initial implementation of tag following

src/app/components/stream/hashtag/hashtag.component.html

@@ -2,7 +2,8 @@
     <div class="hashtag-header">
         <a href (click)="goToTop()" class="hashtag-header__gototop" title="go to top">
             <h3 class="hashtag-header__title">#{{hashtagElement.tag}}</h3>
-
+            <button *ngIf="isHashtagFollowingAvailable && !isFollowingHashtag" class="btn-custom-secondary hashtag-header__follow-button" (click)="followThisHashtag($event)" title="follow hashtag" [disabled]="followingLoading">follow</button>
+            <button *ngIf="isHashtagFollowingAvailable && isFollowingHashtag" class="btn-custom-secondary hashtag-header__follow-button" (click)="unfollowThisHashtag($event)" title="unfollow hashtag" [disabled]="unfollowingLoading">unfollow</button>
             <button class="btn-custom-secondary hashtag-header__add-column" (click)="addColumn($event)" title="add column to board" [hidden]="columnAdded">add column</button>
         </a>
     </div>

src/app/components/stream/hashtag/hashtag.component.scss

@@ -40,6 +40,14 @@ $inner-column-size: 320px;
         border: 1px solid black;
         color: white;
     }
+    &__follow-button {
+        position: absolute;
+        top: 7px;
+        right: 100px;
+        padding: 0 10px 0 10px;
+        border: 1px solid black;
+        color: white;
+    }
 }
 
 .hashtag-stream {

src/app/components/stream/hashtag/hashtag.component.ts

@@ -1,11 +1,12 @@
 import { Component, OnInit, Output, EventEmitter, Input, ViewChild, OnDestroy } from '@angular/core';
-import { Subject, Subscription } from 'rxjs';
+import { Subject, Subscription, Observable } from 'rxjs';
 import { Store } from '@ngxs/store';
 
 import { StreamElement, StreamTypeEnum, AddStream } from '../../../states/streams.state';
 import { OpenThreadEvent, ToolsService } from '../../../services/tools.service';
 import { StreamStatusesComponent } from '../stream-statuses/stream-statuses.component';
 import { AccountInfo } from '../../../states/accounts.state';
+import { MastodonWrapperService } from '../../../services/mastodon-wrapper.service';
 
 @Component({
     selector: 'app-hashtag',
@@ -38,12 +39,25 @@ export class HashtagComponent implements OnInit, OnDestroy {
     private lastUsedAccount: AccountInfo;
     private refreshSubscription: Subscription;
     private goToTopSubscription: Subscription;
+    isHashtagFollowingAvailable: boolean;
+    isFollowingHashtag: boolean;
+
+    private accounts$: Observable<AccountInfo[]>;
+
+    private accountSub: Subscription;
+
+    followingLoading: boolean;
+    unfollowingLoading: boolean;
 
     columnAdded: boolean;
 
     constructor(
         private readonly store: Store,
-        private readonly toolsService: ToolsService) { }
+        private readonly toolsService: ToolsService,
+        private readonly mastodonService: MastodonWrapperService) {
+            this.accounts$ = this.store.select(state => state.registeredaccounts.accounts);
+        }
+
 
     ngOnInit() {
         if(this.refreshEventEmitter) {
@@ -57,11 +71,22 @@ export class HashtagComponent implements OnInit, OnDestroy {
                 this.goToTop();
             })
         }
+        this.lastUsedAccount = this.toolsService.getSelectedAccounts()[0];
+        this.updateHashtagFollowStatus(this.lastUsedAccount);
+
+        this.accountSub = this.accounts$.subscribe((accounts: AccountInfo[]) => {
+            const selectedAccounts = accounts.filter(x => x.isSelected);
+            if (selectedAccounts.length > 0) {
+                this.lastUsedAccount = selectedAccounts[0];
+                this.updateHashtagFollowStatus(this.lastUsedAccount);
+            }
+        });
     }
 
     ngOnDestroy(): void {
         if(this.refreshSubscription) this.refreshSubscription.unsubscribe();
         if (this.goToTopSubscription) this.goToTopSubscription.unsubscribe();
+        if (this.accountSub) this.accountSub.unsubscribe();
     }
 
     goToTop(): boolean {
@@ -83,6 +108,10 @@ export class HashtagComponent implements OnInit, OnDestroy {
 
     refresh(): any {
         this.lastUsedAccount = this.toolsService.getSelectedAccounts()[0];
+        this.updateHashtagFollowStatus(this.lastUsedAccount);
+        if (this.isHashtagFollowingAvailable) {
+            this.checkIfFollowingHashtag(this.lastUsedAccount);
+        }
         this.appStreamStatuses.refresh();
     }
 
@@ -99,4 +128,41 @@ export class HashtagComponent implements OnInit, OnDestroy {
     browseThread(openThreadEvent: OpenThreadEvent): void {
         this.browseThreadEvent.next(openThreadEvent);
     }
+
+    private updateHashtagFollowStatus(account: AccountInfo): void {
+        this.toolsService.getInstanceInfo(account).then(instanceInfo => {
+            if (instanceInfo.major >= 4) {
+                this.isHashtagFollowingAvailable = true;
+                this.checkIfFollowingHashtag(account);
+            } else {
+                this.isHashtagFollowingAvailable = false;
+            }
+        });
+    }
+
+    private checkIfFollowingHashtag(account: AccountInfo): void {
+        this.mastodonService.getHashtag(account, this.hashtagElement.tag).then(tag => {
+            this.isFollowingHashtag = tag.following;
+        });
+    }
+
+    followThisHashtag(event): boolean {
+        this.followingLoading = true;
+        event.stopPropagation();
+        this.mastodonService.followHashtag(this.lastUsedAccount, this.hashtagElement.tag).then(tag => {
+            this.isFollowingHashtag = tag.following;
+            this.followingLoading = false;
+        });
+        return false
+    }
+
+    unfollowThisHashtag(event): boolean {
+        this.unfollowingLoading = true;
+        event.stopPropagation();
+        this.mastodonService.unfollowHashtag(this.lastUsedAccount, this.hashtagElement.tag).then(tag => {
+            this.isFollowingHashtag = tag.following;
+            this.unfollowingLoading = false;
+        });
+        return false
+    }
 }

src/app/services/mastodon-wrapper.service.ts

@@ -1,7 +1,7 @@
 import { Injectable } from '@angular/core';
 import { Store } from '@ngxs/store';
 
-import { Account, Status, Results, Context, Relationship, Instance, Attachment, Notification, List, Poll, Emoji, Conversation, ScheduledStatus, TokenData } from "./models/mastodon.interfaces";
+import { Account, Status, Results, Context, Relationship, Instance, Attachment, Notification, List, Poll, Emoji, Conversation, ScheduledStatus, TokenData, Tag } from "./models/mastodon.interfaces";
 import { AccountInfo, UpdateAccount } from '../states/accounts.state';
 import { StreamTypeEnum, StreamElement } from '../states/streams.state';
 import { FavoriteResult, VisibilityEnum, PollParameters, MastodonService, BookmarkResult, FollowingResult } from './mastodon.service';
@@ -267,6 +267,27 @@ export class MastodonWrapperService {
             });
     }
 
+    followHashtag(currentlyUsedAccount: AccountInfo, hashtag: string): Promise<Tag> {
+        return this.refreshAccountIfNeeded(currentlyUsedAccount)
+            .then((refreshedAccount: AccountInfo) => {
+                return this.mastodonService.followHashtag(refreshedAccount, hashtag);
+            });
+    }
+
+    unfollowHashtag(currentlyUsedAccount: AccountInfo, hashtag: string): Promise<Tag> {
+        return this.refreshAccountIfNeeded(currentlyUsedAccount)
+            .then((refreshedAccount: AccountInfo) => {
+                return this.mastodonService.unfollowHashtag(refreshedAccount, hashtag);
+            });
+    }
+
+    getHashtag(currentlyUsedAccount: AccountInfo, hashtag: string): Promise<Tag> {
+        return this.refreshAccountIfNeeded(currentlyUsedAccount)
+            .then((refreshedAccount: AccountInfo) => {
+                return this.mastodonService.getHashtag(refreshedAccount, hashtag);
+            });
+    }
+
     uploadMediaAttachment(account: AccountInfo, file: File, description: string): Promise<Attachment> {
         return this.refreshAccountIfNeeded(account)
             .then((refreshedAccount: AccountInfo) => {

src/app/services/mastodon.service.ts

@@ -2,7 +2,7 @@ import { Injectable } from '@angular/core';
 import { HttpHeaders, HttpClient, HttpResponse } from '@angular/common/http';
 
 import { ApiRoutes } from './models/api.settings';
-import { Account, Status, Results, Context, Relationship, Instance, Attachment, Notification, List, Poll, Emoji, Conversation, ScheduledStatus } from "./models/mastodon.interfaces";
+import { Account, Status, Results, Context, Relationship, Instance, Attachment, Notification, List, Poll, Emoji, Conversation, ScheduledStatus, Tag } from "./models/mastodon.interfaces";
 import { AccountInfo } from '../states/accounts.state';
 import { StreamTypeEnum, StreamElement } from '../states/streams.state';
 
@@ -289,6 +289,24 @@ export class MastodonService {
 
     }
 
+    followHashtag(currentlyUsedAccount: AccountInfo, hashtag: string): Promise<Tag> {
+        const route = `https://${currentlyUsedAccount.instance}${this.apiRoutes.followHashtag}`.replace('{0}', hashtag);
+        const headers = new HttpHeaders({ 'Authorization': `Bearer ${currentlyUsedAccount.token.access_token}` });
+        return this.httpClient.post<Tag>(route, null, { headers: headers }).toPromise();
+    }
+
+    unfollowHashtag(currentlyUsedAccount: AccountInfo, hashtag: string): Promise<Tag> {
+        const route = `https://${currentlyUsedAccount.instance}${this.apiRoutes.unfollowHashtag}`.replace('{0}', hashtag);
+        const headers = new HttpHeaders({ 'Authorization': `Bearer ${currentlyUsedAccount.token.access_token}` });
+        return this.httpClient.post<Tag>(route, null, { headers: headers }).toPromise();
+    }
+
+    getHashtag(currentlyUsedAccount: AccountInfo, hashtag: string): Promise<Tag> {
+        const route = `https://${currentlyUsedAccount.instance}${this.apiRoutes.getHashtag}`.replace('{0}', hashtag);
+        const headers = new HttpHeaders({ 'Authorization': `Bearer ${currentlyUsedAccount.token.access_token}` });
+        return this.httpClient.get<Tag>(route, { headers: headers }).toPromise();
+    }
+
     uploadMediaAttachment(account: AccountInfo, file: File, description: string): Promise<Attachment> {
         let input = new FormData();
         input.append('file', file);

src/app/services/models/api.settings.ts

@@ -75,4 +75,7 @@ export class ApiRoutes {
     getBookmarks = '/api/v1/bookmarks';
     getFollowers = '/api/v1/accounts/{0}/followers';
     getFollowing = '/api/v1/accounts/{0}/following';
+    followHashtag = '/api/v1/tags/{0}/follow';
+    unfollowHashtag = '/api/v1/tags/{0}/unfollow';
+    getHashtag = '/api/v1/tags/{0}';
 }

src/app/services/models/mastodon.interfaces.ts

@@ -250,3 +250,16 @@ export interface StatusParams {
     scheduled_at: string;
     application_id: string;
 }
+
+export interface TagHistory {
+    day: string;
+    uses: number;
+    accounts: number;
+}
+
+export interface Tag {
+    name: string;
+    url: string;
+    history: TagHistory[];
+    following: boolean;
+}