Better leader last_action calculation

app.rb

@@ -7,20 +7,12 @@ get '/' do
   @raids = Raid.order('created_at DESC').page(params[:page])
   leaders = Leader.all
   last_update = leaders.first ? leaders.first.created_at : DateTime.new(0)
-  rebuild_leaders if last_update + 300 < DateTime.now
-
-  @top20 = leaders.map { |l| { user: l.leader, date: nil } }
-
-  @top20.each_with_index do |hash, i|
-    @raids.each do |raid|
-      if raid.attacker == hash[:user] || raid.defender == hash[:user]
-        @top20[i][:date] = raid.created_at
-        break
-      end
-    end
+  if last_update + 300 < DateTime.now
+    rebuild_leaders
   end
 
-  @top20 = @top20.select { |h| h[:date] }.sort_by { |h| h[:date] } + @top20.reject { |h| h[:date] }
+  leaders = Leader.all.includes(:last_attack, :last_defense)
+  @top20 = leaders.select { |l| l.last_action }.sort_by { |l| l.last_action } + leaders.reject { |l| l.last_action }
 
   erb :index
 end

models/leader.rb

@@ -1,3 +1,18 @@
 class Leader < ActiveRecord::Base
+  has_one :last_attack, foreign_key: :attacker, primary_key: :leader, class_name: 'Raid'
+  has_one :last_defense, foreign_key: :defender, primary_key: :leader, class_name: 'Raid'
 
+  def last_action
+    if last_attack == nil && last_defense == nil
+      @last_action = nil
+    elsif last_defense == nil
+      @last_action = last_attack.created_at
+    elsif last_attack == nil
+      @last_action = last_defense.created_at
+    else
+       @last_action = (last_attack.created_at > last_defense.created_at) ? last_attack.created_at : last_defense.created_at
+    end
+
+    return @last_action
+  end
 end

views/index.erb

@@ -34,7 +34,7 @@
 <div class="col-md-3">
   <div class="well well-lg text-center"><strong><%= Time.now.utc.strftime('%H:%M on %m-%d-%Y') %></strong></div>
   <ul class="list-group">
-    <% @top20.each do |user| %>
-      <li class="list-group-item"><%= user[:user] %><span class="pull-right"><small><%= user[:date].strftime('%H:%M on %m-%d-%Y') if user[:date] %></small></li>
+    <% @top20.each do |leader| %>
+      <li class="list-group-item"><%= leader.leader %><span class="pull-right"><small><%= leader.last_action.strftime('%H:%M on %m-%d-%Y') if leader.last_action %></small></li>
     <% end %>
 </div>