Fix infinite scroll on big screens

4 files changed, 52 insertions, 23 deletions

diff --git a/client/src/app/shared/video/abstract-video-list.html b/client/src/app/shared/video/abstract-video-list.html
index efd369bca..13aedcc74 100644
--- a/client/src/app/shared/video/abstract-video-list.html
+++ b/client/src/app/shared/video/abstract-video-list.html
@@ -19,7 +19,7 @@
 
   <div class="no-results" i18n *ngIf="pagination.totalItems === 0">No results.</div>
   <div
-    myInfiniteScroller (nearOfBottom)="onNearOfBottom()" [autoInit]="true"
+    myInfiniteScroller (nearOfBottom)="onNearOfBottom()" [autoInit]="true" [dataObservable]="onDataSubject.asObservable()"
     class="videos"
   >
     <ng-container *ngFor="let video of videos; trackBy: videoById;">
diff --git a/client/src/app/shared/video/abstract-video-list.ts b/client/src/app/shared/video/abstract-video-list.ts
index 8a247a9af..2926b179b 100644
--- a/client/src/app/shared/video/abstract-video-list.ts
+++ b/client/src/app/shared/video/abstract-video-list.ts
@@ -1,7 +1,7 @@
 import { debounceTime, first, tap } from 'rxjs/operators'
 import { OnDestroy, OnInit } from '@angular/core'
 import { ActivatedRoute, Router } from '@angular/router'
-import { fromEvent, Observable, of, Subscription } from 'rxjs'
+import { fromEvent, Observable, of, Subject, Subscription } from 'rxjs'
 import { AuthService } from '../../core/auth'
 import { ComponentPagination } from '../rest/component-pagination.model'
 import { VideoSortField } from './sort-field.type'
@@ -59,6 +59,8 @@ export abstract class AbstractVideoList implements OnInit, OnDestroy, DisableFor
     blacklistInfo: false
   }
 
+  onDataSubject = new Subject<any[]>()
+
   protected abstract notifier: Notifier
   protected abstract authService: AuthService
   protected abstract route: ActivatedRoute
@@ -147,6 +149,8 @@ export abstract class AbstractVideoList implements OnInit, OnDestroy, DisableFor
         if (this.groupByDate) this.buildGroupedDateLabels()
 
         this.onMoreVideos()
+
+        this.onDataSubject.next(data)
       },
 
       error => this.notifier.error(error.message)
diff --git a/client/src/app/shared/video/infinite-scroller.directive.ts b/client/src/app/shared/video/infinite-scroller.directive.ts
index b1e88882c..9f613c5fa 100644
--- a/client/src/app/shared/video/infinite-scroller.directive.ts
+++ b/client/src/app/shared/video/infinite-scroller.directive.ts
@@ -1,14 +1,15 @@
-import { distinct, distinctUntilChanged, filter, map, share, startWith, throttleTime } from 'rxjs/operators'
-import { Directive, ElementRef, EventEmitter, Input, OnDestroy, OnInit, Output } from '@angular/core'
-import { fromEvent, Subscription } from 'rxjs'
+import { distinctUntilChanged, filter, map, share, startWith, tap, throttleTime } from 'rxjs/operators'
+import { AfterContentChecked, Directive, ElementRef, EventEmitter, Input, OnDestroy, OnInit, Output } from '@angular/core'
+import { fromEvent, Observable, Subscription } from 'rxjs'
 
 @Directive({
   selector: '[myInfiniteScroller]'
 })
-export class InfiniteScrollerDirective implements OnInit, OnDestroy {
+export class InfiniteScrollerDirective implements OnInit, OnDestroy, AfterContentChecked {
   @Input() percentLimit = 70
   @Input() autoInit = false
   @Input() onItself = false
+  @Input() dataObservable: Observable<any[]>
 
   @Output() nearOfBottom = new EventEmitter<void>()
 
@@ -17,10 +18,22 @@ export class InfiniteScrollerDirective implements OnInit, OnDestroy {
   private scrollDownSub: Subscription
   private container: HTMLElement
 
+  private checkScroll = false
+
   constructor (private el: ElementRef) {
     this.decimalLimit = this.percentLimit / 100
   }
 
+  ngAfterContentChecked () {
+    if (this.checkScroll) {
+      this.checkScroll = false
+
+      console.log('Checking if the initial state has a scroll.')
+
+      if (this.hasScroll() === false) this.nearOfBottom.emit()
+    }
+  }
+
   ngOnInit () {
     if (this.autoInit === true) return this.initialize()
   }
@@ -30,14 +43,15 @@ export class InfiniteScrollerDirective implements OnInit, OnDestroy {
   }
 
   initialize () {
-    if (this.onItself) {
-      this.container = this.el.nativeElement
-    }
+    this.container = this.onItself
+      ? this.el.nativeElement
+      : document.documentElement
 
     // Emit the last value
     const throttleOptions = { leading: true, trailing: true }
 
-    const scrollObservable = fromEvent(this.container || window, 'scroll')
+    const scrollableElement = this.onItself ? this.container : window
+    const scrollObservable = fromEvent(scrollableElement, 'scroll')
       .pipe(
         startWith(null as string), // FIXME: typings
         throttleTime(200, undefined, throttleOptions),
@@ -49,23 +63,34 @@ export class InfiniteScrollerDirective implements OnInit, OnDestroy {
     // Scroll Down
     this.scrollDownSub = scrollObservable
       .pipe(
-        // Check we scroll down
-        filter(({ current }) => {
-          const res = this.lastCurrentBottom < current
-
-          this.lastCurrentBottom = current
-          return res
-        }),
-        filter(({ current, maximumScroll }) => maximumScroll <= 0 || (current / maximumScroll) > this.decimalLimit)
+        filter(({ current }) => this.isScrollingDown(current)),
+        filter(({ current, maximumScroll }) => (current / maximumScroll) > this.decimalLimit)
       )
       .subscribe(() => this.nearOfBottom.emit())
+
+    if (this.dataObservable) {
+      this.dataObservable
+          .pipe(filter(d => d.length !== 0))
+          .subscribe(() => this.checkScroll = true)
+    }
   }
 
   private getScrollInfo () {
-    if (this.container) {
-      return { current: this.container.scrollTop, maximumScroll: this.container.scrollHeight }
-    }
+    return { current: this.container.scrollTop, maximumScroll: this.getMaximumScroll() }
+  }
+
+  private getMaximumScroll () {
+    return this.container.scrollHeight - window.innerHeight
+  }
+
+  private hasScroll () {
+    return this.getMaximumScroll() > 0
+  }
+
+  private isScrollingDown (current: number) {
+    const result = this.lastCurrentBottom < current
 
-    return { current: window.scrollY, maximumScroll: document.body.clientHeight - window.innerHeight }
+    this.lastCurrentBottom = current
+    return result
   }
 }
diff --git a/client/src/app/shared/video/videos-selection.component.html b/client/src/app/shared/video/videos-selection.component.html
index 120c168cd..2b4b353cf 100644
--- a/client/src/app/shared/video/videos-selection.component.html
+++ b/client/src/app/shared/video/videos-selection.component.html
@@ -1,6 +1,6 @@
 <div class="no-results" i18n *ngIf="pagination.totalItems === 0">No results.</div>
 
-<div myInfiniteScroller [autoInit]="true" (nearOfBottom)="onNearOfBottom()" class="videos">
+<div myInfiniteScroller [autoInit]="true" (nearOfBottom)="onNearOfBottom()" [dataObservable]="onDataSubject.asObservable()" class="videos">
   <div class="video" *ngFor="let video of videos; let i = index; trackBy: videoById">
 
     <div class="checkbox-container">