Step 6.7: Create NewChatComponent

src/pages/new-chat/new-chat.ts

@@ -0,0 +1,74 @@
+import { Component, OnInit } from '@angular/core';
+import { MeteorObservable, ObservableCursor } from 'meteor-rxjs';
+import { NavController, ViewController, AlertController } from 'ionic-angular';
+import { Chats, Users } from 'api/collections/whatsapp-collections';
+import { User } from 'api/models/whatsapp-models';
+
+@Component({
+  selector: 'new-chat',
+  templateUrl: 'new-chat.html'
+})
+export class NewChatComponent implements OnInit {
+  users;
+  senderId: string;
+
+  constructor(
+    public navCtrl: NavController,
+    public viewCtrl: ViewController,
+    public 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(): ObservableCursor<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();
+  }
+}