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/* 
 * The MIT License
 *
 * Copyright 2016 Benny Lutati.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */
package bc.proxies;

import bc.dsl.JavaDSL;
import bc.proxies.Wrapper.OperationMediator;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.Map;

/**
 *
 * @author bennyl
 */
public class Wrapper implements InvocationHandler {

    private static Map primitiveDefaults = JavaDSL.cassoc(
            int.class, 0,
            float.class, 0f,
            double.class, 0.0,
            char.class, '1',
            boolean.class, false);
    
    private static Method PERFORM_METHOD;
    private static Method BEFORE_METHOD;
    private static Method AFTER_METHOD;
    private static Method APPLY_METHOD;

    static {
        try {
            PERFORM_METHOD = WrapConfigurator.class.getMethod("perform", Operation.class);
            BEFORE_METHOD = OperationMediator.class.getMethod("before");
            APPLY_METHOD = WrapConfigurator.class.getMethod("applyOn", Object.class);
            AFTER_METHOD = OperationMediator.class.getMethod("after");
        } catch (NoSuchMethodException e) {
            throw new NoSuchMethodError(e.getMessage());
        }
    }
    
    private T target;
    private HashMap beforeMap = new HashMap();
    private HashMap afterMap = new HashMap();
    private Operation lastOp;
    private Method lastMethod;

    private Wrapper() {
        //NEVER INSTANTIATE DIRECTLY!
    }

    public static  WrapConfigurator configure(Class interfaze) {

        return (WrapConfigurator) java.lang.reflect.Proxy.newProxyInstance(
                ClassLoader.getSystemClassLoader(),
                new Class[]{interfaze, OperationMediator.class, WrapConfigurator.class},
                new Wrapper());
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

        if (method.equals(PERFORM_METHOD)) {
            lastOp = (Operation) args[0];
            return proxy;
        } else if (method.equals(BEFORE_METHOD) || method.equals(AFTER_METHOD)) {
            lastMethod = method;
            return proxy;
        } else if (method.equals(APPLY_METHOD)) {
            target = (T) args[0];
            return proxy;
        } else if (lastMethod != null) {
            if (lastMethod.equals(BEFORE_METHOD)) {
                beforeMap.put(method, lastOp);
            }else if (lastMethod.equals(AFTER_METHOD)){
                afterMap.put(method, lastOp);
            }
            lastMethod = null;
            if (method.getReturnType().isPrimitive()){
                return primitiveDefaults.get(method.getReturnType());
            }
            return null;
        } else {
            if (beforeMap.containsKey(method)) {
                beforeMap.get(method).operate(args);
            }
            
            Object ret = method.invoke(target, args);
            
            if (afterMap.containsKey(method)) {
                afterMap.get(method).operate(args);
            }
            
            return ret;
        }
    }

    public static interface OperationMediator {
        T before();
        T after();
    }

    public static interface WrapConfigurator {
        OperationMediator perform(Operation op);
        T applyOn(T target);
    }
}