added solution

src/App.tsx

@@ -1,156 +1,52 @@
 /* eslint-disable jsx-a11y/control-has-associated-label */
-import React from 'react';
+import React, { useEffect, useRef, useState } from 'react';
 
-export const App: React.FC = () => {
-  return (
-    <div className="todoapp">
-      <h1 className="todoapp__title">todos</h1>
-
-      <div className="todoapp__content">
-        <header className="todoapp__header">
-          {/* this button should have `active` class only if all todos are completed */}
-          <button
-            type="button"
-            className="todoapp__toggle-all active"
-            data-cy="ToggleAllButton"
-          />
-
-          {/* Add a todo on form submit */}
-          <form>
-            <input
-              data-cy="NewTodoField"
-              type="text"
-              className="todoapp__new-todo"
-              placeholder="What needs to be done?"
-            />
-          </form>
-        </header>
-
-        <section className="todoapp__main" data-cy="TodoList">
-          {/* This is a completed todo */}
-          <div data-cy="Todo" className="todo completed">
-            <label className="todo__status-label">
-              <input
-                data-cy="TodoStatus"
-                type="checkbox"
-                className="todo__status"
-                checked
-              />
-            </label>
-
-            <span data-cy="TodoTitle" className="todo__title">
-              Completed Todo
-            </span>
+import { FilterType } from './types/FilterType';
+import { Footer } from './components/Footer';
+import { Header } from './components/Header';
+import { TodoList } from './components/TodoList';
+import { useTodos } from './components/TodosContext';
 
-            {/* Remove button appears only on hover */}
-            <button type="button" className="todo__remove" data-cy="TodoDelete">
-              ×
-            </button>
-          </div>
-
-          {/* This todo is an active todo */}
-          <div data-cy="Todo" className="todo">
-            <label className="todo__status-label">
-              <input
-                data-cy="TodoStatus"
-                type="checkbox"
-                className="todo__status"
-              />
-            </label>
-
-            <span data-cy="TodoTitle" className="todo__title">
-              Not Completed Todo
-            </span>
-
-            <button type="button" className="todo__remove" data-cy="TodoDelete">
-              ×
-            </button>
-          </div>
-
-          {/* This todo is being edited */}
-          <div data-cy="Todo" className="todo">
-            <label className="todo__status-label">
-              <input
-                data-cy="TodoStatus"
-                type="checkbox"
-                className="todo__status"
-              />
-            </label>
+export const App: React.FC = () => {
+  const { todos, setTodos } = useTodos();
+  const [query, setQuery] = useState<string>('');
+  const [filter, setFilter] = useState<FilterType>(FilterType.All);
 
-            {/* This form is shown instead of the title and remove button */}
-            <form>
-              <input
-                data-cy="TodoTitleField"
-                type="text"
-                className="todo__title-field"
-                placeholder="Empty todo will be deleted"
-                value="Todo is being edited now"
-              />
-            </form>
-          </div>
+  const inputRef = useRef<HTMLInputElement | null>(null);
 
-          {/* This todo is in loadind state */}
-          <div data-cy="Todo" className="todo">
-            <label className="todo__status-label">
-              <input
-                data-cy="TodoStatus"
-                type="checkbox"
-                className="todo__status"
-              />
-            </label>
+  useEffect(() => {
+    if (inputRef.current) {
+      inputRef.current.focus();
+    }
+  }, [todos]);
 
-            <span data-cy="TodoTitle" className="todo__title">
-              Todo is being saved now
-            </span>
+  const isAllCompleted = todos.every(todo => todo.completed);
 
-            <button type="button" className="todo__remove" data-cy="TodoDelete">
-              ×
-            </button>
-          </div>
-        </section>
+  const handleAllTodoCompleted = () => {
+    const updatedTodos = todos.map(todo => ({
+      ...todo,
+      completed: !isAllCompleted,
+    }));
 
-        {/* Hide the footer if there are no todos */}
-        <footer className="todoapp__footer" data-cy="Footer">
-          <span className="todo-count" data-cy="TodosCounter">
-            3 items left
-          </span>
+    setTodos(updatedTodos);
+  };
 
-          {/* Active link should have the 'selected' class */}
-          <nav className="filter" data-cy="Filter">
-            <a
-              href="#/"
-              className="filter__link selected"
-              data-cy="FilterLinkAll"
-            >
-              All
-            </a>
+  return (
+    <div className="todoapp">
+      <h1 className="todoapp__title">todos</h1>
 
-            <a
-              href="#/active"
-              className="filter__link"
-              data-cy="FilterLinkActive"
-            >
-              Active
-            </a>
+      <div className="todoapp__content">
+        <Header
+          query={query}
+          setQuery={setQuery}
+          isAllCompleted={isAllCompleted}
+          handleAllTodoCompleted={handleAllTodoCompleted}
+          inputRef={inputRef}
+        />
 
-            <a
-              href="#/completed"
-              className="filter__link"
-              data-cy="FilterLinkCompleted"
-            >
-              Completed
-            </a>
-          </nav>
+        {todos.length > 0 && <TodoList filter={filter} />}
 
-          {/* this button should be disabled if there are no completed todos */}
-          <button
-            type="button"
-            className="todoapp__clear-completed"
-            data-cy="ClearCompletedButton"
-          >
-            Clear completed
-          </button>
-        </footer>
+        {todos.length > 0 && <Footer filter={filter} setFilter={setFilter} />}
       </div>
     </div>
   );

src/components/Filter.tsx

@@ -0,0 +1,40 @@
+import React from 'react';
+import cn from 'classnames';
+
+import { FilterType } from '../types/FilterType';
+
+const filters = [
+  { type: FilterType.All, href: '#/', dataCy: 'FilterLinkAll' },
+  { type: FilterType.Active, href: '#/active', dataCy: 'FilterLinkActive' },
+  {
+    type: FilterType.Completed,
+    href: '#/completed',
+    dataCy: 'FilterLinkCompleted',
+  },
+];
+
+type Props = {
+  filter: FilterType;
+  setFilter: (filter: FilterType) => void;
+};
+
+export const Filter: React.FC<Props> = ({ filter, setFilter }) => (
+  <nav className="filter" data-cy="Filter">
+    {filters.map(({ type, href, dataCy }) => (
+      <a
+        key={type}
+        href={href}
+        className={cn('filter__link', {
+          selected: filter === type,
+        })}
+        data-cy={dataCy}
+        onClick={event => {
+          event.preventDefault();
+          setFilter(type);
+        }}
+      >
+        {type}
+      </a>
+    ))}
+  </nav>
+);

src/components/Footer.tsx

@@ -0,0 +1,42 @@
+import React from 'react';
+
+import { FilterType } from '../types/FilterType';
+import { Filter } from './Filter';
+import { useTodos } from './TodosContext';
+
+type Props = {
+  filter: FilterType;
+  setFilter: (filter: FilterType) => void;
+};
+
+export const Footer: React.FC<Props> = ({ filter, setFilter }) => {
+  const { todos, setTodos } = useTodos();
+
+  const numberOfActiveTodos = todos.filter(todo => !todo.completed).length;
+
+  const handleDeleteCompletedTodos = () => {
+    const unCompletedTodos = todos.filter(todo => !todo.completed);
+
+    setTodos(unCompletedTodos);
+  };
+
+  return (
+    <footer className="todoapp__footer" data-cy="Footer">
+      <span className="todo-count" data-cy="TodosCounter">
+        {numberOfActiveTodos} items left
+      </span>
+
+      <Filter filter={filter} setFilter={setFilter} />
+
+      <button
+        type="button"
+        className="todoapp__clear-completed"
+        data-cy="ClearCompletedButton"
+        disabled={!todos.some(todo => todo.completed)}
+        onClick={handleDeleteCompletedTodos}
+      >
+        Clear completed
+      </button>
+    </footer>
+  );
+};

src/components/Header.tsx

@@ -0,0 +1,54 @@
+import React from 'react';
+import cn from 'classnames';
+import { useTodos } from './TodosContext';
+
+type Props = {
+  query: string;
+  setQuery: (query: string) => void;
+  isAllCompleted: boolean;
+  handleAllTodoCompleted: () => void;
+  inputRef: React.RefObject<HTMLInputElement>;
+};
+
+export const Header: React.FC<Props> = ({
+  query,
+  setQuery,
+  isAllCompleted,
+  handleAllTodoCompleted,
+  inputRef,
+}) => {
+  const { todos, addTodo } = useTodos();
+
+  const handleAddTodo = (event: React.KeyboardEvent<HTMLInputElement>) => {
+    if (event.key === 'Enter' && query.trim() !== '') {
+      addTodo(query.trim());
+      setQuery('');
+    }
+  };
+
+  return (
+    <header className="todoapp__header">
+      {todos.length > 0 && (
+        <button
+          type="button"
+          className={cn('todoapp__toggle-all', { active: isAllCompleted })}
+          data-cy="ToggleAllButton"
+          onClick={handleAllTodoCompleted}
+        />
+      )}
+
+      <form>
+        <input
+          ref={inputRef}
+          data-cy="NewTodoField"
+          type="text"
+          className="todoapp__new-todo"
+          placeholder="What needs to be done?"
+          value={query}
+          onChange={event => setQuery(event.target.value)}
+          onKeyDown={handleAddTodo}
+        />
+      </form>
+    </header>
+  );
+};