package com.xcong.excoin.modules.gateApi.wsHandler;

import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;
import com.xcong.excoin.modules.gateApi.GateGridTradeService;
import lombok.extern.slf4j.Slf4j;
import org.java_websocket.client.WebSocketClient;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.nio.charset.StandardCharsets;

/**
 * 私有频道处理器的抽象基类。
 *
 * <h3>封装内容</h3>
 * <ul>
 *   <li>HMAC-SHA512 签名计算（UTF-8 编码）</li>
 *   <li>认证请求 JSON 构建（id/time/channel/payload/auth）</li>
 *   <li>subscribe / unsubscribe 的默认实现（含签名）</li>
 *   <li>用户 ID 获取（从 {@link GateGridTradeService#getUserId()}）</li>
 * </ul>
 *
 * <h3>签名算法</h3>
 * {@code SIGN = Hex(HmacSHA512(secret_utf8, "channel={channel}&event={event}&time={timeSec}"_utf8))}
 *
 * <h3>子类</h3>
 * {@link com.xcong.excoin.modules.gateApi.wsHandler.handler.PositionsChannelHandler}、
 * {@link com.xcong.excoin.modules.gateApi.wsHandler.handler.PositionClosesChannelHandler}
 *
 * @author Administrator
 */
@Slf4j
public abstract class AbstractPrivateChannelHandler implements GateChannelHandler {

    private static final char[] HEX_ARRAY = "0123456789abcdef".toCharArray();

    private final String channelName;
    private final String apiKey;
    private final String apiSecret;
    private final String contract;
    private final GateGridTradeService gridTradeService;

    public AbstractPrivateChannelHandler(String channelName,
                                          String apiKey, String apiSecret,
                                          String contract,
                                          GateGridTradeService gridTradeService) {
        this.channelName = channelName;
        this.apiKey = apiKey;
        this.apiSecret = apiSecret;
        this.contract = contract;
        this.gridTradeService = gridTradeService;
    }

    /** @return 频道名称（如 "futures.positions"） */
    @Override
    public String getChannelName() { return channelName; }

    /**
     * 发送带签名的订阅请求。
     *
     * <h3>请求格式</h3>
     * <pre>
     * {
     *   "id":     &lt;唯一请求ID&gt;,
     *   "time":   &lt;unix时间戳(秒)&gt;,
     *   "channel":"futures.positions",
     *   "event":  "subscribe",
     *   "payload":[userId, contract],
     *   "auth":   {"method":"api_key", "KEY":&lt;APIKEY&gt;, "SIGN":&lt;HMAC-SHA512签名&gt;}
     * }
     * </pre>
     */
    @Override
    public void subscribe(WebSocketClient ws) {
        long timeSec = System.currentTimeMillis() / 1000;
        JSONObject msg = buildAuthRequest("subscribe", buildUid(), timeSec);
        ws.send(msg.toJSONString());
        log.info("[{}] 订阅成功, 合约:{}", channelName, contract);
    }

    /**
     * 发送带签名的取消订阅请求，与 subscribe 结构一致。
     * payload: [contract]，无 userId（取消订阅不需要用户ID）。
     */
    @Override
    public void unsubscribe(WebSocketClient ws) {
        long timeSec = System.currentTimeMillis() / 1000;
        JSONObject msg = new JSONObject();
        msg.put("id", timeSec * 1000000 + (System.currentTimeMillis() % 1000));
        msg.put("time", timeSec);
        msg.put("channel", channelName);
        msg.put("event", "unsubscribe");
        JSONArray payload = new JSONArray();
        payload.add(contract);
        msg.put("payload", payload);
        JSONObject auth = new JSONObject();
        auth.put("method", "api_key");
        auth.put("KEY", apiKey);
        auth.put("SIGN", hs512Sign("unsubscribe", timeSec));
        msg.put("auth", auth);
        ws.send(msg.toJSONString());
        log.info("[{}] 取消订阅成功, 合约:{}", channelName, contract);
    }

    /** @return 网格交易服务实例 */
    protected GateGridTradeService getGridTradeService() { return gridTradeService; }
    /** @return 当前订阅的合约名称 */
    protected String getContract() { return contract; }

    /**
     * 从策略服务获取用户 ID，用于私有频道订阅的 payload[0]。
     *
     * @return 用户 ID 字符串，获取失败返回空字符串
     */
    private String buildUid() {
        return gridTradeService != null && gridTradeService.getUserId() != null
                ? String.valueOf(gridTradeService.getUserId()) : "";
    }

    /**
     * 构建认证请求 JSON。
     * 包含 id、time、channel、event、payload[userId, contract]、auth 字段。
     *
     * @param event   事件类型（"subscribe" / "unsubscribe"）
     * @param uid     认证用户 ID
     * @param timeSec unix 时间戳（秒）
     * @return 完整的认证请求 JSONObject
     */
    private JSONObject buildAuthRequest(String event, String uid, long timeSec) {
        JSONObject msg = new JSONObject();
        msg.put("id", timeSec * 1000000 + (System.currentTimeMillis() % 1000));
        msg.put("time", timeSec);
        msg.put("channel", channelName);
        msg.put("event", event);
        JSONArray payload = new JSONArray();
        payload.add(uid);
        payload.add(contract);
        msg.put("payload", payload);
        JSONObject auth = new JSONObject();
        auth.put("method", "api_key");
        auth.put("KEY", apiKey);
        auth.put("SIGN", hs512Sign(event, timeSec));
        msg.put("auth", auth);
        return msg;
    }

    /**
     * HMAC-SHA512 签名计算。
     *
     * <h3>签名算法</h3>
     * <pre>
     *   message = "channel={channelName}&event={event}&time={timeSec}"
     *   SIGN = Hex(HmacSHA512(apiSecret(UTF-8), message(UTF-8)))
     * </pre>
     *
     * <h3>错误处理</h3>
     * 签名计算失败时返回空字符串（日志记录错误），不抛异常，
     * 避免阻塞 WebSocket 回调线程。
     *
     * @param event   事件类型
     * @param timeSec unix 时间戳（秒）
     * @return 十六进制签名字符串，失败返回 ""
     */
    private String hs512Sign(String event, long timeSec) {
        try {
            String message = "channel=" + channelName + "&event=" + event + "&time=" + timeSec;
            Mac mac = Mac.getInstance("HmacSHA512");
            SecretKeySpec spec = new SecretKeySpec(apiSecret.getBytes(StandardCharsets.UTF_8), "HmacSHA512");
            mac.init(spec);
            byte[] hash = mac.doFinal(message.getBytes(StandardCharsets.UTF_8));
            StringBuilder hex = new StringBuilder(hash.length * 2);
            for (byte b : hash) {
                hex.append(HEX_ARRAY[(b >> 4) & 0xF]);
                hex.append(HEX_ARRAY[b & 0xF]);
            }
            return hex.toString();
        } catch (Exception e) {
            log.error("[{}] 签名计算失败", channelName, e);
            return "";
        }
    }
}