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Supports writing Java objects to ORC files.
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/*
 * Copyright (c) 2017 Eclectic Logic LLC
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.eclecticlogic.orc.impl;

import com.eclecticlogic.orc.impl.bootstrap.GeneratorUtil;
import net.sf.cglib.proxy.MethodInterceptor;
import net.sf.cglib.proxy.MethodProxy;

import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.stream.Stream;

/**
 * Created by kabram
 */
public class PropertyInterceptor implements MethodInterceptor {

    private final SchemaSpi schema;
    private final ProxyManager proxyManager;


    public PropertyInterceptor(ProxyManager proxyManager, SchemaSpi schema) {
        this.schema = schema;
        this.proxyManager = proxyManager;
    }


    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        if (schema != null) {
            schema.add(method);
        }
        return getReturnValue(method);
    }


    @SuppressWarnings("unchecked")
    Object getReturnValue(Method method) {
        Class returnType = method.getReturnType();
        if (returnType.isPrimitive()) {
            return GeneratorUtil.getDefaultValueForPrimitiveType(method.getReturnType());
        } else if (Modifier.isFinal(returnType.getModifiers()) || !isDefaultConstructable(returnType)) {
            // Cannot sub-class a final class or a class with no default constructor and therefore cannot make a proxy
            return null;
        } else {
            return proxyManager.generate(returnType);
        }
    }


    /**
     * Attribution: http://stackoverflow.com/questions/27810634/how-can-i-check-a-class-has-no-arguments-constructor
     *
     * @param clazz
     * @return true if clazz has a contructor with 0 parameters.
     */
    private boolean isDefaultConstructable(Class clazz) {
        return Stream.of(clazz.getConstructors()).anyMatch((c) -> c.getParameterCount() == 0);
    }
}