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package org.wickedsource.docxstamper.proxy;

import javassist.util.proxy.ProxyFactory;
import org.wickedsource.docxstamper.api.commentprocessor.ICommentProcessor;

import java.util.HashMap;
import java.util.Map;

/**
 * Allows an object to be wrapped by a proxy so that it will implement additional interfaces.
 *
 * @param  the type of the root object.
 */
public class ProxyBuilder {

	private T root;

	private Map, ICommentProcessor> interfacesToImplementations = new HashMap<>();

	/**
	 * Specifies the root object for the proxy that shall be enhanced.
	 *
	 * @param rootObject the root object.
	 * @return this builder for chaining.
	 */
	public ProxyBuilder withRoot(T rootObject) {
		this.root = rootObject;
		return this;
	}

	/**
	 * Specifies an interfaces and an implementation of an interface by which the root object
	 * shall be extended.
	 *
	 * @param interfaceClass the class of the interface
	 * @param interfaceImpl  an implementation of the interface
	 * @return this builder for chaining.
	 */
	public ProxyBuilder withInterface(Class interfaceClass, ICommentProcessor interfaceImpl) {
		this.interfacesToImplementations.put(interfaceClass, interfaceImpl);
		return this;
	}

	/**
	 * Creates a proxy object out of the specified root object and the specified interfaces
	 * and implementations.
	 *
	 * @return a proxy object that is still of type T but additionally implements all specified
	 * interfaces.
	 * @throws ProxyException if the proxy could not be created.
	 */
	public T build() throws ProxyException {

		if (this.root == null) {
			throw new IllegalArgumentException("root must not be null!");
		}

		if (this.interfacesToImplementations.isEmpty()) {
			throw new IllegalArgumentException(
					"at least one interface and implementation must be specified!");
		}

		try {
			ProxyMethodHandler methodHandler = new ProxyMethodHandler(root,
					interfacesToImplementations);
			ProxyFactory proxyFactory = new ProxyFactory();
			proxyFactory.setSuperclass(root.getClass());
			proxyFactory.setInterfaces(interfacesToImplementations.keySet().toArray(new Class[]{}));
			return (T) proxyFactory.create(new Class[0], new Object[0], methodHandler);
		} catch (Exception e) {
			throw new ProxyException(e);
		}
	}


}