package com.zhentao.information.handler;

import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.timeout.IdleState;
import io.netty.handler.timeout.IdleStateEvent;
import lombok.extern.slf4j.Slf4j;
import org.springframework.stereotype.Component;

/**
 * 心跳处理器
 * 处理客户端的心跳检测
 */
@Slf4j
@Component
@ChannelHandler.Sharable
public class HeartbeatHandler extends ChannelInboundHandlerAdapter {

    private static final int MAX_MISSED_HEARTBEATS = 3;
    private int missedHeartbeats = 0;

    /**
     * 处理用户事件
     * 当触发IdleStateEvent时调用
     * @param ctx Channel上下文
     * @param evt 事件对象
     */
    @Override
    public void userEventTriggered(ChannelHandlerContext ctx, Object evt) throws Exception {
        if (evt instanceof IdleStateEvent) {
            IdleStateEvent event = (IdleStateEvent) evt;
            
            if (event.state() == IdleState.READER_IDLE) {
                missedHeartbeats++;
                log.warn("读空闲，已错过 {} 次心跳", missedHeartbeats);
                
                if (missedHeartbeats >= MAX_MISSED_HEARTBEATS) {
                    log.error("读空闲超时，关闭连接：{}", ctx.channel().id().asLongText());
                    ctx.close();
                } else {
                    // 发送心跳检测消息
                    ctx.writeAndFlush("ping");
                }
            } else if (event.state() == IdleState.WRITER_IDLE) {
                // 发送心跳检测消息
                ctx.writeAndFlush("ping");
            }
        } else {
            super.userEventTriggered(ctx, evt);
        }
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        if (msg instanceof String && "pong".equals(msg)) {
            // 收到心跳响应，重置计数器
            missedHeartbeats = 0;
            log.debug("收到心跳响应");
        } else {
            super.channelRead(ctx, msg);
        }
    }

    @Override
    public void channelInactive(ChannelHandlerContext ctx) throws Exception {
        log.info("连接断开：{}", ctx.channel().id().asLongText());
        super.channelInactive(ctx);
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
        log.error("心跳处理器异常", cause);
        ctx.close();
    }
}