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.

app/views/filters/_fields.html.haml

@@ -1,16 +0,0 @@
-.fields-row
-  .fields-row__column.fields-row__column-6.fields-group
-    = f.input :phrase, as: :string, wrapper: :with_label, hint: false
-  .fields-row__column.fields-row__column-6.fields-group
-    = f.input :expires_in, wrapper: :with_label, collection: [30.minutes, 1.hour, 6.hours, 12.hours, 1.day, 1.week].map(&:to_i), label_method: lambda { |i| I18n.t("invites.expires_in.#{i}") }, include_blank: I18n.t('invites.expires_in_prompt')
-
-.fields-group
-  = f.input :context, wrapper: :with_block_label, collection: CustomFilter::VALID_CONTEXTS, as: :check_boxes, collection_wrapper_tag: 'ul', item_wrapper_tag: 'li', label_method: lambda { |context| I18n.t("filters.contexts.#{context}") }, include_blank: false
-
-%hr.spacer/
-
-.fields-group
-  = f.input :irreversible, wrapper: :with_label
-
-.fields-group
-  = f.input :whole_word, wrapper: :with_label

app/views/filters/_filter.html.haml

@@ -0,0 +1,32 @@
+.filters-list__item{ class: [filter.expired? && 'expired'] }
+  = link_to edit_filter_path(filter), class: 'filters-list__item__title' do
+    = filter.title
+
+    - if filter.expires?
+      .expiration{ title: t('filters.index.expires_on', date: l(filter.expires_at)) }
+        - if filter.expired?
+          = t('invites.expired')
+        - else
+          = t('filters.index.expires_in', distance: distance_of_time_in_words_to_now(filter.expires_at))
+
+  .filters-list__item__permissions
+    %ul.permissions-list
+      - unless filter.keywords.empty?
+        %li.permissions-list__item
+          .permissions-list__item__icon
+            = fa_icon('paragraph')
+          .permissions-list__item__text
+            .permissions-list__item__text__title
+              = t('filters.index.keywords', count: filter.keywords.size)
+            .permissions-list__item__text__type
+              - keywords = filter.keywords.map(&:keyword)
+              - keywords = keywords.take(5) + ['…'] if keywords.size > 5 # TODO
+              = keywords.join(', ')
+
+  .announcements-list__item__action-bar
+    .announcements-list__item__meta
+      = t('filters.index.contexts', contexts: filter.context.map { |context| I18n.t("filters.contexts.#{context}") }.join(', '))
+
+    %div
+      = table_link_to 'pencil', t('filters.edit.title'), edit_filter_path(filter)
+      = table_link_to 'times', t('filters.index.delete'), filter_path(filter), method: :delete, data: { confirm: t('admin.accounts.are_you_sure') }

app/views/filters/_filter_fields.html.haml

@@ -0,0 +1,33 @@
+.fields-row
+  .fields-row__column.fields-row__column-6.fields-group
+    = f.input :title, as: :string, wrapper: :with_label, hint: false
+  .fields-row__column.fields-row__column-6.fields-group
+    = f.input :expires_in, wrapper: :with_label, collection: [30.minutes, 1.hour, 6.hours, 12.hours, 1.day, 1.week].map(&:to_i), label_method: lambda { |i| I18n.t("invites.expires_in.#{i}") }, include_blank: I18n.t('invites.expires_in_prompt')
+
+.fields-group
+  = f.input :context, wrapper: :with_block_label, collection: CustomFilter::VALID_CONTEXTS, as: :check_boxes, collection_wrapper_tag: 'ul', item_wrapper_tag: 'li', label_method: lambda { |context| I18n.t("filters.contexts.#{context}") }, include_blank: false
+
+%hr.spacer/
+
+.fields-group
+  = f.input :filter_action, as: :radio_buttons, collection: %i(warn hide), include_blank: false, wrapper: :with_block_label, label_method: ->(action) { safe_join([t("simple_form.labels.filters.actions.#{action}"), content_tag(:span, t("simple_form.hints.filters.actions.#{action}"), class: 'hint')]) }, hint: t('simple_form.hints.filters.action'), required: true
+
+%hr.spacer/
+
+%h4= t('filters.edit.keywords')
+
+.table-wrapper
+  %table.table.keywords-table
+    %thead
+      %tr
+        %th= t('simple_form.labels.defaults.phrase')
+        %th= t('simple_form.labels.defaults.whole_word')
+        %th
+    %tbody
+      = f.simple_fields_for :keywords do |keyword|
+        = render 'keyword_fields', f: keyword
+    %tfoot
+      %tr
+        %td{ colspan: 3}
+          = link_to_add_association f, :keywords, class: 'table-action-link', partial: 'keyword_fields', 'data-association-insertion-node': '.keywords-table tbody', 'data-association-insertion-method': 'append' do
+            = safe_join([fa_icon('plus'), t('filters.edit.add_keyword')])

app/views/filters/_keyword_fields.html.haml

@@ -0,0 +1,8 @@
+%tr.nested-fields
+  %td= f.input :keyword, as: :string
+  %td
+    .label_input__wrapper= f.input_field :whole_word
+  %td
+    = f.hidden_field :id if f.object&.persisted? # Required so Rails doesn't put the field outside of the <tr/>
+    = link_to_remove_association(f, class: 'table-action-link') do
+      = safe_join([fa_icon('times'), t('filters.index.delete')])

app/views/filters/edit.html.haml

@@ -2,7 +2,7 @@
   = t('filters.edit.title')
 
 = simple_form_for @filter, url: filter_path(@filter), method: :put do |f|
-  = render 'fields', f: f
+  = render 'filter_fields', f: f
 
   .actions
     = f.button :button, t('generic.save_changes'), type: :submit

app/views/filters/index.html.haml

@@ -7,18 +7,5 @@
 - if @filters.empty?
   %div.muted-hint.center-text= t 'filters.index.empty'
 - else
-  .table-wrapper
-    %table.table
-      %thead
-        %tr
-          %th= t('simple_form.labels.defaults.phrase')
-          %th= t('simple_form.labels.defaults.context')
-          %th
-      %tbody
-        - @filters.each do |filter|
-          %tr
-            %td= filter.phrase
-            %td= filter.context.map { |context| I18n.t("filters.contexts.#{context}") }.join(', ')
-            %td
-              = table_link_to 'pencil', t('filters.edit.title'), edit_filter_path(filter)
-              = table_link_to 'times', t('filters.index.delete'), filter_path(filter), method: :delete
+  .applications-list
+    = render partial: 'filter', collection: @filters

app/views/filters/new.html.haml

@@ -2,7 +2,7 @@
   = t('filters.new.title')
 
 = simple_form_for @filter, url: filters_path do |f|
-  = render 'fields', f: f
+  = render 'filter_fields', f: f
 
   .actions
-    = f.button :button, t('filters.new.title'), type: :submit
+    = f.button :button, t('filters.new.save'), type: :submit