package foundation.handler;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;

import javax.servlet.http.HttpServletResponse;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import foundation.handler.envelop.EnvelopWriter;
import foundation.route.Operation;


public abstract class BaseHandler extends MethodPublisher implements IHandler {

	protected static Logger logger; 
	
	static {
		logger = LogManager.getLogger(Handler.class);
	}
	
	public BaseHandler() {
 
	}
	
	public void receive(Operation operation, DataPool dataPool, HttpServletResponse response) throws Exception {
		//1. create pool and writer
		ResultPool resultPool = new ResultPool(response);
		
		try {
			EnvelopWriter writer = new EnvelopWriter(response);
			
			//2. before execute
			boolean proceed = beforeDispatch(operation, dataPool, resultPool);
				
			//3. execute
			if (proceed) {
				dispatch(operation, dataPool, resultPool);
			}

			//4. flush
			if (resultPool.isFireReplay()) {
				writer.replay(resultPool);
				writer.flush();
			}			
		}
		finally {
			resultPool.free();
		}
	}
	
	protected boolean beforeDispatch(Operation operator, DataPool dataPool, ResultPool resultPool) throws Exception {
		return true;
	}
	
	protected void dispatch(Operation operator, DataPool dataPool, ResultPool resultPool) throws Exception {
		String methodName = operator.getOperator();
		Method method = methodMap.get(methodName);
		
		if (method == null) {
			logger.error("method exec error: {} not exists", methodName);
			return;
		}
		
		try {
			invokeMethod(method, dataPool, resultPool);
		}
		catch (InvocationTargetException e) {
			e.printStackTrace();
			Throwable throwable = e.getTargetException();

			if (throwable == null) {
				throw e;
			}
			else {
				throw (Exception) throwable;
			}
		}
	}
	
	protected abstract void invokeMethod(Method method, DataPool dataPool, ResultPool resultPool) throws Exception;
	
	protected void onError(Exception e) throws Exception {
		logger.error(e);
		
		if (logger.isTraceEnabled()) {
			e.printStackTrace();
		}
	}

}