swisspost · alizedebray · Sep 24, 2024
@@ -9,7 +9,7 @@
   top: -5px;
   right: 0;
   padding: post.$size-mini;
-  background-color: var(--post-light);
+  background-color: post.$white;
   border: post.$border-width solid post.$border-color;
   border-radius: post.$border-radius;
   font-size: post.$font-size-sm;

@@ -1,101 +1,146 @@
 import React, { useEffect, useState } from 'react';
 import { IconButton, WithTooltip } from '@storybook/components';
 
-const STYLESHEET_ID = 'preview-stylesheet';
+const THEMES = ['Post'] as const;
+const CHANNELS = ['External', 'Internal'] as const;
+const MODES = ['Light', 'Dark'] as const;
+
+/*
+ * Stylesheets
+ */
+const getStylesheetUrl = (theme: string, channel: string) => {
+  return `/styles/${theme.toLowerCase()}-${channel.toLowerCase()}.css`;
+};
+const possibleStylesheets = THEMES.flatMap(theme => {
+  return CHANNELS.map(channel => getStylesheetUrl(theme, channel));
+});
+
+/*
+ * Backgrounds
+ */
+const backgroundClasses: { [key in (typeof MODES)[number]]: string } = {
+  Light: 'bg-white',
+  Dark: 'bg-dark',
+};
+const getBackgroundClass = (mode: string) => {
+  return mode in backgroundClasses ? backgroundClasses[mode] : '';
+};
+const possibleBackgrounds = MODES.map(mode => getBackgroundClass(mode));
+
+/*
+ * Local storage access
+ */
 const STORAGE_KEY_PREFIX = 'swisspost-documentation';
-const THEMES = ['Post'];
-const CHANNELS = ['External', 'Internal'];
-const MODES = ['Light', 'Dark'];
+const store = (key: string, value: string) => {
+  return localStorage.setItem(`${STORAGE_KEY_PREFIX}-${key}`, value);
+};
+const stored = (key: string): string => {
+  return localStorage.getItem(`${STORAGE_KEY_PREFIX}-${key}`);
+};
+
+/*
+ * Helpers
+ */
+const debounce = <T extends unknown[]>(callback: (...args: T) => void, timeout: number) => {
+  let timer;
+  return (...args: T) => {
+    clearTimeout(timer);
+    timer = setTimeout(() => {
+      callback(...args);
+    }, timeout);
+  };
+};
 
 function StylesSwitcher() {
-  const [currentTheme, setCurrentTheme] = useState<string>(
-    localStorage.getItem(`${STORAGE_KEY_PREFIX}-theme`) || THEMES[0],
-  );
-  const [currentChannel, setCurrentChannel] = useState<string>(
-    localStorage.getItem(`${STORAGE_KEY_PREFIX}-channel`) || CHANNELS[0],
-  );
-  const [currentMode, setCurrentMode] = useState<string>(
-    localStorage.getItem(`${STORAGE_KEY_PREFIX}-mode`) || MODES[0],
-  );
+  let observer: MutationObserver;
 
-  /**
-   * Sets the 'data-color-mode' attribute and preview stylesheet when the addon initializes
-   */
-  useEffect(() => {
-    setPreviewStylesheet();
-    setDataColorModeAttribute();
-  });
+  const [currentTheme, setCurrentTheme] = useState<string>(stored('theme') || THEMES[0]);
+  const [currentChannel, setCurrentChannel] = useState<string>(stored('channel') || CHANNELS[0]);
+  const [currentMode, setCurrentMode] = useState<string>(stored('mode') || MODES[0]);
+
+  const [preview, setPreview] = useState<Document>();
+  const [stories, setStories] = useState<NodeListOf<Element>>();
 
   /**
-   * Sets the stylesheet matching the selected theme and channel in the preview document head
+   * Retrieves the preview document after the first rendering
    */
-  const setPreviewStylesheet = () => {
-    const preview = getPreviewDocument();
-    const previewHead = preview && preview.querySelector('head');
+  useEffect(() => {
+    const previewIFrame = document.querySelector('iframe#storybook-preview-iframe');
 
-    if (!previewHead) return;
+    if (!previewIFrame) return;
 
-    let stylesheetLink = previewHead.querySelector(`#${STYLESHEET_ID}`);
+    previewIFrame.addEventListener('load', () => {
+      setPreview((previewIFrame as HTMLIFrameElement).contentWindow.document);
+    });
+  }, []);
 
-    if (!stylesheetLink) {
-      stylesheetLink = document.createElement('link');
-      stylesheetLink.setAttribute('rel', 'stylesheet');
-      stylesheetLink.setAttribute('id', STYLESHEET_ID);
-      previewHead.appendChild(stylesheetLink);
-    }
+  /**
+   * Retrieves all the stories when the preview content changes
+   */
+  useEffect(() => {
+    if (!preview || observer) return;
 
-    stylesheetLink.setAttribute(
-      'href',
-      `/styles/${currentTheme.toLowerCase()}-${currentChannel.toLowerCase()}.css`,
+    observer = new MutationObserver(
+      debounce(() => {
+        setStories(preview.querySelectorAll('.sbdocs-preview, .sb-main-padded'));
+      }, 200),
     );
-  };
+
+    observer.observe(preview.body, { childList: true, subtree: true });
+  }, [preview]);
 
   /**
-   * Sets the 'data-color-mode' attribute of the preview body to match the selected mode
+   * Sets the expected stylesheet in the preview head when the theme or channel changes
    */
-  const setDataColorModeAttribute = () => {
-    const preview = getPreviewDocument();
+  useEffect(() => {
     if (!preview) return;
 
-    const mode = currentMode.toLowerCase();
-    const storyContainers = preview.querySelectorAll('.sbdocs-preview, .sb-main-padded');
-    storyContainers.forEach(storyContainer => {
-      storyContainer.classList.remove('bg-light', 'bg-dark');
-      storyContainer.classList.add(`bg-${mode}`);
-      storyContainer.setAttribute('data-color-mode', mode);
+    possibleStylesheets.forEach(stylesheet => {
+      const stylesheetLink = preview.head.querySelector(`link[href="${stylesheet}"]`);
+      if (stylesheetLink) stylesheetLink.remove();
     });
-  };
+
+    preview.head.insertAdjacentHTML(
+      'beforeend',
+      `<link rel="stylesheet" href="${getStylesheetUrl(currentTheme, currentChannel)}" />`,
+    );
+  }, [preview, currentTheme, currentChannel]);
 
   /**
-   * Returns the Document contained in the preview iframe
+   * Sets the expected 'data-color-mode' attribute on all story containers when the mode changes
    */
-  const getPreviewDocument = (): Document | undefined => {
-    const preview = document.querySelector('#storybook-preview-iframe');
-    return preview && (preview as HTMLIFrameElement).contentWindow.document;
-  };
+  useEffect(() => {
+    if (!stories) return;
+
+    stories.forEach(story => {
+      story.classList.remove(...possibleBackgrounds);
+      story.classList.add(getBackgroundClass(currentMode));
+      story.setAttribute('data-color-mode', currentMode.toLowerCase());
+    });
+  }, [stories, currentMode]);
 
   /**
    * Applies selected theme and registers it to the local storage
    */
   const applyTheme = (theme: string) => {
+    store('theme', theme);
     setCurrentTheme(theme);
-    localStorage.setItem(`${STORAGE_KEY_PREFIX}-theme`, theme);
   };
 
   /**
    * Applies selected channel and registers it to the local storage
    */
   const applyChannel = (channel: string) => {
+    store('channel', channel);
     setCurrentChannel(channel);
-    localStorage.setItem(`${STORAGE_KEY_PREFIX}-channel`, channel);
   };
 
   /**
    * Applies selected mode and registers it to the local storage
    */
   const applyMode = (mode: string) => {
+    store('mode', mode);
     setCurrentMode(mode);
-    localStorage.setItem(`${STORAGE_KEY_PREFIX}-mode`, mode);
   };
 
   return (

@@ -8,6 +8,7 @@
 <link rel="icon" href="/favicon.svg" type="image/svg+xml" />
 <link rel="apple-touch-icon" href="/apple-touch-icon.png" />
 <link rel="manifest" href="/site.webmanifest" />
+<link rel="stylesheet" href="/styles/post-external.css" />
 
 <meta name="design-system-settings" data-post-icon-base="/post-icons" />
 <meta http-equiv="Content-Security-Policy" content="connect-src 'self' *.coveo.com *.post.ch" />

@@ -177,6 +177,10 @@
   overflow-x: hidden;
 }
 
+.sbdocs-preview:not([data-color-mode]) {
+  display: none;
+}
+
 .fake-content {
   position: relative;
   min-height: calc(1.6rem * 8);