FEATURE: add "email in-reply-to user option"

We no longer include previous replies as "context", instead
we include and excerpt of the post being replied to at the bottom
of notifications, this information was previously missing.

Users may opt in to emailing previous replies if they wish
or opt out of "in-reply-to" which makes sense in some email clients that
are smarter about displaying a tree of replies.

app/assets/javascripts/discourse/models/user.js.es6

@@ -158,6 +158,7 @@ const User = RestModel.extend({
             'external_links_in_new_tab',
             'email_digests',
             'email_direct',
+            'email_in_reply_to',
             'email_private_messages',
             'email_previous_replies',
             'dynamic_favicon',

app/assets/javascripts/discourse/templates/user/preferences.hbs

@@ -180,6 +180,7 @@
         <label>{{i18n 'user.email_previous_replies.title'}}</label>
         {{combo-box valueAttribute="value" content=previousRepliesOptions value=model.user_option.email_previous_replies}}
       </div>
+      {{preference-checkbox labelKey="user.email_in_reply_to" checked=model.user_option.email_in_reply_to}}
       {{preference-checkbox labelKey="user.email_private_messages" checked=model.user_option.email_private_messages}}
       {{preference-checkbox labelKey="user.email_direct" checked=model.user_option.email_direct}}
       <span class="pref-mailing-list-mode">{{preference-checkbox labelKey="user.mailing_list_mode" checked=model.user_option.mailing_list_mode}}</span>

app/mailers/user_notifications.rb

@@ -193,9 +193,9 @@ class UserNotifications < ActionMailer::Base
     include UserNotificationsHelper
   end
 
-  def self.get_context_posts(post, topic_user)
-    user_option = topic_user.try(:user).try(:user_option)
-    if user_option && (user_option.email_previous_replies == UserOption.previous_replies_type[:never])
+  def self.get_context_posts(post, topic_user, user)
+
+    if user.user_option.email_previous_replies == UserOption.previous_replies_type[:never]
       return []
     end
 
@@ -210,7 +210,7 @@ class UserNotifications < ActionMailer::Base
                         .order('created_at desc')
                         .limit(SiteSetting.email_posts_context)
 
-    if topic_user && topic_user.last_emailed_post_number && user_option.try(:email_previous_replies) == UserOption.previous_replies_type[:unless_emailed]
+    if topic_user && topic_user.last_emailed_post_number && user.user_option.email_previous_replies == UserOption.previous_replies_type[:unless_emailed]
       context_posts = context_posts.where("post_number > ?", topic_user.last_emailed_post_number)
     end
 
@@ -280,7 +280,7 @@ class UserNotifications < ActionMailer::Base
 
     context = ""
     tu = TopicUser.get(post.topic_id, user)
-    context_posts = self.class.get_context_posts(post, tu)
+    context_posts = self.class.get_context_posts(post, tu, user)
 
     # make .present? cheaper
     context_posts = context_posts.to_a
@@ -296,11 +296,13 @@ class UserNotifications < ActionMailer::Base
     if opts[:use_template_html]
       topic_excerpt = post.excerpt.gsub("\n", " ") if post.is_first_post? && post.excerpt
     else
+      in_reply_to_post = post.reply_to_post if user.user_option.email_in_reply_to
       html = UserNotificationRenderer.new(Rails.configuration.paths["app/views"]).render(
         template: 'email/notification',
         format: :html,
         locals: { context_posts: context_posts,
                   post: post,
+                  in_reply_to_post: in_reply_to_post,
                   classes: RTL.new(user).css_class
         }
       )

app/models/user_option.rb

@@ -16,6 +16,7 @@ class UserOption < ActiveRecord::Base
     self.automatically_unpin_topics = SiteSetting.default_topics_automatic_unpin
     self.email_private_messages = SiteSetting.default_email_private_messages
     self.email_previous_replies = SiteSetting.default_email_previous_replies
+    self.email_in_reply_to = SiteSetting.default_email_in_reply_to
 
     self.enable_quoting = SiteSetting.default_other_enable_quoting
     self.external_links_in_new_tab = SiteSetting.default_other_external_links_in_new_tab

app/serializers/user_option_serializer.rb

@@ -14,7 +14,8 @@ class UserOptionSerializer < ApplicationSerializer
              :edit_history_public,
              :auto_track_topics_after_msecs,
              :new_topic_duration_minutes,
-             :email_previous_replies
+             :email_previous_replies,
+             :email_in_reply_to
 
 
   def include_edit_history_public?

app/services/user_updater.rb

@@ -21,7 +21,8 @@ class UserUpdater
     :digest_after_days,
     :new_topic_duration_minutes,
     :auto_track_topics_after_msecs,
-    :email_previous_replies
+    :email_previous_replies,
+    :email_in_reply_to
   ]
 
   def initialize(actor, user)
@@ -53,10 +54,10 @@ class UserUpdater
 
 
     save_options = false
-    OPTION_ATTR.each do |attribute|
-      if attributes[attribute].present?
-        save_options = true
 
+    OPTION_ATTR.each do |attribute|
+      if attributes.key?(attribute)
+        save_options = true
 
         if [true,false].include?(user.user_option.send(attribute))
           val = attributes[attribute].to_s == 'true'

app/views/email/_post.html.erb

@@ -1,4 +1,4 @@
-<table class='post-wrapper <%= post.whisper? ? "whisper" : "" %>'>
+<table class='post-wrapper <%= post.whisper? ? "whisper" : "" %> <%= use_excerpt ? "excerpt" : ""%>'>
   <tbody>
     <tr>
       <td>
@@ -23,7 +23,7 @@
       </td>
     </tr>
     <tr>
-      <td class='body'><%= format_for_email(post.cooked) %></td>
+      <td class='body'><%= format_for_email(use_excerpt ? post.excerpt :  post.cooked) %></td>
     </tr>
   </tbody>
 </table>

app/views/email/notification.html.erb

@@ -2,17 +2,22 @@
 
   <div class='header-instructions'>%{header_instructions}</div>
 
-  <%= render partial: 'email/post', locals: { post: post } %>
+  <%= render partial: 'email/post', locals: { post: post, use_excerpt: false } %>
+
+  <% if in_reply_to_post.present? || context_posts.present? %>
+    <div class='footer'>%{respond_instructions}</div>
+    <hr>
+  <% end %>
+
+  <% if in_reply_to_post.present? %>
+    <h4 class='.previous-discussion'><%= t "user_notifications.in_reply_to" %></h4>
+    <%= render partial: 'email/post', locals: { post: in_reply_to_post, use_excerpt: true} %>
+  <% end %>
 
   <% if context_posts.present? %>
-    <div class='footer'>%{respond_instructions}</div>
-
-    <hr>
-
     <h4 class='.previous-discussion'><%= t "user_notifications.previous_discussion" %></h4>
-
     <% context_posts.each do |p| %>
-      <%= render partial: 'email/post', locals: { post: p } %>
+      <%= render partial: 'email/post', locals: { post: p, use_excerpt: false } %>
     <% end %>
   <% end %>