Refactor: Separated "Other Videos" section into a dedicated component/service (#969)

* Separated "Other Videos" section into a dedicated component/service

I'm currently working on some proof-of-concepts for recommendation
providers that could work with PeerTube to provide useful video
suggestions to the user.

As a first step, I want to have great clarity about how PeerTube,
itself, will surface these videos to the user.

With this branch, I'm refactoring the "recommendations" to make it
easier to swap out different recommender implementations quickly.

Stop recommender from including the video that's being watched.

Ensure always 5 recommendations

* Treat recommendations as a stream of values, rather than a single async value.

* Prioritize readability over HTTP response size early-optimization.

* Simplify pipe

3 files changed, 6 insertions, 35 deletions

diff --git a/client/src/app/videos/+video-watch/video-watch.component.html b/client/src/app/videos/+video-watch/video-watch.component.html
index 2c8305777..16d657a65 100644
--- a/client/src/app/videos/+video-watch/video-watch.component.html
+++ b/client/src/app/videos/+video-watch/video-watch.component.html
@@ -197,19 +197,10 @@
           </div>
         </div>
 
-        <my-video-comments [video]="video" [user]="user"></my-video-comments>
-      </div>
-
-      <div class="ml-3 ml-sm-0 col-12 col-md-3 other-videos">
-        <div i18n class="title-page title-page-single">
-          Other videos
-        </div>
-
-        <div *ngFor="let video of otherVideosDisplayed">
-          <my-video-miniature [video]="video" [user]="user"></my-video-miniature>
-        </div>
-      </div>
+      <my-video-comments [video]="video" [user]="user"></my-video-comments>
     </div>
+    <my-recommended-videos class="ml-3 ml-sm-0 col-12 col-md-3"
+                           [inputVideo]="video" [user]="user"></my-recommended-videos>
   </div>
 
 
diff --git a/client/src/app/videos/+video-watch/video-watch.component.ts b/client/src/app/videos/+video-watch/video-watch.component.ts
index d838ebe79..25643cfde 100644
--- a/client/src/app/videos/+video-watch/video-watch.component.ts
+++ b/client/src/app/videos/+video-watch/video-watch.component.ts
@@ -15,7 +15,6 @@ import '../../../assets/player/peertube-videojs-plugin'
 import { AuthService, ConfirmService } from '../../core'
 import { RestExtractor, VideoBlacklistService } from '../../shared'
 import { VideoDetails } from '../../shared/video/video-details.model'
-import { Video } from '../../shared/video/video.model'
 import { VideoService } from '../../shared/video/video.service'
 import { MarkdownService } from '../shared'
 import { VideoDownloadComponent } from './modal/video-download.component'
@@ -43,8 +42,6 @@ export class VideoWatchComponent implements OnInit, OnDestroy {
   @ViewChild('videoSupportModal') videoSupportModal: VideoSupportComponent
   @ViewChild('videoBlacklistModal') videoBlacklistModal: VideoBlacklistComponent
 
-  otherVideosDisplayed: Video[] = []
-
   player: videojs.Player
   playerElement: HTMLVideoElement
   userRating: UserVideoRateType = null
@@ -60,7 +57,6 @@ export class VideoWatchComponent implements OnInit, OnDestroy {
   remoteServerDown = false
 
   private videojsLocaleLoaded = false
-  private otherVideos: Video[] = []
   private paramsSub: Subscription
 
   constructor (
@@ -96,16 +92,6 @@ export class VideoWatchComponent implements OnInit, OnDestroy {
       this.hasAlreadyAcceptedPrivacyConcern = true
     }
 
-    this.videoService.getVideos({ currentPage: 1, itemsPerPage: 5 }, '-createdAt')
-        .subscribe(
-          data => {
-            this.otherVideos = data.videos
-            this.updateOtherVideosDisplayed()
-          },
-
-          err => console.error(err)
-        )
-
     this.paramsSub = this.route.params.subscribe(routeParams => {
       const uuid = routeParams[ 'uuid' ]
 
@@ -365,8 +351,6 @@ export class VideoWatchComponent implements OnInit, OnDestroy {
     this.completeDescriptionShown = false
     this.remoteServerDown = false
 
-    this.updateOtherVideosDisplayed()
-
     if (this.video.isVideoNSFWForUser(this.user, this.serverService.getConfig())) {
       const res = await this.confirmService.confirm(
         this.i18n('This video contains mature or explicit content. Are you sure you want to watch it?'),
@@ -474,12 +458,6 @@ export class VideoWatchComponent implements OnInit, OnDestroy {
     this.setVideoLikesBarTooltipText()
   }
 
-  private updateOtherVideosDisplayed () {
-    if (this.video && this.otherVideos && this.otherVideos.length > 0) {
-      this.otherVideosDisplayed = this.otherVideos.filter(v => v.uuid !== this.video.uuid)
-    }
-  }
-
   private setOpenGraphTags () {
     this.metaService.setTitle(this.video.name)
 
diff --git a/client/src/app/videos/+video-watch/video-watch.module.ts b/client/src/app/videos/+video-watch/video-watch.module.ts
index 7920147b2..5582ab40f 100644
--- a/client/src/app/videos/+video-watch/video-watch.module.ts
+++ b/client/src/app/videos/+video-watch/video-watch.module.ts
@@ -16,6 +16,7 @@ import { VideoWatchComponent } from './video-watch.component'
 import { NgxQRCodeModule } from 'ngx-qrcode2'
 import { NgbTooltipModule } from '@ng-bootstrap/ng-bootstrap'
 import { VideoBlacklistComponent } from '@app/videos/+video-watch/modal/video-blacklist.component'
+import { RecommendationsModule } from '@app/videos/recommendations/recommendations.module'
 import { TextareaAutosizeModule } from 'ngx-textarea-autosize'
 
 @NgModule({
@@ -25,7 +26,8 @@ import { TextareaAutosizeModule } from 'ngx-textarea-autosize'
     ClipboardModule,
     NgbTooltipModule,
     NgxQRCodeModule,
-    TextareaAutosizeModule
+    TextareaAutosizeModule,
+    RecommendationsModule
   ],
 
   declarations: [