package org.skywalking.apm.plugin.tomcat78x;

import java.lang.reflect.Method;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.skywalking.apm.agent.core.context.CarrierItem;
import org.skywalking.apm.agent.core.context.ContextCarrier;
import org.skywalking.apm.agent.core.context.ContextManager;
import org.skywalking.apm.agent.core.context.tag.Tags;
import org.skywalking.apm.agent.core.context.trace.AbstractSpan;
import org.skywalking.apm.agent.core.context.trace.SpanLayer;
import org.skywalking.apm.agent.core.context.trace.TraceSegment;
import org.skywalking.apm.agent.core.plugin.interceptor.enhance.EnhancedInstance;
import org.skywalking.apm.agent.core.plugin.interceptor.enhance.InstanceMethodsAroundInterceptor;
import org.skywalking.apm.agent.core.plugin.interceptor.enhance.MethodInterceptResult;
import org.skywalking.apm.network.trace.component.ComponentsDefine;

/**
 * {@link TomcatInvokeInterceptor} fetch the serialized context data by using {@link
 * HttpServletRequest#getHeader(String)}. The {@link TraceSegment#refs} of current trace segment will reference to the
 * trace segment id of the previous level if the serialized context is not null.
 */
public class TomcatInvokeInterceptor implements InstanceMethodsAroundInterceptor {

    /**
     * * The {@link TraceSegment#refs} of current trace segment will reference to the
     * trace segment id of the previous level if the serialized context is not null.
     *
     * @param objInst
     * @param method
     * @param allArguments
     * @param argumentsTypes
     * @param result change this result, if you want to truncate the method.
     * @throws Throwable
     */
    @Override public void beforeMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
        Class<?>[] argumentsTypes, MethodInterceptResult result) throws Throwable {
        HttpServletRequest request = (HttpServletRequest)allArguments[0];
        ContextCarrier contextCarrier = new ContextCarrier();

        CarrierItem next = contextCarrier.items();
        while (next.hasNext()) {
            next = next.next();
            next.setHeadValue(request.getHeader(next.getHeadKey()));
        }

        AbstractSpan span = ContextManager.createEntrySpan(request.getRequestURI(), contextCarrier);
        Tags.URL.set(span, request.getRequestURL().toString());
        Tags.HTTP.METHOD.set(span, request.getMethod());
        span.setComponent(ComponentsDefine.TOMCAT);
        SpanLayer.asHttp(span);

    }

    @Override public Object afterMethod(EnhancedInstance objInst, Method method, Object[] allArguments,
        Class<?>[] argumentsTypes, Object ret) throws Throwable {
        HttpServletResponse response = (HttpServletResponse)allArguments[1];

        AbstractSpan span = ContextManager.activeSpan();
        if (response.getStatus() >= 400) {
            span.errorOccurred();
            Tags.STATUS_CODE.set(span, Integer.toString(response.getStatus()));
        }
        ContextManager.stopSpan();
        return ret;
    }

    @Override public void handleMethodException(EnhancedInstance objInst, Method method, Object[] allArguments,
        Class<?>[] argumentsTypes, Throwable t) {
        AbstractSpan span = ContextManager.activeSpan();
        span.log(t);
        span.errorOccurred();
    }
}
