Support lazy download thumbnails

server/lib/files-cache/video-previews-simple-file-cache.ts

@@ -0,0 +1,58 @@
+import { join } from 'path'
+import { FILES_CACHE } from '../../initializers/constants'
+import { VideoModel } from '../../models/video/video'
+import { AbstractSimpleFileCache } from './shared/abstract-simple-file-cache'
+import { doRequestAndSaveToFile } from '@server/helpers/requests'
+import { ThumbnailModel } from '@server/models/video/thumbnail'
+import { ThumbnailType } from '@shared/models'
+import { logger } from '@server/helpers/logger'
+
+class VideoPreviewsSimpleFileCache extends AbstractSimpleFileCache <string> {
+
+  private static instance: VideoPreviewsSimpleFileCache
+
+  private constructor () {
+    super()
+  }
+
+  static get Instance () {
+    return this.instance || (this.instance = new this())
+  }
+
+  async getFilePathImpl (filename: string) {
+    const thumbnail = await ThumbnailModel.loadWithVideoByFilename(filename, ThumbnailType.PREVIEW)
+    if (!thumbnail) return undefined
+
+    if (thumbnail.Video.isOwned()) return { isOwned: true, path: thumbnail.getPath() }
+
+    return this.loadRemoteFile(thumbnail.Video.uuid)
+  }
+
+  // Key is the video UUID
+  protected async loadRemoteFile (key: string) {
+    const video = await VideoModel.loadFull(key)
+    if (!video) return undefined
+
+    if (video.isOwned()) throw new Error('Cannot load remote preview of owned video.')
+
+    const preview = video.getPreview()
+    const destPath = join(FILES_CACHE.PREVIEWS.DIRECTORY, preview.filename)
+    const remoteUrl = preview.getOriginFileUrl(video)
+
+    try {
+      await doRequestAndSaveToFile(remoteUrl, destPath)
+
+      logger.debug('Fetched remote preview %s to %s.', remoteUrl, destPath)
+
+      return { isOwned: false, path: destPath }
+    } catch (err) {
+      logger.info('Cannot fetch remote preview file %s.', remoteUrl, { err })
+
+      return undefined
+    }
+  }
+}
+
+export {
+  VideoPreviewsSimpleFileCache
+}