Provide hasPreview in files_versions DAV API

This allow to no request non existing previews
I also set some properties to the img element to reduce preview loading to what the browser think is necessary

Signed-off-by: Louis Chemineau <louis@chmn.me>

apps/files_versions/lib/Sabre/Plugin.php

@@ -27,7 +27,11 @@ declare(strict_types=1);
 namespace OCA\Files_Versions\Sabre;
 
 use OC\AppFramework\Http\Request;
+use OCA\DAV\Connector\Sabre\FilesPlugin;
+use OCA\Files_Versions\Versions\IVersionManager;
+use OCP\Files\NotFoundException;
 use OCP\IRequest;
+use OCP\IUserSession;
 use Sabre\DAV\Exception\NotFound;
 use Sabre\DAV\INode;
 use Sabre\DAV\PropFind;
@@ -39,12 +43,13 @@ use Sabre\HTTP\ResponseInterface;
 
 class Plugin extends ServerPlugin {
 	private Server $server;
-	private IRequest $request;
 
 	public const VERSION_LABEL = '{http://nextcloud.org/ns}version-label';
 
 	public function __construct(
-		IRequest $request
+		private IRequest $request,
+		private IVersionManager $versionManager,
+		private IUserSession $userSession,
 	) {
 		$this->request = $request;
 	}
@@ -89,8 +94,25 @@ class Plugin extends ServerPlugin {
 	}
 
 	public function propFind(PropFind $propFind, INode $node): void {
+		$user = $this->userSession->getUser();
+
 		if ($node instanceof VersionFile) {
 			$propFind->handle(self::VERSION_LABEL, fn() => $node->getLabel());
+
+			if ($user !== null) {
+				$propFind->handle(FilesPlugin::HAS_PREVIEW_PROPERTYNAME, function () use ($node, $user) {
+					try {
+						$this->versionManager->getVersionFile(
+							$user,
+							$node->getSourceFile(),
+							$node->getVersion()->getRevisionId()
+						);
+						return true;
+					} catch (NotFoundException $ex) {
+						return false;
+					}
+				});
+			}
 		}
 	}
 

apps/files_versions/lib/Sabre/VersionFile.php

@@ -31,6 +31,7 @@ use OCA\Files_Versions\Versions\INameableVersion;
 use OCA\Files_Versions\Versions\INameableVersionBackend;
 use OCA\Files_Versions\Versions\IVersion;
 use OCA\Files_Versions\Versions\IVersionManager;
+use OCP\Files\FileInfo;
 use OCP\Files\NotFoundException;
 use Sabre\DAV\Exception\Forbidden;
 use Sabre\DAV\Exception\NotFound;
@@ -60,6 +61,10 @@ class VersionFile implements IFile {
 		}
 	}
 
+	public function getSourceFile(): FileInfo {
+		return $this->version->getSourceFile();
+	}
+
 	public function getContentType(): string {
 		return $this->version->getMimeType();
 	}

apps/files_versions/src/components/Version.vue

@@ -23,9 +23,12 @@
 			:force-display-actions="true"
 			data-files-versions-version>
 			<template #icon>
-				<img v-if="!previewError"
+				<img v-if="(isCurrent || version.hasPreview) && !previewError"
 					:src="previewURL"
 					alt=""
+					decoding="async"
+					fetchpriority="low"
+					loading="lazy"
 					class="version__image"
 					@error="previewError = true">
 				<div v-else

apps/files_versions/src/utils/davRequest.js

@@ -30,5 +30,6 @@ export default `<?xml version="1.0"?>
 		<d:getcontenttype />
 		<d:getlastmodified />
 		<nc:version-label />
+		<nc:has-preview />
 	</d:prop>
 </d:propfind>`

apps/files_versions/src/utils/versions.js

@@ -36,6 +36,7 @@ import moment from '@nextcloud/moment'
  * @property {string} size - Human readable size
  * @property {string} type - 'file'
  * @property {number} mtime - Version creation date as a timestamp
+ * @property {boolean} hasPreview - Whether the version has a preview
  * @property {string} preview - Preview URL of the version
  * @property {string} url - Download URL of the version
  * @property {string|null} fileVersion - The version id, null for the current version
@@ -98,6 +99,7 @@ function formatVersion(version, fileInfo) {
 		size: version.size,
 		type: version.type,
 		mtime: moment(version.lastmod).unix() * 1000,
+		hasPreview: version.props['has-preview'] === 1,
 		preview: generateUrl('/apps/files_versions/preview?file={file}&version={fileVersion}', {
 			file: joinPaths(fileInfo.path, fileInfo.name),
 			fileVersion: version.basename,