Add alternate comparison types to versions

- The types are:
-- Previous: The default and the previously used type
-- Subsequent: Compares against the next version
-- Current: Compares against the current version
- Allow switching between comparison types in index and diff views
-- Have links vary depending upon current comparison type

app/models/artist_commentary_version.rb

@@ -15,6 +15,20 @@ class ArtistCommentaryVersion < ApplicationRecord
     @previous.first
   end
 
+  def subsequent
+    @subsequent ||= begin
+      ArtistCommentaryVersion.where("post_id = ? and updated_at > ?", post_id, updated_at).order("updated_at asc").limit(1).to_a
+    end
+    @subsequent.first
+  end
+
+  def current
+    @current ||= begin
+      ArtistCommentaryVersion.where("post_id = ?", post_id).order("updated_at desc").limit(1).to_a
+    end
+    @current.first
+  end
+
   def self.status_fields
     {
       original_title: "OrigTitle",

app/models/artist_version.rb

@@ -30,6 +30,20 @@ class ArtistVersion < ApplicationRecord
     @previous.first
   end
 
+  def subsequent
+    @subsequent ||= begin
+      ArtistVersion.where("artist_id = ? and created_at > ?", artist_id, created_at).order("created_at asc").limit(1).to_a
+    end
+    @subsequent.first
+  end
+
+  def current
+    @previous ||= begin
+      ArtistVersion.where("artist_id = ?", artist_id).order("created_at desc").limit(1).to_a
+    end
+    @previous.first
+  end
+
   def self.status_fields
     {
       name: "Renamed",
@@ -43,28 +57,50 @@ class ArtistVersion < ApplicationRecord
     }
   end
 
-  def other_names_changed
-    ((other_names - previous.other_names) | (previous.other_names - other_names)).length > 0
+  def other_names_changed(type)
+    other = self.send(type)
+    ((other_names - other.other_names) | (other.other_names - other_names)).length.positive?
   end
 
-  def urls_changed
-    ((urls - previous.urls) | (previous.urls - urls)).length > 0
+  def urls_changed(type)
+    other = self.send(type)
+    ((urls - other.urls) | (other.urls - urls)).length.positive?
   end
 
-  def was_deleted
-    is_deleted && !previous.is_deleted
+  def was_deleted(type)
+    other = self.send(type)
+    if type == "previous"
+      is_deleted && !other.is_deleted
+    else
+      !is_deleted && other.is_deleted
+    end
   end
 
-  def was_undeleted
-    !is_deleted && previous.is_deleted
+  def was_undeleted(type)
+    other = self.send(type)
+    if type == "previous"
+      !is_deleted && other.is_deleted
+    else
+      is_deleted && !other.is_deleted
+    end
   end
 
-  def was_banned
-    is_banned && !previous.is_banned
+  def was_banned(type)
+    other = self.send(type)
+    if type == "previous"
+      is_banned && !other.is_banned
+    else
+      !is_banned && other.is_banned
+    end
   end
 
-  def was_unbanned
-    !is_banned && previous.is_banned
+  def was_unbanned(type)
+    other = self.send(type)
+    if type == "previous"
+      !is_banned && other.is_banned
+    else
+      is_banned && !other.is_banned
+    end
   end
 
   def self.available_includes

app/models/note_version.rb

@@ -14,11 +14,25 @@ class NoteVersion < ApplicationRecord
 
   def previous
     @previous ||= begin
-      NoteVersion.where("note_id = ? and updated_at < ?", note_id, updated_at).order("updated_at desc").limit(1).to_a
+      NoteVersion.where("note_id = ? and version < ?", note_id, version).order("updated_at desc").limit(1).to_a
     end
     @previous.first
   end
 
+  def subsequent
+    @subsequent ||= begin
+      NoteVersion.where("note_id = ? and version > ?", note_id, version).order("updated_at asc").limit(1).to_a
+    end
+    @subsequent.first
+  end
+
+  def current
+    @current ||= begin
+      NoteVersion.where("note_id = ?", note_id).order("updated_at desc").limit(1).to_a
+    end
+    @current.first
+  end
+
   def self.status_fields
     {
       body: "Body",
@@ -29,20 +43,32 @@ class NoteVersion < ApplicationRecord
     }
   end
 
-  def was_moved
-    x != previous.x || y != previous.y
+  def was_moved(type)
+    other = self.send(type)
+    x != other.x || y != other.y
   end
 
-  def was_resized
-    width != previous.width || height != previous.height
+  def was_resized(type)
+    other = self.send(type)
+    width != other.width || height != other.height
   end
 
-  def was_deleted
-    !is_active && previous.is_active
+  def was_deleted(type)
+    other = self.send(type)
+    if type == "previous"
+      !is_active && other.is_active
+    else
+      is_active && !other.is_active
+    end
   end
 
-  def was_undeleted
-    is_active && !previous.is_active
+  def was_undeleted(type)
+    other = self.send(type)
+    if type == "previous"
+      is_active && !other.is_active
+    else
+      !is_active && other.is_active
+    end
   end
 
   def self.available_includes

app/models/pool_version.rb

@@ -96,6 +96,20 @@ class PoolVersion < ApplicationRecord
     @previous.first
   end
 
+  def subsequent
+    @subsequent ||= begin
+      PoolVersion.where("pool_id = ? and version > ?", pool_id, version).order("version asc").limit(1).to_a
+    end
+    @subsequent.first
+  end
+
+  def current
+    @current ||= begin
+      PoolVersion.where("pool_id = ?", pool_id).order("version desc").limit(1).to_a
+    end
+    @current.first
+  end
+
   def self.status_fields
     {
       posts_changed: "Posts",
@@ -108,24 +122,45 @@ class PoolVersion < ApplicationRecord
     }
   end
 
-  def posts_changed
-    ((post_ids - previous.post_ids) | (previous.post_ids - post_ids)).length > 0
+  def posts_changed(type)
+    other = self.send(type)
+    ((post_ids - other.post_ids) | (other.post_ids - post_ids)).length.positive?
   end
 
-  def was_deleted
-    is_deleted && !previous.is_deleted
+  def was_deleted(type)
+    other = self.send(type)
+    if type == "previous"
+      is_deleted && !other.is_deleted
+    else
+      !is_deleted && other.is_deleted
+    end
   end
 
-  def was_undeleted
-    !is_deleted && previous.is_deleted
+  def was_undeleted(type)
+    other = self.send(type)
+    if type == "previous"
+      !is_deleted && other.is_deleted
+    else
+      is_deleted && !other.is_deleted
+    end
   end
 
-  def was_activated
-    is_active && !previous.is_active
+  def was_activated(type)
+    other = self.send(type)
+    if type == "previous"
+      is_active && !other.is_active
+    else
+      !is_active && other.is_active
+    end
   end
 
-  def was_deactivated
-    !is_active && previous.is_active
+  def was_deactivated(type)
+    other = self.send(type)
+    if type == "previous"
+      !is_active && other.is_active
+    else
+      is_active && !other.is_active
+    end
   end
 
   def pretty_name

app/models/post_version.rb

@@ -99,6 +99,20 @@ class PostVersion < ApplicationRecord
     @previous.first
   end
 
+  def subsequent
+    @subsequent ||= begin
+      PostVersion.where("post_id = ? and version > ?", post_id, version).order("version asc").limit(1).to_a
+    end
+    @subsequent.first
+  end
+
+  def current
+    @current ||= begin
+      PostVersion.where("post_id = ?", post_id).order("version desc").limit(1).to_a
+    end
+    @current.first
+  end
+
   def visible?
     post&.visible?
   end

app/models/wiki_page_version.rb

@@ -30,6 +30,20 @@ class WikiPageVersion < ApplicationRecord
     @previous.first
   end
 
+  def subsequent
+    @subsequent ||= begin
+      WikiPageVersion.where("wiki_page_id = ? and id > ?", wiki_page_id, id).order("id asc").limit(1).to_a
+    end
+    @subsequent.first
+  end
+
+  def current
+    @current ||= begin
+      WikiPageVersion.where("wiki_page_id = ?", wiki_page_id).order("id desc").limit(1).to_a
+    end
+    @current.first
+  end
+
   def self.status_fields
     {
       body: "Body",
@@ -40,16 +54,27 @@ class WikiPageVersion < ApplicationRecord
     }
   end
 
-  def other_names_changed
-    ((other_names - previous.other_names) | (previous.other_names - other_names)).length > 0
+  def other_names_changed(type)
+    other = self.send(type)
+    ((other_names - other.other_names) | (other.other_names - other_names)).length.positive?
   end
 
-  def was_deleted
-    is_deleted && !previous.is_deleted
+  def was_deleted(type)
+    other = self.send(type)
+    if type == "previous"
+      is_deleted && !other.is_deleted
+    else
+      !is_deleted && other.is_deleted
+    end
   end
 
-  def was_undeleted
-    !is_deleted && previous.is_deleted
+  def was_undeleted(type)
+    other = self.send(type)
+    if type == "previous"
+      !is_deleted && other.is_deleted
+    else
+      is_deleted && !other.is_deleted
+    end
   end
 
   def self.available_includes