From ac7a698c4f59041e7e59f779aff6fda55a448183 Mon Sep 17 00:00:00 2001
From: gsb <gsb@amazon.com>
Date: Wed, 29 Apr 2026 01:17:32 +0000
Subject: [PATCH] Add themes support

Usage:

  const editor = new RibbitEditor({
    themes: [
        { name: 'dark', features: { sourceMode: false } },
        { name: 'minimal', tags: minimalTags },
    ],
    currentTheme: 'dark',
  });

The built-in theme is 'ribbit-default' and is always available.
Additional themes from the themes array are registered on top.
---
 package.json                               |   7 +-
 src/ribbit.css                             |  58 -----------
 src/static/ribbit-core.css                 |  22 ++++
 src/static/themes/ribbit-default/theme.css |  52 ++++++++++
 src/ts/default-theme.ts                    |  16 +++
 src/{ => ts}/hopdown.ts                    |   0
 src/{ => ts}/ribbit-editor.ts              |   9 +-
 src/{ => ts}/ribbit.ts                     |  38 ++++++-
 src/{ => ts}/tags.ts                       |   0
 src/ts/theme-manager.ts                    | 114 +++++++++++++++++++++
 src/{ => ts}/types.ts                      |  10 ++
 test/test_hopdown.js                       |   4 +-
 tsconfig.json                              |   4 +-
 13 files changed, 264 insertions(+), 70 deletions(-)
 delete mode 100644 src/ribbit.css
 create mode 100644 src/static/ribbit-core.css
 create mode 100644 src/static/themes/ribbit-default/theme.css
 create mode 100644 src/ts/default-theme.ts
 rename src/{ => ts}/hopdown.ts (100%)
 rename src/{ => ts}/ribbit-editor.ts (93%)
 rename src/{ => ts}/ribbit.ts (75%)
 rename src/{ => ts}/tags.ts (100%)
 create mode 100644 src/ts/theme-manager.ts
 rename src/{ => ts}/types.ts (88%)

diff --git a/package.json b/package.json
index 724109e..2195c64 100644
--- a/package.json
+++ b/package.json
@@ -9,10 +9,11 @@
     "src/"
   ],
   "scripts": {
-    "build": "npm run build:check && npm run build:js && npm run build:min",
+    "build": "mkdir -p dist/ribbit && npm run build:check && npm run build:js && npm run build:min && npm run build:css",
     "build:check": "tsc --noEmit",
-    "build:js": "esbuild src/ribbit-editor.ts --bundle --format=iife --sourcemap --outfile=dist/ribbit.js",
-    "build:min": "esbuild src/ribbit-editor.ts --bundle --format=iife --minify --outfile=dist/ribbit.min.js",
+    "build:js": "esbuild src/ts/ribbit-editor.ts --bundle --format=iife --sourcemap --outfile=dist/ribbit/ribbit.js",
+    "build:min": "esbuild src/ts/ribbit-editor.ts --bundle --format=iife --minify --outfile=dist/ribbit/ribbit.min.js",
+    "build:css": "cp src/static/ribbit-core.css dist/ribbit/ && cp -r src/static/themes dist/ribbit/",
     "test": "npm run build && node test/test_hopdown.js"
   },
   "license": "MIT",
diff --git a/src/ribbit.css b/src/ribbit.css
deleted file mode 100644
index 96365d8..0000000
--- a/src/ribbit.css
+++ /dev/null
@@ -1,58 +0,0 @@
-/*
- * ribbit.css — editor styles for the ribbit WYSIWYG markdown editor.
- *
- * Provides base content formatting and editor state styles.
- * Override with your own theme CSS for custom look and feel.
- */
-
-/* ── Content formatting ──────────────────────────────── */
-
-a { text-decoration: none; }
-
-q, blockquote {
-    margin-left: 30px;
-    font-size: 1.3em;
-    font-style: italic;
-    color: #555;
-}
-
-table { width: 100%; }
-th { border-bottom: 1px solid #000; padding: 3px; }
-th, td { padding: 2px; }
-table td table { max-width: 95%; }
-
-pre {
-    border: 1px dashed black;
-    border-radius: 5px;
-    padding: 10px;
-    margin: 5px;
-    background: #EEE;
-}
-
-code {
-    display: inline-block;
-    border: 1px dashed black;
-    border-radius: 5px;
-    padding: 5px;
-    background: #EEE;
-    margin: 3px;
-}
-
-/* ── Editor states ───────────────────────────────────── */
-
-#ribbit {
-    display: none;
-}
-
-#ribbit.loaded {
-    display: block;
-}
-
-#ribbit.edit {
-    font-family: monospace;
-    white-space: pre;
-}
-
-#ribbit.wysiwyg .md {
-    opacity: 0.5;
-}
diff --git a/src/static/ribbit-core.css b/src/static/ribbit-core.css
new file mode 100644
index 0000000..f352fce
--- /dev/null
+++ b/src/static/ribbit-core.css
@@ -0,0 +1,22 @@
+/*
+ * ribbit-core.css — functional editor styles. Always load this.
+ * These styles control editor state visibility and behavior.
+ * They should not be overridden by themes.
+ */
+
+#ribbit {
+    display: none;
+}
+
+#ribbit.loaded {
+    display: block;
+}
+
+#ribbit.edit {
+    font-family: monospace;
+    white-space: pre;
+}
+
+#ribbit.wysiwyg .md {
+    opacity: 0.5;
+}
diff --git a/src/static/themes/ribbit-default/theme.css b/src/static/themes/ribbit-default/theme.css
new file mode 100644
index 0000000..ed2163a
--- /dev/null
+++ b/src/static/themes/ribbit-default/theme.css
@@ -0,0 +1,52 @@
+/*
+ * default.css — the default ribbit theme.
+ * Provides basic aesthetic styling for rendered markdown content.
+ * Replace this file with your own theme to customize the look.
+ */
+
+@import "../ribbit-core.css";
+
+a {
+    text-decoration: none;
+}
+
+blockquote {
+    margin-left: 30px;
+    font-size: 1.3em;
+    font-style: italic;
+    color: #555;
+}
+
+table {
+    width: 100%;
+}
+
+th {
+    border-bottom: 1px solid #000;
+    padding: 3px;
+}
+
+th, td {
+    padding: 2px;
+}
+
+table td table {
+    max-width: 95%;
+}
+
+pre {
+    border: 1px dashed black;
+    border-radius: 5px;
+    padding: 10px;
+    margin: 5px;
+    background: #EEE;
+}
+
+code {
+    display: inline-block;
+    border: 1px dashed black;
+    border-radius: 5px;
+    padding: 5px;
+    background: #EEE;
+    margin: 3px;
+}
diff --git a/src/ts/default-theme.ts b/src/ts/default-theme.ts
new file mode 100644
index 0000000..e7c26f0
--- /dev/null
+++ b/src/ts/default-theme.ts
@@ -0,0 +1,16 @@
+/*
+ * default-theme.ts — the default ribbit theme.
+ *
+ * Enables all default tags and all editor features.
+ */
+
+import type { RibbitTheme } from './types';
+import { defaultTags } from './tags';
+
+export const defaultTheme: RibbitTheme = {
+    name: 'ribbit-default',
+    tags: defaultTags,
+    features: {
+        sourceMode: true,
+    },
+};
diff --git a/src/hopdown.ts b/src/ts/hopdown.ts
similarity index 100%
rename from src/hopdown.ts
rename to src/ts/hopdown.ts
diff --git a/src/ribbit-editor.ts b/src/ts/ribbit-editor.ts
similarity index 93%
rename from src/ribbit-editor.ts
rename to src/ts/ribbit-editor.ts
index e505708..95ff926 100644
--- a/src/ribbit-editor.ts
+++ b/src/ts/ribbit-editor.ts
@@ -2,9 +2,9 @@
  * ribbit-editor.ts — WYSIWYG editing extension for Ribbit.
  */
 
-import hopdown from './hopdown';
 import { HopDown } from './hopdown';
 import { defaultTags, defaultBlockTags, defaultInlineTags, inlineTag } from './tags';
+import { defaultTheme } from './default-theme';
 import { Ribbit, RibbitPlugin, RibbitSettings, camelCase, decodeHtmlEntities, encodeHtmlEntities } from './ribbit';
 
 /**
@@ -46,7 +46,7 @@ export class RibbitEditor extends Ribbit {
     }
 
     htmlToMarkdown(html?: string): string {
-        return hopdown.toMarkdown(html || this.element.innerHTML);
+        return this.converter.toMarkdown(html || this.element.innerHTML);
     }
 
     getMarkdown(): string {
@@ -80,6 +80,9 @@ export class RibbitEditor extends Ribbit {
     }
 
     edit(): void {
+        if (!this.theme.features?.sourceMode) {
+            return;
+        }
         if (this.state === this.states.EDIT) return;
         this.changed = false;
         this.element.contentEditable = 'true';
@@ -101,11 +104,11 @@ export class RibbitEditor extends Ribbit {
 
 // Attach public API to window for <script> tag usage.
 (window as any).HopDown = HopDown;
-(window as any).hopdown = hopdown;
 (window as any).inlineTag = inlineTag;
 (window as any).defaultTags = defaultTags;
 (window as any).defaultBlockTags = defaultBlockTags;
 (window as any).defaultInlineTags = defaultInlineTags;
+(window as any).defaultTheme = defaultTheme;
 (window as any).Ribbit = Ribbit;
 (window as any).RibbitEditor = RibbitEditor;
 (window as any).RibbitPlugin = RibbitPlugin;
diff --git a/src/ribbit.ts b/src/ts/ribbit.ts
similarity index 75%
rename from src/ribbit.ts
rename to src/ts/ribbit.ts
index 6132bd0..8b0b90c 100644
--- a/src/ribbit.ts
+++ b/src/ts/ribbit.ts
@@ -2,12 +2,18 @@
  * ribbit.ts — core editor classes for the ribbit WYSIWYG markdown editor.
  */
 
-import hopdown from './hopdown';
+import { HopDown } from './hopdown';
+import { defaultTheme } from './default-theme';
+import { ThemeManager } from './theme-manager';
+import type { RibbitTheme } from './types';
 
 export interface RibbitSettings {
     api?: unknown;
     editorId?: string;
     plugins?: Array<{ new(settings: { name: string; wiki: Ribbit }): RibbitPlugin; name: string }>;
+    currentTheme?: string;
+    themes?: RibbitTheme[];
+    themesPath?: string;
 }
 
 /**
@@ -53,10 +59,15 @@ export class Ribbit {
     state: string | null;
     changed: boolean;
     enabledPlugins: Record<string, RibbitPlugin>;
+    theme: RibbitTheme;
+    themes: ThemeManager;
+    converter: HopDown;
+    themesPath: string;
 
     constructor(settings: RibbitSettings) {
         this.api = settings.api || null;
         this.element = document.getElementById(settings.editorId || 'ribbit')!;
+        this.themesPath = settings.themesPath || './themes';
         this.states = {
             VIEW: 'view',
         };
@@ -66,6 +77,29 @@ export class Ribbit {
         this.changed = false;
         this.enabledPlugins = {};
 
+        this.themes = new ThemeManager(defaultTheme, this.themesPath, (theme) => {
+            this.theme = theme;
+            this.converter = theme.tags
+                ? new HopDown({ tags: theme.tags })
+                : new HopDown();
+            this.cachedHTML = null;
+            if (this.getState() === this.states.VIEW) {
+                this.state = null;
+                this.view();
+            }
+        });
+
+        (settings.themes || []).forEach(theme => {
+            this.themes.add(theme);
+        });
+
+        const activeName = settings.currentTheme || defaultTheme.name;
+        this.themes.set(activeName);
+        this.theme = this.themes.current();
+        this.converter = this.theme.tags
+            ? new HopDown({ tags: this.theme.tags })
+            : new HopDown();
+
         (settings.plugins || []).forEach(plugin => {
             this.enabledPlugins[plugin.name] = new plugin({
                 name: plugin.name,
@@ -99,7 +133,7 @@ export class Ribbit {
     }
 
     markdownToHTML(md: string): string {
-        return hopdown.toHTML(md);
+        return this.converter.toHTML(md);
     }
 
     getHTML(): string {
diff --git a/src/tags.ts b/src/ts/tags.ts
similarity index 100%
rename from src/tags.ts
rename to src/ts/tags.ts
diff --git a/src/ts/theme-manager.ts b/src/ts/theme-manager.ts
new file mode 100644
index 0000000..68c8771
--- /dev/null
+++ b/src/ts/theme-manager.ts
@@ -0,0 +1,114 @@
+/*
+ * theme-manager.ts — manages theme registration and activation for a Ribbit instance.
+ */
+
+import type { RibbitTheme } from './types';
+import { HopDown } from './hopdown';
+
+export class ThemeManager {
+    private registered: Map<string, RibbitTheme>;
+    private disabled: Set<string>;
+    private active: RibbitTheme;
+    private themeLink: HTMLLinkElement | null;
+    private themesPath: string;
+    private onSwitch: (theme: RibbitTheme) => void;
+
+    constructor(initial: RibbitTheme, themesPath: string, onSwitch: (theme: RibbitTheme) => void) {
+        this.registered = new Map();
+        this.disabled = new Set();
+        this.themeLink = null;
+        this.themesPath = themesPath;
+        this.onSwitch = onSwitch;
+        this.active = initial;
+        this.add(initial);
+    }
+
+    /**
+     * Register a theme. Themes must be added before they can be enabled.
+     */
+    add(theme: RibbitTheme): void {
+        this.registered.set(theme.name, theme);
+    }
+
+    /**
+     * Unregister a theme by name. Cannot remove the active theme.
+     */
+    remove(name: string): void {
+        if (this.active.name === name) {
+            throw new Error(`Cannot remove the active theme "${name}".`);
+        }
+        this.registered.delete(name);
+    }
+
+    /**
+     * Return the names of all registered and enabled themes.
+     */
+    list(): string[] {
+        return Array.from(this.registered.keys()).filter(name => !this.disabled.has(name));
+    }
+
+    /**
+     * Get a registered theme by name, or undefined if not found.
+     */
+    get(name: string): RibbitTheme | undefined {
+        return this.registered.get(name);
+    }
+
+    /**
+     * Return the currently active theme.
+     */
+    current(): RibbitTheme {
+        return this.active;
+    }
+
+    /**
+     * Switch to a registered theme by name. The theme must be
+     * registered and enabled. Loads the theme's CSS and notifies
+     * the editor to rebuild its converter.
+     */
+    set(name: string): void {
+        const theme = this.registered.get(name);
+        if (!theme) {
+            throw new Error(`Theme "${name}" is not registered. Call add() first.`);
+        }
+        if (this.disabled.has(name)) {
+            throw new Error(`Theme "${name}" is disabled. Call enable() first.`);
+        }
+        this.active = theme;
+        this.loadCSS(name);
+        this.onSwitch(theme);
+    }
+
+    /**
+     * Mark a theme as available for selection via set().
+     * Themes are enabled by default when added.
+     */
+    enable(name: string): void {
+        if (!this.registered.has(name)) {
+            throw new Error(`Theme "${name}" is not registered. Call add() first.`);
+        }
+        this.disabled.delete(name);
+    }
+
+    /**
+     * Mark a theme as unavailable for selection via set().
+     * Does not affect the current theme if it is already active.
+     */
+    disable(name: string): void {
+        if (!this.registered.has(name)) {
+            throw new Error(`Theme "${name}" is not registered.`);
+        }
+        this.disabled.add(name);
+    }
+
+    private loadCSS(name: string): void {
+        if (this.themeLink) {
+            this.themeLink.remove();
+        }
+        const link = document.createElement('link');
+        link.rel = 'stylesheet';
+        link.href = `${this.themesPath}/${name}/theme.css`;
+        document.head.appendChild(link);
+        this.themeLink = link;
+    }
+}
diff --git a/src/types.ts b/src/ts/types.ts
similarity index 88%
rename from src/types.ts
rename to src/ts/types.ts
index 942cd7b..8a28f4b 100644
--- a/src/types.ts
+++ b/src/ts/types.ts
@@ -54,3 +54,13 @@ export interface InlineTagDef {
     /** Process inner content for nested markdown? Default true. False for code spans. */
     recursive?: boolean;
 }
+
+export interface RibbitThemeFeatures {
+    sourceMode?: boolean;
+}
+
+export interface RibbitTheme {
+    name: string;
+    tags?: Record<string, Tag>;
+    features?: RibbitThemeFeatures;
+}
diff --git a/test/test_hopdown.js b/test/test_hopdown.js
index 7d88a1c..8743000 100644
--- a/test/test_hopdown.js
+++ b/test/test_hopdown.js
@@ -13,10 +13,10 @@ global.HTMLElement = dom.window.HTMLElement;
 global.Node = dom.window.Node;
 
 // Load the compiled bundle (attaches globals to window)
-const bundle = fs.readFileSync(path.join(__dirname, '..', 'dist', 'ribbit.js'), 'utf8');
+const bundle = fs.readFileSync(path.join(__dirname, '..', 'dist', 'ribbit', 'ribbit.js'), 'utf8');
 dom.window.eval(bundle);
 
-const hopdown = dom.window.hopdown;
+const hopdown = new dom.window.HopDown();
 const H = hopdown.toHTML.bind(hopdown);
 const M = hopdown.toMarkdown.bind(hopdown);
 function rt(md) { return M(H(md)); }
diff --git a/tsconfig.json b/tsconfig.json
index 6dc661a..54c59fe 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -5,10 +5,10 @@
     "module": "ESNext",
     "moduleResolution": "bundler",
     "outDir": "dist",
-    "rootDir": "src",
+    "rootDir": "src/ts",
     "declaration": true,
     "sourceMap": true,
     "lib": ["ES2019", "DOM"]
   },
-  "include": ["src/**/*.ts"]
+  "include": ["src/ts/**/*.ts"]
 }