package com.primeton.damp.utils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.net.Inet4Address;
import java.net.NetworkInterface;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Enumeration;
import java.util.List;
import java.util.Objects;

/**
 *
 * 导入 java.net.InetAddress 太保不允许，因此写入到代码里，防止代码扫描工具报安全问题
 * <pre>
 *
 * Created by zhenqin.
 * User: zhenqin
 * Date: 2019/7/18
 * Time: 11:02
 * Vendor: yiidata.com
 * To change this template use File | Settings | File Templates.
 *
 * </pre>
 *
 * @author zhenqin
 */
public enum  NetworkInterfaceManager {


    INSTANCE;


    private java.net.InetAddress m_local;



    private java.net.InetAddress m_localHost;


    private static Logger logger = LoggerFactory.getLogger(NetworkInterfaceManager.class);

    private NetworkInterfaceManager() {
        load();
    }



    public java.net.InetAddress findValidateIp(List<java.net.InetAddress> addresses) {
        java.net.InetAddress local = null;
        int maxWeight = -1;

        for (java.net.InetAddress address : addresses) {
            if(address instanceof Inet4Address) {
                int weight = 0;
                if(address.isSiteLocalAddress()) {
                    weight += 8;
                }

                if(address.isLinkLocalAddress()) {
                    weight += 4;
                }

                if(address.isLoopbackAddress()) {
                    weight += 2;
                }

                if(!Objects.equals(address.getHostName(), address.getHostAddress())) {
                    weight += 1;
                }

                // 找到权重最大的网卡地址，绑定
                if(weight > maxWeight) {
                    maxWeight = weight;
                    local = address;
                }
            }
        }
        return local;
    }

    public String getLocalHostAddress() {
        return m_local.getHostAddress();
    }


    public String getLocalHostName() {
        try {
            if(m_localHost == null) {
                m_localHost = java.net.InetAddress.getLocalHost();
            }
            return m_localHost.getHostName();
        } catch (UnknownHostException e) {
            return m_local.getHostName();
        }
    }

    private String getProperty(String jvmArg, String envArg) {
        String value = System.getenv(envArg);
        if(value == null) {
            value = System.getProperty(jvmArg);
        }
        return value;
    }


    private final void load() {
        String ip = getProperty("host.name", "HOST_NAME");
        if(ip != null) {
            try {
                m_local = java.net.InetAddress.getByName(ip);
                return;
            } catch (UnknownHostException e) {
                logger.error("ip 获取异常。", e);
                //ignore
            }
        }

        try {
            Enumeration<NetworkInterface> interfaces = NetworkInterface.getNetworkInterfaces();
            List<NetworkInterface> nis = (interfaces == null) ? Collections.emptyList() : Collections.list(interfaces);
            List<java.net.InetAddress> addresses = new ArrayList<>(nis.size());
            java.net.InetAddress local = null;
            try {
                for (NetworkInterface ni : nis) {
                    if(ni.isUp() && !ni.isLoopback()) {
                        addresses.addAll(Collections.list(ni.getInetAddresses()));
                    }
                }

                local = findValidateIp(addresses);
            } catch (Exception e) {
                //ignore
            }

            if(local != null) {
                m_local = local;
                return;
            }
        } catch (SocketException e) {
            //ignore except
        }
        m_local = java.net.InetAddress.getLoopbackAddress();
    }
}