<?php

declare(strict_types=1);

namespace App\Services;

use Core\Security;
use Core\Database;
use PDO;

class QrTokenService
{
    /**
     * Generates a dynamic QR token valid for 90 seconds.
     */
    public static function generateToken(int $userId): array
    {
        $pdo = Database::getConnection();
        $stmt = $pdo->prepare('
            SELECT s.id AS sub_id, s.membership_number, s.status, s.qr_seed, s.expires_at, u.full_name
            FROM subscriptions s
            JOIN users u ON u.id = s.user_id
            WHERE s.user_id = :uid AND s.status = "ACTIVE"
            ORDER BY s.id DESC
            LIMIT 1
        ');
        $stmt->execute([':uid' => $userId]);
        $sub = $stmt->fetch(PDO::FETCH_ASSOC);

        if (!$sub) {
            return [
                'success' => false,
                'message' => 'No active membership found for this user.',
            ];
        }

        $appConfig = require __DIR__ . '/../../config/app.php';
        $secConfig = require __DIR__ . '/../../config/security.php';

        $secret = $appConfig['secret'] . ':' . $sub['qr_seed'];
        $lifetime = (int)($secConfig['qr_token_lifetime'] ?? 90);

        $token = Security::generateDynamicQrToken(
            $userId,
            $sub['membership_number'],
            $lifetime,
            $secret
        );

        return [
            'success' => true,
            'token' => $token,
            'membership_number' => $sub['membership_number'],
            'full_name' => $sub['full_name'],
            'expires_in' => $lifetime,
            'valid_until' => time() + $lifetime,
        ];
    }

    /**
     * Verifies a QR token scanned by a hospital or hotel receptionist.
     */
    public static function verifyScannedToken(string $token, int $partnerId, ?string $staffName = null): array
    {
        // Decode base64 payload to get user ID without signature first
        $parts = explode('.', $token);
        if (count($parts) !== 2) {
            return ['success' => false, 'message' => 'Invalid QR token format.'];
        }

        $json = base64_decode(strtr($parts[0], '-_', '+/'));
        $tempPayload = json_decode((string)$json, true);

        if (!isset($tempPayload['uid'], $tempPayload['mem'])) {
            return ['success' => false, 'message' => 'Corrupted token payload.'];
        }

        $pdo = Database::getConnection();
        $stmt = $pdo->prepare('
            SELECT s.id AS sub_id, s.membership_number, s.status, s.qr_seed, s.expires_at,
                   u.id AS user_id, u.full_name, u.phone, u.avatar_url
            FROM subscriptions s
            JOIN users u ON u.id = s.user_id
            WHERE u.id = :uid AND s.membership_number = :mem
            LIMIT 1
        ');
        $stmt->execute([
            ':uid' => (int)$tempPayload['uid'],
            ':mem' => $tempPayload['mem'],
        ]);
        $record = $stmt->fetch(PDO::FETCH_ASSOC);

        if (!$record) {
            return ['success' => false, 'message' => 'Membership record not found.'];
        }

        $appConfig = require __DIR__ . '/../../config/app.php';
        $secret = $appConfig['secret'] . ':' . $record['qr_seed'];

        $verified = Security::verifyDynamicQrToken($token, $secret);
        if (!$verified) {
            return [
                'success' => false,
                'message' => 'Token has expired or signature is counterfeit. Please refresh code in app.',
            ];
        }

        // Get partner discount details
        $pStmt = $pdo->prepare('SELECT id, name_ar, type, discount_percentage FROM partners WHERE id = :pid LIMIT 1');
        $pStmt->execute([':pid' => $partnerId]);
        $partner = $pStmt->fetch(PDO::FETCH_ASSOC);

        $discount = $partner ? (float)$partner['discount_percentage'] : 50.00;

        // Log verification entry for audit & statistics
        $logStmt = $pdo->prepare('
            INSERT INTO verification_logs (subscription_id, partner_id, verifier_staff_name, applied_discount, service_type, scanned_token_signature, verified_at)
            VALUES (:sub_id, :pid, :staff, :discount, :stype, :sig, NOW())
        ');
        $logStmt->execute([
            ':sub_id' => $record['sub_id'],
            ':pid' => $partnerId,
            ':staff' => $staffName ?: 'Front Desk',
            ':discount' => $discount,
            ':stype' => $partner['type'] ?? 'HOSPITAL',
            ':sig' => substr($parts[1], 0, 64),
        ]);

        return [
            'success' => true,
            'is_valid' => true,
            'membership_number' => $record['membership_number'],
            'member_name' => $record['full_name'],
            'member_phone' => $record['phone'],
            'status' => $record['status'],
            'expires_at' => $record['expires_at'],
            'partner_name' => $partner['name_ar'] ?? 'Partner',
            'discount_percentage' => $discount,
            'verified_at' => date('Y-m-d H:i:s'),
        ];
    }
}