Added frequently used emojis to new picker

Adds frequently used emoji section to the new picker
Also adds emojis to frequently used when clicking
emojis.

https://gitlab.com/gitlab-org/gitlab/-/issues/23607

app/assets/javascripts/emoji/components/category.vue

 <script>
 import { GlIntersectionObserver } from '@gitlab/ui';
-import { capitalizeFirstCharacter } from '~/lib/utils/text_utility';
+import { humanize } from '~/lib/utils/text_utility';
 import EmojiGroup from './emoji_group.vue';
 
 export default {
@@ -25,7 +25,7 @@ export default {
   },
   computed: {
     categoryTitle() {
-      return capitalizeFirstCharacter(this.category);
+      return humanize(this.category);
     },
   },
   methods: {
@@ -33,9 +33,6 @@ export default {
       this.renderGroup = true;
       this.$emit('appear', this.category);
     },
-    categoryDissappeared() {
-      this.renderGroup = false;
-    },
   },
 };
 </script>

app/assets/javascripts/emoji/components/picker.vue

 <script>
 import { GlIcon, GlDropdown, GlSearchBoxByType } from '@gitlab/ui';
+import { findLastIndex } from 'lodash';
 import VirtualList from 'vue-virtual-scroll-list';
 import { CATEGORY_NAMES } from '~/emoji';
 import { CATEGORY_ICON_MAP } from '../constants';
 import Category from './category.vue';
 import EmojiList from './emoji_list.vue';
-import { getEmojiCategories } from './utils';
+import { addToFrequentlyUsed, getEmojiCategories, hasFrequentlyUsedEmojis } from './utils';
 
 export default {
   components: {
@@ -25,13 +26,16 @@ export default {
   },
   data() {
     return {
-      currentCategory: null,
+      currentCategory: 0,
       searchValue: '',
     };
   },
   computed: {
     categoryNames() {
-      return CATEGORY_NAMES.map((category) => ({
+      return CATEGORY_NAMES.filter((c) => {
+        if (c === 'frequently_used') return hasFrequentlyUsedEmojis();
+        return true;
+      }).map((category) => ({
         name: category,
         icon: CATEGORY_ICON_MAP[category],
       }));
@@ -50,6 +54,7 @@ export default {
     selectEmoji(name) {
       this.$emit('click', name);
       this.$refs.dropdown.hide();
+      addToFrequentlyUsed(name);
     },
     getBoundaryElement() {
       return document.querySelector('.content-wrapper') || 'scrollParent';
@@ -58,6 +63,11 @@ export default {
       this.$refs.virtualScoller.setScrollTop(0);
       this.$refs.virtualScoller.forceRender();
     },
+    async onScroll(event, { offset }) {
+      const categories = await getEmojiCategories();
+
+      this.currentCategory = findLastIndex(Object.values(categories), ({ top }) => offset >= top);
+    },
   },
 };
 </script>
@@ -86,10 +96,10 @@ export default {
         class="gl-display-flex gl-mx-5 gl-border-b-solid gl-border-gray-100 gl-border-b-1"
       >
         <button
-          v-for="category in categoryNames"
+          v-for="(category, index) in categoryNames"
           :key="category.name"
           :class="{
-            'gl-text-black-normal! emoji-picker-category-active': category.name === currentCategory,
+            'gl-text-black-normal! emoji-picker-category-active': index === currentCategory,
           }"
           type="button"
           class="gl-border-0 gl-border-b-2 gl-border-b-solid gl-flex-fill-1 gl-text-gray-300 gl-pt-3 gl-pb-3 gl-bg-transparent emoji-picker-category-tab"
@@ -100,18 +110,20 @@ export default {
       </div>
       <emoji-list :search-value="searchValue">
         <template #default="{ filteredCategories }">
-          <virtual-list ref="virtualScoller" :size="258" :remain="1" :bench="2" variable>
+          <virtual-list
+            ref="virtualScoller"
+            :size="258"
+            :remain="1"
+            :bench="2"
+            variable
+            :onscroll="onScroll"
+          >
             <div
               v-for="(category, categoryKey) in filteredCategories"
               :key="categoryKey"
               :style="{ height: category.height + 'px' }"
             >
-              <category
-                :category="categoryKey"
-                :emojis="category.emojis"
-                @appear="categoryAppeared"
-                @click="selectEmoji"
-              />
+              <category :category="categoryKey" :emojis="category.emojis" @click="selectEmoji" />
             </div>
           </virtual-list>
         </template>

app/assets/javascripts/emoji/components/utils.js

-import { chunk, memoize } from 'lodash';
+import Cookies from 'js-cookie';
+import { chunk, memoize, uniq } from 'lodash';
 import { initEmojiMap, getEmojiCategoryMap } from '~/emoji';
 import { EMOJIS_PER_ROW, EMOJI_ROW_HEIGHT, CATEGORY_ROW_HEIGHT } from '../constants';
 
 export const generateCategoryHeight = (emojisLength) =>
   emojisLength * EMOJI_ROW_HEIGHT + CATEGORY_ROW_HEIGHT;
 
+export const getFrequentlyUsedEmojis = () => {
+  const savedEmojis = Cookies.get('frequently_used_emojis');
+
+  if (!savedEmojis) return null;
+
+  const emojis = chunk(uniq(savedEmojis.split(',')), 9);
+
+  return {
+    frequently_used: {
+      emojis,
+      top: 0,
+      height: generateCategoryHeight(emojis.length),
+    },
+  };
+};
+
+export const addToFrequentlyUsed = (emoji) => {
+  const frequentlyUsedEmojis = uniq(
+    (Cookies.get('frequently_used_emojis') || '')
+      .split(',')
+      .filter((e) => e)
+      .concat(emoji),
+  );
+
+  Cookies.set('frequently_used_emojis', frequentlyUsedEmojis.join(','), { expires: 365 });
+};
+
+export const hasFrequentlyUsedEmojis = () => getFrequentlyUsedEmojis() !== null;
+
 export const getEmojiCategories = memoize(async () => {
   await initEmojiMap();
 
   const categories = await getEmojiCategoryMap();
-  let top = 0;
+  const frequentlyUsedEmojis = getFrequentlyUsedEmojis();
+  let top = frequentlyUsedEmojis
+    ? frequentlyUsedEmojis.frequently_used.top + frequentlyUsedEmojis.frequently_used.height
+    : 0;
 
   return Object.freeze(
-    Object.keys(categories).reduce((acc, category) => {
-      const emojis = chunk(categories[category], EMOJIS_PER_ROW);
-      const height = generateCategoryHeight(emojis.length);
-      const newAcc = {
-        ...acc,
-        [category]: { emojis, height, top },
-      };
-      top += height;
-
-      return newAcc;
-    }, {}),
+    Object.keys(categories)
+      .filter((c) => c !== 'frequently_used')
+      .reduce((acc, category) => {
+        const emojis = chunk(categories[category], EMOJIS_PER_ROW);
+        const height = generateCategoryHeight(emojis.length);
+        const newAcc = {
+          ...acc,
+          [category]: { emojis, height, top },
+        };
+        top += height;
+
+        return newAcc;
+      }, frequentlyUsedEmojis || {}),
   );
 });

app/assets/javascripts/emoji/constants.js

 export const CATEGORY_ICON_MAP = {
+  frequently_used: 'history',
   activity: 'dumbbell',
   people: 'smiley',
   nature: 'nature',