4 files changed, 50 insertions, 1 deletions
diff --git a/app/controllers/admin/instances_controller.rb b/app/controllers/admin/instances_controller.rb
index 3296e08db..22f02e5d0 100644
--- a/app/controllers/admin/instances_controller.rb
+++ b/app/controllers/admin/instances_controller.rb
@@ -14,8 +14,12 @@ module Admin
 
     private
 
+    def filtered_instances
+      InstanceFilter.new(filter_params).results
+    end
+
     def paginated_instances
-      Account.remote.by_domain_accounts.page(params[:page])
+      filtered_instances.page(params[:page])
     end
 
     helper_method :paginated_instances
@@ -27,5 +31,11 @@ module Admin
     def subscribeable_accounts
       Account.with_followers.remote.where(domain: params[:by_domain])
     end
+
+    def filter_params
+      params.permit(
+        :domain_name
+      )
+    end
   end
 end
diff --git a/app/models/account.rb b/app/models/account.rb
index 864b3cb6e..f175c7081 100644
--- a/app/models/account.rb
+++ b/app/models/account.rb
@@ -104,6 +104,7 @@ class Account < ApplicationRecord
   scope :by_domain_accounts, -> { group(:domain).select(:domain, 'COUNT(*) AS accounts_count').order('accounts_count desc') }
   scope :matches_username, ->(value) { where(arel_table[:username].matches("#{value}%")) }
   scope :matches_display_name, ->(value) { where(arel_table[:display_name].matches("#{value}%")) }
+  scope :matches_domain, ->(value) { where(arel_table[:domain].matches("%#{value}%")) }
 
   delegate :email,
            :current_sign_in_ip,
diff --git a/app/models/instance_filter.rb b/app/models/instance_filter.rb
new file mode 100644
index 000000000..5073cf1fa
--- /dev/null
+++ b/app/models/instance_filter.rb
@@ -0,0 +1,28 @@
+# frozen_string_literal: true
+
+class InstanceFilter
+  attr_reader :params
+
+  def initialize(params)
+    @params = params
+  end
+
+  def results
+    scope = Account.remote.by_domain_accounts
+    params.each do |key, value|
+      scope.merge!(scope_for(key, value)) if value.present?
+    end
+    scope
+  end
+
+  private
+
+  def scope_for(key, value)
+    case key.to_s
+    when 'domain_name'
+      Account.matches_domain(value)
+    else
+      raise "Unknown filter: #{key}"
+    end
+  end
+end
diff --git a/app/views/admin/instances/index.html.haml b/app/views/admin/instances/index.html.haml
index edbd3b217..3314ce077 100644
--- a/app/views/admin/instances/index.html.haml
+++ b/app/views/admin/instances/index.html.haml
@@ -1,6 +1,16 @@
 - content_for :page_title do
   = t('admin.instances.title')
 
+= form_tag admin_instances_url, method: 'GET', class: 'simple_form' do
+  .fields-group
+    - %i(domain_name).each do |key|
+      .input.string.optional
+        = text_field_tag key, params[key], class: 'string optional', placeholder: I18n.t("admin.instances.#{key}")
+
+    .actions
+      %button= t('admin.instances.search')
+      = link_to t('admin.instances.reset'), admin_instances_path, class: 'button negative'
+
 .table-wrapper
   %table.table
     %thead