allow messages to come from system instead of a user

app/controllers/messages_controller.rb

@@ -51,20 +51,22 @@ class MessagesController < ApplicationController
     @cur_url = "/messages"
     @title = @message.subject
 
-    @new_message = Message.new
-    @new_message.recipient_username = (@message.author_user_id == @user.id ?
-      @message.recipient.username : @message.author.username)
+    if @message.author
+      @new_message = Message.new
+      @new_message.recipient_username = (@message.author_user_id == @user.id ?
+        @message.recipient.username : @message.author.username)
+
+      if @message.subject.match(/^re:/i)
+        @new_message.subject = @message.subject
+      else
+        @new_message.subject = "Re: #{@message.subject}"
+      end
+    end
 
     if @message.recipient_user_id == @user.id
       @message.has_been_read = true
       @message.save
     end
-
-    if @message.subject.match(/^re:/i)
-      @new_message.subject = @message.subject
-    else
-      @new_message.subject = "Re: #{@message.subject}"
-    end
   end
 
   def destroy

app/mailers/email_message.rb

@@ -9,7 +9,7 @@ class EmailMessage < ActionMailer::Base
     mail(
       :to => user.email,
       :subject => "[#{Rails.application.name}] Private Message from " <<
-        "#{message.author.username}: #{message.subject}"
+        "#{message.author_username}: #{message.subject}"
     )
   end
 end

app/models/message.rb

@@ -7,7 +7,6 @@ class Message < ActiveRecord::Base
     :foreign_key => "author_user_id"
 
   validates_presence_of :recipient
-  validates_presence_of :author
 
   attr_accessor :recipient_username
 
@@ -27,6 +26,14 @@ class Message < ActiveRecord::Base
     self.short_id = ShortId.new(self.class).generate
   end
 
+  def author_username
+    if self.author
+      self.author.username
+    else
+      "System"
+    end
+  end
+
   def check_for_both_deleted
     if self.deleted_by_author? && self.deleted_by_recipient?
       self.destroy
@@ -51,10 +58,11 @@ class Message < ActiveRecord::Base
     if self.recipient.pushover_messages?
       self.recipient.pushover!({
         :title => "#{Rails.application.name} message from " <<
-          "#{self.author.username}: #{self.subject}",
+          "#{self.author_username}: #{self.subject}",
         :message => self.plaintext_body,
         :url => self.url,
-        :url_title => "Reply to #{self.author.username}",
+        :url_title => (self.author ? "Reply to #{self.author_username}" :
+          "View message"),
       })
     end
   end

app/views/messages/index.html.erb

@@ -36,8 +36,12 @@
         <tr class="<%= message.has_been_read? ? "" : "bold" %>">
           <td><%= check_box_tag "delete_#{message.short_id}" %></td>
           <td><% if @direction == :in %>
-              <a href="/u/<%= message.author.username %>"><%=
-                message.author.username %></a>
+              <% if message.author %>
+                <a href="/u/<%= message.author.username %>"><%=
+                  message.author.username %></a>
+              <% else %>
+                <%= message.author_username %>
+              <% end %>
             <% else %>
               <a href="/u/<%= message.recipient.username %>"><%=
                 message.recipient.username %></a>

app/views/messages/show.html.erb

@@ -11,12 +11,17 @@
     <%= @message.subject %>
 
     <div class="sublegend">
-      Sent from <a href="/u/<%= @message.author.username %>"><%=
-        @message.author.username %></a>
-      <% if @message.author.is_admin? %>
-        (administrator)
-      <% elsif @message.author.is_moderator? %>
-        (moderator)
+      Sent from
+      <% if @message.author %>
+        <a href="/u/<%= @message.author.username %>"><%=
+          @message.author.username %></a>
+        <% if @message.author.is_admin? %>
+          (administrator)
+        <% elsif @message.author.is_moderator? %>
+          (moderator)
+        <% end %>
+      <% else %>
+        <%= @message.author_username %>
       <% end %>
       to
       <a href="/u/<%= @message.recipient.username %>"><%=
@@ -51,27 +56,35 @@
   <br>
 
   <div class="legend">
-    Compose Reply To <%= @new_message.recipient_username %>
+    Compose Reply
+    <% if @new_message %>
+      To <%= @new_message.recipient_username %>
+    <% end %>
   </div>
 
-  <%= form_for @new_message, :method => :post do |f| %>
-    <%= f.hidden_field :recipient_username %>
+  <% if @new_message %>
+    <%= form_for @new_message, :method => :post do |f| %>
+      <%= f.hidden_field :recipient_username %>
 
-    <%= error_messages_for @new_message %>
+      <%= error_messages_for @new_message %>
 
-    <div class="boxline">
-      <%= f.text_field :subject, :style => "width: 500px;",
-        :autocomplete => "off" %>
-    </div>
+      <div class="boxline">
+        <%= f.text_field :subject, :style => "width: 500px;",
+          :autocomplete => "off" %>
+      </div>
 
-    <div class="boxline">
-      <%= f.text_area :body, :style => "width: 500px;", :rows => 5,
-        :autocomplete => "off" %>
-    </div>
+      <div class="boxline">
+        <%= f.text_area :body, :style => "width: 500px;", :rows => 5,
+          :autocomplete => "off" %>
+      </div>
 
-    <div class="boxline">
-      <p></p>
-      <%= submit_tag "Send Message" %>
-    </div>
+      <div class="boxline">
+        <p></p>
+        <%= submit_tag "Send Message" %>
+      </div>
+    <% end %>
+  <% else %>
+    This message cannot be replied to.  Please contact a moderator for
+    assistance.
   <% end %>
 </div>