add post count estimates for bulk update requests

app/logical/alias_and_implication_importer.rb

@@ -78,6 +78,28 @@ class AliasAndImplicationImporter
     end
   end
 
+  def estimate_update_count
+    tokens = self.class.tokenize(text)
+    tokens.inject(0) do |sum, token|
+      case token[0]
+      when :create_alias
+        sum + TagAlias.new(antecedent_name: token[1], consequent_name: token[2]).estimate_update_count
+
+      when :create_implication
+        sum + TagImplication.new(antecedent_name: token[1], consequent_name: token[2]).estimate_update_count
+
+      when :mass_update
+        sum + Moderator::TagBatchChange.new(token[1], token[2]).estimate_update_count
+
+      when :change_category
+        sum + Tag.find_by_name(token[1]).try(:post_count) || 0
+
+      else
+        sum + 0
+      end
+    end
+  end
+
 private
 
   def parse(tokens, approver)

app/logical/moderator/tag_batch_change.rb

@@ -20,6 +20,10 @@ module Moderator
       ModAction.log("processed mass update: #{antecedent} -> #{consequent}",:mass_update)
     end
 
+    def estimate_update_count
+      PostReadOnly.tag_match(antecedent).count
+    end
+
     def migrate_posts(normalized_antecedent, normalized_consequent)
       ::Post.tag_match(normalized_antecedent.join(" ")).find_each do |post|
         post.reload

app/models/bulk_update_request.rb

@@ -229,4 +229,8 @@ class BulkUpdateRequest < ApplicationRecord
   def is_rejected?
     status == "rejected"
   end
+
+  def estimate_update_count
+    AliasAndImplicationImporter.new(script, nil).estimate_update_count
+  end
 end

app/models/tag_relationship.rb

@@ -192,6 +192,10 @@ class TagRelationship < ApplicationRecord
     end
   end
 
+  def estimate_update_count
+    Post.fast_count(antecedent_name, skip_cache: true)
+  end
+
   extend SearchMethods
   include MessageMethods
 end

app/views/bulk_update_requests/show.html.erb

@@ -9,6 +9,7 @@
       <li><strong>Creator</strong> <%= link_to_user @bulk_update_request.user %></li>
       <li><strong>Date</strong> <%= @bulk_update_request.created_at %></li>
       <li><strong>Status</strong>: <%= @bulk_update_request.status %></li>
+      <li><strong title="How many posts will be affected">Estimate</strong>: <%= @bulk_update_request.estimate_update_count %></li>
 
       <% if CurrentUser.is_admin? && @bulk_update_request.is_pending? %>
         <li><strong>Commands</strong> <%= link_to "Approve", approve_bulk_update_request_path(@bulk_update_request), :method => :post %></li>