Added join requests to Groups

• Added:
- join requests to Groups
- redux actions, reducers
- controller and functionality for fetching join requests, accepting, rejecting join requests

app/controllers/api/v1/groups/requests_controller.rb

@@ -0,0 +1,97 @@
+# frozen_string_literal: true
+
+class Api::V1::Groups::RequestsController < Api::BaseController
+  include Authorization
+
+  before_action -> { doorkeeper_authorize! :read, :'read:groups' }, only: [:show]
+  before_action -> { doorkeeper_authorize! :write, :'write:groups' }, except: [:show]
+
+  before_action :require_user!
+  before_action :set_group
+
+  after_action :insert_pagination_headers, only: :show
+
+  def show
+    @accounts = load_accounts
+    render json: @accounts, each_serializer: REST::AccountSerializer
+  end
+
+  def create
+    authorize @group, :leave?
+    GroupJoinRequest.where(group: @group, account_id: current_account.id).destroy_all
+    render json: @group, serializer: REST::GroupRelationshipSerializer, relationships: relationships
+  end
+
+  def approve_request
+    GroupJoinRequest.where(group: @group, account_id: params[:accountId]).destroy_all
+    GroupAccount.create(group: @group, account_id: params[:accountId])
+    render json: {"message": "ok"}
+  end
+
+  def reject_request
+    GroupJoinRequest.where(group: @group, account_id: params[:accountId]).destroy_all
+    render json: {"message": "ok"}
+  end
+
+  private
+
+  def relationships
+    GroupRelationshipsPresenter.new([@group.id], current_user.account_id)
+  end
+
+  def set_group
+    @group = Group.find(params[:group_id])
+  end
+
+  def load_accounts
+    if unlimited?
+      @group.join_requests.includes(:account_stat).all
+    else
+      @group.join_requests.includes(:account_stat).paginate_by_max_id(limit_param(DEFAULT_ACCOUNTS_LIMIT), params[:max_id], params[:since_id])
+    end
+  end
+
+  def insert_pagination_headers
+    set_pagination_headers(next_path, prev_path)
+  end
+
+  def next_path
+    return if unlimited?
+
+    if records_continue?
+      api_v1_group_join_requests_url pagination_params(max_id: pagination_max_id)
+    end
+  end
+
+  def prev_path
+    return if unlimited?
+
+    unless @accounts.empty?
+      api_v1_group_join_requests_url pagination_params(since_id: pagination_since_id)
+    end
+  end
+
+  def pagination_max_id
+    @accounts.last.id
+  end
+
+  def pagination_since_id
+    @accounts.first.id
+  end
+
+  def records_continue?
+    @accounts.size == limit_param(DEFAULT_ACCOUNTS_LIMIT)
+  end
+
+  def pagination_params(core_params)
+    params.slice(:limit).permit(:limit).merge(core_params)
+  end
+
+  def unlimited?
+    params[:limit] == '0'
+  end
+
+  def group_account_params
+    params.permit(:role, :write_permissions)
+  end
+end