perf(files): fetch previews faster and cache properly

Signed-off-by: John Molakvoæ <skjnldsv@protonmail.com>

7 files changed, 243 insertions, 34 deletions

diff --git a/apps/files/appinfo/routes.php b/apps/files/appinfo/routes.php
index e4af2367906..a82490f7cae 100644
--- a/apps/files/appinfo/routes.php
+++ b/apps/files/appinfo/routes.php
@@ -134,6 +134,11 @@ $application->registerRoutes(
 				'verb' => 'GET'
 			],
 			[
+				'name' => 'api#serviceWorker',
+				'url' => '/preview-service-worker.js',
+				'verb' => 'GET'
+			],
+			[
 				'name' => 'view#index',
 				'url' => '/{view}',
 				'verb' => 'GET',
diff --git a/apps/files/lib/Controller/ApiController.php b/apps/files/lib/Controller/ApiController.php
index 9baf5e97892..85507132edd 100644
--- a/apps/files/lib/Controller/ApiController.php
+++ b/apps/files/lib/Controller/ApiController.php
@@ -42,10 +42,12 @@ use OCA\Files\Service\TagService;
 use OCA\Files\Service\UserConfig;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http;
+use OCP\AppFramework\Http\ContentSecurityPolicy;
 use OCP\AppFramework\Http\DataResponse;
 use OCP\AppFramework\Http\FileDisplayResponse;
 use OCP\AppFramework\Http\JSONResponse;
 use OCP\AppFramework\Http\Response;
+use OCP\AppFramework\Http\StreamResponse;
 use OCP\Files\File;
 use OCP\Files\Folder;
 use OCP\Files\NotFoundException;
@@ -417,4 +419,22 @@ class ApiController extends Controller {
 		$node = $this->userFolder->get($folderpath);
 		return $node->getType();
 	}
+	
+	/**
+	 * @NoAdminRequired
+	 * @NoCSRFRequired
+	 */
+	public function serviceWorker(): StreamResponse {
+		$response = new StreamResponse(__DIR__ . '/../../../../dist/preview-service-worker.js');
+		$response->setHeaders([
+			'Content-Type' => 'application/javascript',
+			'Service-Worker-Allowed' => '/'
+		]);
+		$policy = new ContentSecurityPolicy();
+		$policy->addAllowedWorkerSrcDomain("'self'");
+		$policy->addAllowedScriptDomain("'self'");
+		$policy->addAllowedConnectDomain("'self'");
+		$response->setContentSecurityPolicy($policy);
+		return $response;
+	}
 }
diff --git a/apps/files/src/components/FileEntry.vue b/apps/files/src/components/FileEntry.vue
index 9f1df025e1f..84990a5ba39 100644
--- a/apps/files/src/components/FileEntry.vue
+++ b/apps/files/src/components/FileEntry.vue
@@ -31,10 +31,18 @@
 		<!-- Icon or preview -->
 		<td class="files-list__row-icon">
 			<FolderIcon v-if="source.type === 'folder'" />
+
 			<!-- Decorative image, should not be aria documented -->
-			<span v-else-if="previewUrl"
-				:style="{ backgroundImage: `url('${previewUrl}')` }"
-				class="files-list__row-icon-preview" />
+			<span v-else-if="previewUrl && !backgroundFailed"
+				ref="previewImg"
+				class="files-list__row-icon-preview"
+				:style="{ backgroundImage }" />
+
+			<span v-else-if="mimeUrl"
+				class="files-list__row-icon-preview files-list__row-icon-preview--mime"
+				:style="{ backgroundImage: mimeUrl }" />
+
+			<FileIcon v-else />
 		</td>
 
 		<!-- Link to file and -->
@@ -65,6 +73,7 @@ import { Folder, File } from '@nextcloud/files'
 import { Fragment } from 'vue-fragment'
 import { join } from 'path'
 import { translate } from '@nextcloud/l10n'
+import FileIcon from 'vue-material-design-icons/File.vue'
 import FolderIcon from 'vue-material-design-icons/Folder.vue'
 import TrashCan from 'vue-material-design-icons/TrashCan.vue'
 import Pencil from 'vue-material-design-icons/Pencil.vue'
@@ -73,19 +82,24 @@ import NcActions from '@nextcloud/vue/dist/Components/NcActions.js'
 import NcCheckboxRadioSwitch from '@nextcloud/vue/dist/Components/NcCheckboxRadioSwitch.js'
 import Vue from 'vue'
 
-import logger from '../logger'
+import logger from '../logger.js'
 import { useSelectionStore } from '../store/selection'
 import { useFilesStore } from '../store/files'
 import { loadState } from '@nextcloud/initial-state'
+import { debounce } from 'debounce'
 
 // TODO: move to store
 // TODO: watch 'files:config:updated' event
 const userConfig = loadState('files', 'config', {})
 
+// The preview service worker cache name (see webpack config)
+const SWCacheName = 'previews'
+
 export default Vue.extend({
 	name: 'FileEntry',
 
 	components: {
+		FileIcon,
 		FolderIcon,
 		Fragment,
 		NcActionButton,
@@ -96,10 +110,6 @@ export default Vue.extend({
 	},
 
 	props: {
-		index: {
-			type: Number,
-			required: true,
-		},
 		source: {
 			type: [File, Folder],
 			required: true,
@@ -118,6 +128,8 @@ export default Vue.extend({
 	data() {
 		return {
 			userConfig,
+			backgroundImage: '',
+			backgroundFailed: false,
 		}
 	},
 
@@ -171,6 +183,32 @@ export default Vue.extend({
 				return null
 			}
 		},
+
+		mimeUrl() {
+			const mimeType = this.source.mime || 'application/octet-stream'
+			const mimeUrl = window.OC?.MimeType?.getIconUrl?.(mimeType)
+			if (mimeUrl) {
+				return `url(${mimeUrl})`
+			}
+			return ''
+		},
+	},
+
+	watch: {
+		source() {
+			this.resetPreview()
+			this.debounceIfNotCached()
+		},
+	},
+
+	mounted() {
+		// Init the debounce function on mount and
+		// not when the module is imported ⚠
+		this.debounceGetPreview = debounce(function() {
+			this.fetchAndApplyPreview()
+		}, 150, false)
+
+		this.debounceIfNotCached()
 	},
 
 	methods: {
@@ -180,15 +218,87 @@ export default Vue.extend({
 		 * @param {number} fileId the file id to get
 		 * @return {Folder|File}
 		 */
-		 getNode(fileId) {
+		getNode(fileId) {
 			return this.filesStore.getNode(fileId)
 		},
 
+		async debounceIfNotCached() {
+			if (!this.previewUrl) {
+				return
+			}
+
+			// Check if we already have this preview cached
+			const isCached = await this.isCachedPreview(this.previewUrl)
+			if (isCached) {
+				logger.debug('Preview already cached', { fileId: this.source.attributes.fileid, backgroundFailed: this.backgroundFailed })
+				this.backgroundImage = `url(${this.previewUrl})`
+				this.backgroundFailed = false
+				return
+			}
+
+			// We don't have this preview cached or it expired, requesting it
+			this.debounceGetPreview()
+		},
+
+		 fetchAndApplyPreview() {
+			logger.debug('Fetching preview', { fileId: this.source.attributes.fileid })
+			this.img = new Image()
+			this.img.onload = () => {
+				this.backgroundImage = `url(${this.previewUrl})`
+			}
+			this.img.onerror = (a, b, c) => {
+				this.backgroundFailed = true
+				logger.error('Failed to fetch preview', { fileId: this.source.attributes.fileid, a, b, c })
+			}
+			this.img.src = this.previewUrl
+		},
+
+		resetPreview() {
+			// Reset the preview
+			this.backgroundImage = ''
+			this.backgroundFailed = false
+
+			// If we're already fetching a preview, cancel it
+			if (this.img) {
+				// Do not fail on cancel
+				this.img.onerror = null
+				this.img.src = ''
+				delete this.img
+			}
+		},
+
+		isCachedPreview(previewUrl) {
+			return caches.open(SWCacheName)
+				.then(function(cache) {
+					return cache.match(previewUrl)
+						.then(function(response) {
+							return !!response // or `return response ? true : false`, or similar.
+						})
+				})
+		},
+
 		t: translate,
 	},
 })
 </script>
 
 <style scoped lang="scss">
-@import '../mixins/fileslist-row.scss'
+@import '../mixins/fileslist-row.scss';
+
+.files-list__row-icon-preview:not([style*="background"]) {
+    background: linear-gradient(110deg, var(--color-loading-dark) 0%, var(--color-loading-dark) 25%, var(--color-loading-light) 50%, var(--color-loading-dark) 75%, var(--color-loading-dark) 100%);
+    background-size: 400%;
+	animation: preview-gradient-slide 1s ease infinite;
+}
+</style>
+
+<style>
+@keyframes preview-gradient-slide {
+    from {
+        background-position: 100% 0%;
+    }
+    to {
+        background-position: 0% 0%;
+    }
+}
 </style>
diff --git a/apps/files/src/components/FilesListVirtual.vue b/apps/files/src/components/FilesListVirtual.vue
index 8193c3bed1b..62a4e0e42eb 100644
--- a/apps/files/src/components/FilesListVirtual.vue
+++ b/apps/files/src/components/FilesListVirtual.vue
@@ -20,30 +20,37 @@
   -
   -->
 <template>
-	<VirtualList class="files-list"
-		:data-component="FileEntry"
-		:data-key="getFileId"
-		:data-sources="nodes"
-		:estimate-size="55"
+	<RecycleScroller ref="recycleScroller"
+		class="files-list"
+		key-field="source"
+		:items="nodes"
+		:item-size="55"
 		:table-mode="true"
 		item-class="files-list__row"
-		wrap-class="files-list__body">
-		<template #before>
+		item-tag="tr"
+		list-class="files-list__body"
+		list-tag="tbody"
+		role="table">
+		<template #default="{ item }">
+			<FileEntry :source="item" />
+		</template>
+
+		<!-- <template #before>
 			<caption v-show="false" class="files-list__caption">
 				{{ summary }}
 			</caption>
-		</template>
+		</template> -->
 
-		<template #header>
+		<template #before>
 			<FilesListHeader :nodes="nodes" />
 		</template>
-	</VirtualList>
+	</RecycleScroller>
 </template>
 
 <script lang="ts">
 import { Folder, File } from '@nextcloud/files'
+import { RecycleScroller } from 'vue-virtual-scroller'
 import { translate, translatePlural } from '@nextcloud/l10n'
-import VirtualList from 'vue-virtual-scroll-list'
 import Vue from 'vue'
 
 import FileEntry from './FileEntry.vue'
@@ -53,7 +60,8 @@ export default Vue.extend({
 	name: 'FilesListVirtual',
 
 	components: {
-		VirtualList,
+		RecycleScroller,
+		FileEntry,
 		FilesListHeader,
 	},
 
@@ -69,7 +77,6 @@ export default Vue.extend({
 			FileEntry,
 		}
 	},
-
 	computed: {
 		files() {
 			return this.nodes.filter(node => node.type === 'file')
@@ -88,6 +95,11 @@ export default Vue.extend({
 		},
 	},
 
+	mounted() {
+		// Make the root recycle scroller a table for proper semantics
+		this.$el.querySelector('.vue-recycle-scroller__slot').setAttribute('role', 'thead')
+	},
+
 	methods: {
 		getFileId(node) {
 			return node.attributes.fileid
@@ -101,6 +113,7 @@ export default Vue.extend({
 <style scoped lang="scss">
 .files-list {
 	--row-height: 55px;
+
 	--checkbox-padding: calc((var(--row-height) - var(--checkbox-size)) / 2);
 	--checkbox-size: 24px;
 	--clickable-area: 44px;
@@ -111,25 +124,32 @@ export default Vue.extend({
 	height: 100%;
 
 	&::v-deep {
-		tbody, thead, tfoot {
+		tbody, .vue-recycle-scroller__slot {
 			display: flex;
 			flex-direction: column;
 			width: 100%;
+			// Necessary for virtual scrolling absolute
+			position: relative;
 		}
 
-		thead {
+		// Table header
+		.vue-recycle-scroller__slot {
 			// Pinned on top when scrolling
 			position: sticky;
 			z-index: 10;
 			top: 0;
+			height: var(--row-height);
 			background-color: var(--color-main-background);
 		}
 
 		tr {
+			position: absolute;
 			display: flex;
 			align-items: center;
+			width: 100%;
 			border-bottom: 1px solid var(--color-border);
 		}
 	}
 }
+
 </style>
diff --git a/apps/files/src/main.js b/apps/files/src/main.js
index 56332374051..48b981359ed 100644
--- a/apps/files/src/main.js
+++ b/apps/files/src/main.js
@@ -6,6 +6,7 @@ import Vue from 'vue'
 import { createPinia, PiniaVuePlugin } from 'pinia'
 
 import NavigationService from './services/Navigation.ts'
+import registerPreviewServiceWorker from './services/ServiceWorker.js'
 
 import NavigationView from './views/Navigation.vue'
 import FilesListView from './views/FilesList.vue'
@@ -57,3 +58,6 @@ FilesList.$mount('#app-content-vue')
 
 // Init legacy files views
 processLegacyFilesViews()
+
+// Register preview service worker
+registerPreviewServiceWorker()
diff --git a/apps/files/src/services/ServiceWorker.js b/apps/files/src/services/ServiceWorker.js
new file mode 100644
index 00000000000..223c0681323
--- /dev/null
+++ b/apps/files/src/services/ServiceWorker.js
@@ -0,0 +1,40 @@
+/**
+ * @copyright Copyright (c) 2019 Gary Kim <gary@garykim.dev>
+ *
+ * @author Gary Kim <gary@garykim.dev>
+ *
+ * @license AGPL-3.0-or-later
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+import { generateUrl } from '@nextcloud/router'
+import logger from '../logger.js'
+
+export default () => {
+	if ('serviceWorker' in navigator) {
+		// Use the window load event to keep the page load performant
+		window.addEventListener('load', async () => {
+			try {
+				const url = generateUrl('/apps/files/preview-service-worker.js', {}, { noRewrite: true })
+				const registration = await navigator.serviceWorker.register(url, { scope: '/' })
+				logger.debug('SW registered: ', { registration })
+			} catch (error) {
+				logger.error('SW registration failed: ', { error })
+			}
+		})
+	} else {
+		logger.debug('Service Worker is not enabled on this browser.')
+	}
+}
diff --git a/apps/files/src/views/FilesList.vue b/apps/files/src/views/FilesList.vue
index abca146138e..5e9a098c853 100644
--- a/apps/files/src/views/FilesList.vue
+++ b/apps/files/src/views/FilesList.vue
@@ -56,7 +56,7 @@
 		</NcEmptyContent>
 
 		<!-- File list -->
-		<FilesListVirtual v-else :nodes="dirContents" />
+		<FilesListVirtual v-else ref="filesListVirtual" :nodes="dirContents" />
 	</NcAppContent>
 </template>
 
@@ -116,6 +116,8 @@ export default Vue.extend({
 		return {
 			loading: true,
 			promise: null,
+			sortKey: 'basename',
+			sortAsc: true,
 		}
 	},
 
@@ -160,7 +162,18 @@ export default Vue.extend({
 		 * @return {Node[]}
 		 */
 		dirContents() {
-			return (this.currentFolder?.children || []).map(this.getNode)
+			return [...(this.currentFolder?.children || []).map(this.getNode)]
+				.sort((a, b) => {
+					if (a.type === 'folder' && b.type !== 'folder') {
+						return this.sortAsc ? -1 : 1
+					}
+
+					if (a.type !== 'folder' && b.type === 'folder') {
+						return this.sortAsc ? 1 : -1
+					}
+
+					return (a[this.sortKey] || a.basename).localeCompare(b[this.sortKey] || b.basename) * (this.sortAsc ? 1 : -1)
+				})
 		},
 
 		/**
@@ -206,14 +219,11 @@ export default Vue.extend({
 			// TODO: preserve selection on browsing?
 			this.selectionStore.reset()
 			this.fetchContent()
-		},
 
-		paths(paths) {
-			logger.debug('Paths changed', { paths })
-		},
-
-		currentFolder(currentFolder) {
-			logger.debug('currentFolder changed', { currentFolder })
+			// Scroll to top, force virtual scroller to re-render
+			if (this.$refs?.filesListVirtual?.$el) {
+				this.$refs.filesListVirtual.$el.scrollTop = 0
+			}
 		},
 	},