Add ability to follow hashtags (#18809)

app/controllers/api/v1/featured_tags/suggestions_controller.rb

@@ -6,7 +6,7 @@ class Api::V1::FeaturedTags::SuggestionsController < Api::BaseController
   before_action :set_recently_used_tags, only: :index
 
   def index
-    render json: @recently_used_tags, each_serializer: REST::TagSerializer
+    render json: @recently_used_tags, each_serializer: REST::TagSerializer, relationships: TagRelationshipsPresenter.new(@recently_used_tags, current_user&.account_id)
   end
 
   private

app/controllers/api/v1/followed_tags_controller.rb

@@ -0,0 +1,52 @@
+# frozen_string_literal: true
+
+class Api::V1::FollowedTagsController < Api::BaseController
+  TAGS_LIMIT = 100
+
+  before_action -> { doorkeeper_authorize! :follow, :read, :'read:follows' }, except: :show
+  before_action :require_user!
+  before_action :set_results
+
+  after_action :insert_pagination_headers, only: :show
+
+  def index
+    render json: @results.map(&:tag), each_serializer: REST::TagSerializer, relationships: TagRelationshipsPresenter.new(@results.map(&:tag), current_user&.account_id)
+  end
+
+  private
+
+  def set_results
+    @results = TagFollow.where(account: current_account).joins(:tag).eager_load(:tag).to_a_paginated_by_id(
+      limit_param(TAGS_LIMIT),
+      params_slice(:max_id, :since_id, :min_id)
+    )
+  end
+
+  def insert_pagination_headers
+    set_pagination_headers(next_path, prev_path)
+  end
+
+  def next_path
+    api_v1_followed_tags_url pagination_params(max_id: pagination_max_id) if records_continue?
+  end
+
+  def prev_path
+    api_v1_followed_tags_url pagination_params(since_id: pagination_since_id) unless @results.empty?
+  end
+
+  def pagination_max_id
+    @results.last.id
+  end
+
+  def pagination_since_id
+    @results.first.id
+  end
+
+  def records_continue?
+    @results.size == limit_param(TAG_LIMIT)
+  end
+
+  def pagination_params(core_params)
+    params.slice(:limit).permit(:limit).merge(core_params)
+  end
+end

app/controllers/api/v1/tags_controller.rb

@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+class Api::V1::TagsController < Api::BaseController
+  before_action -> { doorkeeper_authorize! :follow, :write, :'write:follows' }, except: :show
+  before_action :require_user!, except: :show
+  before_action :set_or_create_tag
+
+  override_rate_limit_headers :follow, family: :follows
+
+  def show
+    render json: @tag, serializer: REST::TagSerializer
+  end
+
+  def follow
+    TagFollow.create!(tag: @tag, account: current_account, rate_limit: true)
+    render json: @tag, serializer: REST::TagSerializer
+  end
+
+  def unfollow
+    TagFollow.find_by(account: current_account, tag: @tag)&.destroy!
+    render json: @tag, serializer: REST::TagSerializer
+  end
+
+  private
+
+  def set_or_create_tag
+    @tag = Tag.find_normalized(params[:id]) || Tag.new(name: Tag.normalize(params[:id]), display_name: params[:id])
+  end
+end

app/controllers/api/v1/trends/tags_controller.rb

@@ -8,7 +8,7 @@ class Api::V1::Trends::TagsController < Api::BaseController
   DEFAULT_TAGS_LIMIT = 10
 
   def index
-    render json: @tags, each_serializer: REST::TagSerializer
+    render json: @tags, each_serializer: REST::TagSerializer, relationships: TagRelationshipsPresenter.new(@tags, current_user&.account_id)
   end
 
   private