F-list inverted color theme with auto-detection.

Depends on "light" theme being the default one in f-list. Adds two buttons to TamperMonkey menu itself to switch and auto-detect light/dark.

You will need to install an extension such as Tampermonkey, Greasemonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install an extension such as Tampermonkey or Violentmonkey to install this script.

You will need to install an extension such as Tampermonkey or Userscripts to install this script.

You will need to install an extension such as Tampermonkey to install this script.

You will need to install a user script manager extension to install this script.

(I already have a user script manager, let me install it!)

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install an extension such as Stylus to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

You will need to install a user style manager extension to install this style.

(I already have a user style manager, let me install it!)

// ==UserScript==
// @name         F-list inverted color theme with auto-detection.
// @license      MIT
// @namespace    https://www.f-list.net
// @version      2025-02-24
// @description  Depends on "light" theme being the default one in f-list. Adds two buttons to TamperMonkey menu itself to switch and auto-detect light/dark.
// @author       Me
// @match        https://www.f-list.net/*
// @icon         https://www.google.com/s2/favicons?sz=64&domain=f-list.net
// @require      https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js
// @grant        GM_registerMenuCommand
// @grant        GM_unregisterMenuCommand
// @grant        GM_addStyle
// @grant        GM_setValue
// @grant        GM_getValue

// ==/UserScript==

(function() {
    'use strict';

    // CSS overrides. Note: the colors here are the inverse of what you want.
    const cssCustomDarkOverrides = `
    /* core changes - hue is for a more pleasant shade of background-image elements. */
    html {
        filter: invert(1) hue-rotate(180deg);
    }
    /* invert images again to return them to the original color and hue */
    .inverted-img {
       filter: invert(1) hue-rotate(180deg);
    }
    /* special cases where the core changes above don't work well */
    .messages-both .message-ad {
        background-color: #ccd !important;
    }
    .ads-text-box, .ads-text-box:focus {
        background-color: #ccd !important;
    }
    `;

    // For auto-detection.
    const darkModeMediaQuery = window.matchMedia('(prefers-color-scheme: dark)');

    // Current dark mode state and mutation observer reference.
    let isDarkModeEnabled = false;
    let observer = null;

    // Saved dark mode states.
    const DarkModeStates = Object.freeze({
        AUTO:       "auto",
        MANUAL_ON:  "manual_on",
        MANUAL_OFF: "manual_off"
    });
    let darkModeState = GM_getValue('darkModeState', DarkModeStates.MANUAL_OFF);

    // Hold the menu command IDs so we can update their labels.
    let darkModeCommandId;
    let autoDetectCommandId;

    // Insert custom CSS overrides using jQuery.
    function enableCustomOverrides() {
        if ($('#customOverridesStyle').length === 0) {
            const $styleEl = $('<style>', { id: 'customOverridesStyle', type: 'text/css' }).text(cssCustomDarkOverrides);
            $('head').append($styleEl);
        }
    }

    // Remove custom CSS overrides.
    function disableCustomOverrides() {
        $('#customOverridesStyle').remove();
    }

    // Update GM menu commands with dynamic text based on current state.
    function updateMenuCommands() {
        if (typeof GM_unregisterMenuCommand === 'function') {
            if (darkModeCommandId) { GM_unregisterMenuCommand(darkModeCommandId); }
            if (autoDetectCommandId) { GM_unregisterMenuCommand(autoDetectCommandId); }
        }
        darkModeCommandId = GM_registerMenuCommand(
            darkModeState === DarkModeStates.MANUAL_ON ? "Disable Dark Mode" : "Enable Dark Mode",
            toggleDarkMode
        );
        autoDetectCommandId = GM_registerMenuCommand(
            darkModeState === DarkModeStates.AUTO ? "Disable Auto-Detection" : "Enable Auto-Detection",
            toggleAutoDetection
        );
    }

    // Use jQuery to add the inverted class to images, picture, and video elements.
    function addInvertedClassToNode(node) {
        const $node = $(node);
        if ($node.is('img, picture, video') && !$node.hasClass('inverted-img')) {
            $node.addClass('inverted-img');
        }
        $node.find('img, picture, video').not('.inverted-img').addClass('inverted-img');
    }

    // Enable dark mode: add custom CSS and observe the DOM for new elements.
    function enableDarkMode() {
        enableCustomOverrides();

        observer = new MutationObserver(mutations => {
            mutations.forEach(mutation => {
                mutation.addedNodes.forEach(node => {
                    if (node.nodeType === Node.ELEMENT_NODE) {
                        addInvertedClassToNode(node);
                    }
                });
            });
        });
        observer.observe(document.body, { childList: true, subtree: true });
        $('img, picture, video').not('.inverted-img').addClass('inverted-img');
        isDarkModeEnabled = true;
    }

    // Disable dark mode: remove custom CSS and stop DOM observation.
    function disableDarkMode() {
        disableCustomOverrides();
        if (observer) {
            observer.disconnect();
            observer = null;
        }
        $('img, picture, video').removeClass('inverted-img');
        isDarkModeEnabled = false;
    }

    // Toggle dark mode manually.
    function toggleDarkMode() {
        if (isDarkModeEnabled) {
            darkModeState = DarkModeStates.MANUAL_OFF;
            disableDarkMode();
        } else {
            darkModeState = DarkModeStates.MANUAL_ON;
            enableDarkMode();
        }
        GM_setValue('darkModeState', darkModeState);
        updateMenuCommands();
    }

    // When system dark mode preference changes.
    function handleColorSchemeChange(event) {
        console.log(`Browser changed its preference. Should we use dark mode now? ${event.matches}`);
        event.matches ? enableDarkMode() : disableDarkMode();
    }

    // Update media query listener safely.
    function updateMediaQueryListener() {
        darkModeMediaQuery.removeEventListener('change', handleColorSchemeChange);
        if (darkModeState === DarkModeStates.AUTO) {
            darkModeMediaQuery.addEventListener('change', handleColorSchemeChange);
        }
    }

    // Apply auto-detection or manual override.
    function autoDetectNow() {
        updateMediaQueryListener();
        if (darkModeState === DarkModeStates.AUTO) {
            console.log(`Autodetection active; system preference is dark? ${darkModeMediaQuery.matches}`);
            darkModeMediaQuery.matches ? enableDarkMode() : disableDarkMode();
        } else {
            const manualOn = (darkModeState === DarkModeStates.MANUAL_ON);
            console.log(`Autodetection disabled. Manual override? ${manualOn}`);
            manualOn ? enableDarkMode() : disableDarkMode();
        }
    }

    // Toggle auto-detection.
    function toggleAutoDetection() {
        darkModeState = darkModeState === DarkModeStates.AUTO ? DarkModeStates.MANUAL_OFF : DarkModeStates.AUTO;
        GM_setValue('darkModeState', darkModeState);
        autoDetectNow();
        updateMenuCommands();
    }

    // Initialize.
    autoDetectNow();
    updateMenuCommands();

})();