1 files changed, 93 insertions, 0 deletions

diff --git a/client/src/standalone/videos/shared/playlist-tracker.ts b/client/src/standalone/videos/shared/playlist-tracker.ts
new file mode 100644
index 000000000..75d10b4e2
--- /dev/null
+++ b/client/src/standalone/videos/shared/playlist-tracker.ts
@@ -0,0 +1,93 @@
+import { VideoPlaylist, VideoPlaylistElement } from '../../../../../shared/models'
+
+export class PlaylistTracker {
+  private currentPlaylistElement: VideoPlaylistElement
+
+  constructor (
+    private readonly playlist: VideoPlaylist,
+    private readonly playlistElements: VideoPlaylistElement[]
+  ) {
+
+  }
+
+  getPlaylist () {
+    return this.playlist
+  }
+
+  getPlaylistElements () {
+    return this.playlistElements
+  }
+
+  hasNextPlaylistElement (position?: number) {
+    return !!this.getNextPlaylistElement(position)
+  }
+
+  getNextPlaylistElement (position?: number): VideoPlaylistElement {
+    if (!position) position = this.currentPlaylistElement.position + 1
+
+    if (position > this.playlist.videosLength) {
+      return undefined
+    }
+
+    const next = this.playlistElements.find(e => e.position === position)
+
+    if (!next || !next.video) {
+      return this.getNextPlaylistElement(position + 1)
+    }
+
+    return next
+  }
+
+  hasPreviousPlaylistElement (position?: number) {
+    return !!this.getPreviousPlaylistElement(position)
+  }
+
+  getPreviousPlaylistElement (position?: number): VideoPlaylistElement {
+    if (!position) position = this.currentPlaylistElement.position - 1
+
+    if (position < 1) {
+      return undefined
+    }
+
+    const prev = this.playlistElements.find(e => e.position === position)
+
+    if (!prev || !prev.video) {
+      return this.getNextPlaylistElement(position - 1)
+    }
+
+    return prev
+  }
+
+  nextVideoTitle () {
+    const next = this.getNextPlaylistElement()
+    if (!next) return ''
+
+    return next.video.name
+  }
+
+  setPosition (position: number) {
+    this.currentPlaylistElement = this.playlistElements.find(e => e.position === position)
+    if (!this.currentPlaylistElement || !this.currentPlaylistElement.video) {
+      console.error('Current playlist element is not valid.', this.currentPlaylistElement)
+      this.currentPlaylistElement = this.getNextPlaylistElement()
+    }
+
+    if (!this.currentPlaylistElement) {
+      throw new Error('This playlist does not have any valid element')
+    }
+  }
+
+  setCurrentElement (playlistElement: VideoPlaylistElement) {
+    this.currentPlaylistElement = playlistElement
+  }
+
+  getCurrentElement () {
+    return this.currentPlaylistElement
+  }
+
+  getCurrentPosition () {
+    if (!this.currentPlaylistElement) return -1
+
+    return this.currentPlaylistElement.position
+  }
+}