Add search and sort functions to hashtag admin UI (#11829)

* Add search and sort functions to hashtag admin UI

* Move scope processing from tags_controller to tag_filter

* Fix based on method naming conventions

* Fixed not to get 500 errors for invalid requests

app/models/tag.rb

@@ -39,6 +39,7 @@ class Tag < ApplicationRecord
   scope :listable, -> { where(listable: [true, nil]) }
   scope :discoverable, -> { listable.joins(:account_tag_stat).where(AccountTagStat.arel_table[:accounts_count].gt(0)).order(Arel.sql('account_tag_stats.accounts_count desc')) }
   scope :most_used, ->(account) { joins(:statuses).where(statuses: { account: account }).group(:id).order(Arel.sql('count(*) desc')) }
+  scope :matches_name, ->(value) { where(arel_table[:name].matches("#{value}%")) }
 
   delegate :accounts_count,
            :accounts_count=,

app/models/tag_filter.rb

@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+class TagFilter
+  attr_reader :params
+
+  def initialize(params)
+    @params = params
+  end
+
+  def results
+    scope = Tag.unscoped
+
+    params.each do |key, value|
+      next if key.to_s == 'page'
+
+      scope.merge!(scope_for(key, value.to_s.strip)) if value.present?
+    end
+
+    scope.order(id: :desc)
+  end
+
+  private
+
+  def scope_for(key, value)
+    case key.to_s
+    when 'directory'
+      Tag.discoverable
+    when 'reviewed'
+      Tag.reviewed.order(reviewed_at: :desc)
+    when 'unreviewed'
+      Tag.unreviewed
+    when 'pending_review'
+      Tag.pending_review.order(requested_review_at: :desc)
+    when 'popular'
+      Tag.order('max_score DESC NULLS LAST')
+    when 'active'
+      Tag.order('last_status_at DESC NULLS LAST')
+    when 'name'
+      Tag.matches_name(value)
+    else
+      raise "Unknown filter: #{key}"
+    end
+  end
+end