BookStack/resources/js/code/themes.js

import {tags} from '@lezer/highlight';
import {HighlightStyle, syntaxHighlighting} from '@codemirror/language';
import {EditorView} from '@codemirror/view';
import {oneDarkHighlightStyle, oneDarkTheme} from '@codemirror/theme-one-dark';

const defaultLightHighlightStyle = HighlightStyle.define([
    {
        tag: tags.meta,
        color: '#388938',
    },
    {
        tag: tags.link,
        textDecoration: 'underline',
    },
    {
        tag: tags.heading,
        textDecoration: 'underline',
        fontWeight: 'bold',
    },
    {
        tag: tags.emphasis,
        fontStyle: 'italic',
    },
    {
        tag: tags.strong,
        fontWeight: 'bold',
    },
    {
        tag: tags.strikethrough,
        textDecoration: 'line-through',
    },
    {
        tag: tags.keyword,
        color: '#708',
    },
    {
        tag: [tags.atom, tags.bool, tags.url, tags.contentSeparator, tags.labelName],
        color: '#219',
    },
    {
        tag: [tags.literal, tags.inserted],
        color: '#164',
    },
    {
        tag: [tags.string, tags.deleted],
        color: '#a11',
    },
    {
        tag: [tags.regexp, tags.escape, tags.special(tags.string)],
        color: '#e40',
    },
    {
        tag: tags.definition(tags.variableName),
        color: '#00f',
    },
    {
        tag: tags.local(tags.variableName),
        color: '#30a',
    },
    {
        tag: [tags.typeName, tags.namespace],
        color: '#085',
    },
    {
        tag: tags.className,
        color: '#167',
    },
    {
        tag: [tags.special(tags.variableName), tags.macroName],
        color: '#256',
    },
    {
        tag: tags.definition(tags.propertyName),
        color: '#00c',
    },
    {
        tag: tags.compareOperator,
        color: '#708',
    },
    {
        tag: tags.comment,
        color: '#940',
    },
    {
        tag: tags.invalid,
        color: '#f00',
    },
]);

const defaultThemeSpec = {
    '&': {
        backgroundColor: '#FFF',
        color: '#000',
    },
    '&.cm-focused': {
        outline: 'none',
    },
    '.cm-line': {
        lineHeight: '1.6',
    },
};

/**
 * Get the theme extension to use for editor view instance.
 * @returns {Extension[]}
 */
export function getTheme(viewParentEl) {
    const darkMode = document.documentElement.classList.contains('dark-mode');
    let viewTheme = darkMode ? oneDarkTheme : EditorView.theme(defaultThemeSpec);
    let highlightStyle = darkMode ? oneDarkHighlightStyle : defaultLightHighlightStyle;

    const eventData = {
        darkModeActive: darkMode,
        registerViewTheme(builder) {
            const spec = builder();
            if (spec) {
                viewTheme = EditorView.theme(spec);
            }
        },
        registerHighlightStyle(builder) {
            const tagStyles = builder(tags) || [];
            if (tagStyles.length) {
                highlightStyle = HighlightStyle.define(tagStyles);
            }
        },
    };

    window.$events.emitPublic(viewParentEl, 'library-cm6::configure-theme', eventData);

    return [viewTheme, syntaxHighlighting(highlightStyle)];
}