Keyword/phrase filtering (#7905)

* Add keyword filtering

    GET|POST       /api/v1/filters
    GET|PUT|DELETE /api/v1/filters/:id

- Irreversible filters can drop toots from home or notifications
- Other filters can hide toots through the client app
- Filters use a phrase valid in particular contexts, expiration

* Make sure expired filters don't get applied client-side

* Add missing API methods

* Remove "regex filter" from column settings

* Add tests

* Add test for FeedManager

* Add CustomFilter test

* Add UI for managing filters

* Add streaming API event to allow syncing filters

* Fix tests

1 files changed, 55 insertions, 0 deletions

diff --git a/app/models/custom_filter.rb b/app/models/custom_filter.rb
new file mode 100644
index 000000000..2c1a54375
--- /dev/null
+++ b/app/models/custom_filter.rb
@@ -0,0 +1,55 @@
+# frozen_string_literal: true
+# == Schema Information
+#
+# Table name: custom_filters
+#
+#  id           :bigint(8)        not null, primary key
+#  account_id   :bigint(8)
+#  expires_at   :datetime
+#  phrase       :text             default(""), not null
+#  context      :string           default([]), not null, is an Array
+#  irreversible :boolean          default(FALSE), not null
+#  created_at   :datetime         not null
+#  updated_at   :datetime         not null
+#
+
+class CustomFilter < ApplicationRecord
+  VALID_CONTEXTS = %w(
+    home
+    notifications
+    public
+    thread
+  ).freeze
+
+  include Expireable
+
+  belongs_to :account
+
+  validates :phrase, :context, presence: true
+  validate :context_must_be_valid
+  validate :irreversible_must_be_within_context
+
+  scope :active_irreversible, -> { where(irreversible: true).where(Arel.sql('expires_at IS NULL OR expires_at > NOW()')) }
+
+  before_validation :clean_up_contexts
+  after_commit :remove_cache
+
+  private
+
+  def clean_up_contexts
+    self.context = Array(context).map(&:strip).map(&:presence).compact
+  end
+
+  def remove_cache
+    Rails.cache.delete("filters:#{account_id}")
+    Redis.current.publish("timeline:#{account_id}", Oj.dump(event: :filters_changed))
+  end
+
+  def context_must_be_valid
+    errors.add(:context, I18n.t('filters.errors.invalid_context')) if context.empty? || context.any? { |c| !VALID_CONTEXTS.include?(c) }
+  end
+
+  def irreversible_must_be_within_context
+    errors.add(:irreversible, I18n.t('filters.errors.invalid_irreversible')) if irreversible? && !context.include?('home') && !context.include?('notifications')
+  end
+end