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package io.apptik.rhub.shield;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;

import io.apptik.rhub.RHub;

/**
 * Base class for instantiating Hub Shield.
 * 

 * Normally one will not use this directly but rather
 * more specific helpers based on some concrete Reactive Framework.
 * @param  The specific type of the Hub
 */
public final class ShieldMakerBase {

    /**
     * Generates instance for a given shieldClass interface.
     *
     * @param shieldClass class type of the shield interface
     * @param rHub instance of RHub to fit the shield on
     * @param rHubClass class type of the RHub instance
     * @param  Shield interface type
     * @return instance of the Shield
     */
    public final  T make(Class shieldClass, H rHub, Class rHubClass) {
        Constructor constructor = getShieldImpl(shieldClass, rHubClass);

        if (constructor == null) {
            throw new RuntimeException("Unable to find implementation for " + shieldClass);
        }

        try {
            return constructor.newInstance(rHub);
        } catch (IllegalAccessException e) {
            throw new RuntimeException("Unable to invoke " + constructor, e);
        } catch (InstantiationException e) {
            throw new RuntimeException("Unable to invoke " + constructor, e);
        } catch (InvocationTargetException e) {
            Throwable cause = e.getCause();
            if (cause instanceof RuntimeException) {
                throw (RuntimeException) cause;
            }
            if (cause instanceof Error) {
                throw (Error) cause;
            }
            throw new RuntimeException("Unable to create shield instance.", cause);
        }
    }

    //todo strict or not strict. if not remove Class rHubClass.
    //at this moment we can trust on the shield implementations as they are generated by us.
    private  Constructor getShieldImpl(Class shieldClass, Class rHubClass) {
        Constructor shieldConstructor = null;

        String clsName = shieldClass.getName();

        try {
            Class shieldImpl = Class.forName(clsName + "_Impl");
            //noinspection unchecked
            Constructor[] constructors = shieldImpl.getDeclaredConstructors();
            shieldConstructor = (Constructor) constructors[0];
           // shieldConstructor = (Constructor) shieldImpl.getConstructor(rHubClass);
            System.out.println("Shield Impl found for: " + shieldClass.getName());
        } catch (ClassNotFoundException e) {
            System.out.println("Shield Impl Not found for: " + shieldClass.getName());
        }
//        catch (NoSuchMethodException e) {
//            throw new RuntimeException("Unable to find binding constructor for " + clsName, e);
//        }
        return shieldConstructor;
    }
}