Add support for toggling discussion filter from notes section

Adds discussion note style section under notes app from where
user can toggle discussion when they have selected a filter to show
only system notes.

10 files changed, 253 insertions, 39 deletions

diff --git a/app/assets/javascripts/notes/components/discussion_filter.vue b/app/assets/javascripts/notes/components/discussion_filter.vue
index e03d6e9cd02..31164f74201 100644
--- a/app/assets/javascripts/notes/components/discussion_filter.vue
+++ b/app/assets/javascripts/notes/components/discussion_filter.vue
@@ -7,7 +7,9 @@ import {
   DISCUSSION_FILTERS_DEFAULT_VALUE,
   HISTORY_ONLY_FILTER_VALUE,
   DISCUSSION_TAB_LABEL,
+  DISCUSSION_FILTER_TYPES,
 } from '../constants';
+import notesEventHub from '../event_hub';
 
 export default {
   components: {
@@ -46,6 +48,7 @@ export default {
       this.toggleFilters(currentTab);
     }
 
+    notesEventHub.$on('dropdownSelect', this.selectFilter);
     window.addEventListener('hashchange', this.handleLocationHash);
     this.handleLocationHash();
   },
@@ -53,6 +56,7 @@ export default {
     this.toggleCommentsForm();
   },
   destroyed() {
+    notesEventHub.$off('dropdownSelect', this.selectFilter);
     window.removeEventListener('hashchange', this.handleLocationHash);
   },
   methods: {
@@ -86,12 +90,23 @@ export default {
         this.setTargetNoteHash(hash);
       }
     },
+    filterType(value) {
+      if (value === 0) {
+        return DISCUSSION_FILTER_TYPES.ALL;
+      } else if (value === 1) {
+        return DISCUSSION_FILTER_TYPES.COMMENTS;
+      }
+      return DISCUSSION_FILTER_TYPES.HISTORY;
+    },
   },
 };
 </script>
 
 <template>
-  <div v-if="displayFilters" class="discussion-filter-container d-inline-block align-bottom">
+  <div
+    v-if="displayFilters"
+    class="discussion-filter-container js-discussion-filter-container d-inline-block align-bottom"
+  >
     <button
       id="discussion-filter-dropdown"
       ref="dropdownToggle"
@@ -102,12 +117,17 @@ export default {
       {{ currentFilter.title }} <icon name="chevron-down" />
     </button>
     <div
+      ref="dropdownMenu"
       class="dropdown-menu dropdown-menu-selectable dropdown-menu-right"
       aria-labelledby="discussion-filter-dropdown"
     >
       <div class="dropdown-content">
         <ul>
-          <li v-for="filter in filters" :key="filter.value">
+          <li
+            v-for="filter in filters"
+            :key="filter.value"
+            :data-filter-type="filterType(filter.value)"
+          >
             <button
               :class="{ 'is-active': filter.value === currentValue }"
               class="qa-filter-options"
diff --git a/app/assets/javascripts/notes/components/discussion_filter_note.vue b/app/assets/javascripts/notes/components/discussion_filter_note.vue
new file mode 100644
index 00000000000..46661e06f6d
--- /dev/null
+++ b/app/assets/javascripts/notes/components/discussion_filter_note.vue
@@ -0,0 +1,52 @@
+<script>
+import { GlButton } from '@gitlab/ui';
+import Icon from '~/vue_shared/components/icon.vue';
+import { __, sprintf } from '~/locale';
+
+import notesEventHub from '../event_hub';
+
+export default {
+  components: {
+    GlButton,
+    Icon,
+  },
+  computed: {
+    timelineContent() {
+      return sprintf(
+        __(
+          "You're only seeing %{startTag}other activity%{endTag} in the feed. To add a comment, switch to one of the following options.",
+        ),
+        {
+          startTag: `<b>`,
+          endTag: `</b>`,
+        },
+        false,
+      );
+    },
+  },
+  methods: {
+    selectFilter(value) {
+      notesEventHub.$emit('dropdownSelect', value);
+    },
+  },
+};
+</script>
+
+<template>
+  <li class="timeline-entry note note-wrapper discussion-filter-note js-discussion-filter-note">
+    <div class="timeline-icon">
+      <icon name="comment" />
+    </div>
+    <div class="timeline-content">
+      <div v-html="timelineContent"></div>
+      <div class="discussion-filter-actions mt-2">
+        <gl-button variant="default" @click="selectFilter(0)">
+          {{ __('Show all activity') }}
+        </gl-button>
+        <gl-button variant="default" @click="selectFilter(1)">
+          {{ __('Show comments only') }}
+        </gl-button>
+      </div>
+    </div>
+  </li>
+</template>
diff --git a/app/assets/javascripts/notes/components/notes_app.vue b/app/assets/javascripts/notes/components/notes_app.vue
index 8d3f6d902f8..e2bd59f7631 100644
--- a/app/assets/javascripts/notes/components/notes_app.vue
+++ b/app/assets/javascripts/notes/components/notes_app.vue
@@ -6,6 +6,7 @@ import * as constants from '../constants';
 import eventHub from '../event_hub';
 import noteableNote from './noteable_note.vue';
 import noteableDiscussion from './noteable_discussion.vue';
+import discussionFilterNote from './discussion_filter_note.vue';
 import systemNote from '../../vue_shared/components/notes/system_note.vue';
 import commentForm from './comment_form.vue';
 import placeholderNote from '../../vue_shared/components/notes/placeholder_note.vue';
@@ -24,6 +25,7 @@ export default {
     placeholderNote,
     placeholderSystemNote,
     skeletonLoadingContainer,
+    discussionFilterNote,
   },
   props: {
     noteableData: {
@@ -235,6 +237,7 @@ export default {
           :help-page-path="helpPagePath"
         />
       </template>
+      <discussion-filter-note v-show="commentsDisabled" />
     </ul>
 
     <comment-form v-if="!commentsDisabled" :noteable-type="noteableType" />
diff --git a/app/assets/javascripts/notes/constants.js b/app/assets/javascripts/notes/constants.js
index 78d365fe94b..fba3db8542c 100644
--- a/app/assets/javascripts/notes/constants.js
+++ b/app/assets/javascripts/notes/constants.js
@@ -24,3 +24,9 @@ export const NOTEABLE_TYPE_MAPPING = {
   MergeRequest: MERGE_REQUEST_NOTEABLE_TYPE,
   Epic: EPIC_NOTEABLE_TYPE,
 };
+
+export const DISCUSSION_FILTER_TYPES = {
+  ALL: 'all',
+  COMMENTS: 'comments',
+  HISTORY: 'history',
+};
diff --git a/app/assets/stylesheets/pages/notes.scss b/app/assets/stylesheets/pages/notes.scss
index 7e7eff1346a..1198b9ea143 100644
--- a/app/assets/stylesheets/pages/notes.scss
+++ b/app/assets/stylesheets/pages/notes.scss
@@ -4,7 +4,7 @@ $note-form-margin-left: 72px;
 
 @mixin vertical-line($left) {
   &::before {
-    content: '';
+    content: "";
     border-left: 2px solid $gray-100;
     position: absolute;
     top: 0;
@@ -53,12 +53,12 @@ $note-form-margin-left: 72px;
     &.note-form {
       margin-left: 0;
 
-      @include notes-media('min', map-get($grid-breakpoints, md)) {
+      @include notes-media("min", map-get($grid-breakpoints, md)) {
         margin-left: $note-form-margin-left;
       }
 
       .timeline-icon {
-        @include notes-media('min', map-get($grid-breakpoints, sm)) {
+        @include notes-media("min", map-get($grid-breakpoints, sm)) {
           margin-left: -$note-icon-gutter-width;
         }
       }
@@ -242,7 +242,7 @@ $note-form-margin-left: 72px;
     }
 
     .note-header {
-      @include notes-media('max', map-get($grid-breakpoints, xs)) {
+      @include notes-media("max", map-get($grid-breakpoints, xs)) {
         .inline {
           display: block;
         }
@@ -303,28 +303,8 @@ $note-form-margin-left: 72px;
       }
     }
 
-    .timeline-icon {
-      float: left;
-      display: flex;
-      align-items: center;
-      background-color: $white-light;
-      width: $system-note-icon-size;
-      height: $system-note-icon-size;
-      border: 1px solid $border-color;
-      border-radius: $system-note-icon-size;
-      margin: -6px $gl-padding 0 0;
-
-      svg {
-        width: $system-note-svg-size;
-        height: $system-note-svg-size;
-        fill: $gray-darkest;
-        display: block;
-        margin: 0 auto;
-      }
-    }
-
     .timeline-content {
-      @include notes-media('min', map-get($grid-breakpoints, sm)) {
+      @include notes-media("min", map-get($grid-breakpoints, sm)) {
         margin-left: 30px;
       }
     }
@@ -368,7 +348,7 @@ $note-form-margin-left: 72px;
           }
 
           &::after {
-            content: '';
+            content: "";
             height: 70px;
             position: absolute;
             left: $gl-padding-24;
@@ -380,6 +360,37 @@ $note-form-margin-left: 72px;
       }
     }
   }
+
+  .system-note,
+  .discussion-filter-note {
+    .timeline-icon {
+      float: left;
+      display: flex;
+      align-items: center;
+      background-color: $white-light;
+      width: $system-note-icon-size;
+      height: $system-note-icon-size;
+      border: 1px solid $border-color;
+      border-radius: $system-note-icon-size;
+      margin: -6px $gl-padding 0 0;
+
+      svg {
+        width: $system-note-svg-size;
+        height: $system-note-svg-size;
+        fill: $gray-darkest;
+        display: block;
+        margin: 0 auto;
+      }
+    }
+  }
+
+  .discussion-filter-note {
+    .timeline-icon {
+      width: $system-note-icon-size + 6;
+      height: $system-note-icon-size + 6;
+      margin-top: -8px;
+    }
+  }
 }
 
 // Diff code in discussion view
@@ -579,7 +590,7 @@ $note-form-margin-left: 72px;
 .note-headline-light {
   display: inline;
 
-  @include notes-media('max', map-get($grid-breakpoints, xs)) {
+  @include notes-media("max", map-get($grid-breakpoints, xs)) {
     display: block;
   }
 }
@@ -645,7 +656,7 @@ $note-form-margin-left: 72px;
   margin-left: 10px;
   color: $gray-darkest;
 
-  @include notes-media('max', map-get($grid-breakpoints, sm) - 1) {
+  @include notes-media("max", map-get($grid-breakpoints, sm) - 1) {
     float: none;
     margin-left: 0;
   }
@@ -764,7 +775,7 @@ $note-form-margin-left: 72px;
 }
 
 .line-resolve-all-container {
-  @include notes-media('min', map-get($grid-breakpoints, sm)) {
+  @include notes-media("min", map-get($grid-breakpoints, sm)) {
     margin-right: 0;
   }
 
@@ -905,7 +916,6 @@ $note-form-margin-left: 72px;
 }
 
 .discussion-filter-container {
-
   .btn > svg {
     width: $gl-col-padding;
     height: $gl-col-padding;
@@ -927,7 +937,6 @@ $note-form-margin-left: 72px;
 //This needs to be deleted when Snippet/Commit comments are convered to Vue
 // See https://gitlab.com/gitlab-org/gitlab-ce/issues/53918#note_117038785
 .unstyled-comments {
-
   .discussion-header {
     padding: $gl-padding;
     border-bottom: 1px solid $border-color;
diff --git a/changelogs/unreleased/51819-show-feed-toggle-under-system-notes.yml b/changelogs/unreleased/51819-show-feed-toggle-under-system-notes.yml
new file mode 100644
index 00000000000..76ea4149c56
--- /dev/null
+++ b/changelogs/unreleased/51819-show-feed-toggle-under-system-notes.yml
@@ -0,0 +1,5 @@
+---
+title: Add support for toggling discussion filter from notes section
+merge_request: 25426
+author:
+type: added
diff --git a/locale/gitlab.pot b/locale/gitlab.pot
index bd45b01d463..150e16ed67f 100644
--- a/locale/gitlab.pot
+++ b/locale/gitlab.pot
@@ -6743,9 +6743,15 @@ msgstr ""
 msgid "Sherlock Transactions"
 msgstr ""
 
+msgid "Show all activity"
+msgstr ""
+
 msgid "Show command"
 msgstr ""
 
+msgid "Show comments only"
+msgstr ""
+
 msgid "Show complete raw log"
 msgstr ""
 
@@ -8654,6 +8660,9 @@ msgstr ""
 msgid "You'll need to use different branch names to get a valid comparison."
 msgstr ""
 
+msgid "You're only seeing %{startTag}other activity%{endTag} in the feed. To add a comment, switch to one of the following options."
+msgstr ""
+
 msgid "You're receiving this email because %{reason}."
 msgstr ""
 
diff --git a/spec/javascripts/notes/components/discussion_filter_note_spec.js b/spec/javascripts/notes/components/discussion_filter_note_spec.js
new file mode 100644
index 00000000000..52d2e7ce947
--- /dev/null
+++ b/spec/javascripts/notes/components/discussion_filter_note_spec.js
@@ -0,0 +1,93 @@
+import Vue from 'vue';
+import DiscussionFilterNote from '~/notes/components/discussion_filter_note.vue';
+import eventHub from '~/notes/event_hub';
+
+import mountComponent from '../../helpers/vue_mount_component_helper';
+
+describe('DiscussionFilterNote component', () => {
+  let vm;
+
+  const createComponent = () => {
+    const Component = Vue.extend(DiscussionFilterNote);
+
+    return mountComponent(Component);
+  };
+
+  beforeEach(() => {
+    vm = createComponent();
+  });
+
+  afterEach(() => {
+    vm.$destroy();
+  });
+
+  describe('computed', () => {
+    describe('timelineContent', () => {
+      it('returns string containing instruction for switching feed type', () => {
+        expect(vm.timelineContent).toBe(
+          "You're only seeing <b>other activity</b> in the feed. To add a comment, switch to one of the following options.",
+        );
+      });
+    });
+  });
+
+  describe('methods', () => {
+    describe('selectFilter', () => {
+      it('emits `dropdownSelect` event on `eventHub` with provided param', () => {
+        spyOn(eventHub, '$emit');
+
+        vm.selectFilter(1);
+
+        expect(eventHub.$emit).toHaveBeenCalledWith('dropdownSelect', 1);
+      });
+    });
+  });
+
+  describe('template', () => {
+    it('renders component container element', () => {
+      expect(vm.$el.classList.contains('discussion-filter-note')).toBe(true);
+    });
+
+    it('renders comment icon element', () => {
+      expect(vm.$el.querySelector('.timeline-icon svg use').getAttribute('xlink:href')).toContain(
+        'comment',
+      );
+    });
+
+    it('renders filter information note', () => {
+      expect(vm.$el.querySelector('.timeline-content').innerText.trim()).toContain(
+        "You're only seeing other activity in the feed. To add a comment, switch to one of the following options.",
+      );
+    });
+
+    it('renders filter buttons', () => {
+      const buttonsContainerEl = vm.$el.querySelector('.discussion-filter-actions');
+
+      expect(buttonsContainerEl.querySelector('button:first-child').innerText.trim()).toContain(
+        'Show all activity',
+      );
+
+      expect(buttonsContainerEl.querySelector('button:last-child').innerText.trim()).toContain(
+        'Show comments only',
+      );
+    });
+
+    it('clicking `Show all activity` button calls `selectFilter("all")` method', () => {
+      const showAllBtn = vm.$el.querySelector('.discussion-filter-actions button:first-child');
+      spyOn(vm, 'selectFilter');
+
+      showAllBtn.dispatchEvent(new Event('click'));
+
+      expect(vm.selectFilter).toHaveBeenCalledWith(0);
+    });
+
+    it('clicking `Show comments only` button calls `selectFilter("comments")` method', () => {
+      const showAllBtn = vm.$el.querySelector('.discussion-filter-actions button:last-child');
+      spyOn(vm, 'selectFilter');
+
+      showAllBtn.dispatchEvent(new Event('click'));
+
+      expect(vm.selectFilter).toHaveBeenCalledWith(1);
+    });
+  });
+});
diff --git a/spec/javascripts/notes/components/discussion_filter_spec.js b/spec/javascripts/notes/components/discussion_filter_spec.js
index 91dab58ba7f..1c366aee8e2 100644
--- a/spec/javascripts/notes/components/discussion_filter_spec.js
+++ b/spec/javascripts/notes/components/discussion_filter_spec.js
@@ -1,7 +1,7 @@
 import Vue from 'vue';
 import createStore from '~/notes/stores';
 import DiscussionFilter from '~/notes/components/discussion_filter.vue';
-import { DISCUSSION_FILTERS_DEFAULT_VALUE } from '~/notes/constants';
+import { DISCUSSION_FILTERS_DEFAULT_VALUE, DISCUSSION_FILTER_TYPES } from '~/notes/constants';
 import { mountComponentWithStore } from '../../helpers/vue_mount_component_helper';
 import { discussionFiltersMock, discussionMock } from '../mock_data';
 
@@ -54,14 +54,18 @@ describe('DiscussionFilter component', () => {
   });
 
   it('updates to the selected item', () => {
-    const filterItem = vm.$el.querySelector('.dropdown-menu li:last-child button');
+    const filterItem = vm.$el.querySelector(
+      `.dropdown-menu li[data-filter-type="${DISCUSSION_FILTER_TYPES.HISTORY}"] button`,
+    );
     filterItem.click();
 
     expect(vm.currentFilter.title).toEqual(filterItem.textContent.trim());
   });
 
   it('only updates when selected filter changes', () => {
-    const filterItem = vm.$el.querySelector('.dropdown-menu li:first-child button');
+    const filterItem = vm.$el.querySelector(
+      `.dropdown-menu li[data-filter-type="${DISCUSSION_FILTER_TYPES.ALL}"] button`,
+    );
 
     spyOn(vm, 'filterDiscussion');
     filterItem.click();
@@ -70,21 +74,27 @@ describe('DiscussionFilter component', () => {
   });
 
   it('disables commenting when "Show history only" filter is applied', () => {
-    const filterItem = vm.$el.querySelector('.dropdown-menu li:last-child button');
+    const filterItem = vm.$el.querySelector(
+      `.dropdown-menu li[data-filter-type="${DISCUSSION_FILTER_TYPES.HISTORY}"] button`,
+    );
     filterItem.click();
 
     expect(vm.$store.state.commentsDisabled).toBe(true);
   });
 
   it('enables commenting when "Show history only" filter is not applied', () => {
-    const filterItem = vm.$el.querySelector('.dropdown-menu li:first-child button');
+    const filterItem = vm.$el.querySelector(
+      `.dropdown-menu li[data-filter-type="${DISCUSSION_FILTER_TYPES.ALL}"] button`,
+    );
     filterItem.click();
 
     expect(vm.$store.state.commentsDisabled).toBe(false);
   });
 
   it('renders a dropdown divider for the default filter', () => {
-    const defaultFilter = vm.$el.querySelector('.dropdown-menu li:first-child');
+    const defaultFilter = vm.$el.querySelector(
+      `.dropdown-menu li[data-filter-type="${DISCUSSION_FILTER_TYPES.ALL}"]`,
+    );
 
     expect(defaultFilter.lastChild.classList).toContain('dropdown-divider');
   });
diff --git a/spec/javascripts/notes/components/note_app_spec.js b/spec/javascripts/notes/components/note_app_spec.js
index 82f58dafc78..d716ece3766 100644
--- a/spec/javascripts/notes/components/note_app_spec.js
+++ b/spec/javascripts/notes/components/note_app_spec.js
@@ -126,6 +126,13 @@ describe('note_app', () => {
       expect(wrapper.find('.js-main-target-form').exists()).toBe(false);
     });
 
+    it('should render discussion filter note `commentsDisabled` is true', () => {
+      store.state.commentsDisabled = true;
+      wrapper = mountComponent();
+
+      expect(wrapper.find('.js-discussion-filter-note').exists()).toBe(true);
+    });
+
     it('should render form comment button as disabled', () => {
       expect(wrapper.find('.js-note-new-discussion').attributes('disabled')).toEqual('disabled');
     });