package chat.server.moquette;

import org.apache.log4j.Logger;

import io.netty.buffer.ByteBuf;
import io.netty.channel.Channel;
import io.netty.channel.ChannelDuplexHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.util.Attribute;
import io.netty.util.AttributeKey;

public class MqttBytesMetricsHandler extends ChannelDuplexHandler {
	
    private static Logger logger;
    private static AttributeKey<Metrics> ATTR_KEY_METRICS;
    private static AttributeKey<String> ATTR_KEY_USERNAME;

    private BytesMetricsCollector collector;
    
    static {
    	logger = Logger.getLogger(MqttBytesMetricsHandler.class);
    	ATTR_KEY_METRICS = AttributeKey.valueOf("BytesMetrics");
    	ATTR_KEY_USERNAME = AttributeKey.valueOf("username");
    }

    public MqttBytesMetricsHandler(BytesMetricsCollector collector) {
        this.collector = collector;
    }

    @Override
    public void channelActive(ChannelHandlerContext ctx) throws Exception {
        Attribute<Metrics> attr = ctx.channel().attr(ATTR_KEY_METRICS);
        attr.set(new Metrics());

        super.channelActive(ctx);
    }

    @Override
    public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
        Metrics metrics = ctx.channel().attr(ATTR_KEY_METRICS).get();
        metrics.incrementRead(((ByteBuf) msg).readableBytes());
        ctx.fireChannelRead(msg);
    }

    @Override
    public void write(ChannelHandlerContext ctx, Object msg, ChannelPromise promise) throws Exception {
        Metrics metrics = ctx.channel().attr(ATTR_KEY_METRICS).get();
        metrics.incrementWrote(((ByteBuf) msg).writableBytes());
        ctx.write(msg, promise);
    }

    @Override
    public void close(ChannelHandlerContext ctx, ChannelPromise promise) throws Exception {
        Metrics metrics = ctx.channel().attr(ATTR_KEY_METRICS).get();
        String userId = ctx.channel().attr(ATTR_KEY_USERNAME).get();
        if (userId == null) {
            userId = "";
        }

        logger.info("channel<" + userId + "> closing after" + metrics);
        
        collector.sumReadBytes(metrics.readLength());
        collector.sumWroteBytes(metrics.wroteLength());
        
        super.close(ctx, promise);
    }

    public static Metrics getBytesMetrics(Channel channel) {
        return channel.attr(ATTR_KEY_METRICS).get();
    }

}