Implement basic placeholder skeleton when loading

the post() function now uses await syntax rather than .then()

src/App.css

@@ -8,8 +8,7 @@ body {
   display: flex;
   flex-direction: row;
 
-  margin: 1em;
-  padding: 0;
+  padding: 1em;
 }
 
 .Contents {
@@ -39,7 +38,9 @@ body {
   overflow: clip;
 }
 
-.GalleryItem > img, video {
+.GalleryItem > img,
+.GalleryItem > video {
+  object-fit: contain;
   max-height: 80vh;
 }
 
@@ -62,7 +63,16 @@ body {
   background-color: #0056b3;
 }
 
+.PlaceholderItem > button,
 .ParentDirectoryItem > button {
 	background-color: #4D4F5D;
 }
 
+.PlaceholderItem > a {
+  height: 1em;
+}
+
+.PlaceholderItem > button {
+  height: calc(16px + 10px * 2);
+  width: 6em;
+}

src/App.tsx

@@ -1,185 +1,13 @@
-import React from 'react';
-//import logo from './logo.svg';
 import './App.css';
-import { useState, useEffect } from 'react';
+
+import Gallery from './Gallery/index';
 
 function App() {
-  const [data, setData] = useState('');
-  const [category, setCategory] = useState('');
-
-  useEffect(() => {
-    post(category, (json: string) => {
-      setData(json);
-    });
-  });
-
   return (
     <div className="App">
-      <div className="Header">
-        {getContents(data, true, category, setCategory)}
-      </div>
-      <div className="Contents">
-        {getContents(data, false, category, setCategory)}
-      </div>
+      <Gallery />
     </div>
   );
 }
 
-interface galleryItemInfo {
-  is_dir: boolean;
-  url: string;
-  thumbnail_url: string;
-}
-
-function getContents(
-  data: string,
-  getDir: boolean,
-  category: string,
-  setCategory: (category: string) => void
-) {
-  if (data === '') return;
-
-  let obj = null;
-  try {
-    obj = JSON.parse(data);
-  } catch (error: unknown) {
-    if (!(error instanceof SyntaxError)) {
-      throw new Error(error as unknown as undefined);
-    }
-    return data;
-  }
-
-  return obj
-    .sort((a: galleryItemInfo, b: galleryItemInfo) => {
-      if (a.is_dir && b.is_dir) return 0;
-      if (a.is_dir && !b.is_dir) return -1;
-      if (!a.is_dir && b.is_dir) return 1;
-      if (!a.is_dir && !b.is_dir) return 0;
-    })
-    .filter((item: galleryItemInfo) => {
-      return getDir == item.is_dir;
-    })
-    .map((item: galleryItemInfo, index: number) => {
-      const url = item.url;
-      const thumbnail_url =
-        item.thumbnail_url === null ? item.url : item.thumbnail_url;
-      let onClick = () => {};
-      if (item.is_dir) {
-        onClick = () => {
-          const subCategory = getFileName(url);
-
-          if (category !== '') category = `${category}/${subCategory}`;
-          else category = subCategory;
-          if (subCategory === '..')
-            category = category.split('/').slice(0, -2).join('/');
-
-          setCategory(category);
-        };
-        return (
-          <DirectoryItem
-            key={index}
-            thumbnail_url={thumbnail_url}
-            url={url}
-            onClick={onClick}
-          />
-        );
-      }
-      if (url.endsWith('.mp4')) {
-        return (
-          <VideoItem
-            key={index}
-            thumbnail_url={thumbnail_url}
-            url={url}
-            onClick={onClick}
-          />
-        );
-      }
-      return (
-        <ImageItem
-          key={index}
-          thumbnail_url={thumbnail_url}
-          url={url}
-          onClick={onClick}
-        />
-      );
-    });
-}
-
-interface galleryItem {
-  url: string;
-  thumbnail_url: string;
-  onClick: () => void;
-}
-
-function ImageItem({ thumbnail_url, url }: galleryItem) {
-  return (
-    <div className="GalleryItem">
-      <a href={url} target="_blank">
-        {getFileName(url)}
-      </a>
-      <img src={thumbnail_url} loading="lazy" />
-    </div>
-  );
-}
-
-function VideoItem({ url }: galleryItem) {
-  return (
-    <div className="GalleryItem">
-      <a href={url} target="_blank">
-        {getFileName(url)}
-      </a>
-      <video controls>
-        <source src={url} type="video/mp4" />
-      </video>
-    </div>
-  );
-}
-
-function DirectoryItem({ url, onClick }: galleryItem) {
-  let buttonText = getFileName(url);
-  const isBackButton = buttonText === '..';
-  buttonText = isBackButton ? 'Back' : `Category: ${buttonText}`;
-  const backButtonClass = isBackButton ? 'ParentDirectoryItem' : '';
-  return (
-    <div className={`DirectoryItem ${backButtonClass}`}>
-      <button className="DirectoryItem" onClick={onClick}>
-        {buttonText}
-      </button>
-    </div>
-  );
-}
-
-function getFileName(string: string): string {
-  return string.split('/').at(-1) as unknown as string;
-}
-
-function post(category: string, callback: (text: string) => void) {
-  fetch(
-    //'http://localhost/photo-viewer-backend/php/get.php',
-    'https://dundun.ddns.net/photo-viewer/photo-viewer-backend/php/get.php',
-    {
-      method: 'POST',
-      headers: {
-        'Content-Type': 'application/json',
-      },
-      body: JSON.stringify({
-        category: category,
-      }),
-    }
-  )
-    .then((response) => {
-      if (!response.ok) {
-        throw new Error('Network response was not ok');
-      }
-      return response;
-    })
-    .then((response) => response.text())
-    .then((data) => {
-      callback(data as unknown as string);
-    })
-    .catch((error) => {
-      console.error('There was a problem with the fetch operation:', error);
-    });
-}
-
 export default App;

src/Gallery/index.tsx

@@ -0,0 +1,197 @@
+import React from 'react';
+import '../App.css';
+import placeholderPng from './placeholder.png';
+import { useState, useEffect } from 'react';
+
+function Gallery() {
+  const [data, setData] = useState<galleryItemInfo[]>([]);
+  const [category, setCategory] = useState('');
+
+  useEffect(() => {
+    post(category, (data: galleryItemInfo[]) => {
+      setData(data);
+    });
+  }, [category]);
+
+  const updateCategory = (category: string) => {
+    setData(getPlaceholderData);
+    setCategory(category);
+  };
+
+  return (
+    <div className="Gallery">
+      <div className="Header">
+        {Contents(data, true, category, updateCategory)}
+      </div>
+      <div className="Contents">
+        {Contents(data, false, category, updateCategory)}
+      </div>
+    </div>
+  );
+}
+
+interface galleryItemInfo {
+  is_dir: boolean;
+  url: string;
+  thumbnail_url: string;
+
+  isPlaceholder: boolean;
+}
+
+function Contents(
+  data: galleryItemInfo[],
+  getDir: boolean,
+  category: string,
+  setCategory: (category: string) => void
+) {
+  if (data === null) return;
+
+  return data
+    .sort((a: galleryItemInfo, b: galleryItemInfo): number => {
+      if (a.is_dir && b.is_dir) return 0;
+      if (a.is_dir && !b.is_dir) return -1;
+      if (!a.is_dir && b.is_dir) return 1;
+      if (!a.is_dir && !b.is_dir) return 0;
+      return 0;
+    })
+    .filter((item: galleryItemInfo) => {
+      return getDir == item.is_dir;
+    })
+    .map((item: galleryItemInfo, index: number) => {
+      const itemProps = {
+        key: index,
+        url: item.url,
+        thumbnail_url:
+          item.thumbnail_url === null ? item.url : item.thumbnail_url,
+        onClick: () => {},
+        isPlaceholder: item.isPlaceholder,
+      };
+
+      if (item.is_dir) {
+        itemProps.onClick = () => {
+          const subCategory = getFileName(itemProps.url);
+
+          if (category !== '') category = `${category}/${subCategory}`;
+          else category = subCategory;
+          if (subCategory === '..')
+            category = category.split('/').slice(0, -2).join('/');
+
+          setCategory(category);
+        };
+        return <DirectoryItem {...itemProps} />;
+      }
+      if (itemProps.url.endsWith('.mp4')) {
+        return <VideoItem {...itemProps} />;
+      }
+      return <ImageItem {...itemProps} />;
+    });
+}
+
+interface galleryItem {
+  url: string;
+  thumbnail_url: string;
+  onClick: () => void;
+  isPlaceholder: boolean;
+}
+
+function ImageItem({ thumbnail_url, url, isPlaceholder }: galleryItem) {
+  const placeholderClass = isPlaceholder ? 'PlaceholderItem' : '';
+  return (
+    <div className={`GalleryItem ${placeholderClass}`}>
+      <a href={url} target="_blank">
+        {getFileName(url)}
+      </a>
+      <img src={thumbnail_url} loading="lazy" />
+    </div>
+  );
+}
+
+function VideoItem({ url }: galleryItem) {
+  return (
+    <div className="GalleryItem">
+      <a href={url} target="_blank">
+        {getFileName(url)}
+      </a>
+      <video controls>
+        <source src={url} type="video/mp4" />
+      </video>
+    </div>
+  );
+}
+
+function DirectoryItem({ url, onClick, isPlaceholder }: galleryItem) {
+  let buttonText = getFileName(url);
+  const isBackButton = buttonText === '..';
+  const placeholderClass = isPlaceholder ? 'PlaceholderItem' : '';
+  buttonText = isBackButton ? 'Back' : `${buttonText}`;
+  const backButtonClass = isBackButton ? 'ParentDirectoryItem' : '';
+  return (
+    <div className={`DirectoryItem ${backButtonClass} ${placeholderClass}`}>
+      <button onClick={onClick}>{buttonText}</button>
+    </div>
+  );
+}
+
+function getFileName(string: string): string {
+  return string.split('/').at(-1) as unknown as string;
+}
+
+function getPlaceholderData(): galleryItemInfo[] {
+  const placeholderDir = (): galleryItemInfo => {
+    return {
+      is_dir: true,
+      url: '',
+      thumbnail_url: '',
+      isPlaceholder: true,
+    };
+  };
+  const placeholderImg = (): galleryItemInfo => {
+    return {
+      is_dir: false,
+      url: '',
+      thumbnail_url: `${placeholderPng}`,
+      isPlaceholder: true,
+    };
+  };
+
+  return [
+    placeholderDir(),
+    placeholderDir(),
+    placeholderImg(),
+    placeholderImg(),
+    placeholderImg(),
+  ];
+}
+async function post(
+  category: string,
+  setDataCallback: (data: galleryItemInfo[]) => void
+) {
+  try {
+    const response = await fetch(
+      //'http://localhost/photo-viewer-backend/php/get.php',
+      'https://dundun.ddns.net/photo-viewer/photo-viewer-backend/php/get.php',
+      {
+        method: 'POST',
+        headers: {
+          'Content-Type': 'application/json',
+        },
+        body: JSON.stringify({
+          category: category,
+        }),
+      }
+    );
+    setDataCallback(await response.json());
+  } catch (error) {
+    console.error('Error fetching data: ', error);
+    setDataCallback([
+      {
+        is_dir: false,
+        url: 'error_fetching',
+        thumbnail_url: '',
+        isPlaceholder: false,
+      },
+    ]);
+  }
+}
+
+export default Gallery;