XMLHttpRequest.prototype.open);

  (function(send) {
    XMLHttpRequest.prototype.send = function() {
      if (this._monitored) {
        this.addEventListener('load', () => {
          if (this.status === 404) {
            if (changeFaviconOnArchive) updateFaviconArchived();
            if (showArchivedMessage && !document.getElementById('archived-msg')) {
              addArchivedMessage();
            }
          } else {
            countPostsFromHTML(this.responseText);
            syncPostStatus(this.responseText);
          }
        });
      }
      return send.apply(this, arguments);
    };
  })(XMLHttpRequest.prototype.send);

  function syncPostStatus(responseText) {
    const parser = new DOMParser();
    const doc = parser.parseFromString(responseText, "text/html");
    const currentThreadId = window.location.pathname.split('/res/')[1].split('.')[0];
    const currentPosts = document.querySelectorAll('div.post.reply');
    const updatePosts = doc.querySelectorAll('div.post.reply');

    if (updatePosts.length === 0) return;

    const updatePostIds = new Set();
    updatePosts.forEach(post => {
      const postId = post.id.split('_')[1];
      updatePostIds.add(postId);

      if (postId > lastSeenPostId) {
        lastSeenPostId = postId;
        addUnreadLine();
    }
    });

    currentPosts.forEach(post => {
      if (post.closest('.post.qp.reply')) return;
      if (post.classList.contains('post-hover')) return;

      const postId = post.id.split('_')[1];
      const xthreadId = post.closest('.thread').id.split('_')[1];

      if (xthreadId !== currentThreadId) return;

      const inlineQuoteContainer = post.closest('.inline-quote-container');
      if (inlineQuoteContainer) {
        const inlinedId = inlineQuoteContainer.getAttribute('data-inlined-id');
        if (!updatePostIds.has(inlinedId)) {
          addDeletedIcon(post);
        } else if (post.querySelector('.fa-trash')) {
          removeDeletedIcon(post);
        }
      } else {
        if (!updatePostIds.has(postId)) {
          addDeletedIcon(post);
        } else if (post.querySelector('.fa-trash')) {
          removeDeletedIcon(post);
        }
      }
    });
  }

  function addDeletedIcon(post) {
    if (!showDeletedIcon) return;
    if (!post.querySelector('.post-btn')) return;

    const postNoLink = post.querySelector('.post_no');
    if (postNoLink && !post.querySelector('.fa-trash')) {
      const trashIcon = document.createElement('i');
      trashIcon.classList.add('fa', 'fa-trash');
      trashIcon.title = 'Deleted';
      trashIcon.style.opacity = '0.5';
      trashIcon.style.marginRight = '0px';
      postNoLink.parentNode.insertBefore(trashIcon, postNoLink.nextSibling.nextSibling);
    }
  }

  function removeDeletedIcon(post) {
    if (!showDeletedIcon) return;

    const postNoLink = post.querySelector('.post_no');
    const trashIcon = postNoLink.nextSibling.nextSibling;
    if (trashIcon && trashIcon.classList.contains('fa-trash')) {
      trashIcon.remove();
    }
  }
})();