solution

README.md

@@ -34,3 +34,5 @@ form to add new comments.
 1. Implement comment deletion
     - Delete the commnet immediately not waiting for the server response to improve the UX.
 1. (*) Handle `Add` and `Delete` errors so the user can retry
+
+[DEMO LINK](https://Kinderwagen.github.io/react_dynamic-list-of-posts/)

src/App.tsx

@@ -1,60 +1,86 @@
-import React from 'react';
+import React, { useCallback, useEffect, useState } from 'react';
 import 'bulma/bulma.sass';
 import '@fortawesome/fontawesome-free/css/all.css';
 import './App.scss';
-
 import classNames from 'classnames';
 import { PostsList } from './components/PostsList';
 import { PostDetails } from './components/PostDetails';
 import { UserSelector } from './components/UserSelector';
-import { Loader } from './components/Loader';
+import { User } from './types/User';
+import { Post } from './types/Post';
+import { getUsers } from './api/users';
 
 export const App: React.FC = () => {
+  const [users, setUsers] = useState<User[]>([]);
+  const [selectedUser, setSelectedUser] = useState<User | null>(null);
+  const [selectedPost, setSelectedPost] = useState<Post | null>(null);
+
+  const handleSelectUser = useCallback((user) => {
+    setSelectedUser(user);
+  }, []);
+
+  const handleSelectPost = useCallback((post) => {
+    setSelectedPost(post);
+  }, []);
+
+  useEffect(() => {
+    const getUsersFromServer = async () => {
+      try {
+        const usersFromServer = await getUsers();
+
+        setUsers(usersFromServer);
+      } catch {
+        throw new Error('Can\'t load users');
+      }
+    };
+
+    getUsersFromServer();
+  }, []);
+
   return (
     <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 />
+                <UserSelector
+                  users={users}
+                  selectedUser={selectedUser}
+                  selectUser={handleSelectUser}
+                />
               </div>
 
               <div className="block" data-cy="MainContent">
-                <p data-cy="NoSelectedUser">
-                  No user selected
-                </p>
-
-                <Loader />
-
-                <div
-                  className="notification is-danger"
-                  data-cy="PostsLoadingError"
-                >
-                  Something went wrong!
-                </div>
+                {!selectedUser
+                  ? (
+                    <p data-cy="NoSelectedUser">
+                      No user selected
+                    </p>
+                  )
+                  : (
+                    <PostsList
+                      selectedUserId={selectedUser.id}
+                      selectedPost={selectedPost}
+                      onSelectPost={handleSelectPost}
+                    />
+                  )}
 
-                <div className="notification is-warning" data-cy="NoPostsYet">
-                  No posts yet
-                </div>
-
-                <PostsList />
               </div>
             </div>
           </div>
-
           <div
             data-cy="Sidebar"
             className={classNames(
               'tile',
               'is-parent',
               'is-8-desktop',
               'Sidebar',
-              'Sidebar--open',
+              { 'Sidebar--open': selectedPost },
             )}
           >
             <div className="tile is-child box is-success ">
-              <PostDetails />
+              {selectedPost && <PostDetails post={selectedPost} />}
             </div>
           </div>
         </div>

src/api/comments.ts

@@ -0,0 +1,14 @@
+import { Comment, CommentData } from '../types/Comment';
+import { client } from '../utils/fetchClient';
+
+export const getComments = (postId: number) => {
+  return client.get<Comment[]>(`/comments?postId=${postId}`);
+};
+
+export const deleteComment = (commentId: number) => {
+  return client.delete(`/comments/${commentId}`);
+};
+
+export const postComment = (comment: CommentData) => {
+  return client.post<Comment>('/comments', comment);
+};

src/api/posts.ts

@@ -0,0 +1,6 @@
+import { Post } from '../types/Post';
+import { client } from '../utils/fetchClient';
+
+export const getUserPosts = (userId: number) => {
+  return client.get<Post[]>(`/posts?userId=${userId}`);
+};

src/api/users.ts

@@ -0,0 +1,6 @@
+import { User } from '../types/User';
+import { client } from '../utils/fetchClient';
+
+export const getUsers = () => {
+  return client.get<User[]>('/users');
+};

src/components/CommentsList.tsx

@@ -0,0 +1,169 @@
+import React, { useCallback, useEffect, useState } from 'react';
+import { Comment, CommentData } from '../types/Comment';
+import { Loader } from './Loader';
+import { NewCommentForm } from './NewCommentForm';
+import { deleteComment, getComments, postComment } from '../api/comments';
+
+type Props = {
+  postId: number;
+};
+
+export const CommentsList: React.FC<Props> = ({ postId }) => {
+  const [comments, setComments] = useState<Comment[]>([]);
+  const [isLoading, setIsLoading] = useState(false);
+  const [loadError, setLoadError] = useState(false);
+  const [addError, setAddError] = useState(false);
+  const [deleteError, setDeleteError] = useState(false);
+  const [isFormVisible, setIsFormVisible] = useState(false);
+
+  const addNewComment = useCallback(async (comment: CommentData) => {
+    const newComment = { ...comment, postId };
+
+    try {
+      const addedComment = await postComment(newComment);
+
+      setComments(currentComment => [...currentComment, addedComment]);
+    } catch {
+      setAddError(true);
+    }
+  }, []);
+
+  const deleteSelectedComment = useCallback(async (commentId: number) => {
+    const tempComments = [...comments];
+
+    setComments(currentComments => (
+      currentComments.filter(comment => comment.id !== commentId)
+    ));
+
+    try {
+      setDeleteError(false);
+      await deleteComment(commentId);
+    } catch {
+      setComments(tempComments);
+      setDeleteError(true);
+    }
+  }, []);
+
+  useEffect(() => {
+    const fetchPostComments = async () => {
+      try {
+        setComments([]);
+        setIsFormVisible(false);
+        setLoadError(false);
+        setIsLoading(true);
+        const commentsFromServer = await getComments(postId);
+
+        setComments(commentsFromServer);
+      } catch {
+        setLoadError(true);
+      } finally {
+        setIsLoading(false);
+      }
+    };
+
+    fetchPostComments();
+  }, [postId]);
+
+  useEffect(() => {
+    const deleteErrorTimer = setTimeout(() => {
+      setDeleteError(false);
+    }, 3000);
+
+    return () => clearTimeout(deleteErrorTimer);
+  }, [deleteError]);
+
+  useEffect(() => {
+    const addErrorTimer = setTimeout(() => {
+      setAddError(false);
+    }, 3000);
+
+    return () => clearTimeout(addErrorTimer);
+  }, [addError]);
+
+  if (isLoading) {
+    return <Loader />;
+  }
+
+  if (loadError) {
+    return (
+      <div className="notification is-danger" data-cy="CommentsError">
+        Something went wrong
+      </div>
+    );
+  }
+
+  return (
+    <>
+      {!comments.length
+        ? (
+          <p className="title is-4" data-cy="NoCommentsMessage">
+            No comments yet
+          </p>
+        )
+        : (
+          <>
+            <p className="title is-4">Comments:</p>
+
+            {comments.map(comment => (
+              <article
+                className="message is-small"
+                data-cy="Comment"
+                key={comment.id}
+              >
+                <div className="message-header">
+                  <a
+                    href={`mailto:${comment.email}`}
+                    data-cy="CommentAuthor"
+                  >
+                    {comment.name}
+                  </a>
+                  <button
+                    data-cy="CommentDelete"
+                    type="button"
+                    className="delete is-small"
+                    aria-label="delete"
+                    onClick={() => deleteSelectedComment(comment.id)}
+                  />
+                </div>
+
+                <div className="message-body" data-cy="CommentBody">
+                  {comment.body}
+                </div>
+              </article>
+            ))}
+          </>
+        )}
+
+      {addError && (
+        <div
+          className="notification is-danger"
+          data-cy="CommentsError"
+        >
+          Can&apos;t add new comment
+        </div>
+      )}
+
+      {deleteError && (
+        <div
+          className="notification is-danger"
+          data-cy="CommentsError"
+        >
+          Can&apos;t delete comment
+        </div>
+      )}
+
+      {!isFormVisible
+        ? (
+          <button
+            data-cy="WriteCommentButton"
+            type="button"
+            className="button is-link"
+            onClick={() => setIsFormVisible(true)}
+          >
+            Write a comment
+          </button>
+        )
+        : <NewCommentForm onAddComment={addNewComment} />}
+    </>
+  );
+};