Added v1 of chat sidebar for Twitch VODs

src/app/components/twitch-chat/twitch-chat.component.ts

@@ -0,0 +1,135 @@
+import { AfterViewInit, Component, ElementRef, Input, OnInit, QueryList, ViewChild, ViewChildren } from '@angular/core';
+import { PostsService } from 'app/posts.services';
+
+@Component({
+  selector: 'app-twitch-chat',
+  templateUrl: './twitch-chat.component.html',
+  styleUrls: ['./twitch-chat.component.scss']
+})
+export class TwitchChatComponent implements OnInit, AfterViewInit {
+
+  full_chat = null;
+  visible_chat = null;
+  chat_response_received = false;
+  downloading_chat = false;
+
+  current_chat_index = null;
+
+  CHAT_CHECK_INTERVAL_MS = 200;
+  chat_check_interval_obj = null;
+
+  scrollContainer = null;
+
+  @Input() db_file = null;
+  @Input() current_timestamp = null;
+
+  @ViewChild('scrollContainer') scrollRef: ElementRef;
+
+  constructor(private postsService: PostsService) { }
+
+  ngOnInit(): void {
+    this.getFullChat();
+  }
+
+  ngAfterViewInit() {
+  }
+
+  private isUserNearBottom(): boolean {
+    const threshold = 300;
+    const position = this.scrollContainer.scrollTop + this.scrollContainer.offsetHeight;
+    const height = this.scrollContainer.scrollHeight;
+    return position > height - threshold;
+  }
+
+  scrollToBottom = () => {
+    this.scrollContainer.scrollTop = this.scrollContainer.scrollHeight;
+  }
+
+  addNewChatMessages() {
+    if (!this.scrollContainer) {
+      this.scrollContainer = this.scrollRef.nativeElement;
+    }
+    if (this.current_chat_index === null) {
+      this.current_chat_index = this.getIndexOfNextChat();
+    }
+
+    const latest_chat_timestamp = this.visible_chat.length ? this.visible_chat[this.visible_chat.length - 1]['timestamp'] : 0;
+
+    for (let i = this.current_chat_index + 1; i < this.full_chat.length; i++) {
+      if (this.full_chat[i]['timestamp'] >= latest_chat_timestamp && this.full_chat[i]['timestamp'] <= this.current_timestamp) {
+        this.visible_chat.push(this.full_chat[i]);
+        this.current_chat_index = i;
+        if (this.isUserNearBottom()) {
+          this.scrollToBottom();
+        }
+      } else if (this.full_chat[i]['timestamp'] > this.current_timestamp) {
+        break;
+      }
+    }
+  }
+
+  getIndexOfNextChat() {
+    const index = binarySearch(this.full_chat, 'timestamp', this.current_timestamp);
+    return index;
+  }
+
+  getFullChat() {
+    this.postsService.getFullTwitchChat(this.db_file.id, this.db_file.isAudio ? 'audio' : 'video', null).subscribe(res => {
+      this.chat_response_received = true;
+      if (res['chat']) {
+        this.initializeChatCheck(res['chat']);
+      }
+    });
+  }
+
+  renewChat() {
+    this.visible_chat = [];
+    this.current_chat_index = this.getIndexOfNextChat();
+  }
+
+  downloadTwitchChat() {
+    this.downloading_chat = true;
+    let vodId = this.db_file.url.split('videos/').length > 1 && this.db_file.url.split('videos/')[1];
+    vodId = vodId.split('?')[0];
+    if (!vodId) {
+      this.postsService.openSnackBar('VOD url for this video is not supported. VOD ID must be after "twitch.tv/videos/"');
+    }
+    this.postsService.downloadTwitchChat(this.db_file.id, this.db_file.isAudio ? 'audio' : 'video', vodId, null).subscribe(res => {
+      if (res['chat']) {
+        this.initializeChatCheck(res['chat']);
+      } else {
+        this.downloading_chat = false;
+        this.postsService.openSnackBar('Download failed.')
+      }
+    }, err => {
+      this.downloading_chat = false;
+      this.postsService.openSnackBar('Chat could not be downloaded.')
+    });
+  }
+
+  initializeChatCheck(full_chat) {
+    this.full_chat = full_chat;
+    this.visible_chat = [];
+    this.chat_check_interval_obj = setInterval(() => this.addNewChatMessages(), this.CHAT_CHECK_INTERVAL_MS);
+  }
+
+}
+
+function binarySearch(arr, key, n) {
+  let min = 0;
+  let max = arr.length - 1;
+  let mid;
+  while (min <= max) {
+    // tslint:disable-next-line: no-bitwise
+    mid = (min + max) >>> 1;
+    if (arr[mid][key] === n) {
+      return mid;
+    } else if (arr[mid][key] < n) {
+      min = mid + 1;
+    } else {
+      max = mid - 1;
+    }
+  }
+
+  return min;
+}