/*
 * 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.struts2.rest;

import com.opensymphony.xwork2.Action;
import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.interceptor.MethodFilterInterceptor;
import com.opensymphony.xwork2.interceptor.ValidationAware;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;
import org.apache.struts2.dispatcher.mapper.ActionMapping;

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

import static javax.servlet.http.HttpServletResponse.SC_BAD_REQUEST;

/**
 * An interceptor that makes sure there are not validation errors before allowing the interceptor chain to continue.
 * <b>This interceptor does not perform any validation</b>.
 *
 * <p>
 * Copied from the {@link com.opensymphony.xwork2.interceptor.DefaultWorkflowInterceptor}, this interceptor adds support
 * for error handling of Restful operations.  For example, if an validation error is discovered, a map of errors
 * is created and processed to be returned, using the appropriate content handler for rendering the body.
 * </p>
 *
 * <p>
 * This interceptor does nothing if the name of the method being invoked is specified in the <b>excludeMethods</b>
 * parameter. <b>excludeMethods</b> accepts a comma-delimited list of method names. For example, requests to
 * <b>foo!input.action</b> and <b>foo!back.action</b> will be skipped by this interceptor if you set the
 * <b>excludeMethods</b> parameter to "input, back".
 * </p>
 *
 * <p>
 * <b>Note:</b> As this method extends off MethodFilterInterceptor, it is capable of
 * deciding if it is applicable only to selective methods in the action class. This is done by adding param tags
 * for the interceptor element, naming either a list of excluded method names and/or a list of included method
 * names, whereby includeMethods overrides excludedMethods. A single * sign is interpreted as wildcard matching
 * all methods for both parameters.
 * See {@link MethodFilterInterceptor} for more info.
 * </p>
 *
 * <b>Interceptor parameters:</b>
 *
 * <ul>
 * <li>inputResultName - Default to "input". Determine the result name to be returned when
 * an action / field error is found.</li>
 * </ul>
 *
 * <b>Extending the interceptor:</b>
 * There are no known extension points for this interceptor.
 *
 * <b>Example code:</b>
 *
 * <pre>
 * &lt;action name="someAction" class="com.examples.SomeAction"&gt;
 *     &lt;interceptor-ref name="params"/&gt;
 *     &lt;interceptor-ref name="validation"/&gt;
 *     &lt;interceptor-ref name="workflow"/&gt;
 *     &lt;result name="success"&gt;good_result.ftl&lt;/result&gt;
 * &lt;/action&gt;
 *
 * &lt;-- In this case myMethod as well as mySecondMethod of the action class
 *        will not pass through the workflow process --&gt;
 * &lt;action name="someAction" class="com.examples.SomeAction"&gt;
 *     &lt;interceptor-ref name="params"/&gt;
 *     &lt;interceptor-ref name="validation"/&gt;
 *     &lt;interceptor-ref name="workflow"&gt;
 *         &lt;param name="excludeMethods"&gt;myMethod,mySecondMethod&lt;/param&gt;
 *     &lt;/interceptor-ref name="workflow"&gt;
 *     &lt;result name="success"&gt;good_result.ftl&lt;/result&gt;
 * &lt;/action&gt;
 *
 * &lt;-- In this case, the result named "error" will be used when
 *        an action / field error is found --&gt;
 * &lt;-- The Interceptor will only be applied for myWorkflowMethod method of action
 *        classes, since this is the only included method while any others are excluded --&gt;
 * &lt;action name="someAction" class="com.examples.SomeAction"&gt;
 *     &lt;interceptor-ref name="params"/&gt;
 *     &lt;interceptor-ref name="validation"/&gt;
 *     &lt;interceptor-ref name="workflow"&gt;
 *        &lt;param name="inputResultName"&gt;error&lt;/param&gt;
 *         &lt;param name="excludeMethods"&gt;*&lt;/param&gt;
 *         &lt;param name="includeMethods"&gt;myWorkflowMethod&lt;/param&gt;
 *     &lt;/interceptor-ref&gt;
 *     &lt;result name="success"&gt;good_result.ftl&lt;/result&gt;
 * &lt;/action&gt;
 * </pre>
 *
 * @author Jason Carreira
 * @author Rainer Hermanns
 * @author <a href='mailto:the_mindstorm[at]evolva[dot]ro'>Alexandru Popescu</a>
 * @author Philip Luppens
 * @author tm_jee
 */
public class RestWorkflowInterceptor extends MethodFilterInterceptor {

    private static final long serialVersionUID = 7563014655616490865L;

    private static final Logger LOG = LogManager.getLogger(RestWorkflowInterceptor.class);

    private String inputResultName = Action.INPUT;

    private ContentTypeHandlerManager manager;

    private String postMethodName = "create";
    private String editMethodName = "edit";
    private String newMethodName = "editNew";
    private String putMethodName = "update";

    private int validationFailureStatusCode = SC_BAD_REQUEST;

    @Inject(required = false, value = RestConstants.REST_MAPPER_POST_METHOD_NAME)
    public void setPostMethodName(String postMethodName) {
        this.postMethodName = postMethodName;
    }

    @Inject(required = false, value = RestConstants.REST_MAPPER_EDIT_METHOD_NAME)
    public void setEditMethodName(String editMethodName) {
        this.editMethodName = editMethodName;
    }

    @Inject(required = false, value = RestConstants.REST_MAPPER_NEW_METHOD_NAME)
    public void setNewMethodName(String newMethodName) {
        this.newMethodName = newMethodName;
    }

    @Inject(required = false, value = RestConstants.REST_MAPPER_PUT_METHOD_NAME)
    public void setPutMethodName(String putMethodName) {
        this.putMethodName = putMethodName;
    }

    @Inject(required = false, value = RestConstants.REST_VALIDATION_FAILURE_STATUS_CODE)
    public void setValidationFailureStatusCode(String code) {
        this.validationFailureStatusCode = Integer.parseInt(code);
    }

    @Inject
    public void setContentTypeHandlerManager(ContentTypeHandlerManager mgr) {
        this.manager = mgr;
    }

    /**
     * Set the <code>inputResultName</code> (result name to be returned when
     * a action / field error is found registered). Default to {@link Action#INPUT}
     *
     * @param inputResultName what result name to use when there was validation error(s).
     */
    public void setInputResultName(String inputResultName) {
        this.inputResultName = inputResultName;
    }

    /**
     * Intercept {@link ActionInvocation} and processes the errors using the {@link org.apache.struts2.rest.handler.ContentTypeHandler}
     * appropriate for the request.
     *
     * @return String result name
     */
    protected String doIntercept(ActionInvocation invocation) throws Exception {
        Object action = invocation.getAction();

        if (action instanceof ValidationAware) {
            ValidationAware validationAwareAction = (ValidationAware) action;

            if (validationAwareAction.hasErrors()) {
                LOG.debug("Errors on action {}, returning result name 'input'", validationAwareAction);
                ActionMapping mapping = ActionContext.getContext().getActionMapping();
                String method = inputResultName;
                if (postMethodName.equals(mapping.getMethod())) {
                    method = newMethodName;
                } else if (putMethodName.equals(mapping.getMethod())) {
                    method = editMethodName;
                }


                HttpHeaders info = new DefaultHttpHeaders()
                    .disableCaching()
                    .renderResult(method)
                    .withStatus(validationFailureStatusCode);

                Map<String, Object> errors = new HashMap<>();

                errors.put("actionErrors", validationAwareAction.getActionErrors());
                errors.put("fieldErrors", validationAwareAction.getFieldErrors());
                return manager.handleResult(invocation, info, errors);
            }
        }

        return invocation.invoke();
    }

}
