my solution

src/App.tsx

@@ -1,4 +1,5 @@
 import classNames from 'classnames';
+import * as postsService from './api/posts';
 
 import 'bulma/css/bulma.css';
 import '@fortawesome/fontawesome-free/css/all.css';
@@ -8,53 +9,112 @@ import { PostsList } from './components/PostsList';
 import { PostDetails } from './components/PostDetails';
 import { UserSelector } from './components/UserSelector';
 import { Loader } from './components/Loader';
+import { useEffect, useState } from 'react';
+import { Post } from './types/Post';
 
-export const App = () => (
-  <main className="section">
-    <div className="container">
-      <div className="tile is-ancestor">
-        <div className="tile is-parent">
-          <div className="tile is-child box is-success">
-            <div className="block">
-              <UserSelector />
-            </div>
+export const App = () => {
+  const [userSelectedId, setUserSelectedId] = useState<number | null>(null);
 
-            <div className="block" data-cy="MainContent">
-              <p data-cy="NoSelectedUser">No user selected</p>
+  const [postsByUser, setPostsByUser] = useState<Post[]>([]);
+  const [postSelected, setPostSelected] = useState<Post | null>(null);
 
-              <Loader />
+  const [isError, setIsError] = useState(false);
+  const [isLoading, setIsLoadind] = useState(false);
+  const [isActiveListUsers, setIsActiveListUsers] = useState(false);
 
-              <div
-                className="notification is-danger"
-                data-cy="PostsLoadingError"
-              >
-                Something went wrong!
-              </div>
+  useEffect(() => {
+    if (!userSelectedId) {
+      return;
+    }
+
+    setPostSelected(null);
+    setIsLoadind(true);
+    const getPostsByUser = async () => {
+      try {
+        const postsUser = await postsService.getPosts(userSelectedId);
+
+        setPostSelected(null);
+        setPostsByUser(postsUser);
+      } catch (error) {
+        setIsError(true);
+        setPostsByUser([]);
+      } finally {
+        setIsLoadind(false);
+      }
+    };
 
-              <div className="notification is-warning" data-cy="NoPostsYet">
-                No posts yet
+    getPostsByUser();
+  }, [userSelectedId]);
+
+  const showMessageAboutNotPosts =
+    !postsByUser.length && userSelectedId && !isLoading && !isError;
+
+  return (
+    <main className="section" onClick={() => setIsActiveListUsers(false)}>
+      <div className="container">
+        <div className="tile is-ancestor">
+          <div className="tile is-parent">
+            <div className="tile is-child box is-success">
+              <div className="block">
+                <UserSelector
+                  setIsError={setIsError}
+                  setUserSelectedId={setUserSelectedId}
+                  isActive={isActiveListUsers}
+                  setIsActive={setIsActiveListUsers}
+                  setPostsByUser={setPostsByUser}
+                />
               </div>
 
-              <PostsList />
+              <div className="block" data-cy="MainContent">
+                {!userSelectedId && !isLoading && (
+                  <p data-cy="NoSelectedUser">No user selected</p>
+                )}
+
+                {isLoading && <Loader />}
+
+                {isError && (
+                  <div
+                    className="notification is-danger"
+                    data-cy="PostsLoadingError"
+                  >
+                    Something went wrong!
+                  </div>
+                )}
+
+                {showMessageAboutNotPosts && (
+                  <div className="notification is-warning" data-cy="NoPostsYet">
+                    No posts yet
+                  </div>
+                )}
+
+                {!!postsByUser.length && (
+                  <PostsList
+                    postsByUser={postsByUser}
+                    setPostSelected={setPostSelected}
+                  />
+                )}
+              </div>
             </div>
           </div>
-        </div>
 
-        <div
-          data-cy="Sidebar"
-          className={classNames(
-            'tile',
-            'is-parent',
-            'is-8-desktop',
-            'Sidebar',
-            'Sidebar--open',
-          )}
-        >
-          <div className="tile is-child box is-success ">
-            <PostDetails />
+          <div
+            data-cy="Sidebar"
+            className={classNames(
+              'tile',
+              'is-parent',
+              'is-8-desktop',
+              'Sidebar',
+              { 'Sidebar--open': !!postSelected },
+            )}
+          >
+            {postSelected && (
+              <div className="tile is-child box is-success ">
+                <PostDetails postSelected={postSelected} />
+              </div>
+            )}
           </div>
         </div>
       </div>
-    </div>
-  </main>
-);
+    </main>
+  );
+};

src/api/comments.ts

@@ -0,0 +1,20 @@
+import { client } from '../utils/fetchClient';
+import { Comment } from '../types/Comment';
+
+const url = `/comments`;
+
+export const getComments = (postId: number) => {
+  return client.get<Comment[]>(`${url}?postId=${postId}`);
+};
+
+export const createComment = (comment: Omit<Comment, 'id'>) => {
+  return client.post<Comment>(`${url}`, comment);
+};
+
+export const editComment = (comment: Comment) => {
+  return client.patch<Comment>(`${url}/${comment.id}`, comment);
+};
+
+export const deleteComment = (commentId: number) => {
+  return client.delete(`${url}/${commentId}`);
+};

src/api/posts.ts

@@ -0,0 +1,20 @@
+import { client } from '../utils/fetchClient';
+import { Post } from '../types/Post';
+
+const url = `/posts`;
+
+export const getPosts = (userId: number) => {
+  return client.get<Post[]>(`${url}?userId=${userId}`);
+};
+
+export const createPost = (post: Omit<Post, 'id'>) => {
+  return client.post<Post>(`${url}`, post);
+};
+
+export const editPost = (post: Post) => {
+  return client.patch<Post>(`${url}/${post.id}`, post);
+};
+
+export const deletePost = (postId: number) => {
+  return client.delete(`${url}/${postId}`);
+};

src/api/users.ts

@@ -0,0 +1,20 @@
+import { client } from '../utils/fetchClient';
+import { User } from '../types/User';
+
+const url = `/users`;
+
+export const getUsers = () => {
+  return client.get<User[]>(`${url}`);
+};
+
+export const createUser = (user: Omit<User, 'id'>) => {
+  return client.post<User>(`${url}`, user);
+};
+
+export const editUser = (user: User) => {
+  return client.patch<User>(`${url}/${user.id}`, user);
+};
+
+export const deleteUser = (userId: number) => {
+  return client.delete(`${url}/${userId}`);
+};

src/components/Comment.tsx

@@ -0,0 +1,36 @@
+import React from 'react';
+import { Comment as CommentItem } from '../types/Comment';
+
+type Props = {
+  comment: CommentItem;
+  handleDeleteComment: (commentId: number) => void;
+};
+
+const Comment: React.FC<Props> = props => {
+  const { comment, handleDeleteComment } = props;
+
+  return (
+    <article className="message is-small" data-cy="Comment">
+      <div className="message-header">
+        <a href={`mailto:${comment.email}`} data-cy="CommentAuthor">
+          {comment.name}
+        </a>
+        <button
+          onClick={() => handleDeleteComment(comment.id)}
+          data-cy="CommentDelete"
+          type="button"
+          className="delete is-small"
+          aria-label="delete"
+        >
+          delete button
+        </button>
+      </div>
+
+      <div className="message-body" data-cy="CommentBody">
+        {comment.body}
+      </div>
+    </article>
+  );
+};
+
+export default React.memo(Comment);