add basic user revert functionality

app/controllers/user_reverts_controller.rb

@@ -0,0 +1,15 @@
+class UserRevertsController < ApplicationController
+  before_filter :janitor_only
+
+  def new
+    @user = User.find(params[:user_id])
+  end
+
+  def create
+    user = User.find(params[:user_id])
+    revert = UserRevert.new(user.id)
+    revert.process
+    redirect_to(user_path(user.id))
+  end
+end
+

app/logical/user_revert.rb

@@ -0,0 +1,28 @@
+# reverts all changes made by a user
+class UserRevert
+  THRESHOLD = 1_000
+  class TooManyChangesError < RuntimeError ; end
+
+  attr_reader :user_id
+
+  def initialize(user_id)
+    @user_id = user_id
+  end
+
+  def process
+    validate!
+    revert_post_changes
+  end
+
+  def validate!
+    if PostVersion.where(updater_id: user_id).count > THRESHOLD
+      raise TooManyChangesError.new("This user has too many changes to be reverted")
+    end
+  end
+
+  def revert_post_changes
+    PostVersion.where(updater_id: user_id).find_each do |x|
+      x.undo!
+    end
+  end
+end

app/presenters/user_presenter.rb

@@ -149,7 +149,7 @@ class UserPresenter
   end
 
   def post_version_count(template)
-    template.link_to(user.post_update_count, template.post_versions_path(:search => {:updater_id => user.id}))
+    template.link_to(user.post_update_count, template.post_versions_path(:lr => user.id, :search => {:updater_id => user.id}))
   end
 
   def note_version_count(template)

app/views/post_versions/index.html.erb

@@ -7,6 +7,10 @@
     <% else %>
       <%= render "listing", :post_versions => @post_versions %>
 
+      <% if params[:lr] && CurrentUser.is_janitor? %>
+        <p><%= link_to "Revert this user's changes", new_user_revert_path(:user_id => params[:lr]) %></p>
+      <% end %>
+
       <%= numbered_paginator(@post_versions) %>
     <% end %>
   </div>

app/views/user_reverts/new.html.erb

@@ -0,0 +1,19 @@
+<div id="c-users">
+  <div id="a-new">
+    <h1>Revert Changes</h1>
+
+    <p>You are about to revert all changes made by <%= link_to_user @user %>. Continue?</p>
+
+    <%= form_tag(user_revert_path) do %>
+      <%= hidden_field_tag :user_id, params[:user_id] %>
+
+      <%= submit_tag "Yes" %>
+    <% end %>
+  </div>
+</div>
+
+<%= render "users/secondary_links" %>
+
+<% content_for(:page_title) do %>
+  User Revert - <%= Danbooru.config.app_name %>
+<% end %>

app/views/users/_statistics.html.erb

@@ -56,7 +56,12 @@
 
       <tr>
         <th>Post Changes</th>
-        <td><%= presenter.post_version_count(self) %></td>
+        <td>
+          <%= presenter.post_version_count(self) %>
+          <% if CurrentUser.is_janitor? %>
+            [<%= link_to "revert all", new_user_revert_path(user_id: user.id) %>]
+          <% end %>
+        </td>
       </tr>
 
       <tr>