// ==UserScript==
// @name AH/DLP/QQ/SB/SV & FFNm highlight visited links
// @description Keep a history of visited threads, also highlights watched threads on AH/DLP/QQ/SB/SV.
// @author C89sd
// @version 1.0.7
// @match https://questionablequesting.com/*
// @match https://forum.questionablequesting.com/*
// @match https://forums.spacebattles.com/*
// @match https://forums.sufficientvelocity.com/*
// @match https://forums.darklordpotter.net/*
// @match https://www.alternatehistory.com/*
// @match https://m.fanfiction.net/*
// @grant GM_setValue
// @grant GM_getValue
// @namespace https://greasyfork.org/users/1376767
// @downloadURL none
// ==/UserScript==


// Toasts via LocalStorage reload
const toast = document.createElement('div');
toast.id = 'toast';
toast.style.position = 'fixed';
toast.style.bottom = '20px';
toast.style.right = '20px';
toast.style.backgroundColor = '#333';
toast.style.color = '#fff';
toast.style.padding = '10px';
toast.style.borderRadius = '5px';
toast.style.opacity = '0';
toast.style.display = 'none';
toast.style.transition = 'opacity 0.5s ease';
toast.style.zIndex = '1000';
document.body.appendChild(toast);

function _showToast(message, duration = 20000) { // 20 sec toasts
  toast.innerHTML = ''; // Clear previous content

  if (message.startsWith('ffn_')) {
    const id = message.substring(4); // Extract ID after "ffn_"
    const link = document.createElement('a');
    link.id = 'toast';
    link.href = `https://m.fanfiction.net/s/${id}/`;
    link.textContent = link.href;
    link.style.color = '#1e90ff';
    link.style.textDecoration = 'none';
    link.target = '_blank'; // Open in new tab
    toast.appendChild(link);
  } else {
    toast.textContent = `removed "${message}"`;
  }

  toast.style.display = 'block';
  setTimeout(() => { toast.style.opacity = '1'; }, 10);
  setTimeout(() => { toast.style.opacity = '0'; }, duration - 500);
  setTimeout(() => { toast.style.display = 'none'; }, duration);
}
function showToast(message) {
  localStorage.setItem('toastMessage', message);
}
function showToastOnPageLoad() {
  const message = localStorage.getItem('toastMessage');
  if (message) {
    _showToast(message);
    localStorage.removeItem('toastMessage');
  }
}
window.addEventListener('load', showToastOnPageLoad);


// Colors & Functions
const dom = window.location.hostname;
const sites = ['spacebattles.com', 'sufficientvelocity.com', 'questionablequesting.com', 'alternatehistory.com', 'darklordpotter.net', 'fanfiction.net'];
const [isSB, isSV, isQQ, isAH, isDLP, isFFN] = sites.map(site => dom.includes(site));

const defaultColor =
isSB ? 'rgb(0, 255, 0)'
: isDLP ? 'rgb(150,150,150)'
: isSV ? 'rgb(40, 161, 221)'
: isQQ ? 'rgb(51, 121, 200)'
: isFFN ? 'rgb(15, 55, 160)'
: 'rgb(20, 20, 20)' // isAH
const highlightColor =
isSB ? 'rgb(223, 166, 255)'
: isDLP ? 'rgb(183, 128, 215)'
: isSV ? 'rgb(152, 100, 184)'
: isFFN ? 'rgb(135, 15, 135)'
: 'rgb(119, 69, 150)' // isAH || isQQ
const highlightYellowColor =
isSB ? 'rgb(223, 185, 0)'
: isDLP ? 'rgb(180, 147, 0)'
: isSV ? 'rgb(209, 176, 44)'
: 'rgb(145, 117, 0)' // isAH || isQQ


const threadRegex = new RegExp(`(${sites.map(s => s.replace('.', '\\.')).join('|')}).*?/threads/`);
function isThreadUrl(url) {
  return threadRegex.test(url);
}

const FFNthreadRegex = new RegExp(`^.*?fanfiction.net/s/(\\d+)`);
function isFFNThreadUrl(url) {
  return FFNthreadRegex.test(url);
}

function extractThreadName(url) { // e.g "site.com/threads/[foo-bar].0000/"
  let name = url;
  name = name.replace(/.*?\/threads\//, ''); // 1. Remove aveything before /threads/ included
  name = name.replace(/\/.*/, '');           // 2. Remove eveything after /
  name = name.replace(/\.\d+$/, '');         // 3. Remove trailing `.[digits]`
  return name;
}

function extractFFNThreadName(url) {
  const match = url.match(FFNthreadRegex); // use capture group
  return match ? `ffn_${match[1]}` : null;  // prefix ffn_123456
}

// IF reading a Thread: name of the thread extracted from URL.
// IF outside a Thread (forum/search/etc): placeholder that cannot match, disables a code path that tries to highlight the title later (there isn't one since this isn't a Thread).
const THREAD_NAME = isFFN && isFFNThreadUrl(window.location.href) ? extractFFNThreadName(window.location.href)
                  : isThreadUrl(window.location.href) ? extractThreadName(window.location.href)
                  : '~/~';

// Plugin Storage
function Storage_ReadMap() {
  const rawData = GM_getValue("C89XF_visited", '{}');
  try {
    return JSON.parse(rawData);
  } catch (e) {
    alert('Failed to parse stored data:', e);
  }
}

function Storage_AddEntry(key, val) {
  if (/^\d+$/.test(key)) { return; } //do not save number links eg https://forums.spacebattles.com/threads/372848/ ; edge case seeen in https://forum.questionablequesting.com/threads/fanfic-search-thread.953/post-624056

  var upToDateMap = Storage_ReadMap() // in case another tab wrote to it
  if (upToDateMap[key]) {
    // preserve oldest time
  } else {
    upToDateMap[key] = val;
    GM_setValue("C89XF_visited", JSON.stringify(upToDateMap));
  }
}

function removeMostRecentEntry() {
  const map = Storage_ReadMap();
  let mostRecentKey = null;
  let mostRecentDate = '';

  for (const [key, date] of Object.entries(map)) {
    if (date >= mostRecentDate) {
      mostRecentDate = date;
      mostRecentKey = key;
    }
  }
  if (mostRecentKey) {
    delete map[mostRecentKey];
    GM_setValue("C89XF_visited", JSON.stringify(map));
    showToast(`${mostRecentKey}`); // ${mostRecentDate}`);
    window.location.reload(); // restore old color that was overwritten
  }
}


(() => {
  "use strict";

  // if (isFFN) {
  //   //alert(0)
  //   return
  // }

  const footer = document.createElement('div');
  footer.style.width = '100%';
  footer.style.padding = '5px';
  footer.style.display = 'flex';
  footer.style.justifyContent = 'center';
  footer.style.gap = '10px';
  footer.class = 'footer';

  const navigationBar = isDLP ? document.querySelector('.pageNavLinkGroup') : document.querySelector('.block-outer');
  const threadHasWatchedButton = navigationBar ? Array.from(navigationBar.children).some(child => /Watched|Unwatch/.test(child.textContent)) : false;

  // Turn title into a link
  const firstH1 = isFFN ? document.querySelector('#content > div[align="center"] > b')
                        : document.querySelector('h1');
  if (firstH1) {
    const title = firstH1.lastChild ? firstH1.lastChild : firstH1;
    const titleLink = document.createElement('a');
    titleLink.href = window.location.href;
    if (title) {
      const titleClone = title.cloneNode(true);
      titleLink.appendChild(titleClone);
      title.parentNode.replaceChild(titleLink, title);
    }
  }

  const BTN_1 = isSV ? ['button', 'button--link'] : ['button']
  const BTN_2 = isSV ? ['button'] : (isDLP ? ['button', 'primary'] : ['button', 'button--link'])
  const exportButton = document.createElement('button');
  exportButton.textContent = 'Backup';
  exportButton.classList.add(...BTN_1);
  if (isSV) { exportButton.style.filter = 'brightness(82%)'; }
  exportButton.addEventListener('click', exportVisitedLinks);
  footer.appendChild(exportButton);

  const importButton = document.createElement('button');
  importButton.textContent = 'Restore';
  importButton.classList.add(...BTN_1);
  if (isSV) { importButton.style.filter = 'brightness(82%)'; }
  importButton.addEventListener('click', importVisitedLinks);
  footer.appendChild(importButton);

  const updateButton = document.createElement('button');
  updateButton.textContent = 'Remove latest highlight';
  updateButton.classList.add(...BTN_2);
  updateButton.addEventListener('click', removeMostRecentEntry);
  footer.appendChild(updateButton);

  const xFooter = document.querySelector('footer.p-footer');
  if (xFooter) { xFooter.insertAdjacentElement('afterbegin', footer); }
  else { document.body.appendChild(footer); }

  function exportVisitedLinks() {
    const data = GM_getValue("C89XF_visited", '{}');
    const blob = new Blob([data], {type: 'application/json'});
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = 'visited_links_backup.json';
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);
  }

  function importVisitedLinks() {
    const input = document.createElement('input');
    input.type = 'file';
    input.accept = '.json';
    input.onchange = function(event) {
      const file = event.target.files[0];
      const reader = new FileReader();
      reader.onload = function(e) {
        try {
          const data = JSON.parse(e.target.result);
          GM_setValue("C89XF_visited", JSON.stringify(data));
          alert('Visited links imported successfully. Page will refresh.');
          window.location.reload();
        } catch (error) {
          alert('Error importing file. Please make sure it\'s a valid JSON file.');
        }
      };
      reader.readAsText(file);
    };
    input.click();
  }

  // Set link colors
  const applyLinkStyles = () => {
    const visitedLinks = Storage_ReadMap();
    const links = document.getElementsByTagName("a");

    for (let link of links) {
      const href = link.href;

      // console.log(href)

      if ((isFFN && isFFNThreadUrl(href)) || isThreadUrl(href)) {
        const threadName = isFFN ? extractFFNThreadName(href)
                                 : extractThreadName(href);
        const isLinkToCurrentThread = threadName == THREAD_NAME;
        if (isLinkToCurrentThread && !firstH1.contains(link)) { continue; } // Skip evey link matching the page URL besides the `firstH1` title. Only allow the main title link we created to be highlighted. (This prevents link spam on evey button etc.)

        // seen
        if (visitedLinks[threadName]) { link.style.color = highlightColor; }

        if (!isFFN) {
          // watched
          let isWatched = false;
          if (isLinkToCurrentThread) {
            isWatched = threadHasWatchedButton;
          } else {
            const parent  = isDLP ? link.closest('div.titleText')
                                  : link.closest('div.structItem');
            const hasIcon = isDLP ? parent && parent.getElementsByClassName('fa-eye').length > 0
                                  : parent && parent.getElementsByClassName('structItem-status--watched').length > 0;
            isWatched = hasIcon;
          }
          if (isWatched) { link.style.color = highlightYellowColor; }
        }
      }
    }

    // Global click listener
    if (!document.dataClickListenerAdded) {
      document.addEventListener("click", function(event) {
        // handle links
        const link = event.target.closest('a');
        if (link && link.tagName === 'A') {
          if (link.id == 'toast') { return; } // Toast link is to check the title, it should not update the DB.

          if ((isFFN && isFFNThreadUrl(link.href)) || isThreadUrl(link.href)) {
            const threadName = isFFN ? extractFFNThreadName(link.href)
                                     : extractThreadName(link.href);
            Storage_AddEntry(threadName, new Date().toISOString().slice(0, 19).replace(/[-:T\.]/g, ''));
          }
        }

        if (isFFN) { return } // -- Skip on FFN

        // handle Watch/Unwatch buttons
        const button = event.target.closest('button, input[type="submit"]');
        if (button) {
          const buttonText = button.tagName === 'INPUT' ? button.value : button.textContent;

          if (/Watch/.test(buttonText)) {
            titleLink.style.color = highlightYellowColor;
          }
          if (/Unwatch/.test(buttonText)) {
            if (visitedLinks[THREAD_NAME]) {
              titleLink.style.color = highlightColor;
            } else {
              titleLink.style.color = defaultColor;
            }
          }
        }

      });
      document.dataClickListenerAdded = true;
    }
  };

  // Apply styles on load
  applyLinkStyles();
  // Apply styles when navigating back
  window.addEventListener('pageshow', (event) => {
    if (event.persisted) {
      applyLinkStyles();
    }
  });
})();