<?php
/**
 * invited_onboarding.php — Complete account setup for an invited user.
 *
 * Called by: invited_onboarding.php page AJAX after the user fills in
 *            their name, username, and password.
 *
 * The invited user was created with license='user', status='pending', and
 * default_company = the inviting company. This endpoint activates the account
 * so they can log in using the inviting company's SMTP for OTP delivery.
 *
 * Full flow:
 *   1. Session guard — rejects if 'invited_user_id' is missing.
 *   2. CSRF check.
 *   3. Re-validate token against DB (expiry + status='pending' + license='user').
 *   4. Validate and sanitise input fields.
 *   5. Username format and uniqueness check.
 *   6. Password match and strength check.
 *   7. Hash password.
 *   8. UPDATE user: name, surname, username, password, status='active',
 *      verify_token=NULL, verify_expires_at=NULL.
 *   9. UPDATE company_map_user: invite_token=NULL.
 *   10. Return { success: 1 }.
 */

require_once '../../../session.php';
require_once '../../../config.php';
require_once '../../../preset.php';
define('UNAUTHENTICATED_ROUTE', true);
require_once '../../../assets/utils/db_auth.php';
require_once '../../../assets/utils/classes/PasswordManager.php';

header('Content-Type: application/json; charset=utf-8');

$answer = ['success' => 0, 'message' => ''];

// ── Step 1: Session guard ─────────────────────────────────────────────────────
if (empty($_SESSION['invited_user_id']) || empty($_SESSION['invited_token'])) {
    $answer['message'] = 'Invalid session. Please use your invitation link.';
    http_response_code(403);
    exit(json_encode($answer));
}

$user_id = (int)$_SESSION['invited_user_id'];
$token   = $_SESSION['invited_token'];

// ── Step 2: CSRF check ────────────────────────────────────────────────────────
if ($_SERVER['REQUEST_METHOD'] === 'POST') {
    $csrf = $_SERVER['HTTP_X_CSRF_TOKEN'] ?? '';
    if (empty($csrf) || $csrf !== ($_SESSION['csrf_token'] ?? '')) {
        http_response_code(403);
        $answer['message'] = 'Invalid request.';
        exit(json_encode($answer));
    }
}

$data = json_decode($_POST['json'] ?? '{}', true) ?: [];

try {

    // ── Step 3: Re-validate token ─────────────────────────────────────────────
    $sth = $pdo1->prepare(
        "SELECT user_id FROM user
         WHERE user_id        = :uid
           AND verify_token   = :token
           AND status         = 'pending'
           AND license        = 'user'
           AND verify_expires_at > NOW()
         LIMIT 1"
    );
    $sth->execute([':uid' => $user_id, ':token' => $token]);
    if (!$sth->fetchColumn()) {
        $answer['message'] = 'Invitation has expired or already been used. Please request a new invitation.';
        http_response_code(403);
        exit(json_encode($answer));
    }

    // ── Step 4: Sanitise and validate input ───────────────────────────────────
    $name     = trim($data['name']             ?? '');
    $surname  = trim($data['surname']          ?? '');
    $username = strtolower(trim($data['username'] ?? ''));
    $password = $data['password']              ?? '';
    $confirm  = $data['confirm_password']      ?? '';

    if (!$name || !$surname || !$username || !$password || !$confirm) {
        throw new Exception('All fields are required.');
    }

    // ── Step 5: Username format and uniqueness ────────────────────────────────
    if (!preg_match('/^[a-z0-9_]+$/', $username)) {
        throw new Exception('Username may only contain lowercase letters, numbers and underscores.');
    }

    $sth = $pdo1->prepare("SELECT user_id FROM user WHERE username = :u AND user_id != :uid LIMIT 1");
    $sth->execute([':u' => $username, ':uid' => $user_id]);
    if ($sth->fetchColumn()) {
        throw new Exception('Username is already taken. Please choose another.');
    }

    // ── Step 6: Password match and strength ───────────────────────────────────
    if ($password !== $confirm) {
        throw new Exception('Passwords do not match.');
    }

    $pm     = new PasswordManager($pdo1, $include_url);
    $result = $pm->checkStrength($password, [$name, $surname, $username]);
    if ($result['score'] < PasswordManager::MIN_SCORE) {
        $msg = $result['warning'] ?: ($result['suggestions'][0] ?? 'Please choose a stronger password.');
        throw new Exception('Password is too weak. ' . $msg);
    }

    // ── Step 7–8: Hash and activate account ──────────────────────────────────
    $hashed = password_hash($password, PASSWORD_BCRYPT);

    $pdo1->prepare(
        "UPDATE user
         SET name                = :name,
             surname             = :surname,
             username            = :username,
             password            = :password,
             status              = 'active',
             verify_token        = NULL,
             verify_expires_at   = NULL
         WHERE user_id = :uid"
    )->execute([
        ':name'     => $name,
        ':surname'  => $surname,
        ':username' => $username,
        ':password' => $hashed,
        ':uid'      => $user_id,
    ]);

    // ── Step 9: Clear invite token from company_map_user ─────────────────────
    $pdo1->prepare(
        "UPDATE company_map_user SET invite_token = NULL WHERE user_id = :uid"
    )->execute([':uid' => $user_id]);

    // ── Step 10: Clear session invite keys ────────────────────────────────────
    unset($_SESSION['invited_user_id'], $_SESSION['invited_token']);

    $answer['success'] = 1;
    $answer['message'] = 'Account setup complete.';

} catch (Exception $e) {
    $answer['message'] = $e->getMessage();
    http_response_code(400);
}

exit(json_encode($answer));