/*
 * 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.io.IOException;
import java.io.UnsupportedEncodingException;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.NoSuchElementException;

import jakarta.servlet.DispatcherType;
import jakarta.servlet.RequestDispatcher;
import jakarta.servlet.ServletContext;
import jakarta.servlet.http.HttpServletMapping;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletRequestWrapper;
import jakarta.servlet.http.HttpSession;

import org.apache.catalina.Context;
import org.apache.catalina.Globals;
import org.apache.catalina.Manager;
import org.apache.catalina.Session;
import org.apache.catalina.util.ParameterMap;
import org.apache.catalina.util.RequestUtil;
import org.apache.catalina.util.URLEncoder;
import org.apache.tomcat.util.ExceptionUtils;
import org.apache.tomcat.util.buf.B2CConverter;
import org.apache.tomcat.util.buf.MessageBytes;
import org.apache.tomcat.util.http.Parameters;
import org.apache.tomcat.util.res.StringManager;

/**
 * Wrapper around a <code>jakarta.servlet.http.HttpServletRequest</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.http.HttpServletRequestWrapper</code> class) back into an internal
 * <code>org.apache.catalina.HttpRequest</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!
 *
 * @author Craig R. McClanahan
 * @author Remy Maucherat
 */
class ApplicationHttpRequest extends HttpServletRequestWrapper {

    private static final StringManager sm = StringManager.getManager(ApplicationHttpRequest.class);

    /**
     * The set of attribute names that are special for request dispatchers.
     */
    protected static final String[] specials =
            { 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 };
    /*
     * This duplicates specials to some extent but has been added to improve the performance of [get|set|is]Special().
     * It may be possible to remove specials but that will require changes to AttributeNamesEnumerator.
     */
    private static final Map<String,Integer> specialsMap = new HashMap<>();
    static {
        for (int i = 0; i < specials.length; i++) {
            specialsMap.put(specials[i], Integer.valueOf(i));
        }
    }

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


    private static final int SPECIALS_FIRST_FORWARD_INDEX = 6;


    /**
     * The context for this request.
     */
    protected final Context context;


    /**
     * The context path for this request.
     */
    protected String contextPath = null;


    /**
     * If this request is cross context, since this changes session access behavior.
     */
    protected final boolean crossContext;


    /**
     * The current dispatcher type.
     */
    protected DispatcherType dispatcherType = null;

    /**
     * The HTTP method for this request.
     */
    private String method;

    /**
     * The request parameters for this request. This is initialized from the wrapped request.
     */
    protected Map<String,String[]> parameters = null;


    /**
     * Have the parameters for this request already been parsed?
     */
    private boolean parsedParams = false;


    /**
     * The path information for this request.
     */
    protected String pathInfo = null;


    /**
     * The query parameters for the current request.
     */
    private String queryParamString = null;


    /**
     * The query string for this request.
     */
    protected String queryString = null;


    /**
     * The current request dispatcher path.
     */
    protected Object requestDispatcherPath = null;


    /**
     * The request URI for this request.
     */
    protected String requestURI = null;


    /**
     * The servlet path for this request.
     */
    protected String servletPath = null;


    /**
     * The mapping for this request.
     */
    private HttpServletMapping mapping = null;


    /**
     * The currently active session for this request.
     */
    protected Session session = null;


    /**
     * Special attributes.
     */
    protected final Object[] specialAttributes = new Object[specials.length];


    /*
     * Used to speed up getAttribute(). See that method for details.
     */
    private ApplicationHttpRequest wrappedApplicationHttpRequest;

    /**
     * Construct a new wrapped request around the specified servlet request.
     *
     * @param request      The servlet request being wrapped
     * @param context      The target context for the wrapped request
     * @param crossContext {@code true} if the wrapped request will be a cross-context request, otherwise {@code false}
     */
    ApplicationHttpRequest(HttpServletRequest request, Context context, boolean crossContext) {
        super(request);
        this.context = context;
        this.crossContext = crossContext;
        setRequest(request);
    }


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

    @Override
    public ServletContext getServletContext() {
        if (context == null) {
            return null;
        }
        return context.getServletContext();
    }


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

        if (name.equals(Globals.DISPATCHER_TYPE_ATTR)) {
            return dispatcherType;
        } else if (name.equals(Globals.DISPATCHER_REQUEST_PATH_ATTR)) {
            if (requestDispatcherPath != null) {
                return requestDispatcherPath.toString();
            } else {
                return null;
            }
        }

        int pos = getSpecial(name);
        if (pos == -1) {
            /*
             * With nested includes there will be nested ApplicationHttpRequests. The calls to getSpecial() are
             * relatively expensive and it is known at this point that the attribute is not special. Therefore, jump to
             * the first wrapped request that isn't an instance of ApplicationHttpRequest before calling getAttribute()
             * to avoid a call to getSpecial() for each nested ApplicationHttpRequest.
             */
            ApplicationHttpRequest request = this;
            while (request.wrappedApplicationHttpRequest != null) {
                request = request.wrappedApplicationHttpRequest;
            }
            return request.getRequest().getAttribute(name);
        } else {
            if ((specialAttributes[pos] == null) && (specialAttributes[SPECIALS_FIRST_FORWARD_INDEX] == null) &&
                    (pos >= SPECIALS_FIRST_FORWARD_INDEX)) {
                // If it's a forward special attribute, and null, it means this
                // is an include, so we check the wrapped request since
                // the request could have been forwarded before the include
                return getRequest().getAttribute(name);
            } else {
                return specialAttributes[pos];
            }
        }
    }


    /**
     * Override the <code>getAttributeNames()</code> method of the wrapped request.
     */
    @Override
    public Enumeration<String> getAttributeNames() {
        return new AttributeNamesEnumerator();
    }


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

        if (name.equals(Globals.DISPATCHER_TYPE_ATTR)) {
            dispatcherType = (DispatcherType) value;
            return;
        } else if (name.equals(Globals.DISPATCHER_REQUEST_PATH_ATTR)) {
            requestDispatcherPath = value;
            return;
        }

        if (!setSpecial(name, value)) {
            getRequest().setAttribute(name, value);
        }
    }


    /**
     * Return a RequestDispatcher that wraps the resource at the specified path, which may be interpreted as relative to
     * the current request path.
     *
     * @param path Path of the resource to be wrapped
     */
    @Override
    public RequestDispatcher getRequestDispatcher(String path) {

        if (context == null) {
            return null;
        }

        if (path == null) {
            return null;
        }

        int fragmentPos = path.indexOf('#');
        if (fragmentPos > -1) {
            context.getLogger().warn(sm.getString("applicationHttpRequest.fragmentInDispatchPath", path));
            path = path.substring(0, fragmentPos);
        }

        // If the path is already context-relative, just pass it through
        if (path.startsWith("/")) {
            return context.getServletContext().getRequestDispatcher(path);
        }

        // Convert a request-relative path to a context-relative one
        String servletPath = (String) getAttribute(RequestDispatcher.INCLUDE_SERVLET_PATH);
        if (servletPath == null) {
            servletPath = getServletPath();
        }

        // Add the path info, if there is any
        String pathInfo = getPathInfo();
        String requestPath;

        if (pathInfo == null) {
            requestPath = servletPath;
        } else {
            requestPath = servletPath + pathInfo;
        }

        int pos = requestPath.lastIndexOf('/');
        String relative;
        if (context.getDispatchersUseEncodedPaths()) {
            if (pos >= 0) {
                relative = URLEncoder.DEFAULT.encode(requestPath.substring(0, pos + 1), StandardCharsets.UTF_8) + path;
            } else {
                relative = URLEncoder.DEFAULT.encode(requestPath, StandardCharsets.UTF_8) + path;
            }
        } else {
            if (pos >= 0) {
                relative = requestPath.substring(0, pos + 1) + path;
            } else {
                relative = requestPath + path;
            }
        }

        return context.getServletContext().getRequestDispatcher(relative);
    }


    /**
     * Override the getDispatcherType() method of the wrapped request.
     */
    @Override
    public DispatcherType getDispatcherType() {
        return dispatcherType;
    }


    // --------------------------------------------- HttpServletRequest Methods

    /**
     * Override the <code>getContextPath()</code> method of the wrapped request.
     */
    @Override
    public String getContextPath() {
        return this.contextPath;
    }


    @Override
    public String getMethod() {
        return method;
    }


    /**
     * Override the <code>getParameter()</code> method of the wrapped request.
     *
     * @param name Name of the requested parameter
     */
    @Override
    public String getParameter(String name) {
        parseParameters();

        String[] value = parameters.get(name);
        if (value == null) {
            return null;
        }
        return value[0];
    }


    /**
     * Override the <code>getParameterMap()</code> method of the wrapped request.
     */
    @Override
    public Map<String,String[]> getParameterMap() {
        parseParameters();
        return parameters;
    }


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


    /**
     * Override the <code>getParameterValues()</code> method of the wrapped request.
     *
     * @param name Name of the requested parameter
     */
    @Override
    public String[] getParameterValues(String name) {
        parseParameters();
        return parameters.get(name);
    }


    /**
     * Override the <code>getPathInfo()</code> method of the wrapped request.
     */
    @Override
    public String getPathInfo() {
        return this.pathInfo;
    }


    /**
     * Override the <code>getPathTranslated()</code> method of the wrapped request.
     */
    @Override
    public String getPathTranslated() {
        if (getPathInfo() == null || getServletContext() == null) {
            return null;
        }

        return getServletContext().getRealPath(getPathInfo());
    }


    /**
     * Override the <code>getQueryString()</code> method of the wrapped request.
     */
    @Override
    public String getQueryString() {
        return this.queryString;
    }


    /**
     * Override the <code>getRequestURI()</code> method of the wrapped request.
     */
    @Override
    public String getRequestURI() {
        return this.requestURI;
    }


    /**
     * Override the <code>getRequestURL()</code> method of the wrapped request.
     */
    @Override
    public StringBuffer getRequestURL() {
        return RequestUtil.getRequestURL(this);
    }


    /**
     * Override the <code>getServletPath()</code> method of the wrapped request.
     */
    @Override
    public String getServletPath() {
        return this.servletPath;
    }


    @Override
    public HttpServletMapping getHttpServletMapping() {
        return mapping;
    }


    /**
     * Return the session associated with this Request, creating one if necessary.
     */
    @Override
    public HttpSession getSession() {
        return getSession(true);
    }


    /**
     * Return the session associated with this Request, creating one if necessary and requested.
     *
     * @param create Create a new session if one does not exist
     */
    @Override
    public HttpSession getSession(boolean create) {

        if (crossContext) {

            // There cannot be a session if no context has been assigned yet
            if (context == null) {
                return null;
            }

            // Return the current session if it exists and is valid
            if (session != null && session.isValid()) {
                return session.getSession();
            }

            HttpSession other = super.getSession(false);
            if (create && (other == null)) {
                // First create a session in the first context: the problem is
                // that the top level request is the only one which can
                // create the cookie safely
                other = super.getSession(true);
            }
            if (other != null) {
                Session localSession = null;
                try {
                    localSession = context.getManager().findSession(other.getId());
                    if (localSession != null && !localSession.isValid()) {
                        localSession = null;
                    }
                } catch (IOException e) {
                    // Ignore
                }
                if (localSession == null && create) {
                    localSession = context.getManager().createSession(other.getId());
                }
                if (localSession != null) {
                    localSession.access();
                    session = localSession;
                    return session.getSession();
                }
            }
            return null;

        } else {
            return super.getSession(create);
        }
    }


    /**
     * Returns true if the request specifies a JSESSIONID that is valid within the context of this
     * ApplicationHttpRequest, false otherwise.
     *
     * @return true if the request specifies a JSESSIONID that is valid within the context of this
     *             ApplicationHttpRequest, false otherwise.
     */
    @Override
    public boolean isRequestedSessionIdValid() {

        if (crossContext) {

            String requestedSessionId = getRequestedSessionId();
            if (requestedSessionId == null) {
                return false;
            }
            if (context == null) {
                return false;
            }
            Manager manager = context.getManager();
            if (manager == null) {
                return false;
            }
            Session session = null;
            try {
                session = manager.findSession(requestedSessionId);
            } catch (IOException e) {
                // Ignore
            }
            return (session != null) && session.isValid();

        } else {
            return super.isRequestedSessionIdValid();
        }
    }


    // -------------------------------------------------------- Package Methods

    /**
     * Recycle this request
     */
    public void recycle() {
        if (session != null) {
            try {
                session.endAccess();
            } catch (Throwable t) {
                ExceptionUtils.handleThrowable(t);
                context.getLogger().warn(sm.getString("applicationHttpRequest.sessionEndAccessFail"), t);
            }
        }
    }


    /**
     * Set the context path for this request.
     *
     * @param contextPath The new context path
     */
    void setContextPath(String contextPath) {
        this.contextPath = contextPath;
    }


    /**
     * Set the path information for this request.
     *
     * @param pathInfo The new path info
     */
    void setPathInfo(String pathInfo) {
        this.pathInfo = pathInfo;
    }


    /**
     * Set the query string for this request.
     *
     * @param queryString The new query string
     */
    void setQueryString(String queryString) {
        this.queryString = queryString;
    }


    /**
     * Set the request that we are wrapping.
     *
     * @param request The new wrapped request
     */
    void setRequest(HttpServletRequest request) {

        super.setRequest(request);

        // Type specific version of the wrapped request to speed up getAttribute()
        if (request instanceof ApplicationHttpRequest) {
            wrappedApplicationHttpRequest = (ApplicationHttpRequest) request;
        } else {
            wrappedApplicationHttpRequest = null;
        }

        // Initialize the attributes for this request
        dispatcherType = (DispatcherType) request.getAttribute(Globals.DISPATCHER_TYPE_ATTR);
        requestDispatcherPath = request.getAttribute(Globals.DISPATCHER_REQUEST_PATH_ATTR);

        // Initialize the path elements for this request
        contextPath = request.getContextPath();
        method = request.getMethod();
        pathInfo = request.getPathInfo();
        queryString = request.getQueryString();
        requestURI = request.getRequestURI();
        servletPath = request.getServletPath();
        mapping = request.getHttpServletMapping();
    }


    /**
     * Set the request method for this request.
     *
     * @param method The new request method
     */
    void setMethod(String method) {
        this.method = method;
    }


    /**
     * Set the request URI for this request.
     *
     * @param requestURI The new request URI
     */
    void setRequestURI(String requestURI) {
        this.requestURI = requestURI;
    }


    /**
     * Set the servlet path for this request.
     *
     * @param servletPath The new servlet path
     */
    void setServletPath(String servletPath) {
        this.servletPath = servletPath;
    }


    /**
     * Parses the parameters of this request. If parameters are present in both the query string and the request
     * content, they are merged.
     */
    void parseParameters() {

        if (parsedParams) {
            return;
        }

        Map<String,String[]> requestParameters = getRequest().getParameterMap();
        if (requestParameters instanceof ParameterMap<String,String[]>) {
            parameters = new ParameterMap<>((ParameterMap<String,String[]>) requestParameters);
        } else {
            parameters = new ParameterMap<>(requestParameters);
        }
        mergeParameters();
        ((ParameterMap<String,String[]>) parameters).setLocked(true);
        parsedParams = true;
    }


    /**
     * Save query parameters for this request.
     *
     * @param queryString The query string containing parameters for this request
     */
    void setQueryParams(String queryString) {
        this.queryParamString = queryString;
    }


    void setMapping(HttpServletMapping mapping) {
        this.mapping = mapping;
    }


    // ------------------------------------------------------ Protected Methods

    /**
     * Is this attribute name one of the special ones that is added only for included servlets?
     *
     * @param name Attribute name to be tested
     */
    protected boolean isSpecial(String name) {
        // Performance - see BZ 68089
        if (name.length() < shortestSpecialNameLength) {
            return false;
        }
        return specialsMap.containsKey(name);
    }


    /**
     * Get a special attribute.
     *
     * @return the special attribute pos, or -1 if it is not a special attribute
     */
    protected int getSpecial(String name) {
        // Performance - see BZ 68089
        if (name.length() < shortestSpecialNameLength) {
            return -1;
        }
        Integer index = specialsMap.get(name);
        if (index == null) {
            return -1;
        }
        return index.intValue();
    }


    /**
     * Set a special attribute.
     *
     * @return true if the attribute was a special attribute, false otherwise
     */
    protected boolean setSpecial(String name, Object value) {
        // Performance - see BZ 68089
        if (name.length() < shortestSpecialNameLength) {
            return false;
        }
        Integer index = specialsMap.get(name);
        if (index == null) {
            return false;
        }
        specialAttributes[index.intValue()] = value;
        return true;
    }


    /**
     * Remove a special attribute.
     *
     * @return true if the attribute was a special attribute, false otherwise
     */
    protected boolean removeSpecial(String name) {
        return setSpecial(name, null);
    }


    /**
     * Merge the two sets of parameter values into a single String array.
     *
     * @param values1 First set of values
     * @param values2 Second set of values
     */
    private String[] mergeValues(String[] values1, String[] values2) {

        List<String> results = new ArrayList<>();

        if (values1 != null) {
            results.addAll(Arrays.asList(values1));
        }

        if (values2 != null) {
            results.addAll(Arrays.asList(values2));
        }

        return results.toArray(new String[0]);
    }


    // ------------------------------------------------------ Private Methods

    /**
     * Merge the parameters from the saved query parameter string (if any), and the parameters already present on this
     * request (if any), such that the parameter values from the query string show up first if there are duplicate
     * parameter names.
     */
    private void mergeParameters() {

        if ((queryParamString == null) || (queryParamString.isEmpty())) {
            return;
        }

        // Parse the query string from the dispatch target
        Parameters paramParser = new Parameters();
        MessageBytes queryMB = MessageBytes.newInstance();
        queryMB.setString(queryParamString);

        // TODO
        // - Should only use body encoding if useBodyEncodingForURI is true
        // - Otherwise, should use URIEncoding
        // - The problem is that the connector is not available...
        // - To add to the fun, the URI default changed in Servlet 4.0 to UTF-8

        String encoding = getCharacterEncoding();
        Charset charset = null;
        if (encoding != null) {
            try {
                charset = B2CConverter.getCharset(encoding);
                queryMB.setCharset(charset);
            } catch (UnsupportedEncodingException e) {
                // Fall-back to default (ISO-8859-1)
                charset = StandardCharsets.ISO_8859_1;
            }
        }

        paramParser.setQuery(queryMB);
        paramParser.setQueryStringCharset(charset);
        paramParser.handleQueryParameters();

        // Insert the additional parameters from the dispatch target
        Enumeration<String> dispParamNames = paramParser.getParameterNames();
        while (dispParamNames.hasMoreElements()) {
            String dispParamName = dispParamNames.nextElement();
            String[] dispParamValues = paramParser.getParameterValues(dispParamName);
            String[] originalValues = parameters.get(dispParamName);
            if (originalValues == null) {
                parameters.put(dispParamName, dispParamValues);
                continue;
            }
            parameters.put(dispParamName, mergeValues(dispParamValues, originalValues));
        }
    }


    // ----------------------------------- AttributeNamesEnumerator Inner Class

    /**
     * Utility class used to expose the special attributes as being available as request attributes.
     */
    protected class AttributeNamesEnumerator implements Enumeration<String> {

        protected int pos = -1;
        protected final int last;
        protected final Enumeration<String> parentEnumeration;
        protected String next = null;

        public AttributeNamesEnumerator() {
            int last = -1;
            parentEnumeration = getRequest().getAttributeNames();
            for (int i = specialAttributes.length - 1; i >= 0; i--) {
                if (getAttribute(specials[i]) != null) {
                    last = i;
                    break;
                }
            }
            this.last = last;
        }

        @Override
        public boolean hasMoreElements() {
            return ((pos != last) || (next != null) || ((next = findNext()) != null));
        }

        @Override
        public String nextElement() {
            if (pos != last) {
                for (int i = pos + 1; i <= last; i++) {
                    if (getAttribute(specials[i]) != null) {
                        pos = i;
                        return specials[i];
                    }
                }
            }
            String result = next;
            if (next != null) {
                next = findNext();
            } else {
                throw new NoSuchElementException();
            }
            return result;
        }

        protected String findNext() {
            String result = null;
            while ((result == null) && (parentEnumeration.hasMoreElements())) {
                String current = parentEnumeration.nextElement();
                if (!isSpecial(current)) {
                    result = current;
                }
            }
            return result;
        }
    }
}
