Add followed tags list

Signed-off-by: marcin mikołajczak <git@mkljczk.pl>

app/soapbox/features/followed_tags/index.tsx

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+import debounce from 'lodash/debounce';
+import React, { useEffect } from 'react';
+import { defineMessages, useIntl, FormattedMessage } from 'react-intl';
+
+import { fetchFollowedHashtags, expandFollowedHashtags } from 'soapbox/actions/tags';
+import Hashtag from 'soapbox/components/hashtag';
+import ScrollableList from 'soapbox/components/scrollable-list';
+import { Column } from 'soapbox/components/ui';
+import PlaceholderHashtag from 'soapbox/features/placeholder/components/placeholder-hashtag';
+import { useAppDispatch, useAppSelector } from 'soapbox/hooks';
+
+const messages = defineMessages({
+  heading: { id: 'column.followed_tags', defaultMessage: 'Followed hashtags' },
+});
+
+const handleLoadMore = debounce((dispatch) => {
+  dispatch(expandFollowedHashtags());
+}, 300, { leading: true });
+
+const FollowedTags = () => {
+  const intl = useIntl();
+  const dispatch = useAppDispatch();
+
+  useEffect(() => {
+    dispatch(fetchFollowedHashtags());
+  }, []);
+
+  const tags = useAppSelector((state => state.followed_tags.items));
+  const isLoading = useAppSelector((state => state.followed_tags.isLoading));
+  const hasMore = useAppSelector((state => !!state.followed_tags.next));
+
+  const emptyMessage = <FormattedMessage id='empty_column.followed_tags' defaultMessage="You haven't followed any hashtag yet." />;
+
+  return (
+    <Column label={intl.formatMessage(messages.heading)}>
+      <ScrollableList
+        scrollKey='followed_tags'
+        emptyMessage={emptyMessage}
+        isLoading={isLoading}
+        hasMore={hasMore}
+        onLoadMore={() => handleLoadMore(dispatch)}
+        placeholderComponent={PlaceholderHashtag}
+        placeholderCount={5}
+        itemClassName='pb-3'
+      >
+        {tags.map(tag => <Hashtag key={tag.name} hashtag={tag} />)}
+      </ScrollableList>
+    </Column>
+  );
+};
+
+export default FollowedTags;

app/soapbox/reducers/followed_tags.ts

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+import { List as ImmutableList, Record as ImmutableRecord } from 'immutable';
+
+import {
+  FOLLOWED_HASHTAGS_FETCH_REQUEST,
+  FOLLOWED_HASHTAGS_FETCH_SUCCESS,
+  FOLLOWED_HASHTAGS_FETCH_FAIL,
+  FOLLOWED_HASHTAGS_EXPAND_REQUEST,
+  FOLLOWED_HASHTAGS_EXPAND_SUCCESS,
+  FOLLOWED_HASHTAGS_EXPAND_FAIL,
+} from 'soapbox/actions/tags';
+import { normalizeTag } from 'soapbox/normalizers';
+
+import type { AnyAction } from 'redux';
+import type { APIEntity, Tag } from 'soapbox/types/entities';
+
+const ReducerRecord = ImmutableRecord({
+  items: ImmutableList<Tag>(),
+  isLoading: false,
+  next: null,
+});
+
+export default function followed_tags(state = ReducerRecord(), action: AnyAction) {
+  switch (action.type) {
+    case FOLLOWED_HASHTAGS_FETCH_REQUEST:
+      return state.set('isLoading', true);
+    case FOLLOWED_HASHTAGS_FETCH_SUCCESS:
+      return state.withMutations(map => {
+        map.set('items', ImmutableList(action.followed_tags.map((item: APIEntity) => normalizeTag(item))));
+        map.set('isLoading', false);
+        map.set('next', action.next);
+      });
+    case FOLLOWED_HASHTAGS_FETCH_FAIL:
+      return state.set('isLoading', false);
+    case FOLLOWED_HASHTAGS_EXPAND_REQUEST:
+      return state.set('isLoading', true);
+    case FOLLOWED_HASHTAGS_EXPAND_SUCCESS:
+      return state.withMutations(map => {
+        map.update('items', list => list.concat(action.followed_tags.map((item: APIEntity) => normalizeTag(item))));
+        map.set('isLoading', false);
+        map.set('next', action.next);
+      });
+    case FOLLOWED_HASHTAGS_EXPAND_FAIL:
+      return state.set('isLoading', false);
+    default:
+      return state;
+  }
+}