22 files changed, 317 insertions, 116 deletions

diff --git a/config/environments/production.rb b/config/environments/production.rb
index 29d6194dd..00571a35a 100644
--- a/config/environments/production.rb
+++ b/config/environments/production.rb
@@ -104,10 +104,14 @@ Rails.application.configure do
   config.action_mailer.delivery_method = ENV.fetch('SMTP_DELIVERY_METHOD', 'smtp').to_sym
 
   config.action_dispatch.default_headers = {
-    'Server'                 => 'Mastodon',
-    'X-Frame-Options'        => 'DENY',
-    'X-Content-Type-Options' => 'nosniff',
-    'X-XSS-Protection'       => '1; mode=block',
+    'Server'                  => 'Mastodon',
+    'X-Frame-Options'         => 'DENY',
+    'X-Content-Type-Options'  => 'nosniff',
+    'X-XSS-Protection'        => '1; mode=block',
+    'Referrer-Policy'         => 'same-origin',
+    'Strict-Transport-Security' => 'max-age=63072000; includeSubDomains; preload',
+    'X-Clacks-Overhead' => 'GNU Natalie Nguyen'
+
   }
 
   config.x.otp_secret = ENV.fetch('OTP_SECRET')
diff --git a/config/i18n-tasks.yml b/config/i18n-tasks.yml
index c2d6a7838..1e223fbde 100644
--- a/config/i18n-tasks.yml
+++ b/config/i18n-tasks.yml
@@ -59,6 +59,7 @@ ignore_unused:
   - 'errors.429'
   - 'admin.accounts.roles.*'
   - 'admin.action_logs.actions.*'
+  - 'themes.*'
   - 'statuses.attached.*'
 
 ignore_inconsistent_interpolations:
diff --git a/config/initializers/0_duplicate_migrations.rb b/config/initializers/0_duplicate_migrations.rb
new file mode 100644
index 000000000..4ab806587
--- /dev/null
+++ b/config/initializers/0_duplicate_migrations.rb
@@ -0,0 +1,40 @@
+# Some migrations have been present in glitch-soc for a long time and have then
+# been merged in upstream Mastodon, under a different version number.
+#
+# This puts us in an uneasy situation in which if we remove upstream's
+# migration file, people migrating from upstream will end up having a conflict
+# with their already-ran migration.
+#
+# On the other hand, if we keep upstream's migration and remove our own,
+# any current glitch-soc user will have a conflict during migration.
+#
+# For lack of a better solution, as those migrations are indeed identical,
+# we decided monkey-patching Rails' Migrator to completely ignore the duplicate,
+# keeping only the one that has run, or an arbitrary one.
+
+ALLOWED_DUPLICATES = [20180410220657, 20180831171112].freeze
+
+module ActiveRecord
+  class Migrator
+    def self.new(direction, migrations, target_version = nil)
+      migrated = Set.new(Base.connection.migration_context.get_all_versions)
+
+      migrations.group_by(&:name).each do |name, duplicates|
+        if duplicates.length > 1 && duplicates.all? { |m| ALLOWED_DUPLICATES.include?(m.version) }
+          # We have a set of allowed duplicates. Keep the migrated one, if any.
+          non_migrated = duplicates.reject { |m| migrated.include?(m.version.to_i) }
+
+          if duplicates.length == non_migrated.length || non_migrated.length == 0
+            # There weren't any migrated one, so we have to pick one “canonical” migration
+            migrations = migrations - duplicates[1..-1]
+          else
+            # Just reject every duplicate which hasn't been migrated yet
+            migrations = migrations - non_migrated
+          end
+        end
+      end
+
+      super(direction, migrations, target_version)
+    end
+  end
+end
diff --git a/config/initializers/content_security_policy.rb b/config/initializers/content_security_policy.rb
index af7d16aaf..810aa2880 100644
--- a/config/initializers/content_security_policy.rb
+++ b/config/initializers/content_security_policy.rb
@@ -2,41 +2,42 @@
 # For further information see the following documentation
 # https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Security-Policy
 
-def host_to_url(str)
-  "http#{Rails.configuration.x.use_https ? 's' : ''}://#{str}" unless str.blank?
-end
-
-base_host = Rails.configuration.x.web_domain
-
-assets_host   = Rails.configuration.action_controller.asset_host
-assets_host ||= host_to_url(base_host)
-
-media_host   = host_to_url(ENV['S3_ALIAS_HOST'])
-media_host ||= host_to_url(ENV['S3_CLOUDFRONT_HOST'])
-media_host ||= host_to_url(ENV['S3_HOSTNAME']) if ENV['S3_ENABLED'] == 'true'
-media_host ||= assets_host
+if Rails.env.production?
+  assets_host = Rails.configuration.action_controller.asset_host || "https://#{ENV['WEB_DOMAIN'] || ENV['LOCAL_DOMAIN']}"
+  data_hosts = [assets_host]
+
+  if ENV['S3_ENABLED'] == 'true'
+    attachments_host = "https://#{ENV['S3_ALIAS_HOST'] || ENV['S3_CLOUDFRONT_HOST'] || ENV['S3_HOSTNAME'] || "s3-#{ENV['S3_REGION'] || 'us-east-1'}.amazonaws.com"}"
+    attachments_host = "https://#{Addressable::URI.parse(attachments_host).host}"
+  elsif ENV['SWIFT_ENABLED'] == 'true'
+    attachments_host = ENV['SWIFT_OBJECT_URL']
+    attachments_host = "https://#{Addressable::URI.parse(attachments_host).host}"
+  else
+    attachments_host = nil
+  end
 
-Rails.application.config.content_security_policy do |p|
-  p.base_uri        :none
-  p.default_src     :none
-  p.frame_ancestors :none
-  p.font_src        :self, assets_host
-  p.img_src         :self, :https, :data, :blob, assets_host
-  p.style_src       :self, :unsafe_inline, assets_host
-  p.media_src       :self, :https, :data, assets_host
-  p.frame_src       :self, :https
-  p.manifest_src    :self, assets_host
+  data_hosts << attachments_host unless attachments_host.nil?
 
-  if Rails.env.development?
-    webpacker_urls = %w(ws http).map { |protocol| "#{protocol}#{Webpacker.dev_server.https? ? 's' : ''}://#{Webpacker.dev_server.host_with_port}" }
+  if ENV['PAPERCLIP_ROOT_URL']
+    url = Addressable::URI.parse(assets_host) + ENV['PAPERCLIP_ROOT_URL']
+    data_hosts << "https://#{url.host}"
+  end
 
-    p.connect_src :self, :data, :blob, assets_host, media_host, Rails.configuration.x.streaming_api_base_url, *webpacker_urls
-    p.script_src  :self, :unsafe_inline, :unsafe_eval, assets_host
-    p.worker_src  :self, :blob, assets_host
-  else
-    p.connect_src :self, :data, :blob, assets_host, media_host, Rails.configuration.x.streaming_api_base_url
-    p.script_src  :self, assets_host
-    p.worker_src  :self, :blob, assets_host
+  data_hosts.uniq!
+
+  Rails.application.config.content_security_policy do |p|
+    p.base_uri        :none
+    p.default_src     :none
+    p.frame_ancestors :none
+    p.script_src      :self, assets_host
+    p.font_src        :self, assets_host
+    p.img_src         :self, :data, :blob, *data_hosts
+    p.style_src       :self, :unsafe_inline, assets_host
+    p.media_src       :self, :data, *data_hosts
+    p.frame_src       :self, :https
+    p.worker_src      :self, :blob, assets_host
+    p.connect_src     :self, :blob, :data, Rails.configuration.x.streaming_api_base_url, *data_hosts
+    p.manifest_src    :self, assets_host
   end
 end
 
diff --git a/config/initializers/cors.rb b/config/initializers/cors.rb
index 55f8c9c91..bc782bc76 100644
--- a/config/initializers/cors.rb
+++ b/config/initializers/cors.rb
@@ -30,5 +30,9 @@ Rails.application.config.middleware.insert_before 0, Rack::Cors do
       headers: :any,
       methods: [:post],
       credentials: false
+    resource '/assets/*', headers: :any, methods: [:get, :head, :options]
+    resource '/stylesheets/*', headers: :any, methods: [:get, :head, :options]
+    resource '/javascripts/*', headers: :any, methods: [:get, :head, :options]
+    resource '/packs/*', headers: :any, methods: [:get, :head, :options]
   end
 end
diff --git a/config/initializers/locale.rb b/config/initializers/locale.rb
new file mode 100644
index 000000000..04ed31646
--- /dev/null
+++ b/config/initializers/locale.rb
@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+I18n.load_path += Dir[Rails.root.join('app', 'javascript', 'flavours', '*', 'names.{rb,yml}').to_s]
+I18n.load_path += Dir[Rails.root.join('app', 'javascript', 'flavours', '*', 'names', '*.{rb,yml}').to_s]
+I18n.load_path += Dir[Rails.root.join('app', 'javascript', 'skins', '*', '*', 'names.{rb,yml}').to_s]
+I18n.load_path += Dir[Rails.root.join('app', 'javascript', 'skins', '*', '*', 'names', '*.{rb,yml}').to_s]
diff --git a/config/locales/en.yml b/config/locales/en.yml
index d768cef33..8262a5868 100644
--- a/config/locales/en.yml
+++ b/config/locales/en.yml
@@ -273,6 +273,7 @@ en:
       feature_timeline_preview: Timeline preview
       features: Features
       hidden_service: Federation with hidden services
+      keybase: Keybase integration
       open_reports: open reports
       pending_tags: hashtags waiting for review
       pending_users: users waiting for review
@@ -454,9 +455,15 @@ en:
         title: Show rationale
       enable_bootstrap_timeline_accounts:
         title: Enable default follows for new users
+      enable_keybase:
+        desc_html: Allow your users to prove their identity via keybase
+        title: Enable keybase integration
       hero:
         desc_html: Displayed on the frontpage. At least 600x100px recommended. When not set, falls back to server thumbnail
         title: Hero image
+      hide_followers_count:
+        desc_html: Do not show followers count on user profiles
+        title: Hide followers count
       mascot:
         desc_html: Displayed on multiple pages. At least 293×205px recommended. When not set, falls back to default mascot
         title: Mascot image
@@ -488,6 +495,12 @@ en:
       show_known_fediverse_at_about_page:
         desc_html: When disabled, restricts the public timeline linked from the landing page to showing only local content
         title: Include federated content on unauthenticated public timeline page
+      show_reblogs_in_public_timelines:
+        desc_html: Show public boosts of public toots in local and public timelines.
+        title: Show boosts in public timelines
+      show_replies_in_public_timelines:
+        desc_html: In addition to public self-replies (threads), show public replies in local and public timelines.
+        title: Show replies in public timelines
       show_staff_badge:
         desc_html: Show a staff badge on a user page
         title: Show staff badge
@@ -761,6 +774,7 @@ en:
     no_batch_actions_available: No batch actions available on this page
     order_by: Order by
     save_changes: Save changes
+    use_this: Use this
     validation_errors:
       one: Something isn't quite right yet! Please review the error below
       other: Something isn't quite right yet! Please review %{count} errors below
@@ -1019,6 +1033,7 @@ en:
     edit_profile: Edit profile
     export: Data export
     featured_tags: Featured hashtags
+    flavours: Flavours
     identity_proofs: Identity proofs
     import: Import
     import_and_export: Import and export
diff --git a/config/locales/ja.yml b/config/locales/ja.yml
index 8197423af..e26fe3942 100644
--- a/config/locales/ja.yml
+++ b/config/locales/ja.yml
@@ -753,6 +753,7 @@ ja:
     no_batch_actions_available: このページに一括操作はありません
     order_by: 並び順
     save_changes: 変更を保存
+    use_this: これを使う
     validation_errors:
       other: エラーが発生しました！ 以下の%{count}個のエラーを確認してください
   html_validator:
@@ -1005,6 +1006,7 @@ ja:
     edit_profile: プロフィールを編集
     export: データのエクスポート
     featured_tags: 注目のハッシュタグ
+    flavours: フレーバー
     identity_proofs: Identity proofs
     import: データのインポート
     import_and_export: インポート・エクスポート
diff --git a/config/locales/pl.yml b/config/locales/pl.yml
index eec58bc5e..e243162e8 100644
--- a/config/locales/pl.yml
+++ b/config/locales/pl.yml
@@ -670,6 +670,7 @@ pl:
     copy: Kopiuj
     order_by: Uporządkuj według
     save_changes: Zapisz zmiany
+    use_this: Użyj tego
     validation_errors:
       few: Coś jest wciąż nie tak! Przejrzyj %{count} poniższe błędy
       many: Coś jest wciąż nie tak! Przejrzyj %{count} poniższych błędów
@@ -899,6 +900,7 @@ pl:
     edit_profile: Edytuj profil
     export: Eksportowanie danych
     featured_tags: Wyróżnione hashtagi
+    flavours: Odmiany
     identity_proofs: Dowody tożsamości
     import: Importowanie danych
     import_and_export: Import i eksport
diff --git a/config/locales/simple_form.en.yml b/config/locales/simple_form.en.yml
index 65951b73b..9b467f84e 100644
--- a/config/locales/simple_form.en.yml
+++ b/config/locales/simple_form.en.yml
@@ -34,6 +34,10 @@ en:
         phrase: Will be matched regardless of casing in text or content warning of a toot
         scopes: Which APIs the application will be allowed to access. If you select a top-level scope, you don't need to select individual ones.
         setting_aggregate_reblogs: Do not show new boosts for toots that have been recently boosted (only affects newly-received boosts)
+        setting_default_content_type_html: When writing toots, assume they are written in raw HTML, unless specified otherwise
+        setting_default_content_type_markdown: When writing toots, assume they are using Markdown for rich text formatting, unless specified otherwise
+        setting_default_content_type_plain: When writing toots, assume they are plain text with no special formatting, unless specified otherwise (default Mastodon behavior)
+        setting_default_language: The language of your toots can be detected automatically, but it's not always accurate
         setting_default_sensitive: Sensitive media is hidden by default and can be revealed with a click
         setting_display_media_default: Hide media marked as sensitive
         setting_display_media_hide_all: Always hide all media
@@ -41,6 +45,7 @@ en:
         setting_hide_network: Who you follow and who follows you will not be shown on your profile
         setting_noindex: Affects your public profile and status pages
         setting_show_application: The application you use to toot will be displayed in the detailed view of your toots
+        setting_skin: Reskins the selected Mastodon flavour
         setting_use_blurhash: Gradients are based on the colors of the hidden visuals but obfuscate any details
         setting_use_pending_items: Hide timeline updates behind a click instead of automatically scrolling the feed
         username: Your username will be unique on %{domain}
@@ -114,6 +119,10 @@ en:
         setting_auto_play_gif: Auto-play animated GIFs
         setting_boost_modal: Show confirmation dialog before boosting
         setting_crop_images: Crop images in non-expanded toots to 16x9
+        setting_default_content_type: Default format for toots
+        setting_default_content_type_html: HTML
+        setting_default_content_type_markdown: Markdown
+        setting_default_content_type_plain: Plain text
         setting_default_language: Posting language
         setting_default_privacy: Posting privacy
         setting_default_sensitive: Always mark media as sensitive
@@ -123,10 +132,14 @@ en:
         setting_display_media_hide_all: Hide all
         setting_display_media_show_all: Show all
         setting_expand_spoilers: Always expand toots marked with content warnings
+        setting_favourite_modal: Show confirmation dialog before favouriting (applies to Glitch flavour only)
+        setting_hide_followers_count: Hide your followers count
         setting_hide_network: Hide your network
         setting_noindex: Opt-out of search engine indexing
         setting_reduce_motion: Reduce motion in animations
         setting_show_application: Disclose application used to send toots
+        setting_skin: Skin
+        setting_system_emoji_font: Use system's default font for emojis (applies to Glitch flavour only)
         setting_system_font_ui: Use system's default font
         setting_theme: Site theme
         setting_trends: Show today's trends
diff --git a/config/locales/simple_form.ja.yml b/config/locales/simple_form.ja.yml
index 63475167c..3e2855e58 100644
--- a/config/locales/simple_form.ja.yml
+++ b/config/locales/simple_form.ja.yml
@@ -123,6 +123,7 @@ ja:
         setting_display_media_hide_all: 非表示
         setting_display_media_show_all: 表示
         setting_expand_spoilers: 閲覧注意としてマークされたトゥートを常に展開する
+        setting_favourite_modal: お気に入りをする前に確認ダイアログを表示する
         setting_hide_network: 繋がりを隠す
         setting_noindex: 検索エンジンによるインデックスを拒否する
         setting_reduce_motion: アニメーションの動きを減らす
diff --git a/config/locales/simple_form.pl.yml b/config/locales/simple_form.pl.yml
index 695817985..d3d726440 100644
--- a/config/locales/simple_form.pl.yml
+++ b/config/locales/simple_form.pl.yml
@@ -33,6 +33,7 @@ pl:
         setting_hide_network: Informacje o tym, kto Cię śledzi i kogo śledzisz nie będą widoczne
         setting_noindex: Wpływa na widoczność strony profilu i Twoich wpisów
         setting_show_application: W informacjach o wpisie będzie widoczna informacja o aplikacji, z której został wysłany
+        setting_skin: Zmienia wygląd używanej odmiany Mastodona
         setting_use_blurhash: Gradienty są oparte na kolorach ukrywanej zawartości, ale uniewidaczniają wszystkie szczegóły
         username: Twoja nazwa użytkownika będzie niepowtarzalna na %{domain}
         whole_word: Jeśli słowo lub fraza składa się jedynie z liter lub cyfr, filtr będzie zastosowany tylko do pełnych wystąpień
@@ -102,12 +103,13 @@ pl:
         setting_display_media_hide_all: Ukryj wszystko
         setting_display_media_show_all: Pokaż wszystko
         setting_expand_spoilers: Zawsze rozwijaj wpisy oznaczone ostrzeżeniem o zawartości
+        setting_favourite_modal: Pytaj o potwierdzenie przed dodaniem do ulubionych
         setting_hide_network: Ukryj swoją sieć
         setting_noindex: Nie indeksuj mojego profilu w wyszukiwarkach internetowych
         setting_reduce_motion: Ogranicz ruch w animacjach
         setting_show_application: Informuj o aplikacji z której wysłano wpisy
+        setting_skin: Motyw
         setting_system_font_ui: Używaj domyślnej czcionki systemu
-        setting_theme: Motyw strony
         setting_unfollow_modal: Pytaj o potwierdzenie przed cofnięciem śledzenia
         setting_use_blurhash: Pokazuj kolorowe gradienty dla ukrytej zawartości multimedialnej
         severity: Priorytet
diff --git a/config/navigation.rb b/config/navigation.rb
index eebd4f75e..ab4262182 100644
--- a/config/navigation.rb
+++ b/config/navigation.rb
@@ -16,6 +16,12 @@ SimpleNavigation::Configuration.run do |navigation|
       s.item :other, safe_join([fa_icon('cog fw'), t('preferences.other')]), settings_preferences_other_url
     end
 
+    n.item :flavours, safe_join([fa_icon('paint-brush fw'), t('settings.flavours')]), settings_flavours_url do |flavours|
+      Themes.instance.flavours.each do |flavour|
+        flavours.item flavour.to_sym, safe_join([fa_icon('star fw'), t("flavours.#{flavour}.name", default: flavour)]), settings_flavour_url(flavour)
+      end
+    end
+
     n.item :relationships, safe_join([fa_icon('users fw'), t('settings.relationships')]), relationships_url, if: -> { current_user.functional? }
     n.item :filters, safe_join([fa_icon('filter fw'), t('filters.index.title')]), filters_path, highlights_on: %r{/filters}, if: -> { current_user.functional? }
 
diff --git a/config/routes.rb b/config/routes.rb
index 5411cff58..49edb4602 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -136,6 +136,8 @@ Rails.application.routes.draw do
       end
     end
 
+    resources :flavours, only: [:index, :show, :update], param: :flavour
+
     resource :delete, only: [:show, :destroy]
     resource :migration, only: [:show, :create]
 
@@ -305,6 +307,7 @@ Rails.application.routes.draw do
       end
 
       namespace :timelines do
+        resource :direct, only: :show, controller: :direct
         resource :home, only: :show, controller: :home
         resource :public, only: :show, controller: :public
         resources :tag, only: :show
@@ -325,7 +328,11 @@ Rails.application.routes.draw do
 
       resources :media,        only: [:create, :update]
       resources :blocks,       only: [:index]
-      resources :mutes,        only: [:index]
+      resources :mutes,        only: [:index] do
+        collection do
+          get 'details'
+        end
+      end
       resources :favourites,   only: [:index]
       resources :bookmarks,    only: [:index]
       resources :reports,      only: [:create]
@@ -355,9 +362,10 @@ Rails.application.routes.draw do
         end
       end
 
-      resources :notifications, only: [:index, :show] do
+      resources :notifications, only: [:index, :show, :destroy] do
         collection do
           post :clear
+          delete :destroy_multiple
         end
 
         member do
diff --git a/config/settings.yml b/config/settings.yml
index 002473643..00a4421e4 100644
--- a/config/settings.yml
+++ b/config/settings.yml
@@ -2,7 +2,7 @@
 # important settings can be changed from the admin interface.
 
 defaults: &defaults
-  site_title: Mastodon
+  site_title: 'dev.glitch.social'
   site_short_description: ''
   site_description: ''
   site_extended_description: ''
@@ -13,23 +13,28 @@ defaults: &defaults
   profile_directory: true
   closed_registrations_message: ''
   open_deletion: true
+  timeline_preview: false
   min_invite_role: 'admin'
-  timeline_preview: true
   show_staff_badge: true
   default_sensitive: false
   hide_network: false
   unfollow_modal: false
   boost_modal: false
+  favourite_modal: false
   delete_modal: true
   auto_play_gif: false
   display_media: 'default'
   expand_spoilers: false
   preview_sensitive_media: false
   reduce_motion: false
-  show_application: true
+  show_application: false
   system_font_ui: false
+  system_emoji_font: false
   noindex: false
-  theme: 'default'
+  hide_followers_count: false
+  enable_keybase: true
+  flavour: 'glitch'
+  skin: 'default'
   aggregate_reblogs: true
   advanced_layout: false
   use_blurhash: true
@@ -66,6 +71,9 @@ defaults: &defaults
   activity_api_enabled: true
   peers_api_enabled: true
   show_known_fediverse_at_about_page: true
+  show_reblogs_in_public_timelines: false
+  show_replies_in_public_timelines: false
+  default_content_type: 'text/plain'
   spam_check_enabled: true
   show_domain_blocks: 'disabled'
   show_domain_blocks_rationale: 'disabled'
diff --git a/config/themes.yml b/config/themes.yml
deleted file mode 100644
index 9c21c9459..000000000
--- a/config/themes.yml
+++ /dev/null
@@ -1,3 +0,0 @@
-default: styles/application.scss
-contrast: styles/contrast.scss
-mastodon-light: styles/mastodon-light.scss
diff --git a/config/webpack/configuration.js b/config/webpack/configuration.js
index 80a094c72..926af9b39 100644
--- a/config/webpack/configuration.js
+++ b/config/webpack/configuration.js
@@ -1,15 +1,61 @@
 // Common configuration for webpacker loaded from config/webpacker.yml
 
-const { resolve } = require('path');
+const { basename, dirname, extname, join, resolve } = require('path');
 const { env } = require('process');
 const { safeLoad } = require('js-yaml');
-const { readFileSync } = require('fs');
+const { lstatSync, readFileSync } = require('fs');
+const glob = require('glob');
 
 const configPath = resolve('config', 'webpacker.yml');
 const settings = safeLoad(readFileSync(configPath), 'utf8')[env.RAILS_ENV || env.NODE_ENV];
+const flavourFiles = glob.sync('app/javascript/flavours/*/theme.yml');
+const skinFiles = glob.sync('app/javascript/skins/*/*');
+const flavours = {};
 
-const themePath = resolve('config', 'themes.yml');
-const themes = safeLoad(readFileSync(themePath), 'utf8');
+const core = function () {
+  const coreFile = resolve('app', 'javascript', 'core', 'theme.yml');
+  const data = safeLoad(readFileSync(coreFile), 'utf8');
+  if (!data.pack_directory) {
+    data.pack_directory = dirname(coreFile);
+  }
+  return data.pack ? data : {};
+}();
+
+for (let i = 0; i < flavourFiles.length; i++) {
+  const flavourFile = flavourFiles[i];
+  const data = safeLoad(readFileSync(flavourFile), 'utf8');
+  data.name = basename(dirname(flavourFile));
+  data.skin = {};
+  if (!data.pack_directory) {
+    data.pack_directory = dirname(flavourFile);
+  }
+  if (data.locales) {
+    data.locales = join(dirname(flavourFile), data.locales);
+  }
+  if (data.pack && typeof data.pack === 'object') {
+    flavours[data.name] = data;
+  }
+}
+
+for (let i = 0; i < skinFiles.length; i++) {
+  const skinFile = skinFiles[i];
+  let skin = basename(skinFile);
+  const name = basename(dirname(skinFile));
+  if (!flavours[name]) {
+    continue;
+  }
+  const data = flavours[name].skin;
+  if (lstatSync(skinFile).isDirectory()) {
+    data[skin] = {};
+    const skinPacks = glob.sync(join(skinFile, '*.{css,scss}'));
+    for (let j = 0; j < skinPacks.length; j++) {
+      const pack = skinPacks[j];
+      data[skin][basename(pack, extname(pack))] = pack;
+    }
+  } else if ((skin = skin.match(/^(.*)\.s?css$/i))) {
+    data[skin[1]] = { common: skinFile };
+  }
+}
 
 function removeOuterSlashes(string) {
   return string.replace(/^\/*/, '').replace(/\/*$/, '');
@@ -31,7 +77,8 @@ const output = {
 
 module.exports = {
   settings,
-  themes,
+  core,
+  flavours,
   env: {
     CDN_HOST: env.CDN_HOST,
     NODE_ENV: env.NODE_ENV,
diff --git a/config/webpack/generateLocalePacks.js b/config/webpack/generateLocalePacks.js
index b71cf2ade..09fba4a18 100644
--- a/config/webpack/generateLocalePacks.js
+++ b/config/webpack/generateLocalePacks.js
@@ -1,52 +1,66 @@
+// A message from upstream:
+// ========================
 // To avoid adding a lot of boilerplate, locale packs are
 // automatically generated here. These are written into the tmp/
 // directory and then used to generate locale_en.js, locale_fr.js, etc.
 
-const fs = require('fs');
-const path = require('path');
+// Glitch note:
+// ============
+// This code has been entirely rewritten to support glitch flavours.
+// However, the underlying process is exactly the same.
+
+const { existsSync, readdirSync, writeFileSync } = require('fs');
+const { join, resolve } = require('path');
 const rimraf = require('rimraf');
 const mkdirp = require('mkdirp');
+const { flavours } = require('./configuration.js');
+
+module.exports = Object.keys(flavours).reduce(function (map, entry) {
+  const flavour = flavours[entry];
+  if (!flavour.locales) {
+    return map;
+  }
+  const locales = readdirSync(flavour.locales).filter(
+    filename => /\.js(?:on)?$/.test(filename) && !/defaultMessages|whitelist|index/.test(filename)
+  );
+  const outPath = resolve('tmp', 'locales', entry);
 
-const localesJsonPath = path.join(__dirname, '../../app/javascript/mastodon/locales');
-const locales = fs.readdirSync(localesJsonPath).filter(filename => {
-  return /\.json$/.test(filename) &&
-    !/defaultMessages/.test(filename) &&
-    !/whitelist/.test(filename);
-}).map(filename => filename.replace(/\.json$/, ''));
-
-const outPath = path.join(__dirname, '../../tmp/packs');
-
-rimraf.sync(outPath);
-mkdirp.sync(outPath);
-
-const outPaths = [];
-
-locales.forEach(locale => {
-  const localePath = path.join(outPath, `locale_${locale}.js`);
-  const baseLocale = locale.split('-')[0]; // e.g. 'zh-TW' -> 'zh'
-  const localeDataPath = [
-    // first try react-intl
-    `../../node_modules/react-intl/locale-data/${baseLocale}.js`,
-    // then check locales/locale-data
-    `../../app/javascript/mastodon/locales/locale-data/${baseLocale}.js`,
-    // fall back to English (this is what react-intl does anyway)
-    '../../node_modules/react-intl/locale-data/en.js',
-  ].filter(filename => fs.existsSync(path.join(outPath, filename)))
-    .map(filename => filename.replace(/..\/..\/node_modules\//, ''))[0];
-
-  const localeContent = `//
-// locale_${locale}.js
+  rimraf.sync(outPath);
+  mkdirp.sync(outPath);
+
+  locales.forEach(function (locale) {
+    const localeName = locale.replace(/\.js(?:on)?$/, '');
+    const localePath = join(outPath, `${localeName}.js`);
+    const baseLocale = localeName.split('-')[0]; // e.g. 'zh-TW' -> 'zh'
+    const localeDataPath = [
+      // first try react-intl
+      `node_modules/react-intl/locale-data/${baseLocale}.js`,
+      // then check locales/locale-data
+      `app/javascript/locales/locale-data/${baseLocale}.js`,
+      // fall back to English (this is what react-intl does anyway)
+      'node_modules/react-intl/locale-data/en.js',
+    ].filter(
+      filename => existsSync(filename)
+    ).map(
+      filename => filename.replace(/(?:node_modules|app\/javascript)\//, '')
+    )[0];
+    const localeContent = `//
+// locales/${entry}/${localeName}.js
 // automatically generated by generateLocalePacks.js
 //
-import messages from '../../app/javascript/mastodon/locales/${locale}.json';
-import localeData from ${JSON.stringify(localeDataPath)};
-import { setLocale } from '../../app/javascript/mastodon/locales';
-setLocale({messages, localeData});
-`;
-  fs.writeFileSync(localePath, localeContent, 'utf8');
-  outPaths.push(localePath);
-});
 
-module.exports = outPaths;
+import messages from '../../../${flavour.locales}/${locale.replace(/\.js$/, '')}';
+import localeData from '${localeDataPath}';
+import { setLocale } from 'locales';
 
+setLocale({
+  localeData,
+  messages,
+});
+`;
+    writeFileSync(localePath, localeContent, 'utf8');
+    map[`locales/${entry}/${localeName}`] = localePath;
+  });
 
+  return map;
+}, {});
diff --git a/config/webpack/rules/babel.js b/config/webpack/rules/babel.js
index 2fc245c43..4d25748ee 100644
--- a/config/webpack/rules/babel.js
+++ b/config/webpack/rules/babel.js
@@ -12,6 +12,7 @@ module.exports = {
     {
       loader: 'babel-loader',
       options: {
+        sourceRoot: 'app/javascript',
         cacheDirectory: join(settings.cache_path, 'babel-loader'),
         cacheCompression: env.NODE_ENV === 'production',
         compact: env.NODE_ENV === 'production',
diff --git a/config/webpack/rules/css.js b/config/webpack/rules/css.js
index bc1f42c13..6ecfb3164 100644
--- a/config/webpack/rules/css.js
+++ b/config/webpack/rules/css.js
@@ -20,6 +20,9 @@ module.exports = {
     {
       loader: 'sass-loader',
       options: {
+        sassOptions: {
+          includePaths: ['app/javascript'],
+        },
         implementation: require('sass'),
         sourceMap: true,
       },
diff --git a/config/webpack/shared.js b/config/webpack/shared.js
index d5e399ced..1741ffdb9 100644
--- a/config/webpack/shared.js
+++ b/config/webpack/shared.js
@@ -6,33 +6,56 @@ const { sync } = require('glob');
 const MiniCssExtractPlugin = require('mini-css-extract-plugin');
 const AssetsManifestPlugin = require('webpack-assets-manifest');
 const CopyPlugin = require('copy-webpack-plugin');
-const extname = require('path-complete-extname');
-const { env, settings, themes, output } = require('./configuration');
+const { env, settings, core, flavours, output } = require('./configuration.js');
 const rules = require('./rules');
-const localePackPaths = require('./generateLocalePacks');
+const localePacks = require('./generateLocalePacks');
+
+function reducePacks (data, into = {}) {
+  if (!data.pack) {
+    return into;
+  }
+  Object.keys(data.pack).reduce((map, entry) => {
+    const pack = data.pack[entry];
+    if (!pack) {
+      return map;
+    }
+    const packFile = typeof pack === 'string' ? pack : pack.filename;
+    if (packFile) {
+      map[data.name ? `flavours/${data.name}/${entry}` : `core/${entry}`] = resolve(data.pack_directory, packFile);
+    }
+    return map;
+  }, into);
+  if (data.name) {
+    Object.keys(data.skin).reduce((map, entry) => {
+      const skin = data.skin[entry];
+      const skinName = entry;
+      if (!skin) {
+        return map;
+      }
+      Object.keys(skin).reduce((map, entry) => {
+        const packFile = skin[entry];
+        if (!packFile) {
+          return map;
+        }
+        map[`skins/${data.name}/${skinName}/${entry}`] = resolve(packFile);
+        return map;
+      }, into);
+      return map;
+    }, into);
+  }
+  return into;
+}
+
+const entries = Object.assign(
+  { locales: resolve('app', 'javascript', 'locales') },
+  localePacks,
+  reducePacks(core),
+  Object.keys(flavours).reduce((map, entry) => reducePacks(flavours[entry], map), {})
+);
 
-const extensionGlob = `**/*{${settings.extensions.join(',')}}*`;
-const entryPath = join(settings.source_path, settings.source_entry_path);
-const packPaths = sync(join(entryPath, extensionGlob));
 
 module.exports = {
-  entry: Object.assign(
-    packPaths.reduce((map, entry) => {
-      const localMap = map;
-      const namespace = relative(join(entryPath), dirname(entry));
-      localMap[join(namespace, basename(entry, extname(entry)))] = resolve(entry);
-      return localMap;
-    }, {}),
-    localePackPaths.reduce((map, entry) => {
-      const localMap = map;
-      localMap[basename(entry, extname(entry, extname(entry)))] = resolve(entry);
-      return localMap;
-    }, {}),
-    Object.keys(themes).reduce((themePaths, name) => {
-      themePaths[name] = resolve(join(settings.source_path, themes[name]));
-      return themePaths;
-    }, {})
-  ),
+  entry: entries,
 
   output: {
     filename: 'js/[name]-[chunkhash].js',
@@ -44,7 +67,7 @@ module.exports = {
 
   optimization: {
     runtimeChunk: {
-      name: 'common',
+      name: 'locales',
     },
     splitChunks: {
       cacheGroups: {
@@ -52,7 +75,9 @@ module.exports = {
         vendors: false,
         common: {
           name: 'common',
-          chunks: 'all',
+          chunks (chunk) {
+            return !(chunk.name in entries);
+          },
           minChunks: 2,
           minSize: 0,
           test: /^(?!.*[\\\/]node_modules[\\\/]react-intl[\\\/]).+$/,
diff --git a/config/webpacker.yml b/config/webpacker.yml
index 4ad78a190..9accd6152 100644
--- a/config/webpacker.yml
+++ b/config/webpacker.yml
@@ -26,6 +26,7 @@ default: &default
     - .tiff
     - .ico
     - .svg
+    - .gif
     - .eot
     - .otf
     - .ttf