package com.mes.util;

import com.alibaba.fastjson2.JSONObject;

import java.io.*;
import java.net.*;
import java.nio.charset.StandardCharsets;
import java.nio.file.*;
import java.util.Properties;
import java.util.concurrent.*;

/**
 * 客户端运行状态代理。
 * - 类型由 ClientType.CODE 硬编码自报
 * - clientId 由服务端根据 (类型, IP) 决定
 * - 心跳上报本地 config.properties 当前内容（currentConfigJson）
 * - 服务端下发 desiredConfigJson 直接合并写回 config.properties（备份 .bak）→ 重启生效
 * - 服务端下发 desiredJarVersion 与本地不一致 → 下载对应 jar → 备份 .bak → 替换 → 重启
 */
public final class ClientRuntimeAgent {
    private static final ScheduledExecutorService EXEC = Executors.newSingleThreadScheduledExecutor(r -> {
        Thread t = new Thread(r, "client-runtime-agent");
        t.setDaemon(true);
        return t;
    });
    private static volatile boolean updating;

    private ClientRuntimeAgent() {}

    public static void start(String serverIp, String station, String line) {
        start(serverIp, station, line, "com.mes.ui.MesClient");
    }

    public static void start(final String serverIp, final String station, final String line, final String mainClass) {
        if (serverIp == null || serverIp.trim().isEmpty()) return;
        send(serverIp, station, line, mainClass);
        EXEC.scheduleAtFixedRate(() -> send(serverIp, station, line, mainClass), 30, 30, TimeUnit.SECONDS);
    }

    private static void send(String serverIp, String station, String line, String mainClass) {
        String type = ClientType.CODE;
        try {
            String body = "clientType=" + enc(type)
                    + "&stationCode=" + enc(station)
                    + "&lineSn=" + enc(line)
                    + "&jarVersion=" + version()
                    + "&configVersion=" + configVersion()
                    + "&status=RUNNING"
                    + "&statusMessage=" + enc("客户端运行中")
                    + "&currentConfigJson=" + enc(readLocalConfigAsJson());
            HttpURLConnection c = (HttpURLConnection) new URL("http://" + serverIp + ":8980/js/a/mes/clientRuntime/heartbeat").openConnection();
            c.setRequestMethod("POST");
            c.setConnectTimeout(5000);
            c.setReadTimeout(10000);
            c.setDoOutput(true);
            c.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
            byte[] bytes = body.getBytes(StandardCharsets.UTF_8);
            c.setFixedLengthStreamingMode(bytes.length);
            try (OutputStream out = c.getOutputStream()) { out.write(bytes); }
            int code = c.getResponseCode();
            System.out.println("[ClientRuntime] heartbeat type=" + type + " code=" + code);
            if (code == 200) {
                String resp = read(c.getInputStream());
                System.out.println("[ClientRuntime] response=" + resp);
                JSONObject data = JSONObject.parseObject(resp).getJSONObject("data");
                if (data != null) {
                    Long cv = data.getLong("desiredConfigVersion");
                    String cfg = data.getString("desiredConfigJson");
                    if (cv != null && cfg != null && !cfg.trim().isEmpty() && cv > configVersion()) {
                        applyConfig(cv, cfg, mainClass);
                        return; // applyConfig 会重启，不用继续处理 jar
                    }
                    Long jv = data.getLong("desiredJarVersion");
                    if (jv != null && jv > version() && !updating) update(serverIp, type, jv, mainClass);
                }
            } else {
                System.err.println("[ClientRuntime] heartbeat rejected code=" + code);
            }
            c.disconnect();
        } catch (Exception e) {
            System.err.println("[ClientRuntime] heartbeat/update failed: " + e.getMessage());
        }
    }

    // 读本地 config/config.properties 转为 JSON 字符串
    private static String readLocalConfigAsJson() {
        Path p = Paths.get("config", "config.properties");
        if (!Files.exists(p)) return "";
        try {
            Properties props = new Properties();
            try (InputStream in = Files.newInputStream(p)) { props.load(in); }
            StringBuilder sb = new StringBuilder("{");
            boolean first = true;
            for (String key : props.stringPropertyNames()) {
                if (!first) sb.append(",");
                first = false;
                sb.append('"').append(esc(key)).append("\":\"").append(esc(props.getProperty(key))).append('"');
            }
            sb.append('}');
            return sb.toString();
        } catch (Exception e) {
            return "";
        }
    }

    /**
     * 应用服务端下发的配置：合并到 config.properties（保留未下发的 key），备份 .bak，然后重启生效。
     */
    private static void applyConfig(long ver, String cfg, String mainClass) throws Exception {
        JSONObject json;
        try { json = JSONObject.parseObject(cfg); } catch (Exception e) { System.err.println("[ClientRuntime] invalid config json"); return; }
        if (json == null || json.isEmpty()) return;

        Path dir = Paths.get("config");
        Files.createDirectories(dir);
        Path pfile = dir.resolve("config.properties");
        Properties props = new Properties();
        if (Files.exists(pfile)) {
            try (InputStream in = Files.newInputStream(pfile)) { props.load(in); }
            Files.copy(pfile, dir.resolve("config.properties.bak"), StandardCopyOption.REPLACE_EXISTING);
        }
        // 合并：JSON 里的 key 覆盖到 properties
        for (String key : json.keySet()) {
            String val = json.getString(key);
            if (val == null) continue;
            props.setProperty(key, val);
        }
        try (OutputStream out = Files.newOutputStream(pfile)) {
            props.store(out, "Updated by ClientRuntimeAgent " + new java.util.Date());
        }
        // 注意：config-version.txt 不在这里写，交给 restartSelf 的 vbs 在启动新 Java 前写
        // 这样即使 restart 失败，version 也不会被更新，下次心跳仍会触发同一个 applyConfig
        System.out.println("[ClientRuntime] config applied v=" + ver + ", restarting");
        restartSelf(mainClass, ver);
    }

    /** 触发升级：下载新 jar → 备份 → 替换 → 重启 */
    private static void update(String serverIp, String type, long target, String mainClass) throws Exception {
        updating = true;
        JSONObject root = JSONObject.parseObject(read(new URL("http://" + serverIp + ":8980/js/a/mes/clientVersion/ver?clientType=" + enc(type) + "&version=" + target).openStream()));
        JSONObject data = root.getJSONObject("data");
        if (data == null) throw new IOException("target version unavailable");
        File jar = currentJar();
        File download = new File(jar.getParentFile(), jar.getName() + ".download");
        download(data.getString("path"), download);
        if (download.length() == 0) throw new IOException("empty download");
        // 版本号不在这里写，改由 VBScript 在移动文件成功后写入，避免 VBS 失败时版本号已变

        File vbs = new File(jar.getParentFile(), "client-update-" + System.currentTimeMillis() + ".vbs");
        String jarPath = jar.getAbsolutePath();
        String bakPath = jarPath + ".bak";
        String downloadPath = download.getAbsolutePath();
        String libGlob = new File(jar.getParentFile(), "lib").getAbsolutePath() + File.separator + "*";
        String workDir = jar.getParentFile().getAbsolutePath();
        String verFile = new File(new File(workDir, "config"), "client-version.txt").getAbsolutePath();
        try (Writer w = new OutputStreamWriter(new FileOutputStream(vbs), StandardCharsets.UTF_8)) {
            w.write(
                "Set sh = CreateObject(\"WScript.Shell\")\r\n" +
                "Set fso = CreateObject(\"Scripting.FileSystemObject\")\r\n" +
                "WScript.Sleep 2000\r\n" +
                "If fso.FileExists(\"" + jarPath + "\") Then\r\n" +
                "  If fso.FileExists(\"" + bakPath + "\") Then fso.DeleteFile \"" + bakPath + "\"\r\n" +
                "  fso.MoveFile \"" + jarPath + "\", \"" + bakPath + "\"\r\n" +
                "End If\r\n" +
                "fso.MoveFile \"" + downloadPath + "\", \"" + jarPath + "\"\r\n" +
                "Set f = fso.CreateTextFile(\"" + verFile + "\", True)\r\n" +
                "f.Write \"" + target + "\"\r\n" +
                "f.Close\r\n" +
                "sh.CurrentDirectory = \"" + workDir + "\"\r\n" +
                "sh.Run \"javaw -cp \"\"" + jarPath + ";" + libGlob + "\"\" " + mainClass + "\", 0, False\r\n" +
                "fso.DeleteFile WScript.ScriptFullName\r\n"
            );
        }
        new ProcessBuilder("wscript.exe", vbs.getAbsolutePath()).start();
        System.exit(0);
    }

    /** 仅重启当前 jar，不替换文件（用于配置生效）；vbs 在启动新 Java 前把 verToWrite 写入 config-version.txt */
    private static void restartSelf(String mainClass, long verToWrite) throws Exception {
        File jar = currentJar();
        File vbs = new File(jar.getParentFile(), "client-restart-" + System.currentTimeMillis() + ".vbs");
        String jarPath = jar.getAbsolutePath();
        String libGlob = new File(jar.getParentFile(), "lib").getAbsolutePath() + File.separator + "*";
        String workDir = jar.getParentFile().getAbsolutePath();
        String verFile = new File(new File(workDir, "config"), "config-version.txt").getAbsolutePath();
        try (Writer w = new OutputStreamWriter(new FileOutputStream(vbs), StandardCharsets.UTF_8)) {
            w.write(
                "Set sh = CreateObject(\"WScript.Shell\")\r\n" +
                "Set fso = CreateObject(\"Scripting.FileSystemObject\")\r\n" +
                "WScript.Sleep 2000\r\n" +
                "Set f = fso.CreateTextFile(\"" + verFile + "\", True)\r\n" +
                "f.Write \"" + verToWrite + "\"\r\n" +
                "f.Close\r\n" +
                "sh.CurrentDirectory = \"" + workDir + "\"\r\n" +
                "sh.Run \"javaw -cp \"\"" + jarPath + ";" + libGlob + "\"\" " + mainClass + "\", 0, False\r\n" +
                "fso.DeleteFile WScript.ScriptFullName\r\n"
            );
        }
        new ProcessBuilder("wscript.exe", vbs.getAbsolutePath()).start();
        System.exit(0);
    }

    private static void download(String u, File f) throws IOException {
        HttpURLConnection c = (HttpURLConnection) new URL(u).openConnection();
        c.setConnectTimeout(10000);
        c.setReadTimeout(120000);
        if (c.getResponseCode() != 200) throw new IOException("download failed");
        try (InputStream in = c.getInputStream(); OutputStream out = new FileOutputStream(f)) {
            byte[] b = new byte[8192];
            int n;
            while ((n = in.read(b)) != -1) out.write(b, 0, n);
        } finally { c.disconnect(); }
    }

    private static File currentJar() throws Exception {
        File f = new File(ClientRuntimeAgent.class.getProtectionDomain().getCodeSource().getLocation().toURI());
        if (!f.isFile()) throw new IOException("not running from jar");
        return f;
    }

    private static long version() { return readLong("client-version.txt", 1); }
    private static long configVersion() { return readLong("config-version.txt", 0); }
    private static long readLong(String n, long d) {
        try { return Long.parseLong(new String(Files.readAllBytes(Paths.get("config", n)), StandardCharsets.UTF_8).trim()); }
        catch (Exception e) { return d; }
    }
    private static String enc(String s) {
        try { return URLEncoder.encode(s == null ? "" : s, "UTF-8"); } catch (Exception e) { return ""; }
    }
    private static String esc(String s) {
        if (s == null) return "";
        return s.replace("\\", "\\\\").replace("\"", "\\\"").replace("\n", "\\n").replace("\r", "\\r").replace("\t", "\\t");
    }
    private static String read(InputStream in) throws IOException {
        try (BufferedReader r = new BufferedReader(new InputStreamReader(in, StandardCharsets.UTF_8))) {
            StringBuilder b = new StringBuilder();
            String l;
            while ((l = r.readLine()) != null) b.append(l);
            return b.toString();
        }
    }
}