Step 6.7: Create NewChatComponent

client/imports/pages/chats/new-chat.component.ts

@@ -0,0 +1,84 @@
+import {Component, OnInit} from '@angular/core';
+import {MeteorObservable, ObservableCursor} from 'meteor-rxjs';
+import {NavController, ViewController, AlertController} from 'ionic-angular';
+import {Meteor} from 'meteor/meteor';
+import {Observable} from 'rxjs/Observable';
+import {Chats} from '../../../../both/collections/chats.collection';
+import {Users} from '../../../../both/collections/users.collection';
+import {User} from '../../../../both/models/user.model';
+import template from './new-chat.component.html';
+import style from "./new-chat.component.scss";
+import 'rxjs/add/operator/mergeMap';
+import 'rxjs/add/operator/startWith';
+
+@Component({
+  selector: 'new-chat',
+  template,
+  styles: [
+    style
+  ]
+})
+export class NewChatComponent implements OnInit {
+  users: Observable<User>;
+  private senderId: string;
+
+  constructor(
+    private navCtrl: NavController, 
+    private viewCtrl: ViewController,
+    private alertCtrl: AlertController
+  ) {
+    this.senderId = Meteor.userId();
+  }
+
+  ngOnInit() {
+    MeteorObservable.autorun().zone().subscribe(() => {
+      this.users = this.findUsers().zone();
+    });
+  }
+
+  addChat(user): void {
+    MeteorObservable.call('addChat', user._id).subscribe({
+      next: () => {
+        this.viewCtrl.dismiss();
+      },
+      error: (e: Error) => {
+        this.viewCtrl.dismiss().then(() => {
+          this.handleError(e)
+        });
+      }
+    });
+  }
+
+  private findUsers(): Observable<User> {
+    return Chats.find({
+        memberIds: this.senderId
+      }, {
+        fields: {
+          memberIds: 1
+        }
+      })
+        .startWith([]) // empty result
+        .mergeMap((chats) => {
+          const recieverIds = chats
+            .map(({memberIds}) => memberIds)
+            .reduce((result, memberIds) => result.concat(memberIds), [])
+            .concat(this.senderId);
+
+          return Users.find({
+            _id: {$nin: recieverIds}
+          })
+        });
+  }
+
+  private handleError(e: Error): void {
+    console.error(e);
+
+    const alert = this.alertCtrl.create({
+      title: 'Oops!',
+      message: e.message,
+      buttons: ['OK']
+    });
+
+    alert.present();
+  }
+}