package xyz.playedu.api.util;

import com.alibaba.fastjson2.JSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import jakarta.servlet.http.HttpServletRequest;
import java.net.InetAddress;
import java.net.UnknownHostException;

public class IpUtil {

    private static final Logger log = LoggerFactory.getLogger(IpUtil.class);

    /**
     * 获取客户端IP
     *
     * @return IP地址 (113.67.10.194)
     * @author fzr
     */
    public static String getIpAddress() {
        HttpServletRequest request = RequestUtil.handler();
        if (request == null) {
            return "unknown";
        }
        String ip = request.getHeader("x-forwarded-for");
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("X-Forwarded-For");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("WL-Proxy-Client-IP");
        }
        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getHeader("X-Real-IP");
        }

        if (ip == null || ip.length() == 0 || "unknown".equalsIgnoreCase(ip)) {
            ip = request.getRemoteAddr();
        }

        return "0:0:0:0:0:0:0:1".equals(ip) ? "127.0.0.1" : getMultistageReverseProxyIp(ip);
    }

    /**
     * 根据IP获取所在地址
     *
     * @param ip Ip地址
     * @return String (广州省 广州市)
     * @author fzr
     */
    public static String getRealAddressByIP(String ip) {
        String IP_URL = "https://whois.pconline.com.cn/ipJson.jsp";
        String UNKNOWN = "XX XX";

        // 内网不查询
        if (IpUtil.internalIp(ip)) {
            return "内网IP";
        }

        try {
            String rspStr = HttpUtil.sendGet(IP_URL, "ip=" + ip + "&json=true", "GBK");
            if (StringUtil.isEmpty(rspStr)) {
                log.error("获取地理位置异常 {}", ip);
                return UNKNOWN;
            }
            JSONObject obj = JSONObject.parseObject(rspStr);
            String region = obj.getString("pro");
            String city = obj.getString("city");
            return String.format("%s %s", region, city);
        } catch (Exception e) {
            log.error("获取地理位置异常 {}", ip);
        }

        return UNKNOWN;
    }

    /**
     * 检查是否为内部IP地址
     *
     * @param ip IP地址
     * @return 结果
     */
    public static boolean internalIp(String ip) {
        byte[] address = textToNumericFormatV4(ip);
        return internalIp(address) || "127.0.0.1".equals(ip);
    }

    /**
     * 检查是否为内部IP地址
     *
     * @param address byte地址
     * @return 结果
     * @author fzr
     */
    private static boolean internalIp(byte[] address) {
        if (address == null || address.length < 2) {
            return true;
        }
        final byte b0 = address[0];
        final byte b1 = address[1];
        // 10.x.x.x/8
        final byte SECTION_1 = 0x0A;
        // 172.16.x.x/12
        final byte SECTION_2 = (byte) 0xAC;
        final byte SECTION_3 = (byte) 0x10;
        final byte SECTION_4 = (byte) 0x1F;
        // 192.168.x.x/16
        final byte SECTION_5 = (byte) 0xC0;
        final byte SECTION_6 = (byte) 0xA8;
        switch (b0) {
            case SECTION_1:
                return true;
            case SECTION_2:
                if (b1 >= SECTION_3 && b1 <= SECTION_4) {
                    return true;
                }
            case SECTION_5:
                if (b1 == SECTION_6) {
                    return true;
                }
            default:
                return false;
        }
    }

    /**
     * 将IPv4地址转换成字节
     *
     * @param text IPv4地址
     * @return byte 字节
     * @author fzr
     */
    public static byte[] textToNumericFormatV4(String text) {
        if (text.length() == 0) {
            return null;
        }

        byte[] bytes = new byte[4];
        String[] elements = text.split("\\.", -1);
        try {
            long l;
            int i;
            switch (elements.length) {
                case 1:
                    l = Long.parseLong(elements[0]);
                    if ((l < 0L) || (l > 4294967295L)) {
                        return null;
                    }
                    bytes[0] = (byte) (int) (l >> 24 & 0xFF);
                    bytes[1] = (byte) (int) ((l & 0xFFFFFF) >> 16 & 0xFF);
                    bytes[2] = (byte) (int) ((l & 0xFFFF) >> 8 & 0xFF);
                    bytes[3] = (byte) (int) (l & 0xFF);
                    break;
                case 2:
                    l = Integer.parseInt(elements[0]);
                    if ((l < 0L) || (l > 255L)) {
                        return null;
                    }
                    bytes[0] = (byte) (int) (l & 0xFF);
                    l = Integer.parseInt(elements[1]);
                    if ((l < 0L) || (l > 16777215L)) {
                        return null;
                    }
                    bytes[1] = (byte) (int) (l >> 16 & 0xFF);
                    bytes[2] = (byte) (int) ((l & 0xFFFF) >> 8 & 0xFF);
                    bytes[3] = (byte) (int) (l & 0xFF);
                    break;
                case 3:
                    for (i = 0; i < 2; ++i) {
                        l = Integer.parseInt(elements[i]);
                        if ((l < 0L) || (l > 255L)) {
                            return null;
                        }
                        bytes[i] = (byte) (int) (l & 0xFF);
                    }
                    l = Integer.parseInt(elements[2]);
                    if ((l < 0L) || (l > 65535L)) {
                        return null;
                    }
                    bytes[2] = (byte) (int) (l >> 8 & 0xFF);
                    bytes[3] = (byte) (int) (l & 0xFF);
                    break;
                case 4:
                    for (i = 0; i < 4; ++i) {
                        l = Integer.parseInt(elements[i]);
                        if ((l < 0L) || (l > 255L)) {
                            return null;
                        }
                        bytes[i] = (byte) (int) (l & 0xFF);
                    }
                    break;
                default:
                    return null;
            }
        } catch (NumberFormatException e) {
            return null;
        }
        return bytes;
    }

    /**
     * 获取IP地址
     *
     * @return 本地IP地址
     * @author fzr
     */
    public static String getHostIp() {
        try {
            return InetAddress.getLocalHost().getHostAddress();
        } catch (UnknownHostException ignored) {
        }
        return "127.0.0.1";
    }

    /**
     * 获取主机名
     *
     * @return 本地主机名
     * @author fzr
     */
    public static String getHostName() {
        try {
            return InetAddress.getLocalHost().getHostName();
        } catch (UnknownHostException ignored) {
        }
        return "未知";
    }

    /**
     * 从多级反向代理中获得第一个非unknown IP地址
     *
     * @param ip 获得的IP地址
     * @return 第一个非unknown IP地址
     * @author fzr
     */
    public static String getMultistageReverseProxyIp(String ip) {
        if (ip != null && ip.indexOf(",") > 0) {
            final String[] ips = ip.trim().split(",");
            for (String subIp : ips) {
                if (!isUnknown(subIp)) {
                    ip = subIp;
                    break;
                }
            }
        }
        return ip;
    }

    /**
     * 检测给定字符串是否为未知,多用于检测HTTP请求相关
     *
     * @param checkString 被检测的字符串
     * @return 是否未知
     * @author fzr
     */
    public static boolean isUnknown(String checkString) {
        return StringUtil.isBlank(checkString) || "unknown".equalsIgnoreCase(checkString);
    }

}