Get relationship and evaluate before following (HD-3)

src/pages/Notifications.tsx

@@ -33,6 +33,7 @@ import NotificationsIcon from "@material-ui/icons/Notifications";
 import Mastodon from "megalodon";
 import { Notification } from "../types/Notification";
 import { Account } from "../types/Account";
+import { Relationship } from "../types/Relationship";
 import { withSnackbar } from "notistack";
 
 interface INotificationsPageState {
@@ -294,6 +295,12 @@ class NotificationsPage extends Component<any, INotificationsPageState> {
     }
 
     followMember(acct: Account) {
+        this.client
+            .get(`/accounts/relationships`, { id: acct.id })
+            .then((resp: any) => {
+                let relationship: Relationship = resp.data[0];
+
+                if (relationship.following == false) {
                     this.client
                         .post(`/accounts/${acct.id}/follow`)
                         .then((resp: any) => {
@@ -308,6 +315,17 @@ class NotificationsPage extends Component<any, INotificationsPageState> {
                             );
                             console.error(err.message);
                         });
+                } else {
+                    this.props.enqueueSnackbar(
+                        "You already follow this account."
+                    );
+                }
+            })
+            .catch((err: Error) => {
+                this.props.enqueueSnackbar("Couldn't find relationship.", {
+                    variant: "error"
+                });
+            });
     }
 
     render() {