diff --git a/README.md b/README.md
index af7dae81f6..707755d7e9 100644
--- a/README.md
+++ b/README.md
@@ -41,4 +41,4 @@ Implement the ability to edit a todo title on double click:
 
 - Implement a solution following the [React task guideline](https://github.com/mate-academy/react_task-guideline#react-tasks-guideline).
 - Use the [React TypeScript cheat sheet](https://mate-academy.github.io/fe-program/js/extra/react-typescript).
-- Replace `<your_account>` with your Github username in the [DEMO LINK](https://<your_account>.github.io/react_todo-app-with-api/) and add it to the PR description.
+- Replace `<your_account>` with your Github username in the [DEMO LINK](https://voronine.github.io/react_todo-app-with-api/) and add it to the PR description.
diff --git a/src/App.tsx b/src/App.tsx
index 5749bdf784..edff99ce95 100644
--- a/src/App.tsx
+++ b/src/App.tsx
@@ -1,24 +1,228 @@
-/* eslint-disable max-len */
-/* eslint-disable jsx-a11y/control-has-associated-label */
-import React from 'react';
-import { UserWarning } from './UserWarning';
+import React, {
+  useEffect,
+  useState,
+  useCallback,
+  useMemo,
+} from 'react';
 
-const USER_ID = 0;
+import { Todo } from './types/Todo';
+import * as todoService from './api/todos';
+import { ForComletedTodo } from './types/enumFilter';
+import { TodoItem } from './Components/TodoItem';
+import { Footer } from './Components/Footer';
+import { Header } from './Components/Header';
+import { ErrorNotification } from './Components/ErrorNotification';
+import { filterTodos } from './Components/helper';
 
 export const App: React.FC = () => {
-  if (!USER_ID) {
-    return <UserWarning />;
-  }
+  const [todos, setTodos] = useState<Todo[]>([]);
+  const [condition, setCondition] = useState(ForComletedTodo.All);
+  const [errorMessage, setErrorMessage] = useState<string | null>(null);
+  const [inputDisabled, setInputDisabled] = useState(false);
+  const [processingTodoIds, setProcessingTodoIds] = useState<number[]>([]);
+  const [tempTodo, setTempTodo] = useState<Todo | null>(null);
+  const [errorTimer, setErrorTimer] = useState<NodeJS.Timeout | null>(null);
+
+  const filteredTodos = useMemo(() => filterTodos(todos, condition),
+    [condition, todos]);
+
+  useEffect(() => {
+    if (errorTimer) {
+      clearTimeout(errorTimer);
+    }
+
+    setErrorTimer(setTimeout(() => {
+      setErrorMessage(null);
+    }, 3000));
+  }, [errorMessage, errorTimer]);
+
+  const hasTodos = !!todos.length;
+
+  const isAllCompleted = todos.every(todo => todo.completed);
+
+  const fetchData = useCallback(async () => {
+    try {
+      setErrorMessage(null);
+      const todosFetch = await todoService.getTodos();
+
+      setTodos(todosFetch);
+    } catch (err) {
+      setErrorMessage('Unable to load todos');
+    }
+  }, []);
+
+  useEffect(() => {
+    fetchData();
+  }, []);
+
+  const hadleAddTodo = async (title: string) => {
+    try {
+      setInputDisabled(true);
+
+      const newTodo = {
+        id: 0,
+        userId: 0,
+        title: title.trim(),
+        completed: false,
+      };
+
+      setTempTodo(newTodo);
+
+      const addedTodo = await todoService.addTodo(title);
+
+      setTodos((prevTodos) => [...prevTodos, addedTodo]);
+    } catch (error) {
+      setErrorMessage('Unable to add a todo');
+      throw error;
+    } finally {
+      setInputDisabled(false);
+      setTempTodo(null);
+    }
+  };
+
+  const handleDeleteTodo = (todoId: number) => {
+    setInputDisabled(true);
+    setProcessingTodoIds((prevTodoIds) => [...prevTodoIds, todoId]);
+
+    return todoService
+      .deleteTodo(todoId)
+      .then((() => {
+        setTodos((prevTodos) => prevTodos.filter(todo => todo.id !== todoId));
+      }))
+      .catch(() => {
+        setErrorMessage('Unable to delete a todo');
+      })
+      .finally(() => {
+        setInputDisabled(false);
+        setProcessingTodoIds(
+          (prevTodoIds) => prevTodoIds.filter(id => id !== todoId),
+        );
+      });
+  };
+
+  const handleRenameTodo = async (todo: Todo, newTodoTitle: string) => {
+    setProcessingTodoIds((prevTodoIds) => [...prevTodoIds, todo.id]);
+
+    return todoService.updateTodo({
+      ...todo,
+      title: newTodoTitle.trim(),
+    })
+      .then(updatedTodo => {
+        setTodos(prevState => prevState.map(currentTodo => (
+          currentTodo.id !== updatedTodo.id
+            ? currentTodo
+            : updatedTodo
+        )));
+      })
+      .catch(() => {
+        setErrorMessage('Unable to update a todo');
+      })
+      .finally(() => {
+        setProcessingTodoIds(
+          (prevTodoIds) => prevTodoIds.filter(id => id !== todo.id),
+        );
+      });
+  };
+
+  const handleClearCompletedTodos = () => {
+    todos.forEach(todo => {
+      if (todo.completed) {
+        handleDeleteTodo(todo.id);
+      }
+    });
+  };
+
+  const handleToggleTodo = async (todo: Todo) => {
+    try {
+      setProcessingTodoIds((prevTodoIds) => [...prevTodoIds, todo.id]);
+
+      const updatedTodo = await todoService.updateTodo({
+        ...todo,
+        completed: !todo.completed,
+      });
+
+      setTodos(prevState => prevState.map(currentTodo => (
+        currentTodo.id !== updatedTodo.id
+          ? currentTodo
+          : updatedTodo
+      )));
+    } catch (error) {
+      setErrorMessage('Unable to update a todo');
+    } finally {
+      setProcessingTodoIds(
+        (prevTodoIds) => prevTodoIds.filter(id => id !== todo.id),
+      );
+    }
+  };
+
+  const handleToggleAllTodos = () => {
+    const activeTodos = todos.filter(todo => !todo.completed);
+
+    if (isAllCompleted) {
+      todos.forEach(handleToggleTodo);
+    } else {
+      activeTodos.forEach(handleToggleTodo);
+    }
+  };
+
+  const handleDelete = async (todoId: number) => {
+    return handleDeleteTodo(todoId);
+  };
+
+  const handleRename = async (todo: Todo, todoTitle: string) => {
+    await handleRenameTodo(todo, todoTitle);
+  };
 
   return (
-    <section className="section container">
-      <p className="title is-4">
-        Copy all you need from the prev task:
-        <br />
-        <a href="https://github.com/mate-academy/react_todo-app-add-and-delete#react-todo-app-add-and-delete">React Todo App - Add and Delete</a>
-      </p>
-
-      <p className="subtitle">Styles are already copied</p>
-    </section>
+    <div className="todoapp">
+      <h1 className="todoapp__title">todos</h1>
+
+      <div className="todoapp__content">
+        <Header
+          onTodoAddError={setErrorMessage}
+          isAllCompleted={isAllCompleted}
+          hasTodos={hasTodos}
+          onTodoAdd={hadleAddTodo}
+          inputDisabled={inputDisabled}
+          onToggleAll={handleToggleAllTodos}
+        />
+
+        <section className="todoapp__main" data-cy="TodoList">
+          {filteredTodos.map(todo => (
+            <TodoItem
+              key={todo.id}
+              todo={todo}
+              onTodoDelete={() => handleDelete(todo.id)}
+              onRenameTodo={(todoTitle) => handleRename(todo, todoTitle)}
+              onTodoToggle={() => handleToggleTodo(todo)}
+              isProcessing={processingTodoIds.includes(todo.id)}
+            />
+          ))}
+        </section>
+
+        {tempTodo && (
+          <TodoItem
+            todo={tempTodo}
+            isProcessing
+          />
+        )}
+
+        {hasTodos && (
+          <Footer
+            todos={todos}
+            condition={condition}
+            setCondition={setCondition}
+            handleClearCompletedTodos={handleClearCompletedTodos}
+          />
+        )}
+      </div>
+
+      <ErrorNotification
+        setErrorMessage={setErrorMessage}
+        errorMessage={errorMessage}
+        errorTimer={errorTimer}
+        setErrorTimer={setErrorTimer}
+      />
+    </div>
   );
 };
diff --git a/src/Components/ErrorNotification.tsx b/src/Components/ErrorNotification.tsx
new file mode 100644
index 0000000000..ceb1847c12
--- /dev/null
+++ b/src/Components/ErrorNotification.tsx
@@ -0,0 +1,60 @@
+import React, { useEffect } from 'react';
+import cn from 'classnames';
+
+type Props = {
+  setErrorMessage: (errorMessage: string | null) => void;
+  errorMessage: string | null;
+  errorTimer: NodeJS.Timeout | null;
+  setErrorTimer: React.Dispatch<React.SetStateAction<NodeJS.Timeout | null>>;
+};
+
+export const ErrorNotification: React.FC<Props> = ({
+  setErrorMessage,
+  errorMessage,
+  errorTimer,
+  setErrorTimer,
+}) => {
+  useEffect(() => {
+    if (errorTimer) {
+      clearTimeout(errorTimer);
+    }
+
+    const newTimer = setTimeout(() => {
+      setErrorMessage(null);
+    }, 3000);
+
+    setErrorTimer(newTimer);
+
+    return () => {
+      if (newTimer) {
+        clearTimeout(newTimer);
+      }
+    };
+  }, [errorMessage, setErrorTimer]);
+
+  return (
+    <div
+      data-cy="ErrorNotification"
+      className={cn(
+        'notification',
+        'is-danger',
+        'is-light',
+        'has-text-weight-normal',
+        {
+          hidden: !errorMessage,
+        },
+      )}
+    >
+
+      <button
+        aria-label="HideErrorButton"
+        data-cy="HideErrorButton"
+        type="button"
+        className="delete"
+        onClick={() => setErrorMessage(null)}
+      />
+
+      {errorMessage}
+    </div>
+  );
+};
diff --git a/src/Components/Footer.tsx b/src/Components/Footer.tsx
new file mode 100644
index 0000000000..2d856c82eb
--- /dev/null
+++ b/src/Components/Footer.tsx
@@ -0,0 +1,38 @@
+import React from 'react';
+import { Todo } from '../types/Todo';
+import { NavMenu } from './NavMenu';
+import { ForComletedTodo } from '../types/enumFilter';
+
+type Props = {
+  todos: Todo[];
+  condition: ForComletedTodo;
+  setCondition: (condition: ForComletedTodo) => void;
+  handleClearCompletedTodos: () => void;
+};
+
+export const Footer: React.FC<Props> = ({
+  todos,
+  condition,
+  setCondition,
+  handleClearCompletedTodos,
+}) => {
+  const activeTodos = todos.filter(todo => !todo.completed).length;
+
+  return (
+    <footer className="todoapp__footer" data-cy="Footer">
+      <span className="todo-count" data-cy="TodosCounter">
+        {`${activeTodos} item${activeTodos !== 1 ? 's' : ''} left`}
+      </span>
+      <NavMenu condition={condition} setCondition={setCondition} />
+      <button
+        type="button"
+        className="todoapp__clear-completed"
+        data-cy="ClearCompletedButton"
+        disabled={!!activeTodos}
+        onClick={handleClearCompletedTodos}
+      >
+        Clear completed
+      </button>
+    </footer>
+  );
+};
diff --git a/src/Components/Header.tsx b/src/Components/Header.tsx
new file mode 100644
index 0000000000..58cc302684
--- /dev/null
+++ b/src/Components/Header.tsx
@@ -0,0 +1,85 @@
+import React, { useEffect, useRef, useState } from 'react';
+import cn from 'classnames';
+
+type Props = {
+  onTodoAdd: (title: string) => Promise<void>;
+  isAllCompleted: boolean;
+  hasTodos: boolean,
+  onTodoAddError: (error: string | null) => void;
+  inputDisabled: boolean;
+  onToggleAll: () => void;
+};
+
+export const Header: React.FC<Props> = ({
+  onTodoAdd,
+  isAllCompleted,
+  hasTodos,
+  onTodoAddError,
+  inputDisabled,
+  onToggleAll,
+}) => {
+  const [title, setTitle] = useState('');
+
+  const handleTitleChange = (event: React.ChangeEvent<HTMLInputElement>) => {
+    setTitle(event.target.value);
+    onTodoAddError(null);
+  };
+
+  const onFormSubmit = (event: React.FormEvent<HTMLFormElement>) => {
+    event.preventDefault();
+
+    const trimmedTitle = title.trim();
+
+    if (!trimmedTitle) {
+      onTodoAddError('Title should not be empty');
+
+      return;
+    }
+
+    onTodoAdd(trimmedTitle)
+      .then(() => {
+        setTitle('');
+      })
+      .catch((error) => {
+        // eslint-disable-next-line no-console
+        console.error(error);
+      });
+  };
+
+  const inputRef = useRef<HTMLInputElement>(null);
+
+  useEffect(() => {
+    if (!inputDisabled && inputRef.current) {
+      inputRef.current.focus();
+    }
+  }, [inputDisabled]);
+
+  return (
+    <header className="todoapp__header">
+      {Boolean(hasTodos) && (
+        <button
+          type="button"
+          aria-label="Toggle All"
+          className={cn('todoapp__toggle-all', {
+            active: isAllCompleted,
+          })}
+          data-cy="ToggleAllButton"
+          onClick={onToggleAll}
+        />
+      )}
+
+      <form onSubmit={onFormSubmit}>
+        <input
+          data-cy="NewTodoField"
+          type="text"
+          className="todoapp__new-todo"
+          placeholder="What needs to be done?"
+          value={title}
+          onChange={handleTitleChange}
+          ref={inputRef}
+          disabled={inputDisabled}
+        />
+      </form>
+    </header>
+  );
+};
diff --git a/src/Components/NavMenu.tsx b/src/Components/NavMenu.tsx
new file mode 100644
index 0000000000..278cc1dec3
--- /dev/null
+++ b/src/Components/NavMenu.tsx
@@ -0,0 +1,33 @@
+import cn from 'classnames';
+import { ForComletedTodo } from '../types/enumFilter';
+
+interface Props {
+  condition: ForComletedTodo;
+  setCondition: (condition: ForComletedTodo) => void;
+}
+
+export const NavMenu: React.FunctionComponent<Props> = ({
+  condition,
+  setCondition,
+}) => {
+  return (
+    <nav
+      className="filter"
+      data-cy="Filter"
+    >
+      {Object.entries(ForComletedTodo).map(([key, value]) => (
+        <a
+          key={value}
+          href={`#/${value}`}
+          data-cy={`FilterLink${key}`}
+          className={cn('filter__link', {
+            selected: value === condition,
+          })}
+          onClick={() => setCondition(value)}
+        >
+          {key}
+        </a>
+      ))}
+    </nav>
+  );
+};
diff --git a/src/Components/TodoItem.tsx b/src/Components/TodoItem.tsx
new file mode 100644
index 0000000000..f66150c9aa
--- /dev/null
+++ b/src/Components/TodoItem.tsx
@@ -0,0 +1,147 @@
+import React, { useEffect, useRef, useState } from 'react';
+import cn from 'classnames';
+import { Todo } from '../types/Todo';
+
+type Props = {
+  todo: Todo;
+  onTodoDelete?: () => void;
+  onRenameTodo?: (todoTitle: string) => void;
+  onTodoToggle?: () => Promise<void>;
+  isProcessing: boolean;
+};
+
+export const TodoItem: React.FC<Props> = ({
+  todo,
+  onTodoDelete = () => { },
+  onRenameTodo = () => { },
+  onTodoToggle = () => { },
+  isProcessing,
+}) => {
+  const { title, completed, id } = todo;
+  const [isEditing, setIsEditing] = useState(false);
+  const [todoTitle, setTodoTitle] = useState(todo.title);
+
+  const handleTodoDoubleClick = () => {
+    setIsEditing(true);
+  };
+
+  const handleTodoSave = async (event: React.FormEvent<HTMLFormElement>) => {
+    event.preventDefault();
+    try {
+      const trimmedTitle = todoTitle.trim();
+
+      if (!trimmedTitle) {
+        setIsEditing(false);
+        await onTodoDelete();
+
+        return;
+      }
+
+      if (todo.title === trimmedTitle) {
+        setIsEditing(false);
+
+        return;
+      }
+
+      if (trimmedTitle) {
+        await onRenameTodo(todoTitle);
+        setIsEditing(false);
+      } else {
+        await onTodoDelete();
+      }
+
+      setIsEditing(false);
+    } catch {
+      //
+    }
+  };
+
+  const handleTodoTitleChange = (
+    event: React.ChangeEvent<HTMLInputElement>,
+  ) => {
+    setTodoTitle(event.target.value);
+  };
+
+  const titleInputRef = useRef<HTMLInputElement | null>(null);
+
+  useEffect(() => {
+    if (isEditing && titleInputRef.current) {
+      titleInputRef.current?.focus();
+    }
+  }, [isEditing, isProcessing]);
+
+  const onKeyUpHandle = (event: React.KeyboardEvent) => {
+    if (event.key === 'Escape') {
+      setIsEditing(false);
+      setTodoTitle(todo.title);
+    }
+  };
+
+  return (
+    <div
+      data-cy="Todo"
+      className={cn('todo', {
+        completed,
+      })}
+      key={id}
+    >
+      <label className="todo__status-label">
+        <input
+          data-cy="TodoStatus"
+          type="checkbox"
+          className="todo__status"
+          checked={completed}
+          onClick={onTodoToggle}
+        />
+      </label>
+
+      {isEditing
+        ? (
+          <form
+            onSubmit={handleTodoSave}
+            onBlur={handleTodoSave}
+          >
+            <input
+              onKeyUp={onKeyUpHandle}
+              ref={titleInputRef}
+              data-cy="TodoTitleField"
+              type="text"
+              className="todo__title-field"
+              placeholder="Empty todo will be deleted"
+              value={todoTitle}
+              onChange={handleTodoTitleChange}
+            />
+          </form>
+        ) : (
+          <>
+            <span
+              data-cy="TodoTitle"
+              className="todo__title"
+              onDoubleClick={handleTodoDoubleClick}
+            >
+              {title.trim()}
+            </span>
+
+            <button
+              type="button"
+              className="todo__remove"
+              data-cy="TodoDelete"
+              onClick={onTodoDelete}
+            >
+              ×
+            </button>
+          </>
+        )}
+
+      <div
+        data-cy="TodoLoader"
+        className={cn('modal overlay', {
+          'is-active': isProcessing,
+        })}
+      >
+        <div className="modal-background has-background-white-ter" />
+        <div className="loader" />
+      </div>
+    </div>
+  );
+};
diff --git a/src/Components/helper.tsx b/src/Components/helper.tsx
new file mode 100644
index 0000000000..1fb9a3be14
--- /dev/null
+++ b/src/Components/helper.tsx
@@ -0,0 +1,17 @@
+import { Todo } from '../types/Todo';
+import { ForComletedTodo } from '../types/enumFilter';
+
+export const filterTodos = (
+  todos: Todo[], condition: ForComletedTodo,
+): Todo[] => {
+  return todos.filter(({ completed }) => {
+    switch (condition) {
+      case ForComletedTodo.Active:
+        return !completed;
+      case ForComletedTodo.Completed:
+        return completed;
+      default:
+        return 1;
+    }
+  });
+};
diff --git a/src/api/todos.ts b/src/api/todos.ts
new file mode 100644
index 0000000000..2ecbf1f0e1
--- /dev/null
+++ b/src/api/todos.ts
@@ -0,0 +1,30 @@
+import { Todo } from '../types/Todo';
+import { client } from '../utils/fetchClient';
+
+export const USER_ID = 11511;
+
+export const getTodos = () => {
+  return client.get<Todo[]>(`/todos?userId=${USER_ID}`);
+};
+
+export const deleteTodo = (todoId: number) => {
+  return client.delete(`/todos/${todoId}`);
+};
+
+export const addTodo = (title: string) => {
+  return client.post<Todo>('/todos', {
+    title,
+    userId: USER_ID,
+    completed: false,
+  });
+};
+
+export const updateTodo = ({
+  id, title, userId, completed,
+}: Todo): Promise<Todo> => {
+  return client.patch(`/todos/${id}`, {
+    title,
+    userId,
+    completed,
+  });
+};
diff --git a/src/index.tsx b/src/index.tsx
index 7de19e0c70..1b06674f67 100644
--- a/src/index.tsx
+++ b/src/index.tsx
@@ -1,5 +1,4 @@
 import { createRoot } from 'react-dom/client';
-
 import 'bulma/css/bulma.css';
 import '@fortawesome/fontawesome-free/css/all.css';
 import './styles/index.scss';
diff --git a/src/styles/todo.scss b/src/styles/todo.scss
index c7f93ff6b9..fc99714ef2 100644
--- a/src/styles/todo.scss
+++ b/src/styles/todo.scss
@@ -8,7 +8,7 @@
   font-size: 24px;
   line-height: 1.4em;
   border-bottom: 1px solid #ededed;
-
+  
   &:last-child {
     border-bottom: 0;
   }
@@ -30,7 +30,7 @@
 
   &__title {
     padding: 12px 15px;
-
+  
     word-break: break-all;
     transition: color 0.4s;
   }
@@ -56,7 +56,7 @@
     border: 0;
     background: none;
     cursor: pointer;
-
+  
     transform: translateY(-2px);
     opacity: 0;
     transition: color 0.2s ease-out;
@@ -65,7 +65,7 @@
       color: #af5b5e;
     }
   }
-
+  
   &:hover &__remove {
     opacity: 1;
   }
@@ -73,13 +73,13 @@
   &__title-field {
     width: 100%;
     padding: 11px 14px;
-
+  
     font-size: inherit;
     line-height: inherit;
     font-family: inherit;
     font-weight: inherit;
     color: inherit;
-
+  
     border: 1px solid #999;
     box-shadow: inset 0 -1px 5px 0 rgba(0, 0, 0, 0.2);
 
@@ -92,58 +92,11 @@
 
   .overlay {
     position: absolute;
-    top: 0;
     left: 0;
     right: 0;
-    height: 58px;
+    bottom: 0;
+    top: 0;
 
     opacity: 0.5;
   }
 }
-
-.item-enter {
-  max-height: 0;
-}
-
-.item-enter-active {
-  overflow: hidden;
-  max-height: 58px;
-  transition: max-height 0.3s ease-in-out;
-}
-
-.item-exit {
-  max-height: 58px;
-}
-
-.item-exit-active {
-  overflow: hidden;
-  max-height: 0;
-  transition: max-height 0.3s ease-in-out;
-}
-
-.temp-item-enter {
-  max-height: 0;
-}
-
-.temp-item-enter-active {
-  overflow: hidden;
-  max-height: 58px;
-  transition: max-height 0.3s ease-in-out;
-}
-
-.temp-item-exit {
-  max-height: 58px;
-}
-
-.temp-item-exit-active {
-  transform: translateY(-58px);
-  max-height: 0;
-  opacity: 0;
-  transition: 0.3s ease-in-out;
-  transition-property: opacity, max-height, transform;
-}
-
-.has-error .temp-item-exit-active {
-  transform: translateY(0);
-  overflow: hidden;
-}
diff --git a/src/styles/todoapp.scss b/src/styles/todoapp.scss
index 9095f1847f..9a14a730e2 100644
--- a/src/styles/todoapp.scss
+++ b/src/styles/todoapp.scss
@@ -121,7 +121,6 @@
     appearance: none;
     -webkit-font-smoothing: antialiased;
     -moz-osx-font-smoothing: grayscale;
-    transition: opacity 0.3s;
 
     &:hover {
       text-decoration: underline;
@@ -130,7 +129,6 @@
     &:active {
       text-decoration: none;
     }
-
     &:disabled {
       visibility: hidden;
     }
diff --git a/src/types/Todo.ts b/src/types/Todo.ts
new file mode 100644
index 0000000000..3f52a5fdde
--- /dev/null
+++ b/src/types/Todo.ts
@@ -0,0 +1,6 @@
+export interface Todo {
+  id: number;
+  userId: number;
+  title: string;
+  completed: boolean;
+}
diff --git a/src/types/enumFilter.ts b/src/types/enumFilter.ts
new file mode 100644
index 0000000000..0f493f3baf
--- /dev/null
+++ b/src/types/enumFilter.ts
@@ -0,0 +1,5 @@
+export enum ForComletedTodo {
+  All = '',
+  Active = 'active',
+  Completed = 'completed',
+}
diff --git a/src/utils/fetchClient.ts b/src/utils/fetchClient.ts
new file mode 100644
index 0000000000..ca588ab63a
--- /dev/null
+++ b/src/utils/fetchClient.ts
@@ -0,0 +1,46 @@
+/* eslint-disable @typescript-eslint/no-explicit-any */
+const BASE_URL = 'https://mate.academy/students-api';
+
+// returns a promise resolved after a given delay
+function wait(delay: number) {
+  return new Promise(resolve => {
+    setTimeout(resolve, delay);
+  });
+}
+
+// To have autocompletion and avoid mistypes
+type RequestMethod = 'GET' | 'POST' | 'PATCH' | 'DELETE';
+
+function request<T>(
+  url: string,
+  method: RequestMethod = 'GET',
+  data: any = null, // we can send any data to the server
+): Promise<T> {
+  const options: RequestInit = { method };
+
+  if (data) {
+    // We add body and Content-Type only for the requests with data
+    options.body = JSON.stringify(data);
+    options.headers = {
+      'Content-Type': 'application/json; charset=UTF-8',
+    };
+  }
+
+  // we wait for testing purpose to see loaders
+  return wait(100)
+    .then(() => fetch(BASE_URL + url, options))
+    .then(response => {
+      if (!response.ok) {
+        throw new Error();
+      }
+
+      return response.json();
+    });
+}
+
+export const client = {
+  get: <T>(url: string) => request<T>(url),
+  post: <T>(url: string, data: any) => request<T>(url, 'POST', data),
+  patch: <T>(url: string, data: any) => request<T>(url, 'PATCH', data),
+  delete: (url: string) => request(url, 'DELETE'),
+};