/*
 * 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.protocol.http.servlet;

import javax.servlet.RequestDispatcher;
import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;

import org.apache.wicket.util.lang.Args;
import org.apache.wicket.util.string.Strings;

/**
 * Represents additional error attributes present in a {@link ServletRequest} when the servlet
 * container is handling an error or a forward to an error page mapped by {@code error-page} element
 * in {@code web.xml}.
 * 
 * See documentation for the following request attributes for the values stored in this object:
 * <ul>
 * <li>{@link RequestDispatcher#ERROR_STATUS_CODE}</li>
 * <li>{@link RequestDispatcher#ERROR_MESSAGE}</li>
 * <li>{@link RequestDispatcher#ERROR_REQUEST_URI}</li>
 * <li>{@link RequestDispatcher#ERROR_SERVLET_NAME}</li>
 * <li>{@link RequestDispatcher#ERROR_EXCEPTION_TYPE}</li>
 * <li>{@link RequestDispatcher#ERROR_EXCEPTION}</li>
 * </ul>
 * 
 * @author igor
 */
public class ErrorAttributes
{
        // javax.servlet.error.status_code
        private final Integer statusCode;
        // javax.servlet.error.message
        private final String message;
        // javax.servlet.error.request_uri
        private final String requestUri;
        // javax.servlet.error.servlet_name
        private final String servletName;
        // javax.servlet.error.exception_type
        private final Class<? extends Throwable> exceptionType;
        // javax.servlet.error.exception
        private final Throwable exception;

        /**
         * Constructor
         * 
         * @param statusCode
         * @param message
         * @param requestUri
         * @param servletName
         * @param exceptionType
         * @param exception
         */
        private ErrorAttributes(Integer statusCode, String message, String requestUri,
                String servletName, Class<? extends Throwable> exceptionType, Throwable exception)
        {
                this.statusCode = statusCode;
                this.message = message;
                this.requestUri = requestUri;
                this.servletName = servletName;
                this.exceptionType = exceptionType;
                this.exception = exception;
        }

        /**
         * Gets statusCode.
         * 
         * @return statusCode
         */
        public Integer getStatusCode()
        {
                return statusCode;
        }

        /**
         * Gets message.
         * 
         * @return message
         */
        public String getMessage()
        {
                return message;
        }

        /**
         * Gets requestUri.
         * 
         * @return requestUri
         */
        public String getRequestUri()
        {
                return requestUri;
        }

        /**
         * Gets servletName.
         * 
         * @return servletName
         */
        public String getServletName()
        {
                return servletName;
        }

        /**
         * Gets exceptionType.
         * 
         * @return exceptionType
         */
        public Class<? extends Throwable> getExceptionType()
        {
                return exceptionType;
        }

        /**
         * Gets exception.
         * 
         * @return exception
         */
        public Throwable getException()
        {
                return exception;
        }

        /**
         * Factory for creating instances of this class.
         * 
         * @param request
         * @return instance of request contains error attributes or {@code null} if it does not.
         */
        public static ErrorAttributes of(HttpServletRequest request, String filterPrefix)
        {
                Args.notNull(request, "request");
                Integer code = (Integer)request.getAttribute(RequestDispatcher.ERROR_STATUS_CODE);
                String message = (String)request.getAttribute(RequestDispatcher.ERROR_MESSAGE);
                String uri = DispatchedRequestUtils.getRequestUri(request, RequestDispatcher.ERROR_REQUEST_URI, filterPrefix);
                String servlet = (String)request.getAttribute(RequestDispatcher.ERROR_SERVLET_NAME);
                @SuppressWarnings("unchecked")
                Class<? extends Throwable> type = (Class<? extends Throwable>)request.getAttribute(RequestDispatcher.ERROR_EXCEPTION_TYPE);
                Throwable ex = (Throwable)request.getAttribute(RequestDispatcher.ERROR_EXCEPTION);

                if (!Strings.isEmpty(uri) || code != null || ex != null)
                {
                        return new ErrorAttributes(code, message, uri, servlet, type, ex);
                }
                return null;
        }

        @Override
        public String toString()
        {
                return "ErrorAttributes{" +
                                "statusCode=" + statusCode +
                                ", message='" + message + '\'' +
                                ", requestUri='" + requestUri + '\'' +
                                ", servletName='" + servletName + '\'' +
                                ", exceptionType=" + exceptionType +
                                ", exception=" + exception +
                                '}';
        }
}