<?php

declare(strict_types=1);

use App\Infrastructure\Database;

if (session_status() !== PHP_SESSION_ACTIVE) {
    session_start();
}

require_once dirname(__DIR__, 2) . '/vendor/autoload.php';
require_once dirname(__DIR__, 2) . '/app/bootstrap.php';
require_once dirname(__DIR__, 2) . '/config/config.php';

if (!function_exists('env')) {
    function env(string $key, ?string $default = null): ?string
    {
        if (array_key_exists($key, $_ENV) && $_ENV[$key] !== '') {
            return (string)$_ENV[$key];
        }
        $v = getenv($key);
        if ($v !== false && $v !== '') {
            return (string)$v;
        }
        return $default;
    }
}
$debug = (env('APP_DEBUG', '0') === '1');

// --- OIDC config ---
$OIDC_ISSUER        = rtrim((string)env('OIDC_ISSUER', ''), '/');
$OIDC_CLIENT_ID     = (string)env('OIDC_CLIENT_ID', '');
$OIDC_CLIENT_SECRET = (string)env('OIDC_CLIENT_SECRET', '');
$OIDC_REDIRECT_URI  = (string)(env('OIDC_REDIRECT_URI') ?: url('oidc/callback'));

if (!$OIDC_ISSUER || !$OIDC_CLIENT_ID || !$OIDC_REDIRECT_URI) {
    http_response_code(500);
    echo $debug ? 'OIDC config manquante.' : 'Erreur.';
    exit;
}

$tokenEndpoint    = $OIDC_ISSUER . '/protocol/openid-connect/token';
$userInfoEndpoint = $OIDC_ISSUER . '/protocol/openid-connect/userinfo';

// --- Checks retour ---
if (!isset($_GET['state'], $_SESSION['oidc_state']) || !hash_equals((string)$_SESSION['oidc_state'], (string)$_GET['state'])) {
    http_response_code(400);
    echo $debug ? 'State invalide.' : 'Requête invalide.';
    exit;
}
unset($_SESSION['oidc_state']);

if (empty($_GET['code'])) {
    http_response_code(400);
    echo $debug ? 'Code manquant.' : 'Requête invalide.';
    exit;
}
$code = (string)$_GET['code'];

$codeVerifier = $_SESSION['oidc_code_verifier'] ?? null;
unset($_SESSION['oidc_code_verifier']); // anti-replay
$expectedNonce = $_SESSION['oidc_nonce'] ?? null;
unset($_SESSION['oidc_nonce']); // anti-replay

if (!$codeVerifier) {
    http_response_code(400);
    echo $debug ? 'PKCE code_verifier manquant.' : 'Requête invalide.';
    exit;
}

// --- Échange code -> tokens ---
$post = [
    'grant_type'    => 'authorization_code',
    'code'          => $code,
    'redirect_uri'  => $OIDC_REDIRECT_URI,
    'client_id'     => $OIDC_CLIENT_ID,
    'code_verifier' => $codeVerifier,
];
if ($OIDC_CLIENT_SECRET !== '') {
    $post['client_secret'] = $OIDC_CLIENT_SECRET;
}

$ch = curl_init($tokenEndpoint);
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_POST           => true,
    CURLOPT_POSTFIELDS     => http_build_query($post, '', '&', PHP_QUERY_RFC3986),
    CURLOPT_TIMEOUT        => 15,
]);
$tokenResponse = curl_exec($ch);
$httpCode      = curl_getinfo($ch, CURLINFO_HTTP_CODE);
$err           = curl_error($ch);
curl_close($ch);

if ($tokenResponse === false || $httpCode !== 200) {
    http_response_code(500);
    echo $debug ? 'Échec échange token: ' . htmlspecialchars($err ?: (string)$tokenResponse) : 'Erreur d’authentification.';
    exit;
}

$tokens      = json_decode((string)$tokenResponse, true) ?: [];
$accessToken = $tokens['access_token'] ?? null;
$idToken     = $tokens['id_token']     ?? null;

if (!$accessToken) {
    http_response_code(500);
    echo $debug ? 'Access token manquant.' : 'Erreur d’authentification.';
    exit;
}

// --- UserInfo ---
$ch = curl_init($userInfoEndpoint);
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER     => ['Authorization: Bearer ' . $accessToken],
    CURLOPT_TIMEOUT        => 10,
]);
$userInfoResponse = curl_exec($ch);
$httpCode         = curl_getinfo($ch, CURLINFO_HTTP_CODE);
curl_close($ch);

if ($userInfoResponse === false || $httpCode !== 200) {
    http_response_code(500);
    echo $debug ? 'Échec UserInfo: ' . htmlspecialchars((string)$userInfoResponse) : 'Erreur d’authentification.';
    exit;
}

$claims = json_decode((string)$userInfoResponse, true) ?: [];

// --- Récup info utiles ---
$email     = $claims['email']              ?? null;
$username  = $claims['preferred_username'] ?? ($email ?: null);
$firstname = $claims['given_name']         ?? null;
$lastname  = $claims['family_name']        ?? null;

if (!$email && $idToken && substr_count($idToken, '.') === 2) {
    [, $p, ] = explode('.', $idToken, 3);
    $payloadJson = base64_decode(strtr($p, '-_', '+/'), true);
    $payload = $payloadJson ? json_decode($payloadJson, true) : null;
    if (is_array($payload) && !empty($payload['email'])) {
        $email = $payload['email'];
    }
}

if (!$email) {
    http_response_code(400);
    echo $debug ? 'Email non fourni par IdP.' : 'Impossible de récupérer votre email.';
    exit;
}

// --- Si l'utilisateur existe déjà -> connecter et redirect ---
$flow = $_SESSION['oidc_flow'] ?? 'login';

// Vérifie existence en base
/** @var \PDO $pdo */
$pdo = Database::get();
$stmt = $pdo->prepare('SELECT id FROM users WHERE email = :email LIMIT 1');
$stmt->execute([':email' => $email]);
$existingId = $stmt->fetchColumn();

// Si flow=login ET utilisateur existe → connexion directe
if ($flow === 'login' && $existingId) {
    $_SESSION['user_id']    = (int)$existingId;
    $_SESSION['user_email'] = $email;
    $_SESSION['oidc'] = [
        'issuer'       => $OIDC_ISSUER,
        'sub'          => $claims['sub'] ?? null,
        'access_token' => $accessToken,
        'id_token'     => $idToken,
        'expires_at'   => time() + (int)($tokens['expires_in'] ?? 3600),
    ];
    $target = $_SESSION['oidc_return_to'] ?? '/';
    unset($_SESSION['oidc_return_to'], $_SESSION['oidc_flow']);
    if (!is_string($target) || $target === '' || $target[0] !== '/') {
        $target = '/';
    }
    header('Location: ' . $target, true, 303);
    exit;
}

// Sinon : go formulaire d’inscription (pré-rempli)
$_SESSION['pending_oidc'] = [
    'issuer'    => $OIDC_ISSUER,
    'sub'       => $claims['sub'] ?? null,
    'email'     => $email,
    'username'  => $claims['preferred_username'] ?? ($email ?: null),
    'firstname' => $claims['given_name'] ?? null,
    'lastname'  => $claims['family_name'] ?? null,
];
unset($_SESSION['oidc_flow']);

header('Location: ' . url('register/from-oidc'), true, 303);
exit;