users: add dark mode account setting (fix #4158).

app/controllers/users_controller.rb

@@ -101,7 +101,7 @@ class UsersController < ApplicationController
     permitted_params = %i[
       password old_password password_confirmation email
       comment_threshold default_image_size favorite_tags blacklisted_tags
-      time_zone per_page custom_style
+      time_zone per_page custom_style theme
 
       receive_email_notifications always_resize_images enable_post_navigation
       new_post_navigation_layout enable_privacy_mode

app/helpers/application_helper.rb

@@ -174,7 +174,7 @@ module ApplicationHelper
   end
 
   def body_attributes(user = CurrentUser.user)
-    attributes = [:id, :name, :level, :level_string, :can_approve_posts?, :can_upload_free?]
+    attributes = [:id, :name, :level, :level_string, :theme, :can_approve_posts?, :can_upload_free?]
     attributes += User::Roles.map { |role| :"is_#{role}?" }
 
     controller_param = params[:controller].parameterize.dasherize

app/models/user.rb

@@ -114,6 +114,8 @@ class User < ApplicationRecord
   belongs_to :inviter, class_name: "User", optional: true
   accepts_nested_attributes_for :dmail_filter
 
+  enum theme: { light: 0, dark: 100 }, _suffix: true
+
   module BanMethods
     def validate_ip_addr_is_not_banned
       if IpBan.is_banned?(CurrentUser.ip_addr)

app/views/users/edit.html.erb

@@ -31,17 +31,17 @@
           </p>
         </div>
 
-        <%= f.input :time_zone, :include_blank => false %>
-        <%= f.input :receive_email_notifications, :as => :select, :include_blank => false, :collection => [["Yes", "true"], ["No", "false"]] %>
-        <%= f.input :comment_threshold, :hint => "Comments below this score will be hidden by default" %>
-        <%= f.input :default_image_size, :hint => "Show original image or show resized #{Danbooru.config.large_image_width} pixel version", :label => "Default image width", :collection => [["850px", "large"], ["original", "original"]], :include_blank => false %>
+        <%= f.input :theme, collection: User.themes.keys, include_blank: false, hint: "The site's colorscheme (light mode or dark mode)." %>
+        <%= f.input :enable_safe_mode, label: "Safe mode", hint: "Show only safe images. Hide questionable and explicit images.", as: :select, include_blank: false, collection: [["Yes", "true"], ["No", "false"]] %>
         
         <% if CurrentUser.user.is_gold? %>
           <%= f.input :per_page, :label => "Posts per page", :as => :select, :hint => "Number of thumbnails per page", :collection => (1..PostSets::Post::MAX_PER_PAGE), :include_blank => false %>
         <% end %>
-
-        <%= f.input :enable_safe_mode, :label => "Safe mode", :hint => "Show only safe images. Hide questionable and explicit images.", :as => :select, :include_blank => false, :collection => [["Yes", "true"], ["No", "false"]] %>
-        <%= f.input :blacklisted_tags, :hint => "Posts with these tags will be hidden. Put each tag on a separate line. <a href='/wiki_pages/help:blacklists'>View help.</a>".html_safe, :input_html => {:size => "40x5", :data => {:autocomplete => "tag-query"}} %>
+        <%= f.input :default_image_size, hint: "Show full original images or resized #{Danbooru.config.large_image_width}px width samples.", label: "Default image width", collection: [["850px", "large"], ["original", "original"]], include_blank: false %>
+        <%= f.input :receive_email_notifications, as: :select, include_blank: false, collection: [["Yes", "true"], ["No", "false"]], hint: "Receive an email when you receive a new dmail." %>
+        <%= f.input :time_zone, include_blank: false, hint: "The timezone to use for timestamps." %>
+        <%= f.input :comment_threshold, hint: "Comments below this score will be hidden by default" %>
+        <%= f.input :blacklisted_tags, hint: "Posts with these tags will be hidden. Put each tag on a separate line. <a href='/wiki_pages/help:blacklists'>View help.</a>".html_safe, :input_html => {:size => "40x5", :data => {:autocomplete => "tag-query"}} %>
       </fieldset>
       
       <fieldset id="advanced-settings-section">