package pl.ibpolsoft.sop.client.service;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.util.Arrays;
import java.util.logging.Logger;
import javax.ejb.NoSuchEJBException;
import pl.ibpolsoft.toolkit.genericprovider.Provider;

/**
 *
 * @author witoldsz
 */
public class EjbLookupRetryProvider<T> implements InvocationHandler {

    private static final Object ERROR = new Object();
    private final Logger logger = Logger.getLogger(EjbLookupRetryProvider.class.getName());
    private final int maxTries = 2;

    private final Provider<EjbLookup> ejbLookupProvider;
    private final Class<T> remoteInterface;
    private final String beanName;
    private Object bean = null;

    public EjbLookupRetryProvider(Provider<EjbLookup> ejbLookupProvider, Class<T>remoteInterface, String beanName) {
        this.ejbLookupProvider = ejbLookupProvider;
        this.remoteInterface = remoteInterface;
        this.beanName = beanName;
    }

    public EjbLookupRetryProvider(Provider<EjbLookup> ejbLookupProvider, Class<T>remoteInterface) {
        this(
                ejbLookupProvider,remoteInterface,
                ejbLookupProvider.create().defaultBeanName(remoteInterface)
                );
    }

    public T getBean() {
        Object proxy = Proxy.newProxyInstance(
                remoteInterface.getClassLoader(),
                new Class[]{ remoteInterface },
                this);

        return remoteInterface.cast(proxy);
    }


    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Object result = ERROR;
        Throwable throwable = null;
        for (int tryCnt = 1; tryCnt <= maxTries; tryCnt++) {
            logger.info(String.format(
                    "try %d: Intercepting method %s, args:%s",
                    tryCnt, method, Arrays.toString(args)));
            try {
                if (bean == null) {
                    bean = ejbLookupProvider.create().getBean(remoteInterface, beanName);
                }
                result = method.invoke(bean, args);
            } catch (InvocationTargetException e) {
                throwable = handleException(e, tryCnt);
                bean = null;
            }
            if (result != ERROR) {
                return result;
            }
        }
        throw throwable;
    }

    private Throwable handleException(InvocationTargetException e, int tryCnt) {
        Throwable result = e.getCause();
        if (result instanceof NoSuchEJBException) {
            logger.warning(String.format(
                    "Got NoSuchEJBException when calling: %s. tryCnt=%d",
                    beanName, tryCnt));
        }
        return e.getCause();
    }
}