1 files changed, 54 insertions, 0 deletions

diff --git a/server/lib/cache/abstract-video-static-file-cache.ts b/server/lib/cache/abstract-video-static-file-cache.ts
new file mode 100644
index 000000000..7eeeb6b3a
--- /dev/null
+++ b/server/lib/cache/abstract-video-static-file-cache.ts
@@ -0,0 +1,54 @@
+import * as AsyncLRU from 'async-lru'
+import { createWriteStream } from 'fs'
+import { join } from 'path'
+import { unlinkPromise } from '../../helpers/core-utils'
+import { logger } from '../../helpers/logger'
+import { CACHE, CONFIG } from '../../initializers'
+import { VideoModel } from '../../models/video/video'
+import { fetchRemoteVideoStaticFile } from '../activitypub'
+import { VideoCaptionModel } from '../../models/video/video-caption'
+
+export abstract class AbstractVideoStaticFileCache <T> {
+
+  protected lru
+
+  abstract getFilePath (params: T): Promise<string>
+
+  // Load and save the remote file, then return the local path from filesystem
+  protected abstract loadRemoteFile (key: string): Promise<string>
+
+  init (max: number) {
+    this.lru = new AsyncLRU({
+      max,
+      load: (key, cb) => {
+        this.loadRemoteFile(key)
+          .then(res => cb(null, res))
+          .catch(err => cb(err))
+      }
+    })
+
+    this.lru.on('evict', (obj: { key: string, value: string }) => {
+      unlinkPromise(obj.value).then(() => logger.debug('%s evicted from %s', obj.value, this.constructor.name))
+    })
+  }
+
+  protected loadFromLRU (key: string) {
+    return new Promise<string>((res, rej) => {
+      this.lru.get(key, (err, value) => {
+        err ? rej(err) : res(value)
+      })
+    })
+  }
+
+  protected saveRemoteVideoFileAndReturnPath (video: VideoModel, remoteStaticPath: string, destPath: string) {
+    return new Promise<string>((res, rej) => {
+      const req = fetchRemoteVideoStaticFile(video, remoteStaticPath, rej)
+
+      const stream = createWriteStream(destPath)
+
+      req.pipe(stream)
+         .on('error', (err) => rej(err))
+         .on('finish', () => res(destPath))
+    })
+  }
+}