Rewrite infinite scroll

1 files changed, 77 insertions, 0 deletions

diff --git a/client/src/app/shared/video/infinite-scroller.directive.ts b/client/src/app/shared/video/infinite-scroller.directive.ts
new file mode 100644
index 000000000..43e014cbd
--- /dev/null
+++ b/client/src/app/shared/video/infinite-scroller.directive.ts
@@ -0,0 +1,77 @@
+import { Directive, EventEmitter, Input, OnInit, Output } from '@angular/core'
+import 'rxjs/add/operator/distinct'
+import 'rxjs/add/operator/startWith'
+import { fromEvent } from 'rxjs/observable/fromEvent'
+
+@Directive({
+  selector: '[myInfiniteScroller]'
+})
+export class InfiniteScrollerDirective implements OnInit {
+  private static PAGE_VIEW_TOP_MARGIN = 500
+
+  @Input() containerHeight: number
+  @Input() pageHeight: number
+  @Input() percentLimit = 70
+  @Input() autoLoading = false
+
+  @Output() nearOfBottom = new EventEmitter<void>()
+  @Output() nearOfTop = new EventEmitter<void>()
+  @Output() pageChanged = new EventEmitter<number>()
+
+  private decimalLimit = 0
+  private lastCurrentBottom = -1
+  private lastCurrentTop = 0
+
+  constructor () {
+    this.decimalLimit = this.percentLimit / 100
+  }
+
+  ngOnInit () {
+    if (this.autoLoading === true) return this.initialize()
+  }
+
+  initialize () {
+    const scrollObservable = fromEvent(window, 'scroll')
+      .startWith(true)
+      .map(() => ({ current: window.scrollY, maximumScroll: document.body.clientHeight - window.innerHeight }))
+
+    // Scroll Down
+    scrollObservable
+      // 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)
+      .debounceTime(200)
+      .distinct()
+      .subscribe(() => this.nearOfBottom.emit())
+
+    // Scroll up
+    scrollObservable
+      // Check we scroll up
+      .filter(({ current }) => {
+        const res = this.lastCurrentTop > current
+
+        this.lastCurrentTop = current
+        return res
+      })
+      .filter(({ current, maximumScroll }) => {
+        return current !== 0 && (1 - (current / maximumScroll)) > this.decimalLimit
+      })
+      .debounceTime(200)
+      .distinct()
+      .subscribe(() => this.nearOfTop.emit())
+
+    // Page change
+    scrollObservable
+      .debounceTime(500)
+      .distinct()
+      .map(({ current }) => Math.max(1, Math.round((current + InfiniteScrollerDirective.PAGE_VIEW_TOP_MARGIN) / this.pageHeight)))
+      .distinctUntilChanged()
+      .subscribe(res => this.pageChanged.emit(res))
+  }
+
+}