<?php
require_once __DIR__ . '/db.php';
require_once __DIR__ . '/mailer.php';

function isLoggedIn(): bool {
    return isset($_SESSION['user_id']) && !empty($_SESSION['user_id']);
}

function requireLogin(): void {
    if (!isLoggedIn()) {
        header('Location: /'); exit;
    }
}

function requireAdmin(): void {
    requireLogin();
    if (empty($_SESSION['is_admin'])) {
        header('Location: /'); exit;
    }
}

function currentUser(): ?array {
    if (!isLoggedIn()) return null;
    $stmt = db()->prepare("SELECT * FROM users WHERE id = ?");
    $stmt->execute([$_SESSION['user_id']]);
    return $stmt->fetch() ?: null;
}

function loginUser(string $username, string $password): array {
    $stmt = db()->prepare("SELECT * FROM users WHERE username = ? AND status = 'active'");
    $stmt->execute([strtolower(trim($username))]);
    $user = $stmt->fetch();

    if (!$user || !password_verify($password, $user['password'])) {
        return ['success' => false, 'error' => 'Invalid username or password.'];
    }

    // Block unverified accounts — admins are always exempt
    if (!$user['email_verified'] && !$user['is_admin']) {
        return [
            'success'    => false,
            'error'      => 'Please verify your email address before logging in. Check your inbox for the verification link.',
            'unverified' => true,
            'email'      => $user['email'],
        ];
    }

    // Auto-verify admin accounts so they're never locked out
    if ($user['is_admin'] && !$user['email_verified']) {
        db()->prepare("UPDATE users SET email_verified=1 WHERE id=?")->execute([$user['id']]);
        $user['email_verified'] = 1;
    }

    $_SESSION['user_id']  = $user['id'];
    $_SESSION['username'] = $user['username'];
    $_SESSION['alias']    = $user['alias'];
    $_SESSION['is_admin'] = $user['is_admin'];

    db()->prepare("UPDATE users SET last_login=NOW() WHERE id=?")->execute([$user['id']]);

    return ['success' => true, 'user' => $user];
}

/**
 * Stage a registration: store in pending_registrations, send verification email.
 * Does NOT create the user row yet.
 */
function initiateRegistration(string $username, string $password, string $alias, string $email, string $referralCode = ''): array {
    $username = strtolower(trim($username));
    $alias    = trim($alias);
    $email    = strtolower(trim($email));

    // Validate
    if (strlen($username) < 3 || strlen($username) > 50)
        return ['success' => false, 'error' => 'Username must be 3–50 characters.'];
    if (!preg_match('/^[a-z0-9_]+$/', $username))
        return ['success' => false, 'error' => 'Username may only contain letters, numbers, and underscores.'];
    if (strlen($password) < 6)
        return ['success' => false, 'error' => 'Password must be at least 6 characters.'];
    if (empty($alias))
        return ['success' => false, 'error' => 'Alias is required.'];
    if (empty($email) || !filter_var($email, FILTER_VALIDATE_EMAIL))
        return ['success' => false, 'error' => 'A valid email address is required to verify your account.'];

    // Check username taken (existing users)
    $s = db()->prepare("SELECT id FROM users WHERE username=?");
    $s->execute([$username]);
    if ($s->fetch()) return ['success' => false, 'error' => 'Username already taken.'];

    // Check email taken (existing users)
    $s = db()->prepare("SELECT id FROM users WHERE email=?");
    $s->execute([$email]);
    if ($s->fetch()) return ['success' => false, 'error' => 'An account with that email already exists.'];

    // Check username in pending
    $s = db()->prepare("SELECT id FROM pending_registrations WHERE username=? AND expires_at > NOW()");
    $s->execute([$username]);
    if ($s->fetch()) return ['success' => false, 'error' => 'Username already reserved. Try again in 24 hours or choose another.'];

    // Check email in pending — resend if already pending
    $s = db()->prepare("SELECT id, token FROM pending_registrations WHERE email=? AND expires_at > NOW()");
    $s->execute([$email]);
    $existing = $s->fetch();
    if ($existing) {
        // Resend verification to same email
        sendVerificationEmail($email, $alias, $existing['token']);
        return ['success' => true, 'resent' => true, 'email' => $email];
    }

    // Delete any expired pending rows for this email/username
    db()->prepare("DELETE FROM pending_registrations WHERE email=? OR (username=? AND expires_at <= NOW())")->execute([$email, $username]);

    // Resolve referral code to user ID
    $referrerId = null;
    if ($referralCode) {
        $refStmt = db()->prepare("SELECT id FROM users WHERE referral_code=? AND status='active'");
        $refStmt->execute([strtoupper(trim($referralCode))]);
        $refUser = $refStmt->fetch();
        if ($refUser) $referrerId = (int)$refUser['id'];
    }

    $token     = bin2hex(random_bytes(32));
    $hash      = password_hash($password, PASSWORD_BCRYPT);
    $expiresAt = date('Y-m-d H:i:s', time() + VERIFY_TTL);

    $stmt = db()->prepare("INSERT INTO pending_registrations (username, password, alias, email, token, referred_by, expires_at) VALUES (?,?,?,?,?,?,?)");
    $stmt->execute([$username, $hash, $alias, $email, $token, $referrerId, $expiresAt]);

    $sent = sendVerificationEmail($email, $alias, $token);

    if (!$sent) {
        // Email failed but keep registration — user can resend from login screen
        error_log('[TomTomGames] Verification email failed for ' . $email);
        return ['success' => true, 'email' => $email, 'mail_warning' => true];
    }

    return ['success' => true, 'email' => $email];
}

/**
 * Consume a verification token: create the real user, delete pending row.
 */
function verifyEmailToken(string $token): array {
    $token = trim($token);
    if (empty($token)) return ['success' => false, 'error' => 'Invalid verification link.'];

    $stmt = db()->prepare("SELECT * FROM pending_registrations WHERE token=? AND expires_at > NOW()");
    $stmt->execute([$token]);
    $pending = $stmt->fetch();

    if (!$pending) {
        return ['success' => false, 'error' => 'This verification link is invalid or has expired. Please register again.'];
    }

    // Check username/email not taken since pending was created
    $s = db()->prepare("SELECT id FROM users WHERE username=? OR email=?");
    $s->execute([$pending['username'], $pending['email']]);
    if ($s->fetch()) {
        db()->prepare("DELETE FROM pending_registrations WHERE token=?")->execute([$token]);
        return ['success' => false, 'error' => 'This username or email was already registered. Please log in.'];
    }

    db()->beginTransaction();
    try {
        // Create the user
        $ins = db()->prepare("INSERT INTO users (username, password, alias, email, email_verified, status) VALUES (?,?,?,?,1,'active')");
        $ins->execute([$pending['username'], $pending['password'], $pending['alias'], $pending['email']]);
        $userId = db()->lastInsertId();

        // Generate unique referral code
        $code = strtoupper(substr(md5($userId . uniqid()), 0, 8));
        db()->prepare("UPDATE users SET referral_code=? WHERE id=?")->execute([$code, $userId]);

        // Track referral if referred_by is in pending
        if (!empty($pending['referred_by'])) {
            $referrerId = (int)$pending['referred_by'];
            try {
                db()->prepare("INSERT IGNORE INTO referrals (referrer_id, referred_id, status) VALUES (?,?,'pending')")
                   ->execute([$referrerId, $userId]);
                db()->prepare("UPDATE users SET referred_by=? WHERE id=?")->execute([$referrerId, $userId]);
            } catch(Exception $e) {}
        }

        // Delete pending row
        db()->prepare("DELETE FROM pending_registrations WHERE token=?")->execute([$token]);

        db()->commit();
    } catch (Exception $e) {
        db()->rollBack();
        return ['success' => false, 'error' => 'Account creation failed. Please try again.'];
    }

    // Auto-login
    $_SESSION['user_id']  = $userId;
    $_SESSION['username'] = $pending['username'];
    $_SESSION['alias']    = $pending['alias'];
    $_SESSION['is_admin'] = 0;

    return ['success' => true, 'username' => $pending['username'], 'alias' => $pending['alias']];
}

/**
 * Resend verification email for an unverified account.
 */
function resendVerification(string $email): array {
    $email = strtolower(trim($email));
    $stmt  = db()->prepare("SELECT id, token FROM pending_registrations WHERE email=? AND expires_at > NOW() ORDER BY id DESC LIMIT 1");
    $stmt->execute([$email]);
    $pending = $stmt->fetch();

    if (!$pending) {
        return ['success' => false, 'error' => 'No pending registration found for that email, or it has expired. Please register again.'];
    }

    $alias = db()->prepare("SELECT alias FROM pending_registrations WHERE id=?");
    $alias->execute([$pending['id']]);
    $row   = $alias->fetch();

    sendVerificationEmail($email, $row['alias'] ?? 'Player', $pending['token']);
    return ['success' => true];
}

function logoutUser(): void {
    $_SESSION = [];
    session_destroy();
}

// ─── Comprehensive Audit Logger ────────────────────────────
function logActivity(
    string  $action,
    ?int    $userId    = null,
    ?int    $adminId   = null,
    string  $entityType= '',
    int     $entityId  = 0,
    string  $detail    = '',
    string  $ip        = '',
    string  $category  = 'general',
    string  $oldValue  = '',
    string  $newValue  = '',
    string  $severity  = 'info'
): void {
    try {
        // Auto-purge entries older than 90 days (probabilistic — 3% of calls)
        if (rand(1, 100) <= 3) {
            db()->exec("DELETE FROM activity_log WHERE created_at < DATE_SUB(NOW(), INTERVAL 90 DAY)");
        }
        $ip        = $ip        ?: ($_SERVER['REMOTE_ADDR']     ?? '');
        $userAgent = substr($_SERVER['HTTP_USER_AGENT'] ?? '', 0, 300);
        $page      = substr(($_SERVER['REQUEST_URI']    ?? ''), 0, 200);
        $sessionId = session_id() ?: '';

        db()->prepare("
            INSERT INTO activity_log
                (user_id, admin_id, action, category, entity_type, entity_id, detail,
                 old_value, new_value, ip, user_agent, page, session_id, severity)
            VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?)
        ")->execute([
            $userId ?: null,
            $adminId ?: null,
            substr($action, 0, 120),
            $category,
            $entityType,
            $entityId ?: null,
            substr($detail, 0, 2000),
            substr($oldValue, 0, 2000),
            substr($newValue, 0, 2000),
            $ip,
            $userAgent,
            $page,
            $sessionId,
            $severity,
        ]);
    } catch (Exception $e) { /* never fail silently */ }
}

// Convenience wrappers
function logPlayerAction(string $action, int $userId, string $detail='', string $category='player', string $severity='info'): void {
    logActivity($action, $userId, null, 'user', $userId, $detail, '', $category, '', '', $severity);
}
function logAdminAction(string $action, int $adminId, string $entityType='', int $entityId=0, string $detail='', string $old='', string $new='', string $severity='info'): void {
    logActivity($action, null, $adminId, $entityType, $entityId, $detail, '', 'admin', $old, $new, $severity);
}
function logSecurityEvent(string $action, ?int $userId=null, string $detail='', string $severity='warning'): void {
    logActivity($action, $userId, null, 'security', 0, $detail, '', 'security', '', '', $severity);
}

// ─── App Version ───────────────────────────────────────────
function getAppVersion(): string {
    try {
        $v = db()->query("SELECT version FROM app_version ORDER BY id DESC LIMIT 1")->fetchColumn();
        return $v ?: '1.0.0';
    } catch(Exception $e) { return '1.0.0'; }
}