Merge branch 'feature/user-auth-middleware'

backend/.gitignore

@@ -1 +1,2 @@
-vendor/
+vendor/
+.phpunit.cache/

backend/app/Auth/BcryptPasswordHasher.php

@@ -0,0 +1,16 @@
+<?php
+
+namespace App\Auth;
+
+class BcryptPasswordHasher implements PasswordHasher
+{
+    public function hash(string $password): string
+    {
+        return password_hash($password, PASSWORD_DEFAULT);
+    }
+
+    public function verify(string $password, string $hash): bool
+    {
+        return password_verify($password, $hash);
+    }
+}

backend/app/Auth/Clock.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace App\Auth;
+
+use DateTimeImmutable;
+
+interface Clock
+{
+    public function now(): DateTimeImmutable;
+}

backend/app/Auth/CreateSessionDto.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace App\Auth;
+
+use App\User\User;
+use DateTimeImmutable;
+
+class CreateSessionDto
+{
+    public function __construct(
+        public string $token,
+        public User $user,
+        public DateTimeImmutable $createdAt,
+        public DateTimeImmutable $expiresAt,
+    ) {
+    }
+}

backend/app/Auth/PasswordHasher.php

@@ -0,0 +1,10 @@
+<?php
+
+namespace App\Auth;
+
+interface PasswordHasher
+{
+    public function hash(string $password): string;
+
+    public function verify(string $password, string $hash): bool;
+}

backend/app/Auth/RandomTokenGenerator.php

@@ -0,0 +1,11 @@
+<?php
+
+namespace App\Auth;
+
+class RandomTokenGenerator implements TokenGenerator
+{
+    public function generate(): string
+    {
+        return bin2hex(random_bytes(32));
+    }
+}

backend/app/Auth/Session.php

@@ -0,0 +1,42 @@
+<?php
+
+namespace App\Auth;
+
+use App\User\User;
+use DateTimeImmutable;
+
+class Session
+{
+    public function __construct(
+        private string $token,
+        private User $user,
+        private DateTimeImmutable $createdAt,
+        private DateTimeImmutable $expiresAt,
+    ) {
+    }
+
+    public function getToken(): string
+    {
+        return $this->token;
+    }
+
+    public function getUser(): User
+    {
+        return $this->user;
+    }
+
+    public function getCreatedAt(): DateTimeImmutable
+    {
+        return $this->createdAt;
+    }
+
+    public function getExpiresAt(): DateTimeImmutable
+    {
+        return $this->expiresAt;
+    }
+
+    public function isExpired(DateTimeImmutable $now): bool
+    {
+        return $now >= $this->expiresAt;
+    }
+}

backend/app/Auth/SessionRepository.php

@@ -0,0 +1,12 @@
+<?php
+
+namespace App\Auth;
+
+interface SessionRepository
+{
+    public function create(CreateSessionDto $dto): Session;
+
+    public function findByToken(string $token): ?Session;
+
+    public function deleteByToken(string $token): void;
+}

backend/app/Auth/SystemClock.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace App\Auth;
+
+use DateTimeImmutable;
+use DateTimeZone;
+
+class SystemClock implements Clock
+{
+    public function now(): DateTimeImmutable
+    {
+        return new DateTimeImmutable('now', new DateTimeZone('UTC'));
+    }
+}

backend/app/Auth/TokenGenerator.php

@@ -0,0 +1,8 @@
+<?php
+
+namespace App\Auth;
+
+interface TokenGenerator
+{
+    public function generate(): string;
+}

backend/app/Auth/UseCases/AuthenticateUser/AuthenticateUser.php

@@ -0,0 +1,52 @@
+<?php
+
+namespace App\Auth\UseCases\AuthenticateUser;
+
+use App\Auth\PasswordHasher;
+use App\Exceptions\BadRequestException;
+use App\Exceptions\UnauthorizedException;
+use App\Shared\ValueObject\EmailAddress;
+use App\User\User;
+use App\User\UserRepository;
+
+class AuthenticateUser
+{
+    public function __construct(
+        private UserRepository $userRepo,
+        private PasswordHasher $hasher,
+    ) {
+    }
+
+    /**
+     * @throws BadRequestException
+     * @throws UnauthorizedException
+     */
+    public function execute(AuthenticateUserRequest $request): User
+    {
+        if ($request->email === null || $request->email === '') {
+            throw new BadRequestException('email is required');
+        }
+        if ($request->password === null || $request->password === '') {
+            throw new BadRequestException('password is required');
+        }
+
+        $user = $this->userRepo->findByEmail(
+            new EmailAddress($request->email),
+        );
+
+        if ($user === null) {
+            throw new UnauthorizedException('invalid credentials');
+        }
+
+        $passwordMatches = $this->hasher->verify(
+            $request->password,
+            $user->getPasswordHash(),
+        );
+
+        if (! $passwordMatches) {
+            throw new UnauthorizedException('invalid credentials');
+        }
+
+        return $user;
+    }
+}

backend/app/Auth/UseCases/AuthenticateUser/AuthenticateUserRequest.php

@@ -0,0 +1,12 @@
+<?php
+
+namespace App\Auth\UseCases\AuthenticateUser;
+
+class AuthenticateUserRequest
+{
+    public function __construct(
+        public ?string $email,
+        public ?string $password,
+    ) {
+    }
+}

backend/app/Auth/UseCases/CreateSession/CreateSession.php

@@ -0,0 +1,35 @@
+<?php
+
+namespace App\Auth\UseCases\CreateSession;
+
+use App\Auth\Clock;
+use App\Auth\CreateSessionDto;
+use App\Auth\Session;
+use App\Auth\SessionRepository;
+use App\Auth\TokenGenerator;
+use App\User\User;
+
+class CreateSession
+{
+    private const SESSION_LIFETIME = '+7 days';
+
+    public function __construct(
+        private SessionRepository $sessionRepo,
+        private TokenGenerator $tokenGenerator,
+        private Clock $clock,
+    ) {
+    }
+
+    public function execute(User $user): Session
+    {
+        $now = $this->clock->now();
+        $expiresAt = $now->modify(self::SESSION_LIFETIME);
+
+        return $this->sessionRepo->create(new CreateSessionDto(
+            token: $this->tokenGenerator->generate(),
+            user: $user,
+            createdAt: $now,
+            expiresAt: $expiresAt,
+        ));
+    }
+}

backend/app/Auth/UseCases/Logout/Logout.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Auth\UseCases\Logout;
+
+use App\Auth\SessionRepository;
+
+class Logout
+{
+    public function __construct(
+        private SessionRepository $sessionRepo,
+    ) {
+    }
+
+    public function execute(?string $token): void
+    {
+        if (! is_string($token) || $token === '') {
+            return;
+        }
+
+        $this->sessionRepo->deleteByToken($token);
+    }
+}

backend/app/Controllers/AuthController.php

@@ -0,0 +1,152 @@
+<?php
+
+namespace App\Controllers;
+
+use App\Auth\UseCases\AuthenticateUser\AuthenticateUser;
+use App\Auth\UseCases\AuthenticateUser\AuthenticateUserRequest;
+use App\Auth\UseCases\CreateSession\CreateSession;
+use App\Auth\UseCases\Logout\Logout;
+use App\Exceptions\BadRequestException;
+use App\Exceptions\UnauthorizedException;
+use App\Middleware\AuthMiddleware;
+use App\User\User;
+use DomainException;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Slim\Psr7\Response;
+use Throwable;
+
+class AuthController
+{
+    public function __construct(
+        private AuthenticateUser $authenticateUser,
+        private CreateSession $createSession,
+        private Logout $logout,
+    ) {
+    }
+
+    public function login(
+        ServerRequestInterface $request,
+    ): ResponseInterface {
+        $body = $this->parseBody($request);
+
+        try {
+            $user = $this->authenticateUser->execute(
+                new AuthenticateUserRequest(
+                    email: $body['email'] ?? null,
+                    password: $body['password'] ?? null,
+                ),
+            );
+        } catch (Throwable $exception) {
+            return $this->errorResponse($exception);
+        }
+
+        $session = $this->createSession->execute($user);
+
+        $response = $this->jsonResponse(
+            ['user' => $this->buildUserPayload($user)],
+            200,
+        );
+
+        $cookieValue = sprintf(
+            '%s=%s; Expires=%s; Path=/; HttpOnly; SameSite=Lax',
+            AuthMiddleware::COOKIE_NAME,
+            $session->getToken(),
+            $session->getExpiresAt()->format('D, d-M-Y H:i:s T'),
+        );
+
+        return $response->withHeader('Set-Cookie', $cookieValue);
+    }
+
+    public function logout(
+        ServerRequestInterface $request,
+    ): ResponseInterface {
+        $cookies = $request->getCookieParams();
+        $token = $cookies[AuthMiddleware::COOKIE_NAME] ?? null;
+
+        $this->logout->execute($token);
+
+        $response = new Response(204);
+
+        $cookieValue = sprintf(
+            '%s=; Expires=%s; Path=/; HttpOnly; SameSite=Lax',
+            AuthMiddleware::COOKIE_NAME,
+            'Thu, 01-Jan-1970 00:00:00 GMT',
+        );
+
+        return $response->withHeader('Set-Cookie', $cookieValue);
+    }
+
+    public function me(
+        ServerRequestInterface $request,
+    ): ResponseInterface {
+        $user = $request->getAttribute('user');
+
+        if (! $user instanceof User) {
+            return $this->jsonResponse(
+                ['error' => 'unauthenticated'],
+                401,
+            );
+        }
+
+        return $this->jsonResponse(
+            ['user' => $this->buildUserPayload($user)],
+            200,
+        );
+    }
+
+    private function buildUserPayload(User $user): array
+    {
+        return [
+            'id' => $user->getId(),
+            'email' => $user->getEmail()->value(),
+        ];
+    }
+
+    private function jsonResponse(
+        array $data,
+        int $status,
+    ): ResponseInterface {
+        $response = new Response($status);
+        $response->getBody()->write(json_encode($data));
+
+        return $response->withHeader('Content-Type', 'application/json');
+    }
+
+    private function errorResponse(Throwable $exception): ResponseInterface
+    {
+        if ($exception instanceof BadRequestException) {
+            return $this->jsonResponse(
+                ['error' => $exception->getMessage()],
+                400,
+            );
+        }
+        if ($exception instanceof UnauthorizedException) {
+            return $this->jsonResponse(
+                ['error' => $exception->getMessage()],
+                401,
+            );
+        }
+        if ($exception instanceof DomainException) {
+            return $this->jsonResponse(
+                ['error' => $exception->getMessage()],
+                409,
+            );
+        }
+        throw $exception;
+    }
+
+    private function parseBody(ServerRequestInterface $request): array
+    {
+        $contentType = $request->getHeaderLine('Content-Type');
+
+        if (str_contains($contentType, 'application/json')) {
+            $body = (string) $request->getBody();
+            $decoded = json_decode($body, true);
+
+            return is_array($decoded) ? $decoded : [];
+        }
+
+        return (array) $request->getParsedBody();
+    }
+}

backend/app/Exceptions/BadRequestException.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace App\Exceptions;
+
+use DomainException;
+
+class BadRequestException extends DomainException
+{
+}

backend/app/Exceptions/UnauthorizedException.php

@@ -0,0 +1,9 @@
+<?php
+
+namespace App\Exceptions;
+
+use DomainException;
+
+class UnauthorizedException extends DomainException
+{
+}

backend/app/Middleware/AuthMiddleware.php

@@ -0,0 +1,60 @@
+<?php
+
+namespace App\Middleware;
+
+use App\Auth\Clock;
+use App\Auth\SessionRepository;
+use Psr\Http\Message\ResponseInterface;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\MiddlewareInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Slim\Psr7\Response;
+
+class AuthMiddleware implements MiddlewareInterface
+{
+    public const COOKIE_NAME = 'auth_token';
+
+    public function __construct(
+        private SessionRepository $sessionRepo,
+        private Clock $clock,
+    ) {
+    }
+
+    public function process(
+        ServerRequestInterface $request,
+        RequestHandlerInterface $handler,
+    ): ResponseInterface {
+        $cookies = $request->getCookieParams();
+        $token = $cookies[self::COOKIE_NAME] ?? null;
+
+        if (! is_string($token) || $token === '') {
+            return $this->unauthorized();
+        }
+
+        $session = $this->sessionRepo->findByToken($token);
+
+        if ($session === null) {
+            return $this->unauthorized();
+        }
+
+        if ($session->isExpired($this->clock->now())) {
+            $this->sessionRepo->deleteByToken($token);
+
+            return $this->unauthorized();
+        }
+
+        $request = $request->withAttribute('user', $session->getUser());
+
+        return $handler->handle($request);
+    }
+
+    private function unauthorized(): ResponseInterface
+    {
+        $response = new Response(401);
+        $response->getBody()->write(
+            json_encode(['error' => 'unauthenticated']),
+        );
+
+        return $response->withHeader('Content-Type', 'application/json');
+    }
+}

backend/app/Shared/ValueObject/EmailAddress.php

@@ -0,0 +1,47 @@
+<?php
+
+namespace App\Shared\ValueObject;
+
+use InvalidArgumentException;
+
+final readonly class EmailAddress
+{
+    private string $normalized;
+
+    private const ERROR_MESSAGE = 'Invalid email address:';
+
+    public function __construct(string $email)
+    {
+
+        $trimmed = trim($email);
+
+        if ($trimmed === '' || ! str_contains($trimmed, '@')) {
+            throw new InvalidArgumentException(self::ERROR_MESSAGE . " $email");
+        }
+
+        [$local, $domain] = explode('@', $trimmed, 2);
+        $domain = mb_strtolower($domain);
+        $normalized = $local . '@' . $domain;
+
+        if (filter_var($normalized, FILTER_VALIDATE_EMAIL) === false) {
+            throw new InvalidArgumentException(self::ERROR_MESSAGE . " $email");
+        }
+
+        $this->normalized = $normalized;
+    }
+
+    public function value(): string
+    {
+        return $this->normalized;
+    }
+
+    public function equals(self $other): bool
+    {
+        return $this->normalized === $other->normalized;
+    }
+
+    public function __toString(): string
+    {
+        return $this->normalized;
+    }
+}

backend/app/User/CreateUserDto.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace App\User;
+
+use App\Shared\ValueObject\EmailAddress;
+
+class CreateUserDto
+{
+    public function __construct(
+        public EmailAddress $email,
+        public string $passwordHash,
+    ) {
+    }
+}

backend/app/User/User.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace App\User;
+
+use App\Shared\ValueObject\EmailAddress;
+
+class User
+{
+    public function __construct(
+        private int $id,
+        private EmailAddress $email,
+        private string $passwordHash,
+    ) {
+    }
+
+    public function getId(): int
+    {
+        return $this->id;
+    }
+
+    public function getEmail(): EmailAddress
+    {
+        return $this->email;
+    }
+
+    public function getPasswordHash(): string
+    {
+        return $this->passwordHash;
+    }
+}

backend/app/User/UserRepository.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace App\User;
+
+use App\Shared\ValueObject\EmailAddress;
+
+interface UserRepository
+{
+    public function create(CreateUserDto $dto): User;
+
+    public function findByEmail(EmailAddress $email): ?User;
+
+    public function find(int $id): ?User;
+}

backend/composer.json

@@ -20,5 +20,8 @@
         "slim/slim": "4.*",
         "slim/psr7": "^1.8",
         "php-di/slim-bridge": "^3.4"
+    },
+    "require-dev": {
+        "phpunit/phpunit": "^13.1"
     }
 }

backend/config/container.php

@@ -0,0 +1,37 @@
+<?php
+
+use App\Auth\BcryptPasswordHasher;
+use App\Auth\Clock;
+use App\Auth\PasswordHasher;
+use App\Auth\RandomTokenGenerator;
+use App\Auth\SystemClock;
+use App\Auth\TokenGenerator;
+use App\Auth\UseCases\AuthenticateUser\AuthenticateUser;
+use App\Auth\UseCases\CreateSession\CreateSession;
+use App\Auth\UseCases\Logout\Logout;
+use App\Controllers\AuthController;
+use App\Middleware\AuthMiddleware;
+use DI\ContainerBuilder;
+use Psr\Container\ContainerInterface;
+
+$builder = new ContainerBuilder();
+
+$builder->addDefinitions([
+
+    // Services
+    PasswordHasher::class => DI\create(BcryptPasswordHasher::class),
+    TokenGenerator::class => DI\create(RandomTokenGenerator::class),
+    Clock::class => DI\create(SystemClock::class),
+
+    // Use cases
+    AuthenticateUser::class => DI\autowire(),
+    CreateSession::class => DI\autowire(),
+    Logout::class => DI\autowire(),
+
+    // HTTP layer
+    AuthController::class => DI\autowire(),
+    AuthMiddleware::class => DI\autowire(),
+
+]);
+
+return $builder->build();

backend/config/routes.php

@@ -0,0 +1,17 @@
+<?php
+
+use App\Controllers\AuthController;
+use App\Middleware\AuthMiddleware;
+use Slim\App;
+use Slim\Routing\RouteCollectorProxy;
+
+return function (App $app): void {
+
+    $app->get('/me', [AuthController::class, 'me'])
+        ->add(AuthMiddleware::class);
+
+    $app->post('/login', [AuthController::class, 'login']);
+
+    $app->post('/logout', [AuthController::class, 'logout'])
+        ->add(AuthMiddleware::class);
+};

backend/phpunit.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:noNamespaceSchemaLocation="vendor/phpunit/phpunit/phpunit.xsd"
+         bootstrap="vendor/autoload.php"
+         cacheDirectory=".phpunit.cache"
+         executionOrder="depends,defects"
+
+         colors="true">
+    <testsuites>
+        <testsuite name="unit">
+            <directory>tests/Unit</directory>
+        </testsuite>
+    </testsuites>
+    <source>
+        <include>
+            <directory>app</directory>
+        </include>
+    </source>
+</phpunit>

backend/public/index.php

@@ -0,0 +1,19 @@
+<?php
+
+use DI\Bridge\Slim\Bridge;
+use Slim\App;
+
+(static function (): void {
+    $root = dirname(__DIR__);
+
+    require $root.'/vendor/autoload.php';
+
+    $container = require $root.'/config/container.php';
+
+    /** @var App $app */
+    $app = Bridge::create($container);
+
+    (require $root.'/config/routes.php')($app);
+
+    $app->run();
+})();

backend/tests/Fakes/FakeClock.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace Tests\Fakes;
+
+use App\Auth\Clock;
+use DateTimeImmutable;
+
+class FakeClock implements Clock
+{
+    public function __construct(private DateTimeImmutable $currentTime)
+    {
+    }
+
+    public function now(): DateTimeImmutable
+    {
+        return $this->currentTime;
+    }
+
+    public function setTime(DateTimeImmutable $newTime): void
+    {
+        $this->currentTime = $newTime;
+    }
+}

backend/tests/Fakes/FakePasswordHasher.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace Tests\Fakes;
+
+use App\Auth\PasswordHasher;
+
+class FakePasswordHasher implements PasswordHasher
+{
+    public function hash(string $password): string
+    {
+        return 'hashed:' . $password;
+    }
+
+    public function verify(string $password, string $hash): bool
+    {
+        return $this->hash($password) === $hash;
+    }
+}

backend/tests/Fakes/FakeSessionRepository.php

@@ -0,0 +1,46 @@
+<?php
+
+namespace Tests\Fakes;
+
+use App\Auth\CreateSessionDto;
+use App\Auth\Session;
+use App\Auth\SessionRepository;
+
+class FakeSessionRepository implements SessionRepository
+{
+    private array $sessions = [];
+
+    public function create(CreateSessionDto $dto): Session
+    {
+        $session = new Session(
+            token: $dto->token,
+            user: $dto->user,
+            createdAt: $dto->createdAt,
+            expiresAt: $dto->expiresAt,
+        );
+        $this->sessions[$dto->token] = $session;
+
+        return $session;
+    }
+
+    public function findByToken(string $token): ?Session
+    {
+        $session = $this->sessions[$token] ?? null;
+
+        if ($session === null) {
+            return null;
+        }
+
+        return new Session(
+            token: $session->getToken(),
+            user: $session->getUser(),
+            createdAt: $session->getCreatedAt(),
+            expiresAt: $session->getExpiresAt(),
+        );
+    }
+
+    public function deleteByToken(string $token): void
+    {
+        unset($this->sessions[$token]);
+    }
+}

backend/tests/Fakes/FakeTokenGenerator.php

@@ -0,0 +1,28 @@
+<?php
+
+namespace Tests\Fakes;
+
+use App\Auth\TokenGenerator;
+use RuntimeException;
+
+class FakeTokenGenerator implements TokenGenerator
+{
+    private int $callCount = 0;
+
+    public function __construct(private array $tokens)
+    {
+    }
+
+    public function generate(): string
+    {
+        if ($this->callCount >= count($this->tokens)) {
+            throw new RuntimeException(
+                'FakeTokenGenerator exhausted'
+            );
+        }
+        $token = $this->tokens[$this->callCount];
+        $this->callCount++;
+
+        return $token;
+    }
+}

backend/tests/Fakes/FakeUserRepository.php

@@ -0,0 +1,63 @@
+<?php
+
+namespace Tests\Fakes;
+
+use App\Shared\ValueObject\EmailAddress;
+use App\User\CreateUserDto;
+use App\User\User;
+use App\User\UserRepository;
+
+class FakeUserRepository implements UserRepository
+{
+    private array $users = [];
+
+    public function create(CreateUserDto $dto): User
+    {
+        $id = $this->nextId();
+
+        $user = new User(
+            id: $id,
+            email: $dto->email,
+            passwordHash: $dto->passwordHash,
+        );
+
+        $this->users[$id] = $user;
+
+        return $user;
+    }
+
+    public function findByEmail(EmailAddress $email): ?User
+    {
+        foreach ($this->users as $user) {
+            if ($user->getEmail()->value() === $email->value()) {
+                return new User(
+                    id: $user->getId(),
+                    email: $user->getEmail(),
+                    passwordHash: $user->getPasswordHash(),
+                );
+            }
+        }
+
+        return null;
+    }
+
+    public function find(int $id): ?User
+    {
+        $user = $this->users[$id] ?? null;
+
+        if ($user === null) {
+            return null;
+        }
+
+        return new User(
+            id: $user->getId(),
+            email: $user->getEmail(),
+            passwordHash: $user->getPasswordHash(),
+        );
+    }
+
+    private function nextId(): int
+    {
+        return count($this->users);
+    }
+}

backend/tests/Unit/Auth/UseCases/AuthenticateUserTest.php

@@ -0,0 +1,126 @@
+<?php
+
+namespace Tests\Unit\Auth\UseCases;
+
+use App\Auth\UseCases\AuthenticateUser\AuthenticateUser;
+use App\Auth\UseCases\AuthenticateUser\AuthenticateUserRequest;
+use App\Exceptions\BadRequestException;
+use App\Exceptions\UnauthorizedException;
+use App\Shared\ValueObject\EmailAddress;
+use App\User\CreateUserDto;
+use PHPUnit\Framework\TestCase;
+use Tests\Fakes\FakePasswordHasher;
+use Tests\Fakes\FakeUserRepository;
+
+class AuthenticateUserTest extends TestCase
+{
+    private FakeUserRepository $userRepo;
+    private FakePasswordHasher $hasher;
+    private AuthenticateUser $useCase;
+
+    protected function setUp(): void
+    {
+        $this->userRepo = new FakeUserRepository();
+        $this->hasher = new FakePasswordHasher();
+        $this->useCase = new AuthenticateUser(
+            $this->userRepo,
+            $this->hasher,
+        );
+
+        $this->userRepo->create(new CreateUserDto(
+            email: new EmailAddress('user@example.com'),
+            passwordHash: $this->hasher->hash('correct-password'),
+        ));
+    }
+
+    public function testAuthenticatesWithValidCredentials(): void
+    {
+        $user = $this->useCase->execute(new AuthenticateUserRequest(
+            email: 'user@example.com',
+            password: 'correct-password',
+        ));
+
+        $this->assertSame('user@example.com', $user->getEmail()->value());
+    }
+
+    public function testThrowsBadRequestWhenEmailIsEmpty(): void
+    {
+        $this->expectException(BadRequestException::class);
+        $this->expectExceptionMessage('email is required');
+
+        $this->useCase->execute(new AuthenticateUserRequest(
+            email: '',
+            password: 'some-password',
+        ));
+    }
+
+    public function testThrowsBadRequestWhenPasswordIsEmpty(): void
+    {
+        $this->expectException(BadRequestException::class);
+        $this->expectExceptionMessage('password is required');
+
+        $this->useCase->execute(new AuthenticateUserRequest(
+            email: 'user@example.com',
+            password: '',
+        ));
+    }
+
+    public function testThrowsBadRequestWhenEmailIsNull(): void
+    {
+        $this->expectException(BadRequestException::class);
+        $this->expectExceptionMessage('email is required');
+
+        $this->useCase->execute(new AuthenticateUserRequest(
+            email: null,
+            password: 'some-password',
+        ));
+    }
+
+    public function testThrowsBadRequestWhenPasswordIsNull(): void
+    {
+        $this->expectException(BadRequestException::class);
+        $this->expectExceptionMessage('password is required');
+
+        $this->useCase->execute(new AuthenticateUserRequest(
+            email: 'user@example.com',
+            password: null,
+        ));
+    }
+
+    public function testThrowsUnauthorizedForUnknownEmail(): void
+    {
+        $this->expectException(UnauthorizedException::class);
+        $this->expectExceptionMessage('invalid credentials');
+
+        $this->useCase->execute(new AuthenticateUserRequest(
+            email: 'unknown@example.com',
+            password: 'some-password',
+        ));
+    }
+
+    public function testThrowsUnauthorizedForWrongPassword(): void
+    {
+        $this->expectException(UnauthorizedException::class);
+        $this->expectExceptionMessage('invalid credentials');
+
+        $this->useCase->execute(new AuthenticateUserRequest(
+            email: 'user@example.com',
+            password: 'wrong-password',
+        ));
+    }
+
+    public function testReturnsNewInstanceOnEachCall(): void
+    {
+        $user1 = $this->useCase->execute(new AuthenticateUserRequest(
+            email: 'user@example.com',
+            password: 'correct-password',
+        ));
+
+        $user2 = $this->useCase->execute(new AuthenticateUserRequest(
+            email: 'user@example.com',
+            password: 'correct-password',
+        ));
+
+        $this->assertNotSame($user1, $user2);
+    }
+}

backend/tests/Unit/Auth/UseCases/CreateSessionTest.php

@@ -0,0 +1,102 @@
+<?php
+
+namespace Tests\Unit\Auth\UseCases;
+
+use App\Auth\UseCases\CreateSession\CreateSession;
+use App\Shared\ValueObject\EmailAddress;
+use App\User\CreateUserDto;
+use App\User\User;
+use DateTimeImmutable;
+use PHPUnit\Framework\TestCase;
+use Tests\Fakes\FakeClock;
+use Tests\Fakes\FakeSessionRepository;
+use Tests\Fakes\FakeTokenGenerator;
+use Tests\Fakes\FakeUserRepository;
+
+class CreateSessionTest extends TestCase
+{
+    private FakeSessionRepository $sessionRepo;
+    private FakeTokenGenerator $tokenGenerator;
+    private FakeClock $clock;
+    private CreateSession $useCase;
+    private User $user;
+
+    protected function setUp(): void
+    {
+        $this->sessionRepo = new FakeSessionRepository();
+        $this->tokenGenerator = new FakeTokenGenerator([
+            'token-1',
+        ]);
+        $this->clock = new FakeClock(
+            new DateTimeImmutable('2026-05-16 12:00:00'),
+        );
+        $this->useCase = new CreateSession(
+            $this->sessionRepo,
+            $this->tokenGenerator,
+            $this->clock,
+        );
+
+        $userRepo = new FakeUserRepository();
+        $this->user = $userRepo->create(new CreateUserDto(
+            email: new EmailAddress('user@example.com'),
+            passwordHash: 'hashed:password',
+        ));
+    }
+
+    public function testCreatesSessionWithGivenToken(): void
+    {
+        $session = $this->useCase->execute($this->user);
+
+        $this->assertSame('token-1', $session->getToken());
+    }
+
+    public function testCreatesSessionWithUser(): void
+    {
+        $session = $this->useCase->execute($this->user);
+
+        $this->assertSame(
+            $this->user->getId(),
+            $session->getUser()->getId(),
+        );
+    }
+
+    public function testCreatesSessionWithCreatedAtFromClock(): void
+    {
+        $session = $this->useCase->execute($this->user);
+
+        $this->assertEquals(
+            new DateTimeImmutable('2026-05-16 12:00:00'),
+            $session->getCreatedAt(),
+        );
+    }
+
+    public function testCreatesSessionWithExpirySevenDaysLater(): void
+    {
+        $session = $this->useCase->execute($this->user);
+
+        $this->assertEquals(
+            new DateTimeImmutable('2026-05-23 12:00:00'),
+            $session->getExpiresAt(),
+        );
+    }
+
+    public function testPersistsSessionInRepository(): void
+    {
+        $session = $this->useCase->execute($this->user);
+
+        $found = $this->sessionRepo->findByToken('token-1');
+
+        $this->assertNotNull($found);
+        $this->assertSame($session->getToken(), $found->getToken());
+    }
+
+    public function testFreshInstanceReturnedOnEachCall(): void
+    {
+        $session = $this->useCase->execute($this->user);
+
+        $this->assertNotSame(
+            $session,
+            $this->sessionRepo->findByToken('token-1'),
+        );
+    }
+}

backend/tests/Unit/Auth/UseCases/LogoutTest.php

@@ -0,0 +1,67 @@
+<?php
+
+namespace Tests\Unit\Auth\UseCases;
+
+use App\Auth\CreateSessionDto;
+use App\Auth\UseCases\Logout\Logout;
+use App\Shared\ValueObject\EmailAddress;
+use App\User\CreateUserDto;
+use DateTimeImmutable;
+use PHPUnit\Framework\TestCase;
+use Tests\Fakes\FakeSessionRepository;
+use Tests\Fakes\FakeUserRepository;
+
+class LogoutTest extends TestCase
+{
+    private FakeSessionRepository $sessionRepo;
+    private Logout $useCase;
+
+    protected function setUp(): void
+    {
+        $this->sessionRepo = new FakeSessionRepository();
+        $this->useCase = new Logout($this->sessionRepo);
+
+        $userRepo = new FakeUserRepository();
+        $user = $userRepo->create(new CreateUserDto(
+            email: new EmailAddress('user@example.com'),
+            passwordHash: 'hashed:password',
+        ));
+
+        $this->sessionRepo->create(new CreateSessionDto(
+            token: 'session-token',
+            user: $user,
+            createdAt: new DateTimeImmutable('2026-05-16 12:00:00'),
+            expiresAt: new DateTimeImmutable('2026-05-23 12:00:00'),
+        ));
+    }
+
+    public function testDeletesSessionByToken(): void
+    {
+        $this->useCase->execute('session-token');
+
+        $this->assertNull(
+            $this->sessionRepo->findByToken('session-token'),
+        );
+    }
+
+    public function testDoesNotThrowForUnknownToken(): void
+    {
+        $this->useCase->execute('nonexistent-token');
+
+        $this->assertTrue(true);
+    }
+
+    public function testDoesNotThrowForNullToken(): void
+    {
+        $this->useCase->execute(null);
+
+        $this->assertTrue(true);
+    }
+
+    public function testDoesNotThrowForEmptyStringToken(): void
+    {
+        $this->useCase->execute('');
+
+        $this->assertTrue(true);
+    }
+}

backend/tests/Unit/Controllers/AuthControllerTest.php

@@ -0,0 +1,170 @@
+<?php
+
+namespace Tests\Unit\Controllers;
+
+use App\Auth\UseCases\AuthenticateUser\AuthenticateUser;
+use App\Auth\UseCases\AuthenticateUser\AuthenticateUserRequest;
+use App\Auth\UseCases\CreateSession\CreateSession;
+use App\Auth\UseCases\Logout\Logout;
+use App\Middleware\AuthMiddleware;
+use App\Controllers\AuthController;
+use App\Shared\ValueObject\EmailAddress;
+use App\User\CreateUserDto;
+use App\User\User;
+use DateTimeImmutable;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\ServerRequestInterface;
+use Slim\Psr7\Factory\ServerRequestFactory;
+use Slim\Psr7\Response;
+use Tests\Fakes\FakeClock;
+use Tests\Fakes\FakePasswordHasher;
+use Tests\Fakes\FakeSessionRepository;
+use Tests\Fakes\FakeTokenGenerator;
+use Tests\Fakes\FakeUserRepository;
+
+class AuthControllerTest extends TestCase
+{
+    private FakeUserRepository $userRepo;
+    private FakeSessionRepository $sessionRepo;
+    private FakePasswordHasher $hasher;
+    private FakeTokenGenerator $tokenGenerator;
+    private FakeClock $clock;
+    private AuthController $controller;
+    private User $user;
+
+    protected function setUp(): void
+    {
+        $this->userRepo = new FakeUserRepository();
+        $this->sessionRepo = new FakeSessionRepository();
+        $this->hasher = new FakePasswordHasher();
+        $this->tokenGenerator = new FakeTokenGenerator([
+            'session-token-1',
+            'session-token-2',
+        ]);
+        $this->clock = new FakeClock(
+            new DateTimeImmutable('2026-05-16 12:00:00'),
+        );
+
+        $authenticateUser = new AuthenticateUser(
+            $this->userRepo,
+            $this->hasher,
+        );
+        $createSession = new CreateSession(
+            $this->sessionRepo,
+            $this->tokenGenerator,
+            $this->clock,
+        );
+        $logout = new Logout($this->sessionRepo);
+
+        $this->controller = new AuthController(
+            $authenticateUser,
+            $createSession,
+            $logout,
+        );
+
+        $this->user = $this->userRepo->create(new CreateUserDto(
+            email: new EmailAddress('user@example.com'),
+            passwordHash: $this->hasher->hash('correct-password'),
+        ));
+    }
+
+    public function testLoginReturnsUserAndSetsCookie(): void
+    {
+        $request = $this->jsonRequest('POST', '/login', [
+            'email' => 'user@example.com',
+            'password' => 'correct-password',
+        ]);
+
+        $response = $this->controller->login($request, new Response());
+
+        $this->assertSame(200, $response->getStatusCode());
+        $this->assertStringContainsString(
+            'user@example.com',
+            (string) $response->getBody(),
+        );
+
+        $cookieHeader = $response->getHeaderLine('Set-Cookie');
+        $this->assertStringContainsString(
+            AuthMiddleware::COOKIE_NAME . '=session-token-1',
+            $cookieHeader,
+        );
+        $this->assertStringContainsString('HttpOnly', $cookieHeader);
+    }
+
+    public function testLoginReturns400ForMissingEmail(): void
+    {
+        $request = $this->jsonRequest('POST', '/login', [
+            'password' => 'correct-password',
+        ]);
+
+        $response = $this->controller->login($request, new Response());
+
+        $this->assertSame(400, $response->getStatusCode());
+    }
+
+    public function testLoginReturns401ForInvalidCredentials(): void
+    {
+        $request = $this->jsonRequest('POST', '/login', [
+            'email' => 'user@example.com',
+            'password' => 'wrong-password',
+        ]);
+
+        $response = $this->controller->login($request, new Response());
+
+        $this->assertSame(401, $response->getStatusCode());
+    }
+
+    public function testLogoutClearsCookieAndReturns204(): void
+    {
+        $request = $this->createRequest()
+            ->withCookieParams([
+                AuthMiddleware::COOKIE_NAME => 'session-token-1',
+            ]);
+
+        $response = $this->controller->logout($request, new Response());
+
+        $this->assertSame(204, $response->getStatusCode());
+
+        $cookieHeader = $response->getHeaderLine('Set-Cookie');
+        $this->assertStringContainsString(
+            AuthMiddleware::COOKIE_NAME . '=',
+            $cookieHeader,
+        );
+    }
+
+    public function testMeReturnsUserFromAttribute(): void
+    {
+        $request = $this->createRequest()
+            ->withAttribute('user', $this->user);
+
+        $response = $this->controller->me($request, new Response());
+
+        $this->assertSame(200, $response->getStatusCode());
+        $this->assertStringContainsString(
+            'user@example.com',
+            (string) $response->getBody(),
+        );
+    }
+
+    private function jsonRequest(
+        string $method,
+        string $path,
+        array $body,
+    ): ServerRequestInterface {
+        $request = $this->createRequest($method, $path)
+            ->withHeader('Content-Type', 'application/json');
+        $request->getBody()->write(json_encode($body));
+        $request->getBody()->rewind();
+
+        return $request;
+    }
+
+    private function createRequest(
+        string $method = 'POST',
+        string $path = '/',
+    ): ServerRequestInterface {
+        $factory = new ServerRequestFactory();
+
+        return $factory->createServerRequest($method, $path);
+    }
+}

backend/tests/Unit/Middleware/AuthMiddlewareTest.php

@@ -0,0 +1,153 @@
+<?php
+
+namespace Tests\Unit\Middleware;
+
+use App\Auth\CreateSessionDto;
+use App\Middleware\AuthMiddleware;
+use App\Shared\ValueObject\EmailAddress;
+use App\User\CreateUserDto;
+use App\User\User;
+use DateTimeImmutable;
+use PHPUnit\Framework\TestCase;
+use Psr\Http\Message\ServerRequestInterface;
+use Psr\Http\Server\RequestHandlerInterface;
+use Slim\Psr7\Factory\ServerRequestFactory;
+use Slim\Psr7\Response;
+use Tests\Fakes\FakeClock;
+use Tests\Fakes\FakeSessionRepository;
+use Tests\Fakes\FakeUserRepository;
+use Tests\Fakes\FakePasswordHasher;
+
+class AuthMiddlewareTest extends TestCase
+{
+    private FakeSessionRepository $sessionRepo;
+    private FakeClock $clock;
+    private AuthMiddleware $middleware;
+    private User $user;
+
+    protected function setUp(): void
+    {
+        $this->sessionRepo = new FakeSessionRepository();
+        $this->clock = new FakeClock(
+            new DateTimeImmutable('2026-05-16 12:00:00'),
+        );
+        $this->middleware = new AuthMiddleware(
+            $this->sessionRepo,
+            $this->clock,
+        );
+
+        $userRepo = new FakeUserRepository();
+        $hasher = new FakePasswordHasher();
+        $this->user = $userRepo->create(new CreateUserDto(
+            email: new EmailAddress('user@example.com'),
+            passwordHash: $hasher->hash('password'),
+        ));
+
+        $this->sessionRepo->create(new CreateSessionDto(
+            token: 'valid-token',
+            user: $this->user,
+            createdAt: new DateTimeImmutable('2026-05-16 12:00:00'),
+            expiresAt: new DateTimeImmutable('2026-05-23 12:00:00'),
+        ));
+    }
+
+    public function testPassesRequestToHandlerWhenCookieIsValid(): void
+    {
+        $request = $this->createRequestWithCookie('valid-token');
+
+        $handler = $this->createMock(RequestHandlerInterface::class);
+        $handler->expects($this->once())
+            ->method('handle')
+            ->with($this->callback(function (ServerRequestInterface $request) {
+                $user = $request->getAttribute('user');
+                return $user instanceof User
+                    && $user->getId() === $this->user->getId();
+            }))
+            ->willReturn(new Response(200));
+
+        $response = $this->middleware->process($request, $handler);
+
+        $this->assertSame(200, $response->getStatusCode());
+    }
+
+    public function testReturns401WhenCookieIsMissing(): void
+    {
+        $request = self::createRequest();
+        $handler = $this->createMock(RequestHandlerInterface::class);
+        $handler->expects($this->never())->method('handle');
+
+        $response = $this->middleware->process($request, $handler);
+
+        $this->assertSame(401, $response->getStatusCode());
+    }
+
+    public function testReturns401WhenCookieIsEmpty(): void
+    {
+        $request = $this->createRequestWithCookie('');
+        $handler = $this->createMock(RequestHandlerInterface::class);
+        $handler->expects($this->never())->method('handle');
+
+        $response = $this->middleware->process($request, $handler);
+
+        $this->assertSame(401, $response->getStatusCode());
+    }
+
+    public function testReturns401WhenTokenIsUnknown(): void
+    {
+        $request = $this->createRequestWithCookie('unknown-token');
+        $handler = $this->createMock(RequestHandlerInterface::class);
+        $handler->expects($this->never())->method('handle');
+
+        $response = $this->middleware->process($request, $handler);
+
+        $this->assertSame(401, $response->getStatusCode());
+    }
+
+    public function testReturns401WhenSessionIsExpired(): void
+    {
+        $this->clock->setTime(
+            new DateTimeImmutable('2026-05-30 12:00:00'),
+        );
+
+        $request = $this->createRequestWithCookie('valid-token');
+        $handler = $this->createMock(RequestHandlerInterface::class);
+        $handler->expects($this->never())->method('handle');
+
+        $response = $this->middleware->process($request, $handler);
+
+        $this->assertSame(401, $response->getStatusCode());
+    }
+
+    public function testDeletesExpiredSession(): void
+    {
+        $this->clock->setTime(
+            new DateTimeImmutable('2026-05-30 12:00:00'),
+        );
+
+        $request = $this->createRequestWithCookie('valid-token');
+        $handler = $this->createStub(RequestHandlerInterface::class);
+
+        $this->middleware->process($request, $handler);
+
+        $this->assertNull(
+            $this->sessionRepo->findByToken('valid-token'),
+        );
+    }
+
+    private static function createRequest(): ServerRequestInterface
+    {
+        $factory = new ServerRequestFactory();
+
+        return $factory->createServerRequest('GET', '/');
+    }
+
+    private function createRequestWithCookie(
+        string $token,
+    ): ServerRequestInterface {
+        $request = self::createRequest();
+
+        return $request->withCookieParams([
+            AuthMiddleware::COOKIE_NAME => $token,
+        ]);
+    }
+}