/*
 * 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.catalina.core;

import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;

import jakarta.servlet.RequestDispatcher;
import jakarta.servlet.ServletRequest;
import jakarta.servlet.ServletRequestWrapper;

/**
 * Wrapper around a <code>jakarta.servlet.ServletRequest</code> that transforms an application request object (which
 * might be the original one passed to a servlet, or might be based on the 2.3
 * <code>jakarta.servlet.ServletRequestWrapper</code> class) back into an internal
 * <code>org.apache.catalina.Request</code>.
 * <p>
 * <strong>WARNING</strong>: Due to Java's lack of support for multiple inheritance, all of the logic in
 * <code>ApplicationRequest</code> is duplicated in <code>ApplicationHttpRequest</code>. Make sure that you keep these
 * two classes in synchronization when making changes!
 */
class ApplicationRequest extends ServletRequestWrapper {

    private static final Set<String> specialsSet =
            new HashSet<>(Arrays.asList(RequestDispatcher.INCLUDE_REQUEST_URI, RequestDispatcher.INCLUDE_CONTEXT_PATH,
                    RequestDispatcher.INCLUDE_SERVLET_PATH, RequestDispatcher.INCLUDE_PATH_INFO,
                    RequestDispatcher.INCLUDE_QUERY_STRING, RequestDispatcher.INCLUDE_MAPPING,
                    RequestDispatcher.FORWARD_REQUEST_URI, RequestDispatcher.FORWARD_CONTEXT_PATH,
                    RequestDispatcher.FORWARD_SERVLET_PATH, RequestDispatcher.FORWARD_PATH_INFO,
                    RequestDispatcher.FORWARD_QUERY_STRING, RequestDispatcher.FORWARD_MAPPING));

    private static final int shortestSpecialNameLength = specialsSet.stream().mapToInt(String::length).min().getAsInt();


    /**
     * The request attributes for this request. This is initialized from the wrapped request, but updates are allowed.
     */
    protected final HashMap<String,Object> attributes = new HashMap<>();

    /**
     * Construct a new wrapped request around the specified servlet request.
     *
     * @param request The servlet request being wrapped
     */
    ApplicationRequest(ServletRequest request) {
        super(request);
        setRequest(request);
    }


    // ------------------------------------------------- ServletRequest Methods

    /**
     * Override the <code>getAttribute()</code> method of the wrapped request.
     *
     * @param name Name of the attribute to retrieve
     */
    @Override
    public Object getAttribute(String name) {
        synchronized (attributes) {
            return attributes.get(name);
        }
    }


    /**
     * Override the <code>getAttributeNames()</code> method of the wrapped request.
     */
    @Override
    public Enumeration<String> getAttributeNames() {
        synchronized (attributes) {
            return Collections.enumeration(attributes.keySet());
        }
    }


    /**
     * Override the <code>removeAttribute()</code> method of the wrapped request.
     *
     * @param name Name of the attribute to remove
     */
    @Override
    public void removeAttribute(String name) {
        synchronized (attributes) {
            attributes.remove(name);
            if (!isSpecial(name)) {
                getRequest().removeAttribute(name);
            }
        }
    }


    /**
     * Override the <code>setAttribute()</code> method of the wrapped request.
     *
     * @param name  Name of the attribute to set
     * @param value Value of the attribute to set
     */
    @Override
    public void setAttribute(String name, Object value) {
        synchronized (attributes) {
            attributes.put(name, value);
            if (!isSpecial(name)) {
                getRequest().setAttribute(name, value);
            }
        }
    }


    private boolean isSpecial(String name) {
        // Performance - see BZ 68089
        if (name.length() < shortestSpecialNameLength) {
            return false;
        }
        return specialsSet.contains(name);
    }


    // ------------------------------------------ ServletRequestWrapper Methods

    /**
     * Set the request that we are wrapping.
     *
     * @param request The new wrapped request
     */
    @Override
    public void setRequest(ServletRequest request) {
        super.setRequest(request);

        // Initialize the attributes for this request
        synchronized (attributes) {
            attributes.clear();
            Enumeration<String> names = request.getAttributeNames();
            while (names.hasMoreElements()) {
                String name = names.nextElement();
                Object value = request.getAttribute(name);
                attributes.put(name, value);
            }
        }
    }
}
