package com.telerobot.fs.utils;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.ByteArrayInputStream;
import java.nio.charset.StandardCharsets;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class XmlUtils {
    protected final static Logger logger = LoggerFactory.getLogger(XmlUtils.class);

    /** 从 contact 标签中提取 sip:user@host:port 的 host:port */
    private static final Pattern CONTACT_HOST_PORT = Pattern.compile(
            "sip:[^@;>\\s]+@([^:;>\\s]+):(\\d+)", Pattern.CASE_INSENSITIVE);

    /**
     * 从 sofia xmlstatus profile X reg 的 XML 中解析已注册分机的 Contact（ip:port）。
     * 匹配规则与 GUI FsConfController.convertProfileRegExtnumXml 对齐：
     * 1) sip-auth-user 等于目标分机；或 2) user（@ 前部分）等于目标分机。
     * 地址优先取 network-ip:network-port（与 GUI 展示一致，为 NAT 后公网地址）；
     * 若缺失再从 contact 的 sip URI 回退解析。
     * 注意：反向注册场景 ESL 事件常见 username=unknown，sip-auth-user 可能为空/unknown，
     * 仅匹配 sip-auth-user 会导致漏找（GUI 能显示而 callcenter 解析不到）。
     *
     * @param xml sofia xmlstatus 响应全文
     * @param extensionNumber 网关 authUsername / 分机号
     * @return ip:port，未找到返回空串
     */
    public static String parseFsOnlineUserListXml(String xml, String extensionNumber) {
        if (StringUtils.isNullOrEmpty(xml) || StringUtils.isNullOrEmpty(extensionNumber)) {
            return "";
        }
        String target = extensionNumber.trim();
        try {
            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            DocumentBuilder builder = factory.newDocumentBuilder();
            Document doc = builder.parse(new ByteArrayInputStream(xml.getBytes(StandardCharsets.UTF_8)));

            NodeList registrations = doc.getElementsByTagName("registration");
            int regCount = registrations.getLength();
            logger.info("parseFsOnlineUserListXml: registration条数={}, 目标分机={}", regCount, target);

            for (int i = 0; i < regCount; i++) {
                Element registration = (Element) registrations.item(i);

                String sipAuthUser = getChildText(registration, "sip-auth-user");
                String userRaw = getChildText(registration, "user");
                String userPart = extractUserPart(userRaw);

                boolean matchedByAuth = target.equals(sipAuthUser);
                boolean matchedByUser = target.equals(userPart);
                if (!matchedByAuth && !matchedByUser) {
                    continue;
                }

                String matchBy = matchedByAuth ? "sip-auth-user" : "user";
                String networkIp = getChildText(registration, "network-ip");
                String networkPort = getChildText(registration, "network-port");
                String contactTag = getChildText(registration, "contact");
                String contact;
                if (!StringUtils.isNullOrEmpty(networkIp) && !StringUtils.isNullOrEmpty(networkPort)) {
                    contact = networkIp + ":" + networkPort;
                } else {
                    contact = extractHostPortFromContact(contactTag);
                    logger.info("parseFsOnlineUserListXml: network-ip/port 缺失，回退解析 contact 标签，matchBy={}, contact={}", matchBy, contact);
                }

                if (StringUtils.isNullOrEmpty(contact)) {
                    logger.warn("parseFsOnlineUserListXml: 已匹配 registration 但 Contact 为空，matchBy={}, user={}, sip-auth-user={}, contactTag={}", matchBy, userRaw, sipAuthUser, contactTag);
                    continue;
                }

                logger.info("parseFsOnlineUserListXml: 匹配成功 index={}, matchBy={}, user={}, sip-auth-user={}, contact={}", i, matchBy, userRaw, sipAuthUser, contact);
                return contact;
            }

            // 未命中时输出少量候选，便于对比 GUI「查看状态」
            int sample = Math.min(regCount, 5);
            for (int i = 0; i < sample; i++) {
                Element registration = (Element) registrations.item(i);
                logger.info("parseFsOnlineUserListXml: 未命中样例[{}] user={}, sip-auth-user={}, network={}:{}",
                        i,
                        getChildText(registration, "user"),
                        getChildText(registration, "sip-auth-user"),
                        getChildText(registration, "network-ip"),
                        getChildText(registration, "network-port"));
            }
        } catch (Throwable e) {
            logger.error("parseFsOnlineUserListXml error! {} {}", e.toString(),
                    CommonUtils.getStackTraceString(e.getStackTrace()));
            // DOM 失败时（contact 含未转义 <> 等）用正则兜底，对齐 GUI 的 user + network-ip
            String fallback = parseFsOnlineUserListXmlByRegex(xml, target);
            if (!StringUtils.isNullOrEmpty(fallback)) {
                return fallback;
            }
        }
        return "";
    }

    /**
     * DOM 解析失败时的正则兜底：按 <user>分机@...</user> 定位 registration 片段，再取 network-ip/port。
     */
    private static String parseFsOnlineUserListXmlByRegex(String xml, String target) {
        try {
            Pattern regBlock = Pattern.compile("<registration>([\\s\\S]*?)</registration>", Pattern.CASE_INSENSITIVE);
            Matcher m = regBlock.matcher(xml);
            int idx = 0;
            while (m.find()) {
                String block = m.group(1);
                String sipAuthUser = extractXmlTag(block, "sip-auth-user");
                String userRaw = extractXmlTag(block, "user");
                String userPart = extractUserPart(userRaw);
                boolean matched = target.equals(sipAuthUser) || target.equals(userPart);
                if (!matched) {
                    idx++;
                    continue;
                }
                String networkIp = extractXmlTag(block, "network-ip");
                String networkPort = extractXmlTag(block, "network-port");
                String contact;
                if (!StringUtils.isNullOrEmpty(networkIp) && !StringUtils.isNullOrEmpty(networkPort)) {
                    contact = networkIp + ":" + networkPort;
                } else {
                    contact = extractHostPortFromContact(extractXmlTag(block, "contact"));
                }
                if (!StringUtils.isNullOrEmpty(contact)) {
                    logger.info("parseFsOnlineUserListXml: 正则兜底匹配成功 index={}, user={}, sip-auth-user={}, contact={}", idx, userRaw, sipAuthUser, contact);
                    return contact;
                }
                idx++;
            }
        } catch (Throwable e) {
            logger.error("parseFsOnlineUserListXmlByRegex error! {}", e.toString());
        }
        return "";
    }

    private static String getChildText(Element parent, String tagName) {
        NodeList list = parent.getElementsByTagName(tagName);
        if (list == null || list.getLength() == 0) {
            return "";
        }
        Node node = list.item(0);
        if (node == null || node.getTextContent() == null) {
            return "";
        }
        return node.getTextContent().trim();
    }

    private static String extractUserPart(String userRaw) {
        if (StringUtils.isNullOrEmpty(userRaw)) {
            return "";
        }
        int at = userRaw.indexOf('@');
        if (at > 0) {
            return userRaw.substring(0, at).trim();
        }
        return userRaw.trim();
    }

    private static String extractHostPortFromContact(String contactTag) {
        if (StringUtils.isNullOrEmpty(contactTag)) {
            return "";
        }
        Matcher matcher = CONTACT_HOST_PORT.matcher(contactTag);
        if (matcher.find()) {
            return matcher.group(1) + ":" + matcher.group(2);
        }
        return "";
    }

    private static String extractXmlTag(String block, String tagName) {
        Pattern p = Pattern.compile("<" + tagName + ">\\s*([^<]*?)\\s*</" + tagName + ">",
                Pattern.CASE_INSENSITIVE);
        Matcher m = p.matcher(block);
        if (m.find()) {
            return m.group(1).trim();
        }
        return "";
    }
}