Gérer les retours de livres par l'admin

Reviewed-on: #6

my-library/src/App.jsx

@@ -1,4 +1,4 @@
-import { Routes, Route } from 'react-router-dom';
+import { Routes, Route, Navigate } from 'react-router-dom';
 import Layout from './components/Layout';
 import Home from './pages/Home';
 import Books from './pages/Books';
@@ -7,18 +7,39 @@ import Profile from './pages/Profile';
 import NotFound from './pages/NotFound';
 import AddBook from './pages/AddBook';
 import BookDetail from './pages/BookDetail';
+import Customers from './pages/Customers';
+import Login from './pages/Login';
+import Reservations from './pages/Reservations';
+import Returns from './pages/Returns';
+import { useAuth } from './context/AuthContext';
+
+function RequireAuth({ children }) {
+  const { user } = useAuth();
+  return user ? children : <Navigate to="/login" replace />;
+}
+
+function RequireAdmin({ children }) {
+  const { user } = useAuth();
+  if (!user) return <Navigate to="/login" replace />;
+  if (user.role !== 'admin') return <Navigate to="/" replace />;
+  return children;
+}
 
 export default function App() {
   return (
     <Routes>
+      <Route path="/login" element={<Login />} />
       <Route path="/" element={<Layout />}>
         <Route index element={<Home />} />
         <Route path="books" element={<Books />} />
-        <Route path="orders" element={<Orders />} />
+        <Route path="books/:bookId" element={<RequireAuth><BookDetail /></RequireAuth>} />
-        <Route path="profile" element={<Profile />} />
+        <Route path="books/new" element={<RequireAdmin><AddBook /></RequireAdmin>} />
+        <Route path="orders" element={<RequireAuth><Orders /></RequireAuth>} />
+        <Route path="reservations" element={<RequireAuth><Reservations /></RequireAuth>} />
+        <Route path="profile" element={<RequireAuth><Profile /></RequireAuth>} />
+        <Route path="customers" element={<RequireAdmin><Customers /></RequireAdmin>} />
+        <Route path="returns" element={<RequireAdmin><Returns /></RequireAdmin>} />
         <Route path="*" element={<NotFound />} />
-        <Route path="books/new" element={<AddBook />} />
-        <Route path="books/:bookId" element={<BookDetail />} />
       </Route>
     </Routes>
   );

my-library/src/api/books.js

@@ -11,3 +11,7 @@ export function registerBook(book) {
 export function getBookById(id) {
   return client.get(`/api/books/${id}`);
 }
+
+export function reserveBook(bookId, reservation) {
+  return client.post(`/api/books/${bookId}/reservations`, reservation);
+}

my-library/src/api/customers.js

@@ -0,0 +1,17 @@
+import client from './client';
+
+export function registerCustomer(customer) {
+  return client.post('/api/customers', customer);
+}
+
+export function findCustomerByPhone(phoneNumber) {
+  return client.get(`/api/customers/phone/${encodeURIComponent(phoneNumber)}`);
+}
+
+export function addLoyaltyPoints(customerId, points) {
+  return client.post(`/api/customers/${customerId}/loyalty/add`, null, { params: { points } });
+}
+
+export function subtractLoyaltyPoints(customerId, points) {
+  return client.post(`/api/customers/${customerId}/loyalty/subtract`, null, { params: { points } });
+}

my-library/src/components/Navbar.jsx

@@ -1,7 +1,16 @@
-import { Link } from 'react-router-dom';
+import { Link, useNavigate } from 'react-router-dom';
+import { useAuth } from '../context/AuthContext';
 import '../styles/navbar.css';
 
 export default function Navbar() {
+  const { user, logout } = useAuth();
+  const navigate = useNavigate();
+
+  function handleLogout() {
+    logout();
+    navigate('/login');
+  }
+
   return (
     <nav className="navbar">
       <Link to="/" className="navbar__logo">Biblio</Link>
@@ -9,13 +18,22 @@ export default function Navbar() {
       <ul className="navbar__links">
         <li><Link to="/">Accueil</Link></li>
         <li><Link to="/books">Catalogue</Link></li>
-        <li><Link to="/orders">Commandes</Link></li>
+        {user && <li><Link to="/orders">Commandes</Link></li>}
-        <li><Link to="/profile">Mon compte</Link></li>
+        {user?.role === 'user' && <li><Link to="/reservations">Mes réservations</Link></li>}
+        {user && <li><Link to="/profile">Mon compte</Link></li>}
+        {user?.role === 'admin' && <li><Link to="/customers">Clients</Link></li>}
+        {user?.role === 'admin' && <li><Link to="/returns">Retours</Link></li>}
       </ul>
 
       <div className="navbar__actions">
-        <button className="btn-ghost">Connexion</button>
+        {user ? (
-        <button className="btn-cta">S'inscrire</button>
+          <>
+            <span>{user.username} ({user.role})</span>
+            <button onClick={handleLogout}>Déconnexion</button>
+          </>
+        ) : (
+          <Link to="/login"><button>Connexion</button></Link>
+        )}
       </div>
     </nav>
   );

my-library/src/context/AuthContext.js

@@ -0,0 +1,39 @@
+import { createContext, useContext, useState } from 'react';
+
+const USERS = [
+  { username: 'admin', password: 'admin', role: 'admin' },
+  { username: 'alice', password: 'bob', role: 'user' },
+];
+
+const AuthContext = createContext(null);
+
+export function AuthProvider({ children }) {
+  const [user, setUser] = useState(() => {
+    const saved = localStorage.getItem('auth');
+    return saved ? JSON.parse(saved) : null;
+  });
+
+  function login(username, password) {
+    const found = USERS.find(u => u.username === username && u.password === password);
+    if (!found) return false;
+    const { password: _, ...safe } = found;
+    setUser(safe);
+    localStorage.setItem('auth', JSON.stringify(safe));
+    return true;
+  }
+
+  function logout() {
+    setUser(null);
+    localStorage.removeItem('auth');
+  }
+
+  return (
+    <AuthContext.Provider value={{ user, login, logout }}>
+      {children}
+    </AuthContext.Provider>
+  );
+}
+
+export function useAuth() {
+  return useContext(AuthContext);
+}

my-library/src/context/ReservationContext.js

@@ -0,0 +1,42 @@
+import { createContext, useContext, useState } from 'react';
+
+const ReservationContext = createContext(null);
+
+export function ReservationProvider({ children }) {
+  const [reservations, setReservations] = useState(() => {
+    const saved = localStorage.getItem('reservations');
+    return saved ? JSON.parse(saved) : [];
+  });
+
+  function addReservation(book, phoneNumber) {
+    const reservation = {
+      reservationId: crypto.randomUUID(),
+      bookId: book.isbn,
+      bookTitle: book.title,
+      bookAuthor: book.author,
+      phoneNumber,
+      status: 'CONFIRMED',
+      reservedAt: new Date().toISOString(),
+    };
+    const updated = [...reservations, reservation];
+    setReservations(updated);
+    localStorage.setItem('reservations', JSON.stringify(updated));
+    return reservation;
+  }
+
+  function cancelReservation(reservationId) {
+    const updated = reservations.filter(r => r.reservationId !== reservationId);
+    setReservations(updated);
+    localStorage.setItem('reservations', JSON.stringify(updated));
+  }
+
+  return (
+    <ReservationContext.Provider value={{ reservations, addReservation, cancelReservation }}>
+      {children}
+    </ReservationContext.Provider>
+  );
+}
+
+export function useReservations() {
+  return useContext(ReservationContext);
+}

my-library/src/context/ReturnContext.js

@@ -0,0 +1,36 @@
+import { createContext, useContext, useState } from 'react';
+
+const ReturnContext = createContext(null);
+
+export function ReturnProvider({ children }) {
+  const [returns, setReturns] = useState(() => {
+    const saved = localStorage.getItem('returns');
+    return saved ? JSON.parse(saved) : [];
+  });
+
+  function addReturn(bookId, bookTitle, customerPhone, reason) {
+    const bookReturn = {
+      returnId: crypto.randomUUID(),
+      bookId,
+      bookTitle,
+      customerPhone,
+      reason,
+      status: 'PROCESSED',
+      returnedAt: new Date().toISOString(),
+    };
+    const updated = [...returns, bookReturn];
+    setReturns(updated);
+    localStorage.setItem('returns', JSON.stringify(updated));
+    return bookReturn;
+  }
+
+  return (
+    <ReturnContext.Provider value={{ returns, addReturn }}>
+      {children}
+    </ReturnContext.Provider>
+  );
+}
+
+export function useReturns() {
+  return useContext(ReturnContext);
+}

my-library/src/context/ReviewContext.js

@@ -0,0 +1,40 @@
+import { createContext, useContext, useState } from 'react';
+
+const ReviewContext = createContext(null);
+
+export function ReviewProvider({ children }) {
+  const [reviews, setReviews] = useState(() => {
+    const saved = localStorage.getItem('reviews');
+    return saved ? JSON.parse(saved) : [];
+  });
+
+  function addReview(bookId, bookTitle, username, rating, comment) {
+    const review = {
+      reviewId: crypto.randomUUID(),
+      bookId,
+      bookTitle,
+      username,
+      rating,
+      comment,
+      createdAt: new Date().toISOString(),
+    };
+    const updated = [...reviews, review];
+    setReviews(updated);
+    localStorage.setItem('reviews', JSON.stringify(updated));
+    return review;
+  }
+
+  function getReviewsByBook(bookId) {
+    return reviews.filter(r => String(r.bookId) === String(bookId));
+  }
+
+  return (
+    <ReviewContext.Provider value={{ reviews, addReview, getReviewsByBook }}>
+      {children}
+    </ReviewContext.Provider>
+  );
+}
+
+export function useReviews() {
+  return useContext(ReviewContext);
+}

my-library/src/index.js

@@ -1,6 +1,10 @@
 import React from 'react';
 import ReactDOM from 'react-dom/client';
 import { BrowserRouter } from 'react-router-dom';
+import { AuthProvider } from './context/AuthContext';
+import { ReservationProvider } from './context/ReservationContext';
+import { ReviewProvider } from './context/ReviewContext';
+import { ReturnProvider } from './context/ReturnContext';
 import App from './App';
 import './styles/global.css';
 
@@ -8,7 +12,15 @@ const root = ReactDOM.createRoot(document.getElementById('root'));
 root.render(
   <React.StrictMode>
     <BrowserRouter>
-      <App />
+      <AuthProvider>
+        <ReservationProvider>
+          <ReviewProvider>
+            <ReturnProvider>
+              <App />
+            </ReturnProvider>
+          </ReviewProvider>
+        </ReservationProvider>
+      </AuthProvider>
     </BrowserRouter>
   </React.StrictMode>
 );

my-library/src/pages/AddBook.jsx

@@ -35,7 +35,7 @@ export default function AddBook() {
 
     registerBook(payload)
       .then((response) => {
-        setMessage({ type: 'success', text: `Livre créé (id : ${response.data}) ✅` });
+        setMessage({ type: 'success', text: `Livre créé (id : ${response.data})` });
         setForm(initialForm);  
       })
       .catch((error) => {

my-library/src/pages/BookDetail.jsx

@@ -1,14 +1,40 @@
 import { useState, useEffect } from 'react';
 import { useParams, Link } from 'react-router-dom';
 import { getBookById } from '../api/books';
+import { useAuth } from '../context/AuthContext';
+import { useReservations } from '../context/ReservationContext';
+import { useReviews } from '../context/ReviewContext';
 
 export default function BookDetail() {
+  const { user } = useAuth();
+  const { addReservation } = useReservations();
+  const { addReview, getReviewsByBook } = useReviews();
+  const [rating, setRating] = useState(5);
+  const [comment, setComment] = useState('');
+  const [reviewStatus, setReviewStatus] = useState(null);
   const { bookId } = useParams();
   const [book, setBook] = useState(null);
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState(null);
+  const [phoneNumber, setPhoneNumber] = useState('');
+  const [reservationStatus, setReservationStatus] = useState(null);
 
-  useEffect(() => {getBookById(bookId).then((response) => setBook(response.data)).catch((err) => {console.error(err);setError('Livre introuvable.');}).finally(() => setLoading(false));}, [bookId]);             
+  useEffect(() => { getBookById(bookId).then((response) => setBook(response.data)).catch((err) => { console.error(err); setError('Livre introuvable.'); }).finally(() => setLoading(false)); }, [bookId]);
+
+  function handleReservation(e) {
+    e.preventDefault();
+    addReservation(book, phoneNumber);
+    setReservationStatus({ success: true, message: 'Réservation effectuée avec succès !' });
+    setPhoneNumber('');
+  }
+
+  function handleReview(e) {
+    e.preventDefault();
+    addReview(book.isbn, book.title, user.username, Number(rating), comment);
+    setReviewStatus({ success: true, message: 'Avis publié avec succès !' });
+    setComment('');
+    setRating(5);
+  }
 
   if (loading) return <main><p>Chargement…</p></main>;
   if (error) return <main><p>{error}</p><Link to="/books">← Retour au catalogue</Link></main>;
@@ -26,6 +52,72 @@ export default function BookDetail() {
       <p>Langue : {book.language}</p>
       <p>Catégories : {book.categories?.join(', ')}</p>
       {book.description && <p>{book.description}</p>}
+
+      <section>
+        <h2>Avis des lecteurs</h2>
+        {getReviewsByBook(book.isbn).length === 0 ? (
+          <p>Aucun avis pour le moment.</p>
+        ) : (
+          <ul>
+            {getReviewsByBook(book.isbn).map(r => (
+              <li key={r.reviewId}>
+                <strong>{r.username}</strong> — {'*'.repeat(r.rating)}
+                <br />
+                {r.comment}
+                <br />
+                <small>{new Date(r.createdAt).toLocaleDateString('fr-FR')}</small>
+              </li>
+            ))}
+          </ul>
+        )}
+        {user?.role === 'user' && (
+          <form onSubmit={handleReview}>
+            <h3>Laisser un avis</h3>
+            <label>
+              Note :
+              <select value={rating} onChange={e => setRating(e.target.value)}>
+                <option value={1}>*</option>
+                <option value={2}>**</option>
+                <option value={3}>***</option>
+                <option value={4}>****</option>
+                <option value={5}>*****</option>
+              </select>
+            </label>
+            <label>
+              Commentaire :
+              <textarea value={comment} onChange={e => setComment(e.target.value)} required />
+            </label>
+            <button type="submit">Publier l'avis</button>
+          </form>
+        )}
+        {reviewStatus && (
+          <p style={{ color: reviewStatus.success ? 'green' : 'red' }}>
+            {reviewStatus.message}
+          </p>
+        )}
+      </section>
+
+      {user?.role === 'user' && <section>
+        <h2>Réserver ce livre</h2>
+        <form onSubmit={handleReservation}>
+          <label>
+            Numéro de téléphone :
+            <input
+              type="tel"
+              value={phoneNumber}
+              onChange={(e) => setPhoneNumber(e.target.value)}
+              placeholder="0612345678"
+              required
+            />
+          </label>
+          <button type="submit">Réserver</button>
+        </form>
+        {reservationStatus && (
+          <p style={{ color: reservationStatus.success ? 'green' : 'red' }}>
+            {reservationStatus.message}
+          </p>
+        )}
+      </section>}
     </main>
   );
 }

my-library/src/pages/Books.jsx

@@ -1,8 +1,10 @@
 import { useState, useEffect } from 'react';
 import { getBooks } from '../api/books';
 import { Link } from 'react-router-dom';
+import { useAuth } from '../context/AuthContext';
 
 export default function Books() {
+  const { user } = useAuth();
   const [books, setBooks] = useState([]);
   const [loading, setLoading] = useState(true);
   const [error, setError] = useState(null);
@@ -28,7 +30,7 @@ export default function Books() {
   return (
     <main>
       <h1>Catalogue</h1>
-      <Link to="/books/new">+ Ajouter un livre</Link>
+      {user?.role === 'admin' && <Link to="/books/new">+ Ajouter un livre</Link>}
       <ul>
         {books.map((book) => (
           <li key={book.isbn}>

my-library/src/pages/Customers.jsx

@@ -0,0 +1,109 @@
+import { useState } from 'react';
+import { registerCustomer, findCustomerByPhone, addLoyaltyPoints, subtractLoyaltyPoints } from '../api/customers';
+
+const initialForm = { firstName: '', lastName: '', phoneNumber: '' };
+
+export default function Customers() {
+  const [form, setForm] = useState(initialForm);
+  const [registerMsg, setRegisterMsg] = useState(null);
+  const [submitting, setSubmitting] = useState(false);
+  const [pointsInput, setPointsInput] = useState('');
+
+  function handleChange(e) {
+    const { name, value } = e.target;
+    setForm((prev) => ({ ...prev, [name]: value }));
+  }
+
+  function handleRegister(e) {
+    e.preventDefault();
+    setSubmitting(true);
+    setRegisterMsg(null);
+    registerCustomer(form)
+      .then((response) => {
+        setRegisterMsg(`Client créé (id : ${response.data})`);
+        setForm(initialForm);
+      })
+      .catch((error) => {
+        console.error(error);
+        setRegisterMsg('Erreur lors de la création du client.');
+      })
+      .finally(() => setSubmitting(false));
+  }
+
+  const [phone, setPhone] = useState('');
+  const [customer, setCustomer] = useState(null);
+  const [searchError, setSearchError] = useState(null);
+
+  function handleSearch(e) {
+    e.preventDefault();
+    setSearchError(null);
+    setCustomer(null);
+    findCustomerByPhone(phone)
+      .then((response) => setCustomer(response.data))
+      .catch((error) => {
+        console.error(error);
+        setSearchError('Aucun client trouvé avec ce numéro.');
+      });
+  }
+  function applyLoyalty(operation) {
+  const points = Number(pointsInput);
+  const action = operation === 'add' ? addLoyaltyPoints : subtractLoyaltyPoints;
+
+  action(customer.id, points)
+    .then((response) => {
+      setCustomer((prev) => ({ ...prev, loyaltyPoints: response.data }));
+      setPointsInput('');
+    })
+    .catch((error) => {
+      console.error(error);
+      if (error.response?.status === 400) setSearchError('Pas assez de points pour ce retrait.');
+      else setSearchError('Erreur lors de la mise à jour des points.');
+    });
+  }
+
+  return (
+    <main>
+      <h1>Gestion des clients</h1>
+
+      <section>
+        <h2>Enregistrer un client</h2>
+        <form onSubmit={handleRegister}>
+          <label>Prénom
+            <input name="firstName" value={form.firstName} onChange={handleChange} required />
+          </label>
+          <label>Nom
+            <input name="lastName" value={form.lastName} onChange={handleChange} required />
+          </label>
+          <label>Téléphone
+            <input name="phoneNumber" value={form.phoneNumber} onChange={handleChange} required />
+          </label>
+          <button type="submit" disabled={submitting}>
+            {submitting ? 'Envoi…' : 'Créer le client'}
+          </button>
+        </form>
+        {registerMsg && <p>{registerMsg}</p>}
+      </section>
+
+      <section>
+        <h2>Rechercher un client</h2>
+        <form onSubmit={handleSearch}>
+          <label>Téléphone
+            <input value={phone} onChange={(e) => setPhone(e.target.value)} required />
+          </label>
+          <button type="submit">Rechercher</button>
+        </form>
+        {searchError && <p>{searchError}</p>}
+        {customer && (
+          <div>
+            <p>{customer.firstName} {customer.lastName}</p>
+            <p>Téléphone : {customer.phoneNumber}</p>
+            <p><strong>Points de fidélité : {customer.loyaltyPoints}</strong></p>
+            <input type="number"value={pointsInput}onChange={(e) => setPointsInput(e.target.value)}placeholder="Nombre de points"/>
+            <button type="button" onClick={() => applyLoyalty('add')}>Ajouter</button>
+            <button type="button" onClick={() => applyLoyalty('subtract')}>Retirer</button>
+          </div>
+        )}
+      </section>
+    </main>
+  );
+}

my-library/src/pages/Login.jsx

@@ -0,0 +1,57 @@
+import { useState } from 'react';
+import { useNavigate } from 'react-router-dom';
+import { useAuth } from '../context/AuthContext';
+
+export default function Login() {
+  const { login } = useAuth();
+  const navigate = useNavigate();
+  const [form, setForm] = useState({ username: '', password: '' });
+  const [error, setError] = useState(null);
+
+  function handleSubmit(e) {
+    e.preventDefault();
+    const ok = login(form.username, form.password);
+    if (ok) {
+      navigate('/');
+    } else {
+      setError('Identifiants incorrects.');
+    }
+  }
+
+  return (
+    <main>
+      <h1>Connexion</h1>
+      <form onSubmit={handleSubmit}>
+        <div>
+          <label>
+            Nom d'utilisateur :
+            <input
+              type="text"
+              value={form.username}
+              onChange={e => setForm(f => ({ ...f, username: e.target.value }))}
+              required
+            />
+          </label>
+        </div>
+        <div>
+          <label>
+            Mot de passe :
+            <input
+              type="password"
+              value={form.password}
+              onChange={e => setForm(f => ({ ...f, password: e.target.value }))}
+              required
+            />
+          </label>
+        </div>
+        <button type="submit">Se connecter</button>
+        {error && <p style={{ color: 'red' }}>{error}</p>}
+      </form>
+      <p>Comptes disponibles :</p>
+      <ul>
+        <li><strong>admin</strong> / admin (administrateur)</li>
+        <li><strong>alice (utilisateur)</strong> / bob (utilisateur)</li>
+      </ul>
+    </main>
+  );
+}

my-library/src/pages/Reservations.jsx

@@ -0,0 +1,37 @@
+import { useReservations } from '../context/ReservationContext';
+import { Link } from 'react-router-dom';
+
+export default function Reservations() {
+  const { reservations, cancelReservation } = useReservations();
+
+  if (reservations.length === 0) {
+    return (
+      <main>
+        <h1>Mes réservations</h1>
+        <p>Aucune réservation pour le moment.</p>
+        <Link to="/books">← Retour au catalogue</Link>
+      </main>
+    );
+  }
+
+  return (
+    <main>
+      <h1>Mes réservations</h1>
+      <ul>
+        {reservations.map(r => (
+          <li key={r.reservationId}>
+            <strong>{r.bookTitle}</strong> — {r.bookAuthor}
+            <br />
+            Téléphone : {r.phoneNumber}
+            <br />
+            Réservé le : {new Date(r.reservedAt).toLocaleDateString('fr-FR')}
+            <br />
+            Statut : {r.status}
+            <br />
+            <button onClick={() => cancelReservation(r.reservationId)}>Annuler</button>
+          </li>
+        ))}
+      </ul>
+    </main>
+  );
+}

my-library/src/pages/Returns.jsx

@@ -0,0 +1,96 @@
+import { useState } from 'react';
+import { useReturns } from '../context/ReturnContext';
+import { getBooks } from '../api/books';
+import { useEffect } from 'react';
+
+export default function Returns() {
+  const { returns, addReturn } = useReturns();
+  const [books, setBooks] = useState([]);
+  const [form, setForm] = useState({ bookId: '', customerPhone: '', reason: '' });
+  const [message, setMessage] = useState(null);
+
+  useEffect(() => {
+    getBooks(0, 100).then(res => setBooks(res.data.content)).catch(console.error);
+  }, []);
+
+  function handleChange(e) {
+    const { name, value } = e.target;
+    setForm(f => ({ ...f, [name]: value }));
+  }
+
+  function handleSubmit(e) {
+    e.preventDefault();
+    const book = books.find(b => String(b.isbn) === String(form.bookId));
+    const bookTitle = book ? book.title : form.bookId;
+    addReturn(form.bookId, bookTitle, form.customerPhone, form.reason);
+    setMessage({ success: true, text: 'Retour enregistré avec succès !' });
+    setForm({ bookId: '', customerPhone: '', reason: '' });
+  }
+
+  return (
+    <main>
+      <h1>Gestion des retours</h1>
+
+      <section>
+        <h2>Enregistrer un retour</h2>
+        <form onSubmit={handleSubmit}>
+          <label>
+            Livre :
+            <select name="bookId" value={form.bookId} onChange={handleChange} required>
+              <option value="">-- Choisir un livre --</option>
+              {books.map(b => (
+                <option key={b.isbn} value={b.isbn}>{b.title} — {b.author}</option>
+              ))}
+            </select>
+          </label>
+          <label>
+            Téléphone du client :
+            <input
+              name="customerPhone"
+              type="tel"
+              value={form.customerPhone}
+              onChange={handleChange}
+              placeholder="0612345678"
+              required
+            />
+          </label>
+          <label>
+            Motif :
+            <textarea
+              name="reason"
+              value={form.reason}
+              onChange={handleChange}
+              placeholder="Motif du retour..."
+              required
+            />
+          </label>
+          <button type="submit">Enregistrer le retour</button>
+        </form>
+        {message && <p style={{ color: message.success ? 'green' : 'red' }}>{message.text}</p>}
+      </section>
+
+      <section>
+        <h2>Historique des retours</h2>
+        {returns.length === 0 ? (
+          <p>Aucun retour enregistré.</p>
+        ) : (
+          <ul>
+            {returns.map(r => (
+              <li key={r.returnId}>
+                <strong>{r.bookTitle}</strong>
+                <br />
+                Client : {r.customerPhone}
+                <br />
+                Motif : {r.reason}
+                <br />
+                Statut : {r.status}
+                <br />
+                <small>{new Date(r.returnedAt).toLocaleDateString('fr-FR')}</small>
+              </li>
+            ))}
+          </ul>
+        )}
+      </section>
+    </main>
+  );
+}

mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/BookDTO.java

@@ -0,0 +1,22 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.book.entity.Category;
+import java.time.LocalDate;
+import java.util.List;
+import lombok.Builder;
+import lombok.Getter;
+
+@Builder
+@Getter
+public class BookDTO {
+  private final long isbn;
+  private final String title;
+  private final String author;
+  private final String publisher;
+  private final LocalDate publicationDate;
+  private final double price;
+  private final int quantity;
+  private final List<Category> categories;
+  private final String description;
+  private final String language;
+}

mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/converter/BookConverter.java

@@ -0,0 +1,42 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.converter;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.book.BookDTO;
+import fr.iut_fbleau.but3.dev62.mylibrary.book.BookInfo;
+import fr.iut_fbleau.but3.dev62.mylibrary.book.entity.Book;
+
+public final class BookConverter {
+
+  private BookConverter() {
+
+  }
+
+  public static Book toDomain(BookInfo book) {
+    return Book.builder()
+        .isbn(book.isbn())
+        .title(book.title())
+        .author(book.author())
+        .publisher(book.publisher())
+        .publicationDate(book.publicationDate())
+        .price(book.price())
+        .quantity(book.quantity())
+        .categories(book.categories())
+        .description(book.description())
+        .language(book.language())
+        .build();
+  }
+
+  public static BookDTO toDTO(Book book) {
+    return BookDTO.builder()
+        .isbn(book.getIsbn())
+        .title(book.getTitle())
+        .author(book.getAuthor())
+        .publisher(book.getPublisher())
+        .publicationDate(book.getPublicationDate())
+        .price(book.getPrice())
+        .quantity(book.getQuantity())
+        .categories(book.getCategories())
+        .description(book.getDescription())
+        .language(book.getLanguage())
+        .build();
+  }
+}

mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookAlreadyExistsException.java

@@ -0,0 +1,13 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import java.text.MessageFormat;
+
+public class BookAlreadyExistsException extends Exception {
+
+  public static final String A_BOOK_WITH_ISBN_ALREADY_EXISTS_MESSAGE = "A book with isbn {0} already exists";
+
+  public BookAlreadyExistsException(long isbn) {
+    // ISBN passe en String pour ne pas que MessageFormat ajoute le separateur de milliers
+    super(MessageFormat.format(A_BOOK_WITH_ISBN_ALREADY_EXISTS_MESSAGE, String.valueOf(isbn)));
+  }
+}

mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookNotFoundException.java

@@ -0,0 +1,13 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import java.text.MessageFormat;
+
+public class BookNotFoundException extends Exception {
+
+  public static final String THE_BOOK_WITH_ISBN_DOES_NOT_EXIST_MESSAGE = "The book with isbn {0} does not exist";
+
+  public BookNotFoundException(long isbn) {
+    // ISBN passe en String pour ne pas que MessageFormat ajoute le separateur de milliers
+    super(MessageFormat.format(THE_BOOK_WITH_ISBN_DOES_NOT_EXIST_MESSAGE, String.valueOf(isbn)));
+  }
+}

mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookQuantityException.java

@@ -0,0 +1,12 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import java.text.MessageFormat;
+
+public class IllegalBookQuantityException extends Exception {
+
+  public static final String CANNOT_REMOVE_STOCK = "Cannot remove {0} units from {1} units in stock";
+
+  public IllegalBookQuantityException(int needed, int actual) {
+    super(MessageFormat.format(CANNOT_REMOVE_STOCK, needed, actual));
+  }
+}

mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/NotValidBookException.java

@@ -0,0 +1,8 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+public class NotValidBookException extends Exception {
+
+  public NotValidBookException(String message) {
+    super(message);
+  }
+}

mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/repository/BookRepository.java

@@ -0,0 +1,42 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.repository;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.book.entity.Book;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Optional;
+import lombok.NoArgsConstructor;
+
+@NoArgsConstructor
+public final class BookRepository {
+
+  private final List<Book> books = new ArrayList<>();
+
+  public List<Book> findAll() {
+    return books;
+  }
+
+  public void deleteAll() {
+    books.clear();
+  }
+
+  public Book save(Book book) {
+    Optional<Book> existing = findByIsbn(book.getIsbn());
+    existing.ifPresent(books::remove);
+    books.add(book);
+    return book;
+  }
+
+  public Optional<Book> findByIsbn(long isbn) {
+    return books.stream()
+        .filter(b -> b.getIsbn() == isbn)
+        .findFirst();
+  }
+
+  public boolean existsByIsbn(long isbn) {
+    return books.stream().anyMatch(b -> b.getIsbn() == isbn);
+  }
+
+  public void delete(Book book) {
+    books.remove(book);
+  }
+}

mylibrary/src/main/java/fr/iut_fbleau/but3/dev62/mylibrary/book/validator/BookValidator.java

@@ -0,0 +1,93 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.validator;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.book.BookInfo;
+import fr.iut_fbleau.but3.dev62.mylibrary.book.exception.NotValidBookException;
+
+public final class BookValidator {
+
+  public static final int TITLE_MAX_LENGTH = 255;
+
+  public static final String ISBN_MUST_BE_POSITIVE = "Isbn must be a positive number";
+  public static final String TITLE_CANNOT_BE_BLANK = "Title cannot be blank";
+  public static final String TITLE_TOO_LONG = "Title cannot exceed " + TITLE_MAX_LENGTH + " characters";
+  public static final String AUTHOR_CANNOT_BE_BLANK = "Author cannot be blank";
+  public static final String PUBLISHER_CANNOT_BE_BLANK = "Publisher cannot be blank";
+  public static final String PUBLICATION_DATE_REQUIRED = "Publication date is required";
+  public static final String PRICE_MUST_BE_POSITIVE = "Price must be strictly positive";
+  public static final String QUANTITY_MUST_BE_POSITIVE_OR_ZERO = "Quantity must be >= 0";
+  public static final String CATEGORIES_REQUIRED = "At least one category is required";
+  public static final String LANGUAGE_CANNOT_BE_BLANK = "Language cannot be blank";
+
+  private BookValidator() {
+
+  }
+
+  public static void validate(BookInfo book) throws NotValidBookException {
+    validateIsbn(book);
+    validateTitle(book);
+    validateAuthor(book);
+    validatePublisher(book);
+    validatePublicationDate(book);
+    validatePrice(book);
+    validateQuantity(book);
+    validateCategories(book);
+    validateLanguage(book);
+  }
+
+  private static void validateIsbn(BookInfo book) throws NotValidBookException {
+    if (book.isbn() <= 0) {
+      throw new NotValidBookException(ISBN_MUST_BE_POSITIVE);
+    }
+  }
+
+  private static void validateTitle(BookInfo book) throws NotValidBookException {
+    if (book.title() == null || book.title().isBlank()) {
+      throw new NotValidBookException(TITLE_CANNOT_BE_BLANK);
+    }
+    if (book.title().length() > TITLE_MAX_LENGTH) {
+      throw new NotValidBookException(TITLE_TOO_LONG);
+    }
+  }
+
+  private static void validateAuthor(BookInfo book) throws NotValidBookException {
+    if (book.author() == null || book.author().isBlank()) {
+      throw new NotValidBookException(AUTHOR_CANNOT_BE_BLANK);
+    }
+  }
+
+  private static void validatePublisher(BookInfo book) throws NotValidBookException {
+    if (book.publisher() == null || book.publisher().isBlank()) {
+      throw new NotValidBookException(PUBLISHER_CANNOT_BE_BLANK);
+    }
+  }
+
+  private static void validatePublicationDate(BookInfo book) throws NotValidBookException {
+    if (book.publicationDate() == null) {
+      throw new NotValidBookException(PUBLICATION_DATE_REQUIRED);
+    }
+  }
+
+  private static void validatePrice(BookInfo book) throws NotValidBookException {
+    if (book.price() <= 0) {
+      throw new NotValidBookException(PRICE_MUST_BE_POSITIVE);
+    }
+  }
+
+  private static void validateQuantity(BookInfo book) throws NotValidBookException {
+    if (book.quantity() < 0) {
+      throw new NotValidBookException(QUANTITY_MUST_BE_POSITIVE_OR_ZERO);
+    }
+  }
+
+  private static void validateCategories(BookInfo book) throws NotValidBookException {
+    if (book.categories() == null || book.categories().isEmpty()) {
+      throw new NotValidBookException(CATEGORIES_REQUIRED);
+    }
+  }
+
+  private static void validateLanguage(BookInfo book) throws NotValidBookException {
+    if (book.language() == null || book.language().isBlank()) {
+      throw new NotValidBookException(LANGUAGE_CANNOT_BE_BLANK);
+    }
+  }
+}

mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/converter/BookConverterTest.java

@@ -0,0 +1,86 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.converter;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.book.BookDTO;
+import fr.iut_fbleau.but3.dev62.mylibrary.book.BookInfo;
+import fr.iut_fbleau.but3.dev62.mylibrary.book.entity.Book;
+import fr.iut_fbleau.but3.dev62.mylibrary.book.entity.Category;
+import java.time.LocalDate;
+import java.util.List;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BookConverterTest {
+
+  @Nested
+  @DisplayName("toDomain() method tests")
+  class ToDomainTests {
+
+    @Test
+    @DisplayName("Should convert BookInfo to Book entity preserving all fields")
+    void testToDomain() {
+      BookInfo info = new BookInfo(
+          9780321125217L,
+          "DDD",
+          "Evans",
+          "Addison-Wesley",
+          LocalDate.of(2003, 8, 22),
+          54.99,
+          10,
+          List.of(Category.SCIENCE),
+          "desc",
+          "EN"
+      );
+
+      Book book = BookConverter.toDomain(info);
+
+      assertEquals(info.isbn(), book.getIsbn());
+      assertEquals(info.title(), book.getTitle());
+      assertEquals(info.author(), book.getAuthor());
+      assertEquals(info.publisher(), book.getPublisher());
+      assertEquals(info.publicationDate(), book.getPublicationDate());
+      assertEquals(info.price(), book.getPrice());
+      assertEquals(info.quantity(), book.getQuantity());
+      assertEquals(info.categories(), book.getCategories());
+      assertEquals(info.description(), book.getDescription());
+      assertEquals(info.language(), book.getLanguage());
+    }
+  }
+
+  @Nested
+  @DisplayName("toDTO() method tests")
+  class ToDTOTests {
+
+    @Test
+    @DisplayName("Should convert Book entity to BookDTO preserving all fields")
+    void testToDTO() {
+      Book book = Book.builder()
+          .isbn(123L)
+          .title("T")
+          .author("A")
+          .publisher("P")
+          .publicationDate(LocalDate.of(2020, 1, 1))
+          .price(9.99)
+          .quantity(5)
+          .categories(List.of(Category.FICTION))
+          .description("d")
+          .language("FR")
+          .build();
+
+      BookDTO dto = BookConverter.toDTO(book);
+
+      assertEquals(123L, dto.getIsbn());
+      assertEquals("T", dto.getTitle());
+      assertEquals("A", dto.getAuthor());
+      assertEquals("P", dto.getPublisher());
+      assertEquals(LocalDate.of(2020, 1, 1), dto.getPublicationDate());
+      assertEquals(9.99, dto.getPrice());
+      assertEquals(5, dto.getQuantity());
+      assertEquals(List.of(Category.FICTION), dto.getCategories());
+      assertEquals("d", dto.getDescription());
+      assertEquals("FR", dto.getLanguage());
+    }
+  }
+}

mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/entity/BookTest.java

@@ -0,0 +1,75 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.entity;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.book.exception.IllegalBookQuantityException;
+import java.time.LocalDate;
+import java.util.List;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BookTest {
+
+  @Test
+  @DisplayName("Builder should create a valid Book instance")
+  void testBookBuilder() {
+    long isbn = 9780321125217L;
+    Book book = Book.builder()
+        .isbn(isbn)
+        .title("Domain-Driven Design")
+        .author("Eric Evans")
+        .publisher("Addison-Wesley")
+        .publicationDate(LocalDate.of(2003, 8, 22))
+        .price(54.99)
+        .quantity(10)
+        .categories(List.of(Category.SCIENCE, Category.REFERENCE))
+        .description("Tackling complexity in the heart of software")
+        .language("EN")
+        .build();
+
+    assertEquals(isbn, book.getIsbn());
+    assertEquals("Domain-Driven Design", book.getTitle());
+    assertEquals("Eric Evans", book.getAuthor());
+    assertEquals("Addison-Wesley", book.getPublisher());
+    assertEquals(LocalDate.of(2003, 8, 22), book.getPublicationDate());
+    assertEquals(54.99, book.getPrice());
+    assertEquals(10, book.getQuantity());
+    assertEquals(List.of(Category.SCIENCE, Category.REFERENCE), book.getCategories());
+    assertEquals("EN", book.getLanguage());
+  }
+
+  @Nested
+  @DisplayName("Stock management")
+  class StockTests {
+
+    @Test
+    @DisplayName("addStock should increase the quantity")
+    void testAddStock() {
+      Book book = Book.builder().quantity(5).build();
+      book.addStock(7);
+      assertEquals(12, book.getQuantity());
+    }
+
+    @Test
+    @DisplayName("removeStock should decrease the quantity")
+    void testRemoveStock() throws IllegalBookQuantityException {
+      Book book = Book.builder().quantity(5).build();
+      book.removeStock(3);
+      assertEquals(2, book.getQuantity());
+    }
+
+    @Test
+    @DisplayName("removeStock should throw when removing more than available")
+    void testRemoveTooMuchStock() {
+      Book book = Book.builder().quantity(5).build();
+      IllegalBookQuantityException exception = assertThrows(
+          IllegalBookQuantityException.class,
+          () -> book.removeStock(10)
+      );
+      assertEquals(5, book.getQuantity());
+      assertTrue(exception.getMessage().contains("10"));
+      assertTrue(exception.getMessage().contains("5"));
+    }
+  }
+}

mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookAlreadyExistsExceptionTest.java

@@ -0,0 +1,26 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BookAlreadyExistsExceptionTest {
+
+  @Test
+  @DisplayName("Exception message should contain the ISBN provided")
+  void testExceptionMessageContainsIsbn() {
+    long isbn = 9780321125217L;
+
+    BookAlreadyExistsException exception = new BookAlreadyExistsException(isbn);
+
+    assertTrue(exception.getMessage().contains(String.valueOf(isbn)));
+  }
+
+  @Test
+  @DisplayName("Exception should expose its message constant")
+  void testConstantMessage() {
+    assertEquals("A book with isbn {0} already exists",
+        BookAlreadyExistsException.A_BOOK_WITH_ISBN_ALREADY_EXISTS_MESSAGE);
+  }
+}

mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/BookNotFoundExceptionTest.java

@@ -0,0 +1,37 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BookNotFoundExceptionTest {
+
+  @Test
+  @DisplayName("Exception message should contain the ISBN provided")
+  void testExceptionMessageContainsIsbn() {
+    long isbn = 9780321125217L;
+
+    BookNotFoundException exception = new BookNotFoundException(isbn);
+
+    assertTrue(exception.getMessage().contains(String.valueOf(isbn)));
+  }
+
+  @Test
+  @DisplayName("Exception should expose its message constant")
+  void testConstantMessage() {
+    assertEquals("The book with isbn {0} does not exist",
+        BookNotFoundException.THE_BOOK_WITH_ISBN_DOES_NOT_EXIST_MESSAGE);
+  }
+
+  @Test
+  @DisplayName("Exception should be properly thrown and caught")
+  void testExceptionCanBeThrownAndCaught() {
+    long isbn = 1L;
+    try {
+      throw new BookNotFoundException(isbn);
+    } catch (BookNotFoundException e) {
+      assertTrue(e.getMessage().contains("1"));
+    }
+  }
+}

mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/IllegalBookQuantityExceptionTest.java

@@ -0,0 +1,33 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import java.text.MessageFormat;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class IllegalBookQuantityExceptionTest {
+
+  @Test
+  @DisplayName("Exception message should contain the requested and actual quantities")
+  void testExceptionMessageContainsQuantities() {
+    IllegalBookQuantityException exception = new IllegalBookQuantityException(10, 3);
+    String expected = "Cannot remove 10 units from 3 units in stock";
+    assertEquals(expected, exception.getMessage());
+  }
+
+  @ParameterizedTest
+  @CsvSource({
+      "10, 3",
+      "100, 0",
+      "5, 4"
+  })
+  @DisplayName("Message should be formatted using the constant template")
+  void testFormattedMessage(int needed, int actual) {
+    IllegalBookQuantityException exception = new IllegalBookQuantityException(needed, actual);
+    String expected = MessageFormat.format(IllegalBookQuantityException.CANNOT_REMOVE_STOCK, needed, actual);
+    assertEquals(expected, exception.getMessage());
+  }
+}

mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/exception/NotValidBookExceptionTest.java

@@ -0,0 +1,44 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.exception;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class NotValidBookExceptionTest {
+
+  @Test
+  @DisplayName("Exception should be created with the provided message")
+  void testExceptionCreation() {
+    String msg = "title cannot be blank";
+    NotValidBookException exception = new NotValidBookException(msg);
+    assertEquals(msg, exception.getMessage());
+  }
+
+  @ParameterizedTest
+  @ValueSource(strings = {
+      "Title cannot be blank",
+      "Author cannot be blank",
+      "Price must be strictly positive",
+      "At least one category is required"
+  })
+  @DisplayName("Exception should propagate any validation message")
+  void testExceptionWithDifferentMessages(String message) {
+    NotValidBookException exception = new NotValidBookException(message);
+    assertEquals(message, exception.getMessage());
+  }
+
+  @Test
+  @DisplayName("Exception should be catchable as a general Exception")
+  void testExceptionInheritance() {
+    String msg = "invalid book";
+    try {
+      throw new NotValidBookException(msg);
+    } catch (Exception e) {
+      assertEquals(NotValidBookException.class, e.getClass());
+      assertEquals(msg, e.getMessage());
+    }
+  }
+}

mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/repository/BookRepositoryTest.java

@@ -0,0 +1,149 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.repository;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.book.entity.Book;
+import fr.iut_fbleau.but3.dev62.mylibrary.book.entity.Category;
+import java.time.LocalDate;
+import java.util.List;
+import java.util.Optional;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BookRepositoryTest {
+
+  private BookRepository repository;
+  private Book book1;
+  private Book book2;
+
+  @BeforeEach
+  void setUp() {
+    repository = new BookRepository();
+
+    book1 = Book.builder()
+        .isbn(1111111111111L)
+        .title("Book One")
+        .author("Author A")
+        .publisher("Pub")
+        .publicationDate(LocalDate.of(2020, 1, 1))
+        .price(10.0)
+        .quantity(2)
+        .categories(List.of(Category.FICTION))
+        .language("EN")
+        .build();
+
+    book2 = Book.builder()
+        .isbn(2222222222222L)
+        .title("Book Two")
+        .author("Author B")
+        .publisher("Pub")
+        .publicationDate(LocalDate.of(2021, 1, 1))
+        .price(20.0)
+        .quantity(0)
+        .categories(List.of(Category.HISTORY))
+        .language("FR")
+        .build();
+  }
+
+  @Test
+  @DisplayName("New repository should be empty")
+  void testNewRepositoryIsEmpty() {
+    assertTrue(repository.findAll().isEmpty());
+  }
+
+  @Nested
+  @DisplayName("Save operations")
+  class SaveOperations {
+
+    @Test
+    @DisplayName("Save should add a new book")
+    void testSave() {
+      Book saved = repository.save(book1);
+      assertEquals(1, repository.findAll().size());
+      assertEquals(book1.getIsbn(), saved.getIsbn());
+    }
+
+    @Test
+    @DisplayName("Save should replace existing book with same ISBN (idempotency)")
+    void testSaveReplacesExisting() {
+      repository.save(book1);
+      Book updated = Book.builder()
+          .isbn(book1.getIsbn())
+          .title("New title")
+          .author("Author A")
+          .publisher("Pub")
+          .publicationDate(LocalDate.of(2020, 1, 1))
+          .price(10.0)
+          .quantity(99)
+          .categories(List.of(Category.FICTION))
+          .language("EN")
+          .build();
+
+      repository.save(updated);
+
+      assertEquals(1, repository.findAll().size());
+      assertEquals(99, repository.findByIsbn(book1.getIsbn()).orElseThrow().getQuantity());
+      assertEquals("New title", repository.findByIsbn(book1.getIsbn()).orElseThrow().getTitle());
+    }
+  }
+
+  @Nested
+  @DisplayName("Find operations")
+  class FindOperations {
+
+    @BeforeEach
+    void seed() {
+      repository.save(book1);
+      repository.save(book2);
+    }
+
+    @Test
+    @DisplayName("findByIsbn returns the matching book")
+    void testFindByIsbn() {
+      Optional<Book> found = repository.findByIsbn(book1.getIsbn());
+      assertTrue(found.isPresent());
+      assertEquals(book1.getTitle(), found.get().getTitle());
+    }
+
+    @Test
+    @DisplayName("findByIsbn returns empty when not found")
+    void testFindByIsbnNotFound() {
+      assertTrue(repository.findByIsbn(99L).isEmpty());
+    }
+
+    @Test
+    @DisplayName("existsByIsbn returns true / false consistently")
+    void testExistsByIsbn() {
+      assertTrue(repository.existsByIsbn(book1.getIsbn()));
+      assertFalse(repository.existsByIsbn(99L));
+    }
+  }
+
+  @Nested
+  @DisplayName("Delete operations")
+  class DeleteOperations {
+
+    @BeforeEach
+    void seed() {
+      repository.save(book1);
+      repository.save(book2);
+    }
+
+    @Test
+    @DisplayName("delete should remove the specified book")
+    void testDelete() {
+      repository.delete(book1);
+      assertEquals(1, repository.findAll().size());
+      assertFalse(repository.existsByIsbn(book1.getIsbn()));
+    }
+
+    @Test
+    @DisplayName("deleteAll should clear the repository")
+    void testDeleteAll() {
+      repository.deleteAll();
+      assertTrue(repository.findAll().isEmpty());
+    }
+  }
+}

mylibrary/src/test/java/fr/iut_fbleau/but3/dev62/mylibrary/book/validator/BookValidatorTest.java

@@ -0,0 +1,167 @@
+package fr.iut_fbleau.but3.dev62.mylibrary.book.validator;
+
+import fr.iut_fbleau.but3.dev62.mylibrary.book.BookInfo;
+import fr.iut_fbleau.but3.dev62.mylibrary.book.entity.Category;
+import fr.iut_fbleau.but3.dev62.mylibrary.book.exception.NotValidBookException;
+import java.time.LocalDate;
+import java.util.List;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BookValidatorTest {
+
+  private BookInfo valid() {
+    return new BookInfo(
+        9780321125217L,
+        "Domain-Driven Design",
+        "Eric Evans",
+        "Addison-Wesley",
+        LocalDate.of(2003, 8, 22),
+        54.99,
+        10,
+        List.of(Category.SCIENCE),
+        "Tackling complexity in the heart of software",
+        "EN"
+    );
+  }
+
+  @Test
+  @DisplayName("Should accept a valid BookInfo")
+  void testValidBook() {
+    assertDoesNotThrow(() -> BookValidator.validate(valid()));
+  }
+
+  @Nested
+  @DisplayName("ISBN validation")
+  class IsbnTests {
+
+    @ParameterizedTest
+    @ValueSource(longs = {0L, -1L, -9999L})
+    @DisplayName("Should reject ISBN that is not strictly positive")
+    void testInvalidIsbn(long isbn) {
+      BookInfo info = new BookInfo(isbn, "T", "A", "P", LocalDate.now(), 1.0, 0, List.of(Category.SCIENCE), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.ISBN_MUST_BE_POSITIVE, ex.getMessage());
+    }
+  }
+
+  @Nested
+  @DisplayName("Title validation")
+  class TitleTests {
+
+    @ParameterizedTest
+    @ValueSource(strings = {"", " ", "\t", "\n"})
+    @DisplayName("Should reject blank title")
+    void testBlankTitle(String title) {
+      BookInfo info = new BookInfo(1L, title, "A", "P", LocalDate.now(), 1.0, 0, List.of(Category.SCIENCE), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.TITLE_CANNOT_BE_BLANK, ex.getMessage());
+    }
+
+    @Test
+    @DisplayName("Should reject null title")
+    void testNullTitle() {
+      BookInfo info = new BookInfo(1L, null, "A", "P", LocalDate.now(), 1.0, 0, List.of(Category.SCIENCE), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.TITLE_CANNOT_BE_BLANK, ex.getMessage());
+    }
+
+    @Test
+    @DisplayName("Should reject title longer than 255 characters")
+    void testTitleTooLong() {
+      String longTitle = "a".repeat(256);
+      BookInfo info = new BookInfo(1L, longTitle, "A", "P", LocalDate.now(), 1.0, 0, List.of(Category.SCIENCE), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.TITLE_TOO_LONG, ex.getMessage());
+    }
+  }
+
+  @Nested
+  @DisplayName("Author / Publisher validation")
+  class AuthorPublisherTests {
+
+    @ParameterizedTest
+    @ValueSource(strings = {"", " ", "\t"})
+    @DisplayName("Should reject blank author")
+    void testBlankAuthor(String author) {
+      BookInfo info = new BookInfo(1L, "T", author, "P", LocalDate.now(), 1.0, 0, List.of(Category.SCIENCE), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.AUTHOR_CANNOT_BE_BLANK, ex.getMessage());
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"", " ", "\t"})
+    @DisplayName("Should reject blank publisher")
+    void testBlankPublisher(String publisher) {
+      BookInfo info = new BookInfo(1L, "T", "A", publisher, LocalDate.now(), 1.0, 0, List.of(Category.SCIENCE), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.PUBLISHER_CANNOT_BE_BLANK, ex.getMessage());
+    }
+  }
+
+  @Nested
+  @DisplayName("Date / Price / Quantity validation")
+  class NumericTests {
+
+    @Test
+    @DisplayName("Should reject null publication date")
+    void testNullDate() {
+      BookInfo info = new BookInfo(1L, "T", "A", "P", null, 1.0, 0, List.of(Category.SCIENCE), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.PUBLICATION_DATE_REQUIRED, ex.getMessage());
+    }
+
+    @ParameterizedTest
+    @ValueSource(doubles = {0.0, -0.01, -10.0})
+    @DisplayName("Should reject non-positive price")
+    void testNonPositivePrice(double price) {
+      BookInfo info = new BookInfo(1L, "T", "A", "P", LocalDate.now(), price, 0, List.of(Category.SCIENCE), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.PRICE_MUST_BE_POSITIVE, ex.getMessage());
+    }
+
+    @ParameterizedTest
+    @ValueSource(ints = {-1, -100})
+    @DisplayName("Should reject negative quantity")
+    void testNegativeQuantity(int quantity) {
+      BookInfo info = new BookInfo(1L, "T", "A", "P", LocalDate.now(), 1.0, quantity, List.of(Category.SCIENCE), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.QUANTITY_MUST_BE_POSITIVE_OR_ZERO, ex.getMessage());
+    }
+  }
+
+  @Nested
+  @DisplayName("Categories / Language validation")
+  class MetadataTests {
+
+    @Test
+    @DisplayName("Should reject empty categories")
+    void testEmptyCategories() {
+      BookInfo info = new BookInfo(1L, "T", "A", "P", LocalDate.now(), 1.0, 0, List.of(), "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.CATEGORIES_REQUIRED, ex.getMessage());
+    }
+
+    @Test
+    @DisplayName("Should reject null categories")
+    void testNullCategories() {
+      BookInfo info = new BookInfo(1L, "T", "A", "P", LocalDate.now(), 1.0, 0, null, "", "EN");
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.CATEGORIES_REQUIRED, ex.getMessage());
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"", " ", "\t"})
+    @DisplayName("Should reject blank language")
+    void testBlankLanguage(String language) {
+      BookInfo info = new BookInfo(1L, "T", "A", "P", LocalDate.now(), 1.0, 0, List.of(Category.SCIENCE), "", language);
+      NotValidBookException ex = assertThrows(NotValidBookException.class, () -> BookValidator.validate(info));
+      assertEquals(BookValidator.LANGUAGE_CANNOT_BE_BLANK, ex.getMessage());
+    }
+  }
+}