platform/sensinact-core/src/main/java/org/eclipse/sensinact/gateway/core/method/AccessMethodResponseBuilder.java

/*
* Copyright (c) 2020 Kentyou.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
*    Kentyou - initial API and implementation
 */
package org.eclipse.sensinact.gateway.core.method;

import java.util.Collections;
import java.util.Deque;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.Stack;

import org.eclipse.sensinact.gateway.common.bundle.Mediator;
import org.eclipse.sensinact.gateway.common.primitive.PathElement;
import org.json.JSONArray;
import org.json.JSONObject;

/**
 * Intermediate {@link AccessMethodExecutor}'s execution result
 * 
 * @param <V>
 *            result data type
 * 
 * @author <a href="mailto:christophe.munilla@cea.fr">Christophe Munilla</a>
 */
@SuppressWarnings("serial")
public abstract class AccessMethodResponseBuilder<T, A extends AccessMethodResponse<T>> extends Stack<T>
		implements PathElement {
	/**
	 * Creates and returns an extended {@link AccessMethodResponse} whose
	 * {@link SnaMessage.Status} is passed as parameter
	 * 
	 * @param status
	 *            the {@link SnaMessage.Status} of the extended
	 *            {@link AccessMethodResponse} to be created
	 * @param accessLevel
	 *            the integer access level of the extended
	 *            {@link AccessMethodResponse} to be created
	 * @return the created {@link AccessMethodResponse}
	 */
	public abstract A createAccessMethodResponse(AccessMethodResponse.Status status);

	/**
	 * Returns the type handled by this AccessMethodResponseBuilder
	 * 
	 * @return this AccessMethodResponseBuilder's handled type
	 */
	public abstract Class<T> getComponentType();

	/**
	 * Mediator used to interact with the OSGi host environment
	 */
	protected final Mediator mediator;

	protected final Object[] parameters;

	protected boolean exitOnError;

	protected Deque<Exception> exceptions = null;

	protected final String uri;

	protected T resultObject;

	/**
	 * Constructor
	 * 
	 * @param mediator
	 *            the {@link Mediator} allowing the AccessMethodResponseBuilder to
	 *            be instantiated to interact with the OSGi host environment
	 * @param uri
	 *            the String uri of the target on which the related
	 *            {@link AccessMethod} is called
	 * @param parameters
	 *            the parameter objects array of parameterizing the related
	 *            {@link AccessMethod} call
	 */
	protected AccessMethodResponseBuilder(Mediator mediator, String uri, Object[] parameters) {
		this(mediator, uri, parameters, true);
	}

	/**
	 * Constructor
	 * 
	 * @param mediator
	 *            the {@link Mediator} allowing the AccessMethodResponseBuilder to
	 *            be instantiated to interact with the OSGi host environment
	 * @param uri
	 *            the String uri of the target on which the related
	 *            {@link AccessMethod} is called
	 * @param parameters
	 *            the parameter objects array of parameterizing the related
	 *            {@link AccessMethod} call
	 * @param exitOnError
	 *            defines whether the {@link AccessMethodResponse} build process
	 *            will have to be interrupted if an error occurred
	 */
	protected AccessMethodResponseBuilder(Mediator mediator, String uri, Object[] parameters, boolean exitOnError) {
		super();
		this.uri = uri;
		this.mediator = mediator;
		this.exitOnError = exitOnError;
		this.parameters = parameters;
	}

	/**
	 * Returns this AccessMethodResult's object parameter whose index is passed as
	 * parameter
	 * 
	 * @param index
	 *            this index of the object parameter
	 * @return this AccessMethodResult's object parameter whose index is passed as
	 *         parameter
	 */
	public Object getParameter(int index) {
		if (index < 0 || this.parameters == null || index >= this.parameters.length) {
			return null;
		}
		return this.parameters[index];
	}

	/**
	 * Returns the length of the parameter objects array of this AccessMethodResult
	 * 
	 * @return the length of this parameter objects array
	 */
	public int length() {
		return this.parameters == null ? 0 : this.parameters.length;
	}

	/**
	 * Registers the exception passed as parameter in this AccessMethodResult
	 * 
	 * @param exception
	 *            the exception to register
	 */
	public void registerException(Exception exception) {
		if (exceptions == null) {
			exceptions = new LinkedList<Exception>();
		}
		exceptions.add(exception);
	}

	/**
	 * Returns an unmodifiable list of {@link Exception}s registered on this
	 * AccessMethodResult
	 * 
	 * @return the list of registered {@link Exception}s
	 */
	public List<Exception> Exceptions() {
		if (exceptions == null) {
			return Collections.<Exception>emptyList();
		}
		return Collections.<Exception>unmodifiableList((List<Exception>) this.exceptions);
	}

	/**
	 * Creates and returns this AccessMethodResult's {@link AccessMethodResponse}
	 */
	public A createAccessMethodResponse() {
		AccessMethodResponse.Status status = (exceptions != null && exceptions.size() > 0)
				? AccessMethodResponse.Status.ERROR
				: AccessMethodResponse.Status.SUCCESS;

		A response = this.createAccessMethodResponse(status);

		if (exceptions != null && exceptions.size() > 0) {
			Iterator<Exception> iterator = exceptions.iterator();
			JSONArray exceptionsArray = new JSONArray();

			while (iterator.hasNext()) {
				Exception exception = iterator.next();
				JSONObject exceptionObject = new JSONObject();
				exceptionObject.put("message", exception.getMessage());

				StringBuilder buffer = new StringBuilder();
				StackTraceElement[] trace = exception.getStackTrace();

				int index = 0;
				int length = trace.length;

				for (; index < length; index++) {
					buffer.append(trace[index].toString());
					buffer.append("\n");
				}
				exceptionObject.put("trace", buffer.toString());
				exceptionsArray.put(exceptionObject);
			}
			response.setErrors(exceptionsArray);
		}
		response.setResponse(this.resultObject);
		return response;
	}

	/**
	 * Sets this AccessMethodResult's JSONObject value
	 * 
	 * @param resultObject
	 *            the JSONObject value to be set
	 */
	public void setAccessMethodObjectResult(T resultObject) {
		this.resultObject = resultObject;
	}

	/**
	 * Returns this AccessMethodResult's JSONObject value
	 * 
	 * @return this result value
	 */
	public T getAccessMethodObjectResult() {
		return this.resultObject;
	}

	/**
	 * Returns the array of parameters parameterizing the calls using this
	 * AccessMethodResult
	 * 
	 * @return the array of parameters parameterizing the calls using this
	 *         AccessMethodResult
	 */
	public Object[] getParameters() {
		return this.parameters;
	}

	/**
	 * Returns true if the execution has to be stopped when an error occurred ;
	 * returns false otherwise
	 * 
	 * @return
	 *         <ul>
	 *         <li>true if the execution has to be stopped on error</li>
	 *         <li>false otherwise</li>
	 *         </ul>
	 */
	public boolean exitOnError() {
		return this.exitOnError;
	}

	/**
	 * Returns true if at least one error has been thrown during the execution
	 * 
	 * @return
	 *         <ul>
	 *         <li>true at least one error has been triggered</li>
	 *         <li>false otherwise</li>
	 *         </ul>
	 */
	public boolean hasError() {
		return this.exceptions != null && this.exceptions.size() > 0;
	}

	/**
	 * @InheritedDoc
	 *
	 * @see PathElement#getPath()
	 */
	@Override
	public String getPath() {
		return this.uri;
	}
}