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Tiles request implementation for Jakarta-Servlet technology.
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/*
 * Copyright 2023 Web-Legacy
 *
 * Licensed 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.tiles.request.jakarta.servlet;

import java.io.IOException;

import org.apache.tiles.request.ApplicationAccess;
import org.apache.tiles.request.ApplicationContext;
import org.apache.tiles.request.Request;
import org.apache.tiles.request.RequestWrapper;

import jakarta.servlet.ServletContext;
import jakarta.servlet.ServletException;

/**
 * Utilities for Tiles request servlet support.
 *
 * Copied from Apache tiles-request-servlet 1.0.7 and adapted for
 * Jakarta EE 9.
 */
public final class ServletUtil {

    /**
     * Constructor.
     */
    private ServletUtil() {
    }

    /**
     * Wraps a ServletException to create an IOException with the root cause if
     * present.
     *
     * @param ex      The exception to wrap.
     * @param message The message of the exception.
     *
     * @return The wrapped exception.
     */
    public static IOException wrapServletException(ServletException ex,
            String message) {
        IOException retValue;
        Throwable rootCause = ex.getRootCause();
        if (rootCause != null) {
            // Replace the ServletException with an IOException, with the root
            // cause of the first as the cause of the latter.
            retValue = new IOException(message, rootCause);
        } else {
            retValue = new IOException(message, ex);
        }

        return retValue;
    }

    /**
     * Returns the application context getting it from the servlet context. It
     * must be first saved creating a {@link ServletApplicationContext} and
     * using {@link ApplicationAccess#register(ApplicationContext)}.
     *
     * @param servletContext The servlet context.
     *
     * @return The application context, if found, {@code null} otherwise.
     */
    public static ApplicationContext getApplicationContext(
            ServletContext servletContext) {
        return (ApplicationContext) servletContext
                .getAttribute(ApplicationAccess.APPLICATION_CONTEXT_ATTRIBUTE);
    }

    /**
     * Opens a TilesRequestContext until it finds a ServletTilesRequestContext.
     *
     * @param request The request to open.
     *
     * @return The servlet-based request context.
     *
     * @throws NotAServletEnvironmentException If a servlet-based request
     *                                         context could not be found.
     */
    public static ServletRequest getServletRequest(Request request) {
        Request currentRequest = request;
        while (true) {
            if (currentRequest == null) {
                throw new NotAServletEnvironmentException(
                        "Last Tiles request context is null");
            }

            if (currentRequest instanceof ServletRequest) {
                return (ServletRequest) currentRequest;
            }
            if (!(currentRequest instanceof RequestWrapper)) {
                throw new NotAServletEnvironmentException(
                        "Not a Servlet environment, not supported");
            }
            currentRequest = ((RequestWrapper)
                    currentRequest).getWrappedRequest();
        }
    }

    /**
     * Gets a servlet context from a TilesApplicationContext.
     *
     * @param applicationContext The application context to analyze.
     *
     * @return The servlet context.
     *
     * @throws NotAServletEnvironmentException If the application context is not
     *                                         servlet-based.
     */
    public static ServletContext getServletContext(
            ApplicationContext applicationContext) {
        if (applicationContext instanceof ServletApplicationContext) {
            return (ServletContext) ((ServletApplicationContext)
                    applicationContext).getContext();
        }

        throw new NotAServletEnvironmentException(
                "Not a Servlet-based environment");
    }
}