FEATURE: allow users to archive messages

Messages are now in 3 buckets

- Inbox for all new messages
- Sent for all sent messages
- Archive for all messages you are done with

You can select messages from your Inbox or Sent and move them to your Archive,
you can move messages out of your Archive similarly

Similar concept applied to group messages, except that archiving and unarchiving
will apply to all group members

lib/topic_query.rb

@@ -117,14 +117,35 @@ class TopicQuery
     end
   end
 
+  def not_archived(list, user)
+    list.joins("LEFT JOIN user_archived_messages um
+                       ON um.user_id = #{user.id.to_i} AND um.topic_id = topics.id")
+               .where('um.user_id IS NULL')
+  end
+
   def list_private_messages(user)
     list = private_messages_for(user, :user)
+
+    list = not_archived(list, user)
+            .where('NOT (topics.participant_count = 1 AND topics.user_id = ?)', user.id)
+
+    create_list(:private_messages, {}, list)
+  end
+
+  def list_private_messages_archive(user)
+    list = private_messages_for(user, :user)
+    list = list.joins(:user_archived_messages).where('user_archived_messages.user_id = ?', user.id)
     create_list(:private_messages, {}, list)
   end
 
   def list_private_messages_sent(user)
     list = private_messages_for(user, :user)
-    list = list.where(user_id: user.id)
+    list = list.where('EXISTS (
+                      SELECT 1 FROM posts
+                      WHERE posts.topic_id = topics.id AND
+                            posts.user_id = ?
+                     )', user.id)
+    list = not_archived(list, user)
     create_list(:private_messages, {}, list)
   end
 
@@ -136,6 +157,18 @@ class TopicQuery
 
   def list_private_messages_group(user)
     list = private_messages_for(user, :group)
+    group_id = Group.where('name ilike ?', @options[:group_name]).pluck(:id).first
+    list = list.joins("LEFT JOIN group_archived_messages gm ON gm.topic_id = topics.id AND
+                      gm.group_id = #{group_id.to_i}")
+    list = list.where("gm.id IS NULL")
+    create_list(:private_messages, {}, list)
+  end
+
+  def list_private_messages_group_archive(user)
+    list = private_messages_for(user, :group)
+    group_id = Group.where('name ilike ?', @options[:group_name]).pluck(:id).first
+    list = list.joins("JOIN group_archived_messages gm ON gm.topic_id = topics.id AND
+                      gm.group_id = #{group_id.to_i}")
     create_list(:private_messages, {}, list)
   end
 
@@ -195,7 +228,9 @@ class TopicQuery
     topics = yield(topics) if block_given?
 
     options = options.merge(@options)
-    if ["activity","default"].include?(options[:order] || "activity") && !options[:unordered]
+    if ["activity","default"].include?(options[:order] || "activity") &&
+        !options[:unordered] &&
+        filter != :private_messages
       topics = prioritize_pinned_topics(topics, options)
     end