/*
 * 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 javax.servlet.http;

import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Enumeration;
import java.util.Map;

import javax.servlet.ServletException;
import javax.servlet.ServletRequest;

/**
 * Extends the {@link javax.servlet.ServletRequest} interface to provide request information for HTTP servlets.
 * <p>
 * The servlet container creates an <code>HttpServletRequest</code> object and passes it as an argument to the servlet's
 * service methods (<code>doGet</code>, <code>doPost</code>, etc).
 */
public interface HttpServletRequest extends ServletRequest {

    /**
     * String identifier for Basic authentication. Value "BASIC"
     */
    String BASIC_AUTH = "BASIC";
    /**
     * String identifier for Form authentication. Value "FORM"
     */
    String FORM_AUTH = "FORM";
    /**
     * String identifier for Client Certificate authentication. Value "CLIENT_CERT"
     */
    String CLIENT_CERT_AUTH = "CLIENT_CERT";
    /**
     * String identifier for Digest authentication. Value "DIGEST"
     */
    String DIGEST_AUTH = "DIGEST";

    /**
     * Returns the name of the authentication scheme used to protect the servlet. All servlet containers support basic,
     * form and client certificate authentication, and may additionally support digest authentication. If the servlet is
     * not authenticated <code>null</code> is returned.
     * <p>
     * Same as the value of the CGI variable AUTH_TYPE.
     *
     * @return one of the static members BASIC_AUTH, FORM_AUTH, CLIENT_CERT_AUTH, DIGEST_AUTH (suitable for ==
     *             comparison) or the container-specific string indicating the authentication scheme, or
     *             <code>null</code> if the request was not authenticated.
     */
    String getAuthType();

    /**
     * Returns an array containing all of the <code>Cookie</code> objects the client sent with this request. This method
     * returns <code>null</code> if no cookies were sent.
     *
     * @return an array of all the <code>Cookies</code> included with this request, or <code>null</code> if the request
     *             has no cookies
     */
    Cookie[] getCookies();

    /**
     * Returns the value of the specified request header as a <code>long</code> value that represents a
     * <code>Date</code> object. Use this method with headers that contain dates, such as
     * <code>If-Modified-Since</code>.
     * <p>
     * The date is returned as the number of milliseconds since January 1, 1970 GMT. The header name is case
     * insensitive.
     * <p>
     * If the request did not have a header of the specified name, this method returns -1. If the header can't be
     * converted to a date, the method throws an <code>IllegalArgumentException</code>.
     *
     * @param name a <code>String</code> specifying the name of the header
     *
     * @return a <code>long</code> value representing the date specified in the header expressed as the number of
     *             milliseconds since January 1, 1970 GMT, or -1 if the named header was not included with the request
     *
     * @exception IllegalArgumentException If the header value can't be converted to a date
     */
    long getDateHeader(String name);

    /**
     * Returns the value of the specified request header as a <code>String</code>. If the request did not include a
     * header of the specified name, this method returns <code>null</code>. If there are multiple headers with the same
     * name, this method returns the first head in the request. The header name is case insensitive. You can use this
     * method with any request header.
     *
     * @param name a <code>String</code> specifying the header name
     *
     * @return a <code>String</code> containing the value of the requested header, or <code>null</code> if the request
     *             does not have a header of that name
     */
    String getHeader(String name);

    /**
     * Returns all the values of the specified request header as an <code>Enumeration</code> of <code>String</code>
     * objects.
     * <p>
     * Some headers, such as <code>Accept-Language</code> can be sent by clients as several headers each with a
     * different value rather than sending the header as a comma separated list.
     * <p>
     * If the request did not include any headers of the specified name, this method returns an empty
     * <code>Enumeration</code>. The header name is case insensitive. You can use this method with any request header.
     *
     * @param name a <code>String</code> specifying the header name
     *
     * @return an <code>Enumeration</code> containing the values of the requested header. If the request does not have
     *             any headers of that name return an empty enumeration. If the container does not allow access to
     *             header information, return null
     */
    Enumeration<String> getHeaders(String name);

    /**
     * Returns an enumeration of all the header names this request contains. If the request has no headers, this method
     * returns an empty enumeration.
     * <p>
     * Some servlet containers do not allow servlets to access headers using this method, in which case this method
     * returns <code>null</code>
     *
     * @return an enumeration of all the header names sent with this request; if the request has no headers, an empty
     *             enumeration; if the servlet container does not allow servlets to use this method, <code>null</code>
     */
    Enumeration<String> getHeaderNames();

    /**
     * Returns the value of the specified request header as an <code>int</code>. If the request does not have a header
     * of the specified name, this method returns -1. If the header cannot be converted to an integer, this method
     * throws a <code>NumberFormatException</code>.
     * <p>
     * The header name is case insensitive.
     *
     * @param name a <code>String</code> specifying the name of a request header
     *
     * @return an integer expressing the value of the request header or -1 if the request doesn't have a header of this
     *             name
     *
     * @exception NumberFormatException If the header value can't be converted to an <code>int</code>
     */
    int getIntHeader(String name);

    /**
     * Obtain the mapping information for this request.
     *
     * @return the mapping information for this request
     */
    default HttpServletMapping getHttpServletMapping() {
        return new HttpServletMapping() {

            @Override
            public String getMatchValue() {
                return "";
            }

            @Override
            public String getPattern() {
                return "";
            }

            @Override
            public String getServletName() {
                return "";
            }

            @Override
            public MappingMatch getMappingMatch() {
                return null;
            }
        };
    }

    /**
     * Returns the name of the HTTP method with which this request was made, for example, GET, POST, or PUT. Same as the
     * value of the CGI variable REQUEST_METHOD.
     *
     * @return a <code>String</code> specifying the name of the method with which this request was made
     */
    String getMethod();

    /**
     * Returns any extra path information associated with the URL the client sent when it made this request. The extra
     * path information follows the servlet path but precedes the query string and will start with a "/" character.
     * <p>
     * This method returns <code>null</code> if there was no extra path information.
     * <p>
     * Same as the value of the CGI variable PATH_INFO.
     *
     * @return a <code>String</code>, decoded by the web container, specifying extra path information that comes after
     *             the servlet path but before the query string in the request URL; or <code>null</code> if the URL does
     *             not have any extra path information
     */
    String getPathInfo();

    /**
     * Returns any extra path information after the servlet name but before the query string, and translates it to a
     * real path. Same as the value of the CGI variable PATH_TRANSLATED.
     * <p>
     * If the URL does not have any extra path information, this method returns <code>null</code> or the servlet
     * container cannot translate the virtual path to a real path for any reason (such as when the web application is
     * executed from an archive). The web container does not decode this string.
     *
     * @return a <code>String</code> specifying the real path, or <code>null</code> if the URL does not have any extra
     *             path information
     */
    String getPathTranslated();

    /**
     * Obtain a builder for generating push requests. {@link PushBuilder} documents how this request will be used as the
     * basis for a push request. Each call to this method will return a new instance, independent of any previous
     * instance obtained.
     *
     * @return A builder that can be used to generate push requests based on this request or {@code null} if push is not
     *             supported. Note that even if a PushBuilder instance is returned, by the time that
     *             {@link PushBuilder#push()} is called, it may no longer be valid to push a request and the push
     *             request will be ignored.
     *
     * @since Servlet 4.0
     */
    default PushBuilder newPushBuilder() {
        return null;
    }

    /**
     * Returns the portion of the request URI that indicates the context of the request. The context path always comes
     * first in a request URI. The path starts with a "/" character but does not end with a "/" character. For servlets
     * in the default (root) context, this method returns "". The container does not decode this string.
     *
     * @return a <code>String</code> specifying the portion of the request URI that indicates the context of the request
     */
    String getContextPath();

    /**
     * Returns the query string that is contained in the request URL after the path. This method returns
     * <code>null</code> if the URL does not have a query string. Same as the value of the CGI variable QUERY_STRING.
     *
     * @return a <code>String</code> containing the query string or <code>null</code> if the URL contains no query
     *             string. The value is not decoded by the container.
     */
    String getQueryString();

    /**
     * Returns the login of the user making this request, if the user has been authenticated, or <code>null</code> if
     * the user has not been authenticated. Whether the user name is sent with each subsequent request depends on the
     * browser and type of authentication. Same as the value of the CGI variable REMOTE_USER.
     *
     * @return a <code>String</code> specifying the login of the user making this request, or <code>null</code> if the
     *             user login is not known
     */
    String getRemoteUser();

    /**
     * Returns a boolean indicating whether the authenticated user is included in the specified logical "role". Roles
     * and role membership can be defined using deployment descriptors. If the user has not been authenticated, the
     * method returns <code>false</code>.
     *
     * @param role a <code>String</code> specifying the name of the role
     *
     * @return a <code>boolean</code> indicating whether the user making this request belongs to a given role;
     *             <code>false</code> if the user has not been authenticated
     */
    boolean isUserInRole(String role);

    /**
     * Returns a <code>java.security.Principal</code> object containing the name of the current authenticated user. If
     * the user has not been authenticated, the method returns <code>null</code>.
     *
     * @return a <code>java.security.Principal</code> containing the name of the user making this request;
     *             <code>null</code> if the user has not been authenticated
     */
    java.security.Principal getUserPrincipal();

    /**
     * Returns the session ID specified by the client. This may not be the same as the ID of the current valid session
     * for this request. If the client did not specify a session ID, this method returns <code>null</code>.
     *
     * @return a <code>String</code> specifying the session ID, or <code>null</code> if the request did not specify a
     *             session ID
     *
     * @see #isRequestedSessionIdValid
     */
    String getRequestedSessionId();

    /**
     * Returns the part of this request's URL from the protocol name up to the query string in the first line of the
     * HTTP request. The web container does not decode this String. For example:
     * <table>
     * <caption>Examples of Returned Values</caption>
     * <tr>
     * <th>First line of HTTP request</th>
     * <th>Returned Value</th>
     * <tr>
     * <td>POST /some/path.html HTTP/1.1
     * <td>
     * <td>/some/path.html
     * <tr>
     * <td>GET http://foo.bar/a.html HTTP/1.0
     * <td>
     * <td>/a.html
     * <tr>
     * <td>HEAD /xyz?a=b HTTP/1.1
     * <td>
     * <td>/xyz
     * </table>
     * <p>
     * To reconstruct a URL with a scheme and host, use {@link #getRequestURL}.
     *
     * @return a <code>String</code> containing the part of the URL from the protocol name up to the query string
     *
     * @see #getRequestURL
     */
    String getRequestURI();

    /**
     * Reconstructs the URL the client used to make the request. The returned URL contains a protocol, server name, port
     * number, and server path, but it does not include query string parameters.
     * <p>
     * Because this method returns a <code>StringBuffer</code>, not a string, you can modify the URL easily, for
     * example, to append query parameters.
     * <p>
     * This method is useful for creating redirect messages and for reporting errors.
     *
     * @return a <code>StringBuffer</code> object containing the reconstructed URL
     */
    StringBuffer getRequestURL();

    /**
     * Returns the part of this request's URL that calls the servlet. This path starts with a "/" character and includes
     * either the servlet name or a path to the servlet, but does not include any extra path information or a query
     * string. Same as the value of the CGI variable SCRIPT_NAME.
     * <p>
     * This method will return an empty string ("") if the servlet used to process this request was matched using the
     * "/*" pattern.
     *
     * @return a <code>String</code> containing the name or path of the servlet being called, as specified in the
     *             request URL, decoded, or an empty string if the servlet used to process the request is matched using
     *             the "/*" pattern.
     */
    String getServletPath();

    /**
     * Returns the current <code>HttpSession</code> associated with this request or, if there is no current session and
     * <code>create</code> is true, returns a new session.
     * <p>
     * If <code>create</code> is <code>false</code> and the request has no valid <code>HttpSession</code>, this method
     * returns <code>null</code>.
     * <p>
     * To make sure the session is properly maintained, you must call this method before the response is committed. If
     * the container is using cookies to maintain session integrity and is asked to create a new session when the
     * response is committed, an IllegalStateException is thrown.
     *
     * @param create <code>true</code> to create a new session for this request if necessary; <code>false</code> to
     *                   return <code>null</code> if there's no current session
     *
     * @return the <code>HttpSession</code> associated with this request or <code>null</code> if <code>create</code> is
     *             <code>false</code> and the request has no valid session
     *
     * @see #getSession()
     */
    HttpSession getSession(boolean create);

    /**
     * Returns the current session associated with this request, or if the request does not have a session, creates one.
     *
     * @return the <code>HttpSession</code> associated with this request
     *
     * @see #getSession(boolean)
     */
    HttpSession getSession();

    /**
     * Changes the session ID of the session associated with this request. This method does not create a new session
     * object it only changes the ID of the current session.
     *
     * @return the new session ID allocated to the session
     *
     * @see HttpSessionIdListener
     *
     * @since Servlet 3.1
     */
    String changeSessionId();

    /**
     * Checks whether the requested session ID is still valid.
     *
     * @return <code>true</code> if this request has an id for a valid session in the current session context;
     *             <code>false</code> otherwise
     *
     * @see #getRequestedSessionId
     * @see #getSession
     */
    boolean isRequestedSessionIdValid();

    /**
     * Checks whether the requested session ID came in as a cookie.
     *
     * @return <code>true</code> if the session ID came in as a cookie; otherwise, <code>false</code>
     *
     * @see #getSession
     */
    boolean isRequestedSessionIdFromCookie();

    /**
     * Checks whether the requested session ID came in as part of the request URL.
     *
     * @return <code>true</code> if the session ID came in as part of a URL; otherwise, <code>false</code>
     *
     * @see #getSession
     */
    boolean isRequestedSessionIdFromURL();

    /**
     * @return {@link #isRequestedSessionIdFromURL()}
     *
     * @deprecated As of Version 2.1 of the Java Servlet API, use {@link #isRequestedSessionIdFromURL} instead.
     */
    @Deprecated
    boolean isRequestedSessionIdFromUrl();

    /**
     * Triggers the same authentication process as would be triggered if the request is for a resource that is protected
     * by a security constraint.
     *
     * @param response The response to use to return any authentication challenge
     *
     * @return <code>true</code> if the user is successfully authenticated and <code>false</code> if not
     *
     * @throws IOException           if the authentication process attempted to read from the request or write to the
     *                                   response and an I/O error occurred
     * @throws IllegalStateException if the authentication process attempted to write to the response after it had been
     *                                   committed
     * @throws ServletException      if the authentication failed and the caller is expected to handle the failure
     *
     * @since Servlet 3.0
     */
    boolean authenticate(HttpServletResponse response) throws IOException, ServletException;

    /**
     * Authenticate the provided user name and password and then associated the authenticated user with the request.
     *
     * @param username The user name to authenticate
     * @param password The password to use to authenticate the user
     *
     * @throws ServletException If any of {@link #getRemoteUser()}, {@link #getUserPrincipal()} or
     *                              {@link #getAuthType()} are non-null, if the configured authenticator does not
     *                              support user name and password authentication or if the authentication fails
     *
     * @since Servlet 3.0
     */
    void login(String username, String password) throws ServletException;

    /**
     * Removes any authenticated user from the request.
     *
     * @throws ServletException If the logout fails
     *
     * @since Servlet 3.0
     */
    void logout() throws ServletException;

    /**
     * Return a collection of all uploaded Parts.
     *
     * @return A collection of all uploaded Parts.
     *
     * @throws IOException           if an I/O error occurs
     * @throws IllegalStateException if size limits are exceeded or no multipart configuration is provided
     * @throws ServletException      if the request is not multipart/form-data
     *
     * @since Servlet 3.0
     */
    Collection<Part> getParts() throws IOException, ServletException;

    /**
     * Gets the named Part or null if the Part does not exist. Triggers upload of all Parts.
     *
     * @param name The name of the Part to obtain
     *
     * @return The named Part or null if the Part does not exist
     *
     * @throws IOException           if an I/O error occurs
     * @throws IllegalStateException if size limits are exceeded
     * @throws ServletException      if the request is not multipart/form-data
     *
     * @since Servlet 3.0
     */
    Part getPart(String name) throws IOException, ServletException;

    /**
     * Start the HTTP upgrade process and create and instance of the provided protocol handler class. The connection
     * will be passed this instance once the current request/response pair has completed processing. Calling this method
     * sets the response status to {@link HttpServletResponse#SC_SWITCHING_PROTOCOLS}.
     *
     * @param <T>                     The type of the upgrade handler
     * @param httpUpgradeHandlerClass The class that implements the upgrade handler
     *
     * @return A newly created instance of the specified upgrade handler type
     *
     * @throws IOException      if an I/O error occurred during the upgrade
     * @throws ServletException if the given httpUpgradeHandlerClass fails to be instantiated
     *
     * @since Servlet 3.1
     */
    <T extends HttpUpgradeHandler> T upgrade(Class<T> httpUpgradeHandlerClass)
            throws IOException, ServletException;

    /**
     * Obtain a Map of the trailer fields that is not backed by the request object.
     *
     * @return A Map of the received trailer fields with all keys lower case or an empty Map if no trailers are present
     *
     * @since Servlet 4.0
     */
    default Map<String,String> getTrailerFields() {
        return Collections.emptyMap();
    }

    /**
     * Are trailer fields ready to be read (there may still be no trailers to read). This method always returns
     * {@code true} if the underlying protocol does not support trailer fields. Otherwise, {@code true} is returned once
     * all of the following are true:
     * <ul>
     * <li>The application has ready all the request data and an EOF has been received or the content-length is
     * zero</li>
     * <li>All trailer fields, if any, have been received</li>
     * </ul>
     *
     * @return {@code true} if trailers are ready to be read
     *
     * @since Servlet 4.0
     */
    default boolean isTrailerFieldsReady() {
        return true;
    }
}
