package io.github.ehlxr.did.server.sdk;

import io.github.ehlxr.did.common.Constants;
import io.github.ehlxr.did.common.NettyUtil;
import io.github.ehlxr.did.common.SdkProto;
import io.github.ehlxr.did.core.SnowFlake;
import io.netty.channel.Channel;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.util.concurrent.Semaphore;
import java.util.concurrent.TimeUnit;

/**
 * 通过雪花算法生成唯一 ID，写入 Channel 返回
 *
 * @author ehlxr
 */
public class SdkServerHandler extends SimpleChannelInboundHandler<SdkProto> {
    private static final Logger logger = LoggerFactory.getLogger(SdkServerHandler.class);
    /**
     * 通过信号量来控制流量
     */
    private final Semaphore semaphore = new Semaphore(Constants.HANDLE_SDK_TPS);
    private final SnowFlake snowFlake;

    SdkServerHandler(SnowFlake snowFlake) {
        this.snowFlake = snowFlake;
    }

    @Override
    protected void channelRead0(ChannelHandlerContext ctx, SdkProto sdkProto) throws Exception {
        if (semaphore.tryAcquire(Constants.ACQUIRE_TIMEOUTMILLIS, TimeUnit.MILLISECONDS)) {
            try {
                sdkProto.setDid(snowFlake.nextId());

                ctx.channel().writeAndFlush(sdkProto).addListener((ChannelFutureListener) channelFuture -> semaphore.release());
            } catch (Exception e) {
                semaphore.release();
                logger.error("SdkServerhandler error", e);
            }
        } else {
            sdkProto.setDid(-1);
            ctx.channel().writeAndFlush(sdkProto);
            String info = String.format("SdkServerHandler tryAcquire semaphore timeout, %dms, waiting thread " + "nums: %d availablePermit: %d",
                    Constants.ACQUIRE_TIMEOUTMILLIS, this.semaphore.getQueueLength(), this.semaphore.availablePermits());
            logger.warn(info);
            throw new Exception(info);
        }
    }

    @Override
    public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
        Channel channel = ctx.channel();
        logger.error("SdkServerHandler channel [{}] error and will be closed", NettyUtil.parseRemoteAddr(channel), cause);
        NettyUtil.closeChannel(channel);
    }
}