<?php

declare(strict_types=1);

namespace App\Security;

use App\BusProNet\ApiClient;
use App\BusProNet\Exception\ApiClientException;
use App\BusProNet\Exception\ImmediateConnectionCloseException;
use App\BusProNet\Exception\TimeoutException;
use App\BusProNet\Model\CrmAttributes;
use App\BusProNet\Model\PersonalData;
use App\Entity\User;
use App\Htmx\HxRedirectResponse;
use App\Message\RoleNominationMessage;
use App\Service\ProfileCompletenessChecker;
use Doctrine\ORM\EntityManagerInterface;
use Psr\Log\LoggerInterface;
use Symfony\Component\HttpFoundation\RedirectResponse;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\Messenger\MessageBusInterface;
use Symfony\Component\Routing\Generator\UrlGeneratorInterface;
use Symfony\Component\Security\Core\Authentication\Token\TokenInterface;
use Symfony\Component\Security\Core\Exception\CustomUserMessageAuthenticationException;
use Symfony\Component\Security\Http\Authenticator\AbstractLoginFormAuthenticator;
use Symfony\Component\Security\Http\Authenticator\Passport\Badge\CsrfTokenBadge;
use Symfony\Component\Security\Http\Authenticator\Passport\Badge\UserBadge;
use Symfony\Component\Security\Http\Authenticator\Passport\Passport;
use Symfony\Component\Security\Http\Authenticator\Passport\SelfValidatingPassport;
use Symfony\Component\Security\Http\EntryPoint\AuthenticationEntryPointInterface;
use Symfony\Component\Security\Http\Util\TargetPathTrait;

/**
 * Authenticates users against the BPN API.
 *
 * The password is kept, RSA-encrypted, because every later BPN call needs it again.
 *
 * BusPro owns the whole role set bar one, and the hotel codes: both are synced on every login, in
 * both directions, so anything the CRM no longer reports is withdrawn here. The exception is
 * ROLE_EMPLOYEE, which BusPro has no selection for and which is derived from the account's email
 * domain — passed to Role::sync() as a claim, so it is granted and revoked by the same machinery. What the CRM claims is
 * not automatically granted, though — Role::sync() turns an administrative claim into a
 * nomination that an administrator has to approve in /admin/user, because BusPro backend users
 * can edit their own CRM selections and would otherwise make themselves administrators.
 */
class BpnAuthenticator extends AbstractLoginFormAuthenticator implements AuthenticationEntryPointInterface
{
    use TargetPathTrait;

    public function __construct(
        private readonly UrlGeneratorInterface $urlGenerator,
        private readonly ApiClient $apiClient,
        private readonly EntityManagerInterface $entityManager,
        private readonly Crypt $crypt,
        private readonly ProfileCompletenessChecker $completenessChecker,
        private readonly LoggerInterface $authLogger,
        private readonly EmployeeDomainMatcher $employeeDomainMatcher,
        private readonly MessageBusInterface $messageBus,
    ) {
    }

    protected function getLoginUrl(Request $request): string
    {
        return $this->urlGenerator->generate('app_login');
    }

    public function authenticate(Request $request): Passport
    {
        // One canonical casing per account. BusPro matches an address case-insensitively and so
        // does the utf8mb4_unicode_ci column, so the casing somebody happens to type must not
        // become the casing every later BusPro call re-sends.
        $email = mb_strtolower(trim($request->request->getString('_username')));
        $passwordPlain = trim($request->request->getString('_password'));

        // BPN requires md5, not a real hash
        $password = md5($passwordPlain);

        try {
            $response = $this->apiClient->getPersonalData($email, $password);
        } catch (ApiClientException $e) {
            $message = $this->isConnectionError($e) ?
                'Der Server ist momentan nicht erreichbar. Bitte versuche es später erneut.' : $e->getMessage();
            throw new CustomUserMessageAuthenticationException($message);
        }

        if (false === $response instanceof PersonalData) {
            throw new CustomUserMessageAuthenticationException('Benutzername oder Passwort ist nicht korrekt.');
        }

        $csrfToken = $request->request->getString('_csrf_token');

        return new SelfValidatingPassport(
            new UserBadge($email, function () use ($email, $password, $response) {
                return $this->createOrUpdateLocalUser($email, $password, $response);
            }),
            [
                new CsrfTokenBadge('authenticate', $csrfToken),
            ]
        );
    }

    private function createOrUpdateLocalUser(string $email, string $password, PersonalData $personalData): User
    {
        try {
            $crmAttributes = $this->apiClient->getCrmAttributes($email, $password);
        } catch (ApiClientException $e) {
            $message = $this->isConnectionError($e) ?
                'Der Server ist momentan nicht erreichbar. Bitte versuche es später erneut. :(' : $e->getMessage();
            throw new CustomUserMessageAuthenticationException($message);
        }

        $encryptedPassword = $this->crypt->encrypt($password);

        $userRepository = $this->entityManager->getRepository(User::class);

        $user = $userRepository->findOneBy(['email' => $email]) ?? new User($email);

        $user
            // Not redundant next to the constructor: an account created before the address was
            // normalized still carries the casing of its very first login, and everything
            // downstream re-sends what is stored rather than what was just typed.
            ->setEmail($email)
            ->setPassword($encryptedPassword)
            ->setPersonId($personalData->personId)
            ->setAddressId($personalData->addressId)
            ->setFirstName($personalData->firstName)
            ->setLastName($personalData->name)
            ->setLastLoginAt(new \DateTimeImmutable())
            ->setProfileComplete($this->completenessChecker->isComplete($personalData))
        ;

        $nominated = $this->syncFromCrm($user, $crmAttributes);

        // Registered only once it is fully populated: syncFromCrm() logs on a channel that writes
        // to the database, and an account already managed at that point would be flushed
        // half-built — which is how a NULL password used to reach the user table. A no-op for an
        // account that came from the repository.
        $this->entityManager->persist($user);
        $this->entityManager->flush();

        // After the flush, deliberately: a first login has no id before it, and the transport is
        // Doctrine-backed, so a message queued ahead of a failing flush would announce a
        // nomination that was never stored.
        if ([] !== $nominated) {
            $this->messageBus->dispatch(new RoleNominationMessage((int) $user->getId(), $nominated));
        }

        return $user;
    }

    /**
     * Writes back what the CRM currently claims: the roles per Role::sync() and the hotel codes
     * verbatim. Both replace what is stored, which is what makes BusPro the source of truth.
     *
     * @return string[] the roles this login newly nominated the account for — the roles
     *                  themselves, not their markers, and empty whenever nothing changed
     */
    private function syncFromCrm(User $user, CrmAttributes $crmAttributes): array
    {
        $previousRoles = $user->getRoles();

        if ([] === $crmAttributes->selectionGroups) {
            // BusPro always answers with the full attribute tree and expresses membership through
            // the `auswahl` flag, so an empty one is a degraded payload rather than a revocation.
            // Syncing it would strip the roles of every user who logs in.
            $this->authLogger->warning('Skipped the role sync: the BPN CRM response carries no selection groups', [
                'email' => $user->getEmail(),
            ]);

            // An existing account keeps everything it has. A brand new one still needs a role,
            // and an empty claim set is exactly what Role::sync() answers with the fallback.
            if ([] !== Role::assignedOnly($previousRoles)) {
                return [];
            }
        }

        $claimedRoles = $crmAttributes->roles;

        // Not a CRM claim: BusPro has no selection for it, so the account's own address decides.
        // Passing it in as a claim rather than setting it afterwards is what makes it revocable —
        // Role::sync() strips every stored role the claim set does not contain.
        if ($this->employeeDomainMatcher->isEmployee($user->getEmail())) {
            $claimedRoles[] = Role::EMPLOYEE;
        }

        $user
            ->setRoles(Role::sync($previousRoles, $claimedRoles))
            ->setHotelCodes(array_values(array_unique($crmAttributes->hotelCodes)))
        ;

        // Compared on the full role sets rather than on the markers alone: nominatedFrom() needs
        // to see ROLE_EMPLOYEE to know whether an EMPLOYEE_ONLY marker counts.
        $nominated = array_values(array_diff(
            array_keys(Role::nominatedFrom($user->getRoles())),
            array_keys(Role::nominatedFrom($previousRoles)),
        ));

        if ([] === $nominated) {
            return [];
        }

        // The CRM claims an administrative role for somebody who does not hold it. It grants
        // nothing until an administrator approves it in /admin/user.
        $this->authLogger->info('Nominated for administrative roles by the BPN CRM', [
            'email' => $user->getEmail(),
            'roles' => $nominated,
        ]);

        // Only the newly appeared nominations reach this point, so a repeat login with a
        // nomination still standing announces nothing. That difference is the whole de-duplication.
        return $nominated;
    }

    public function onAuthenticationSuccess(Request $request, TokenInterface $token, string $firewallName): ?Response
    {
        $this->authLogger->info('Login', [
            'email' => $token->getUserIdentifier(),
        ]);

        $targetPath = $this->getTargetPath($request->getSession(), $firewallName)
            ?? $this->urlGenerator->generate('app_account');

        // A full load avoids hx-boost layout issues
        if ($request->headers->has('HX-Request') && str_contains($targetPath, '/admin')) {
            return new HxRedirectResponse($targetPath);
        }

        return new RedirectResponse($targetPath);
    }

    private function isConnectionError(ApiClientException $e): bool
    {
        if ($e instanceof TimeoutException || $e instanceof ImmediateConnectionCloseException) {
            return true;
        }

        return 'Unable to open socket' === $e->getMessage();
    }
}