/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.wicket.ajax.attributes;

import org.apache.wicket.Component;

/**
 * Interface used to listen at the most important points when Wicket performs an Ajax callback.
 *
 * <p>Each method can return JavaScript that will be used as a body of a function that is executed
 * at the appropriate time. If the method returns {@code null} or an empty string then it is ignored
 * and no function will be executed for this listener. Each JavaScript function receives arguments
 * in the exact order as specified in the method's javadoc.</p>
 *
 *  <p>Ajax call listeners are potential contributors to the page header by implementing
 * {@link org.apache.wicket.markup.html.IComponentAwareHeaderContributor}. E.g. the JavaScript used
 * by the listener may depend on some JavaScript library, by implementing
 * {@link org.apache.wicket.markup.html.IComponentAwareHeaderContributor} interface they can assure
 * it will be loaded.</p>
 * 
 * @since 6.0
 */
public interface IAjaxCallListener
{
	/**
	 * The JavaScript that will be executed on initialization of the Ajax call, immediately after the causing event.
	 * The script will be executed in a function that receives the following
	 * parameters:
	 * <ol>
	 * <li>attrs - the AjaxRequestAttributes as JSON</li>
	 * </ol>
	 * 
	 * @param component
	 *            the Component with the Ajax behavior
	 * @return the JavaScript that will be executed on initialization of the Ajax call.
	 */
	CharSequence getInitHandler(Component component);

	/**
	 * The JavaScript that will be executed before the Ajax call, as early as possible. Even before
	 * the preconditions. The script will be executed in a function that receives the following
	 * parameters:
	 * <ol>
	 * <li>attrs - the AjaxRequestAttributes as JSON</li>
	 * </ol>
	 * 
	 * @param component
	 *            the Component with the Ajax behavior
	 * @return the JavaScript that will be executed before the Ajax call.
	 */
	CharSequence getBeforeHandler(Component component);

	/**
	 * A JavaScript function that is invoked before the request is being executed. If it returns
	 * {@code false} then the execution of the Ajax call will be cancelled. The script will be
	 * executed in a function that receives the following parameters:
	 * <ol>
	 * <li>attrs - the AjaxRequestAttributes as JSON</li>
	 * </ol>
	 * 
	 * @param component
	 *            the Component with the Ajax behavior
	 * @return the JavaScript that should be used to decide whether the Ajax call should be made at
	 *         all.
	 */
	CharSequence getPrecondition(Component component);

	/**
	 * The JavaScript that will be executed right before the execution of the the Ajax call, only if all
	 * preconditions pass. The script will be executed in a function that receives the following
	 * parameters:
	 * <ol>
	 * <li>attrs - the AjaxRequestAttributes as JSON</li>
	 * <li>jqXHR - the jQuery XMLHttpRequest object</li>
	 * <li>settings - the settings used for the jQuery.ajax() call</li>
	 * </ol>
	 * 
	 * @param component
	 *            the Component with the Ajax behavior
	 * @return the JavaScript that will be executed before the Ajax call.
	 */
	CharSequence getBeforeSendHandler(Component component);

	/**
	 * The JavaScript that will be executed after the Ajax call. The script will be executed in a
	 * function that receives the following parameters:
	 * <ol>
	 * <li>attrs - the AjaxRequestAttributes as JSON</li>
	 * </ol>
	 * <strong>Note</strong>: if the Ajax call is synchronous (see
	 * {@link AjaxRequestAttributes#setAsynchronous(boolean)}) then this JavaScript will be executed
	 * after the {@linkplain #getCompleteHandler(org.apache.wicket.Component) complete handler},
	 * otherwise it is executed right after the execution of the Ajax request.
	 * 
	 * @param component
	 *            the Component with the Ajax behavior
	 * @return the JavaScript that will be executed after the start of the Ajax call but before its
	 *         response is returned.
	 */
	CharSequence getAfterHandler(Component component);

	/**
	 * The JavaScript that will be executed after successful return of the Ajax call. The script
	 * will be executed in a function that receives the following parameters:
	 * <ol>
	 * <li>attrs - the AjaxRequestAttributes as JSON</li>
	 * <li>jqXHR - the jQuery XMLHttpRequest object</li>
	 * <li>data - the Ajax response. Its type depends on {@link AjaxRequestAttributes#dataType}</li>
	 * <li>textStatus - the status as text</li>
	 * </ol>
	 * 
	 * @param component
	 *            the Component with the Ajax behavior
	 * @return the JavaScript that will be executed after a successful return of the Ajax call.
	 */
	CharSequence getSuccessHandler(Component component);

	/**
	 * The JavaScript that will be executed after unsuccessful return of the Ajax call. The script
	 * will be executed in a function that receives the following parameters:
	 * <ol>
	 * <li>attrs - the AjaxRequestAttributes as JSON</li>
	 * <li>jqXHR - the jQuery XMLHttpRequest object</li>
	 * <li>errorMessage - in case of HTTP error the textual portion of the HTTP status</li>
	 * <li>textStatus - type of failure: null, "timeout", "error", "abort" or "parsererror"</li>
	 * </ol>
	 * 
	 * @param component
	 *            the Component with the Ajax behavior
	 * @return the JavaScript that will be executed after a unsuccessful return of the Ajax call.
	 */
	CharSequence getFailureHandler(Component component);

	/**
	 * The JavaScript that will be executed after both successful and unsuccessful return of the
	 * Ajax call. The script will be executed in a function that receives the following parameters:
	 * <ol>
	 * <li>attrs - the AjaxRequestAttributes as JSON</li>
	 * <li>jqXHR - the jQuery XMLHttpRequest object</li>
	 * <li>textStatus - the status as text</li>
	 * </ol>
	 * 
	 * @param component
	 *            the Component with the Ajax behavior
	 * @return the JavaScript that will be executed after both successful and unsuccessful return of
	 *         the Ajax call.
	 */
	CharSequence getCompleteHandler(Component component);

	/**
	 * The JavaScript that will be executed after the Ajax call is done, regardless whether it was
	 * sent or not. The script will be executed in a function that receives the following
	 * parameters:
	 * <ol>
	 * <li>attrs - the AjaxRequestAttributes as JSON</li>
	 * </ol>
	 *
	 * @param component
	 *            the Component with the Ajax behavior
	 * @return the JavaScript that will be executed after the Ajax call is done.
	 */
	CharSequence getDoneHandler(Component component);
}
