Revamp post filtering system (#18058)

* Add model for custom filter keywords

* Use CustomFilterKeyword internally

Does not change the API

* Fix /filters/edit and /filters/new

* Add migration tests

* Remove whole_word column from custom_filters (covered by custom_filter_keywords)

* Redesign /filters

Instead of a list, present a card that displays more information and handles
multiple keywords per filter.

* Redesign /filters/new and /filters/edit to add and remove keywords

This adds a new gem dependency: cocoon, as well as a npm dependency:
cocoon-js-vanilla. Those are used to easily populate and remove form fields
from the user interface when manipulating multiple keyword filters at once.

* Add /api/v2/filters to edit filter with multiple keywords

Entities:
- `Filter`: `id`, `title`, `filter_action` (either `hide` or `warn`), `context`
  `keywords`
- `FilterKeyword`: `id`, `keyword`, `whole_word`

API endpoits:
- `GET /api/v2/filters` to list filters (including keywords)
- `POST /api/v2/filters` to create a new filter
  `keywords_attributes` can also be passed to create keywords in one request
- `GET /api/v2/filters/:id` to read a particular filter
- `PUT /api/v2/filters/:id` to update a new filter
  `keywords_attributes` can also be passed to edit, delete or add keywords in
   one request
- `DELETE /api/v2/filters/:id` to delete a particular filter
- `GET /api/v2/filters/:id/keywords` to list keywords for a filter
- `POST /api/v2/filters/:filter_id/keywords/:id` to add a new keyword to a
   filter
- `GET /api/v2/filter_keywords/:id` to read a particular keyword
- `PUT /api/v2/filter_keywords/:id` to edit a particular keyword
- `DELETE /api/v2/filter_keywords/:id` to delete a particular keyword

* Change from `irreversible` boolean to `action` enum

* Remove irrelevent `irreversible_must_be_within_context` check

* Fix /filters/new and /filters/edit with update for filter_action

* Fix Rubocop/Codeclimate complaining about task names

* Refactor FeedManager#phrase_filtered?

This moves regexp building and filter caching to the `CustomFilter` class.

This does not change the functional behavior yet, but this changes how the
cache is built, doing per-custom_filter regexps so that filters can be matched
independently, while still offering caching.

* Perform server-side filtering and output result in REST API

* Fix numerous filters_changed events being sent when editing multiple keywords at once

* Add some tests

* Use the new API in the WebUI

- use client-side logic for filters we have fetched rules for.
  This is so that filter changes can be retroactively applied without
  reloading the UI.
- use server-side logic for filters we haven't fetched rules for yet
  (e.g. network error, or initial timeline loading)

* Minor optimizations and refactoring

* Perform server-side filtering on the streaming server

* Change the wording of filter action labels

* Fix issues pointed out by linter

* Change design of “Show anyway” link in accordence to review comments

* Drop “irreversible” filtering behavior

* Move /api/v2/filter_keywords to /api/v1/filters/keywords

* Rename `filter_results` attribute to `filtered`

* Rename REST::LegacyFilterSerializer to REST::V1::FilterSerializer

* Fix systemChannelId value in streaming server

* Simplify code by removing client-side filtering code

The simplifcation comes at a cost though: filters aren't retroactively
applied anymore.

2 files changed, 28 insertions, 1 deletions

diff --git a/app/presenters/filter_result_presenter.rb b/app/presenters/filter_result_presenter.rb
new file mode 100644
index 000000000..677225f5e
--- /dev/null
+++ b/app/presenters/filter_result_presenter.rb
@@ -0,0 +1,5 @@
+# frozen_string_literal: true
+
+class FilterResultPresenter < ActiveModelSerializers::Model
+  attributes :filter, :keyword_matches
+end
diff --git a/app/presenters/status_relationships_presenter.rb b/app/presenters/status_relationships_presenter.rb
index 4163bb098..d7ffb1954 100644
--- a/app/presenters/status_relationships_presenter.rb
+++ b/app/presenters/status_relationships_presenter.rb
@@ -2,7 +2,7 @@
 
 class StatusRelationshipsPresenter
   attr_reader :reblogs_map, :favourites_map, :mutes_map, :pins_map,
-              :bookmarks_map
+              :bookmarks_map, :filters_map
 
   def initialize(statuses, current_account_id = nil, **options)
     if current_account_id.nil?
@@ -11,12 +11,14 @@ class StatusRelationshipsPresenter
       @bookmarks_map  = {}
       @mutes_map      = {}
       @pins_map       = {}
+      @filters_map    = {}
     else
       statuses            = statuses.compact
       status_ids          = statuses.flat_map { |s| [s.id, s.reblog_of_id] }.uniq.compact
       conversation_ids    = statuses.filter_map(&:conversation_id).uniq
       pinnable_status_ids = statuses.map(&:proper).filter_map { |s| s.id if s.account_id == current_account_id && %w(public unlisted private).include?(s.visibility) }
 
+      @filters_map     = build_filters_map(statuses, current_account_id).merge(options[:filters_map] || {})
       @reblogs_map     = Status.reblogs_map(status_ids, current_account_id).merge(options[:reblogs_map] || {})
       @favourites_map  = Status.favourites_map(status_ids, current_account_id).merge(options[:favourites_map] || {})
       @bookmarks_map   = Status.bookmarks_map(status_ids, current_account_id).merge(options[:bookmarks_map] || {})
@@ -24,4 +26,24 @@ class StatusRelationshipsPresenter
       @pins_map        = Status.pins_map(pinnable_status_ids, current_account_id).merge(options[:pins_map] || {})
     end
   end
+
+  private
+
+  def build_filters_map(statuses, current_account_id)
+    active_filters = CustomFilter.cached_filters_for(current_account_id)
+
+    @filters_map = statuses.each_with_object({}) do |status, h|
+      filter_matches = active_filters.filter_map do |filter, rules|
+        next if rules[:keywords].blank?
+
+        match = rules[:keywords].match(status.proper.searchable_text)
+        FilterResultPresenter.new(filter: filter, keyword_matches: [match.to_s]) unless match.nil?
+      end
+
+      unless filter_matches.empty?
+        h[status.id] = filter_matches
+        h[status.reblog_of_id] = filter_matches if status.reblog?
+      end
+    end
+  end
 end