package com.lanportscanner;

import androidx.annotation.NonNull;

import com.facebook.react.bridge.Arguments;
import com.facebook.react.bridge.Promise;
import com.facebook.react.bridge.ReactApplicationContext;
import com.facebook.react.bridge.ReactContextBaseJavaModule;
import com.facebook.react.bridge.ReactMethod;
import com.facebook.react.bridge.WritableMap;
import com.facebook.react.module.annotations.ReactModule;

import android.content.Context;
import android.net.wifi.WifiInfo;
import android.net.wifi.WifiManager;

import java.math.BigInteger;
import java.net.InetAddress;
import java.net.InterfaceAddress;
import java.net.NetworkInterface;
import java.util.List;
import java.util.Locale;

@ReactModule(name = LanPortScannerModule.NAME)
public class LanPortScannerModule extends ReactContextBaseJavaModule {
    public static final String NAME = "LanPortScanner";

    private static ReactApplicationContext reactContext;

    public LanPortScannerModule(ReactApplicationContext context) {
        super(reactContext);
        reactContext = context;
    }

    @Override
    @NonNull
    public String getName() {
        return NAME;
    }

    @ReactMethod
    public void getNetworkInfo(Promise promise) {
        WritableMap map = Arguments.createMap();

        // Get the IP address
        WifiManager mWifiManager = (WifiManager)
                reactContext.getApplicationContext().getSystemService(Context.WIFI_SERVICE);

        WifiInfo wifiInfo = mWifiManager.getConnectionInfo();
        if (wifiInfo != null) {
            try {
                byte[] ipAddressByteArray =
                        BigInteger.valueOf(wifiInfo.getIpAddress()).toByteArray();
                NetInfoUtils.reverseByteArray(ipAddressByteArray);
                InetAddress inetAddress = InetAddress.getByAddress(ipAddressByteArray);
                String ipAddress = inetAddress.getHostAddress();
                map.putString("ipAddress", ipAddress);

                NetworkInterface netAddress = NetworkInterface.getByInetAddress(inetAddress);

                //Get subnet
                List<InterfaceAddress> addresses = netAddress.getInterfaceAddresses();

                short networkPrefixLength = 0;
                for (InterfaceAddress address : addresses) {
                    boolean isIpV4 = address.getAddress().getAddress().length == 4;
                    if (isIpV4) {
                        networkPrefixLength = address.getNetworkPrefixLength();
                        break;
                    }
                }

                int mask = 0xffffffff << (32 - networkPrefixLength);
                String subnet = String.format(
                        Locale.US,
                        "%d.%d.%d.%d",
                        (mask >> 24 & 0xff),
                        (mask >> 16 & 0xff),
                        (mask >> 8 & 0xff),
                        (mask & 0xff));

                map.putString("subnetMask", subnet);

                promise.resolve(map);
            } catch (Exception e) {
                // Ignore errors
            }
        }
    }
}