no-copy/src/main/java/ru/soune/nocopy/service/geo/GeoCountryService.java

package ru.soune.nocopy.service.geo;

import com.maxmind.geoip2.DatabaseReader;
import com.maxmind.geoip2.model.CountryResponse;
import jakarta.annotation.PostConstruct;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.io.ClassPathResource;
import org.springframework.stereotype.Service;

import java.net.InetAddress;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

@Service
@Slf4j
public class GeoCountryService {

    private DatabaseReader dbReader;
    private final Map<String, String> cache = new ConcurrentHashMap<>();

    @PostConstruct
    public void init() {
        try {
            var resource = new ClassPathResource("geo/GeoLite2-Country.mmdb");
            this.dbReader = new DatabaseReader.Builder(resource.getInputStream()).build();
        } catch (Exception e) {
            log.error("Failed to load Geo DB", e);
        }
    }

    public String getCountry(String input) {
        if (input == null || input.isBlank()) {
            return null;
        }

        String host = extractHost(input);

        if (cache.containsKey(host)) {
            return cache.get(host);
        }

        try {
            InetAddress ip = InetAddress.getByName(host);
            CountryResponse response = dbReader.country(ip);
            String country = response.getCountry().getIsoCode();

            cache.put(host, country != null ? country : "");
            log.debug("{} → {}", host, country);
            return country;

        } catch (Exception e) {
            cache.put(host, "");
            return null;
        }
    }

    private String extractHost(String input) {
        String s = input.replaceFirst("^https?://", "");
        s = s.split("/")[0];
        s = s.split(":")[0];

        return s;
    }
}