Merge "Typo fix"

[mediawiki.git] / includes / api / ApiMain.php

<?php
/**
 *
 *
 * Created on Sep 4, 2006
 *
 * Copyright © 2006 Yuri Astrakhan "<Firstname><Lastname>@gmail.com"
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 * http://www.gnu.org/copyleft/gpl.html
 *
 * @file
 * @defgroup API API
 */

/**
 * This is the main API class, used for both external and internal processing.
 * When executed, it will create the requested formatter object,
 * instantiate and execute an object associated with the needed action,
 * and use formatter to print results.
 * In case of an exception, an error message will be printed using the same formatter.
 *
 * To use API from another application, run it using FauxRequest object, in which
 * case any internal exceptions will not be handled but passed up to the caller.
 * After successful execution, use getResult() for the resulting data.
 *
 * @ingroup API
 */
class ApiMain extends ApiBase {

        /**
         * When no format parameter is given, this format will be used
         */
        const API_DEFAULT_FORMAT = 'xmlfm';

        /**
         * List of available modules: action name => module class
         */
        private static $Modules = array(
                'login' => 'ApiLogin',
                'logout' => 'ApiLogout',
                'createaccount' => 'ApiCreateAccount',
                'query' => 'ApiQuery',
                'expandtemplates' => 'ApiExpandTemplates',
                'parse' => 'ApiParse',
                'opensearch' => 'ApiOpenSearch',
                'feedcontributions' => 'ApiFeedContributions',
                'feedwatchlist' => 'ApiFeedWatchlist',
                'help' => 'ApiHelp',
                'paraminfo' => 'ApiParamInfo',
                'rsd' => 'ApiRsd',
                'compare' => 'ApiComparePages',
                'tokens' => 'ApiTokens',

                // Write modules
                'purge' => 'ApiPurge',
                'setnotificationtimestamp' => 'ApiSetNotificationTimestamp',
                'rollback' => 'ApiRollback',
                'delete' => 'ApiDelete',
                'undelete' => 'ApiUndelete',
                'protect' => 'ApiProtect',
                'block' => 'ApiBlock',
                'unblock' => 'ApiUnblock',
                'move' => 'ApiMove',
                'edit' => 'ApiEditPage',
                'upload' => 'ApiUpload',
                'filerevert' => 'ApiFileRevert',
                'emailuser' => 'ApiEmailUser',
                'watch' => 'ApiWatch',
                'patrol' => 'ApiPatrol',
                'import' => 'ApiImport',
                'userrights' => 'ApiUserrights',
                'options' => 'ApiOptions',
                'imagerotate' => 'ApiImageRotate',
        );

        /**
         * List of available formats: format name => format class
         */
        private static $Formats = array(
                'json' => 'ApiFormatJson',
                'jsonfm' => 'ApiFormatJson',
                'php' => 'ApiFormatPhp',
                'phpfm' => 'ApiFormatPhp',
                'wddx' => 'ApiFormatWddx',
                'wddxfm' => 'ApiFormatWddx',
                'xml' => 'ApiFormatXml',
                'xmlfm' => 'ApiFormatXml',
                'yaml' => 'ApiFormatYaml',
                'yamlfm' => 'ApiFormatYaml',
                'rawfm' => 'ApiFormatJson',
                'txt' => 'ApiFormatTxt',
                'txtfm' => 'ApiFormatTxt',
                'dbg' => 'ApiFormatDbg',
                'dbgfm' => 'ApiFormatDbg',
                'dump' => 'ApiFormatDump',
                'dumpfm' => 'ApiFormatDump',
                'none' => 'ApiFormatNone',
        );

        /**
         * List of user roles that are specifically relevant to the API.
         * array( 'right' => array ( 'msg'    => 'Some message with a $1',
         *                           'params' => array ( $someVarToSubst ) ),
         *                          );
         */
        private static $mRights = array(
                'writeapi' => array(
                        'msg' => 'Use of the write API',
                        'params' => array()
                ),
                'apihighlimits' => array(
                        'msg' => 'Use higher limits in API queries (Slow queries: $1 results; Fast queries: $2 results). The limits for slow queries also apply to multivalue parameters.',
                        'params' => array( ApiBase::LIMIT_SML2, ApiBase::LIMIT_BIG2 )
                )
        );

        /**
         * @var ApiFormatBase
         */
        private $mPrinter;

        private $mModuleMgr, $mResult;
        private $mAction;
        private $mEnableWrite;
        private $mInternalMode, $mSquidMaxage, $mModule;

        private $mCacheMode = 'private';
        private $mCacheControl = array();
        private $mParamsUsed = array();

        /**
         * Constructs an instance of ApiMain that utilizes the module and format specified by $request.
         *
         * @param $context IContextSource|WebRequest - if this is an instance of FauxRequest, errors are thrown and no printing occurs
         * @param bool $enableWrite should be set to true if the api may modify data
         */
        public function __construct( $context = null, $enableWrite = false ) {
                if ( $context === null ) {
                        $context = RequestContext::getMain();
                } elseif ( $context instanceof WebRequest ) {
                        // BC for pre-1.19
                        $request = $context;
                        $context = RequestContext::getMain();
                }
                // We set a derivative context so we can change stuff later
                $this->setContext( new DerivativeContext( $context ) );

                if ( isset( $request ) ) {
                        $this->getContext()->setRequest( $request );
                }

                $this->mInternalMode = ( $this->getRequest() instanceof FauxRequest );

                // Special handling for the main module: $parent === $this
                parent::__construct( $this, $this->mInternalMode ? 'main_int' : 'main' );

                if ( !$this->mInternalMode ) {
                        // Impose module restrictions.
                        // If the current user cannot read,
                        // Remove all modules other than login
                        global $wgUser;

                        if ( $this->getVal( 'callback' ) !== null ) {
                                // JSON callback allows cross-site reads.
                                // For safety, strip user credentials.
                                wfDebug( "API: stripping user credentials for JSON callback\n" );
                                $wgUser = new User();
                                $this->getContext()->setUser( $wgUser );
                        }
                }

                global $wgAPIModules;
                $this->mModuleMgr = new ApiModuleManager( $this );
                $this->mModuleMgr->addModules( self::$Modules, 'action' );
                $this->mModuleMgr->addModules( $wgAPIModules, 'action' );
                $this->mModuleMgr->addModules( self::$Formats, 'format' );

                $this->mResult = new ApiResult( $this );
                $this->mEnableWrite = $enableWrite;

                $this->mSquidMaxage = - 1; // flag for executeActionWithErrorHandling()
                $this->mCommit = false;
        }

        /**
         * Return true if the API was started by other PHP code using FauxRequest
         * @return bool
         */
        public function isInternalMode() {
                return $this->mInternalMode;
        }

        /**
         * Get the ApiResult object associated with current request
         *
         * @return ApiResult
         */
        public function getResult() {
                return $this->mResult;
        }

        /**
         * Get the API module object. Only works after executeAction()
         *
         * @return ApiBase
         */
        public function getModule() {
                return $this->mModule;
        }

        /**
         * Get the result formatter object. Only works after setupExecuteAction()
         *
         * @return ApiFormatBase
         */
        public function getPrinter() {
                return $this->mPrinter;
        }

        /**
         * Set how long the response should be cached.
         *
         * @param $maxage
         */
        public function setCacheMaxAge( $maxage ) {
                $this->setCacheControl( array(
                        'max-age' => $maxage,
                        's-maxage' => $maxage
                ) );
        }

        /**
         * Set the type of caching headers which will be sent.
         *
         * @param string $mode One of:
         *    - 'public':     Cache this object in public caches, if the maxage or smaxage
         *         parameter is set, or if setCacheMaxAge() was called. If a maximum age is
         *         not provided by any of these means, the object will be private.
         *    - 'private':    Cache this object only in private client-side caches.
         *    - 'anon-public-user-private': Make this object cacheable for logged-out
         *         users, but private for logged-in users. IMPORTANT: If this is set, it must be
         *         set consistently for a given URL, it cannot be set differently depending on
         *         things like the contents of the database, or whether the user is logged in.
         *
         *  If the wiki does not allow anonymous users to read it, the mode set here
         *  will be ignored, and private caching headers will always be sent. In other words,
         *  the "public" mode is equivalent to saying that the data sent is as public as a page
         *  view.
         *
         *  For user-dependent data, the private mode should generally be used. The
         *  anon-public-user-private mode should only be used where there is a particularly
         *  good performance reason for caching the anonymous response, but where the
         *  response to logged-in users may differ, or may contain private data.
         *
         *  If this function is never called, then the default will be the private mode.
         */
        public function setCacheMode( $mode ) {
                if ( !in_array( $mode, array( 'private', 'public', 'anon-public-user-private' ) ) ) {
                        wfDebug( __METHOD__ . ": unrecognised cache mode \"$mode\"\n" );
                        // Ignore for forwards-compatibility
                        return;
                }

                if ( !User::isEveryoneAllowed( 'read' ) ) {
                        // Private wiki, only private headers
                        if ( $mode !== 'private' ) {
                                wfDebug( __METHOD__ . ": ignoring request for $mode cache mode, private wiki\n" );
                                return;
                        }
                }

                wfDebug( __METHOD__ . ": setting cache mode $mode\n" );
                $this->mCacheMode = $mode;
        }

        /**
         * @deprecated since 1.17 Private caching is now the default, so there is usually no
         * need to call this function. If there is a need, you can use
         * $this->setCacheMode('private')
         */
        public function setCachePrivate() {
                wfDeprecated( __METHOD__, '1.17' );
                $this->setCacheMode( 'private' );
        }

        /**
         * Set directives (key/value pairs) for the Cache-Control header.
         * Boolean values will be formatted as such, by including or omitting
         * without an equals sign.
         *
         * Cache control values set here will only be used if the cache mode is not
         * private, see setCacheMode().
         *
         * @param $directives array
         */
        public function setCacheControl( $directives ) {
                $this->mCacheControl = $directives + $this->mCacheControl;
        }

        /**
         * Make sure Vary: Cookie and friends are set. Use this when the output of a request
         * may be cached for anons but may not be cached for logged-in users.
         *
         * WARNING: This function must be called CONSISTENTLY for a given URL. This means that a
         * given URL must either always or never call this function; if it sometimes does and
         * sometimes doesn't, stuff will break.
         *
         * @deprecated since 1.17 Use setCacheMode( 'anon-public-user-private' )
         */
        public function setVaryCookie() {
                wfDeprecated( __METHOD__, '1.17' );
                $this->setCacheMode( 'anon-public-user-private' );
        }

        /**
         * Create an instance of an output formatter by its name
         *
         * @param $format string
         *
         * @return ApiFormatBase
         */
        public function createPrinterByName( $format ) {
                $printer = $this->mModuleMgr->getModule( $format, 'format' );
                if ( $printer === null ) {
                        $this->dieUsage( "Unrecognized format: {$format}", 'unknown_format' );
                }
                return $printer;
        }

        /**
         * Execute api request. Any errors will be handled if the API was called by the remote client.
         */
        public function execute() {
                $this->profileIn();
                if ( $this->mInternalMode ) {
                        $this->executeAction();
                } else {
                        $this->executeActionWithErrorHandling();
                }

                $this->profileOut();
        }

        /**
         * Execute an action, and in case of an error, erase whatever partial results
         * have been accumulated, and replace it with an error message and a help screen.
         */
        protected function executeActionWithErrorHandling() {
                // Verify the CORS header before executing the action
                if ( !$this->handleCORS() ) {
                        // handleCORS() has sent a 403, abort
                        return;
                }

                // Exit here if the request method was OPTIONS
                // (assume there will be a followup GET or POST)
                if ( $this->getRequest()->getMethod() === 'OPTIONS' ) {
                        return;
                }

                // In case an error occurs during data output,
                // clear the output buffer and print just the error information
                ob_start();

                $t = microtime( true );
                try {
                        $this->executeAction();
                } catch ( Exception $e ) {
                        // Allow extra cleanup and logging
                        wfRunHooks( 'ApiMain::onException', array( $this, $e ) );

                        // Log it
                        if ( $e instanceof MWException && !( $e instanceof UsageException ) ) {
                                global $wgLogExceptionBacktrace;
                                if ( $wgLogExceptionBacktrace ) {
                                        wfDebugLog( 'exception', $e->getLogMessage() . "\n" . $e->getTraceAsString() . "\n" );
                                } else {
                                        wfDebugLog( 'exception', $e->getLogMessage() );
                                }
                        }

                        // Handle any kind of exception by outputting properly formatted error message.
                        // If this fails, an unhandled exception should be thrown so that global error
                        // handler will process and log it.

                        $errCode = $this->substituteResultWithError( $e );

                        // Error results should not be cached
                        $this->setCacheMode( 'private' );

                        $response = $this->getRequest()->response();
                        $headerStr = 'MediaWiki-API-Error: ' . $errCode;
                        if ( $e->getCode() === 0 ) {
                                $response->header( $headerStr );
                        } else {
                                $response->header( $headerStr, true, $e->getCode() );
                        }

                        // Reset and print just the error message
                        ob_clean();

                        // If the error occurred during printing, do a printer->profileOut()
                        $this->mPrinter->safeProfileOut();
                        $this->printResult( true );
                }

                // Log the request whether or not there was an error
                $this->logRequest( microtime( true ) - $t );

                // Send cache headers after any code which might generate an error, to
                // avoid sending public cache headers for errors.
                $this->sendCacheHeaders();

                if ( $this->mPrinter->getIsHtml() && !$this->mPrinter->isDisabled() ) {
                        echo wfReportTime();
                }

                ob_end_flush();
        }

        /**
         * Check the &origin= query parameter against the Origin: HTTP header and respond appropriately.
         *
         * If no origin parameter is present, nothing happens.
         * If an origin parameter is present but doesn't match the Origin header, a 403 status code
         * is set and false is returned.
         * If the parameter and the header do match, the header is checked against $wgCrossSiteAJAXdomains
         * and $wgCrossSiteAJAXdomainExceptions, and if the origin qualifies, the appropriate CORS
         * headers are set.
         *
         * @return bool False if the caller should abort (403 case), true otherwise (all other cases)
         */
        protected function handleCORS() {
                global $wgCrossSiteAJAXdomains, $wgCrossSiteAJAXdomainExceptions;

                $originParam = $this->getParameter( 'origin' ); // defaults to null
                if ( $originParam === null ) {
                        // No origin parameter, nothing to do
                        return true;
                }

                $request = $this->getRequest();
                $response = $request->response();
                // Origin: header is a space-separated list of origins, check all of them
                $originHeader = $request->getHeader( 'Origin' );
                if ( $originHeader === false ) {
                        $origins = array();
                } else {
                        $origins = explode( ' ', $originHeader );
                }
                if ( !in_array( $originParam, $origins ) ) {
                        // origin parameter set but incorrect
                        // Send a 403 response
                        $message = HttpStatus::getMessage( 403 );
                        $response->header( "HTTP/1.1 403 $message", true, 403 );
                        $response->header( 'Cache-Control: no-cache' );
                        echo "'origin' parameter does not match Origin header\n";
                        return false;
                }
                if ( self::matchOrigin( $originParam, $wgCrossSiteAJAXdomains, $wgCrossSiteAJAXdomainExceptions ) ) {
                        $response->header( "Access-Control-Allow-Origin: $originParam" );
                        $response->header( 'Access-Control-Allow-Credentials: true' );
                        $this->getOutput()->addVaryHeader( 'Origin' );
                }
                return true;
        }

        /**
         * Attempt to match an Origin header against a set of rules and a set of exceptions
         * @param string $value Origin header
         * @param array $rules Set of wildcard rules
         * @param array $exceptions Set of wildcard rules
         * @return bool True if $value matches a rule in $rules and doesn't match any rules in $exceptions, false otherwise
         */
        protected static function matchOrigin( $value, $rules, $exceptions ) {
                foreach ( $rules as $rule ) {
                        if ( preg_match( self::wildcardToRegex( $rule ), $value ) ) {
                                // Rule matches, check exceptions
                                foreach ( $exceptions as $exc ) {
                                        if ( preg_match( self::wildcardToRegex( $exc ), $value ) ) {
                                                return false;
                                        }
                                }
                                return true;
                        }
                }
                return false;
        }

        /**
         * Helper function to convert wildcard string into a regex
         * '*' => '.*?'
         * '?' => '.'
         *
         * @param string $wildcard String with wildcards
         * @return string Regular expression
         */
        protected static function wildcardToRegex( $wildcard ) {
                $wildcard = preg_quote( $wildcard, '/' );
                $wildcard = str_replace(
                        array( '\*', '\?' ),
                        array( '.*?', '.' ),
                        $wildcard
                );
                return "/https?:\/\/$wildcard/";
        }

        protected function sendCacheHeaders() {
                global $wgUseXVO, $wgVaryOnXFP;
                $response = $this->getRequest()->response();
                $out = $this->getOutput();

                if ( $wgVaryOnXFP ) {
                        $out->addVaryHeader( 'X-Forwarded-Proto' );
                }

                if ( $this->mCacheMode == 'private' ) {
                        $response->header( 'Cache-Control: private' );
                        return;
                }

                if ( $this->mCacheMode == 'anon-public-user-private' ) {
                        $out->addVaryHeader( 'Cookie' );
                        $response->header( $out->getVaryHeader() );
                        if ( $wgUseXVO ) {
                                $response->header( $out->getXVO() );
                                if ( $out->haveCacheVaryCookies() ) {
                                        // Logged in, mark this request private
                                        $response->header( 'Cache-Control: private' );
                                        return;
                                }
                                // Logged out, send normal public headers below
                        } elseif ( session_id() != '' ) {
                                // Logged in or otherwise has session (e.g. anonymous users who have edited)
                                // Mark request private
                                $response->header( 'Cache-Control: private' );
                                return;
                        } // else no XVO and anonymous, send public headers below
                }

                // Send public headers
                $response->header( $out->getVaryHeader() );
                if ( $wgUseXVO ) {
                        $response->header( $out->getXVO() );
                }

                // If nobody called setCacheMaxAge(), use the (s)maxage parameters
                if ( !isset( $this->mCacheControl['s-maxage'] ) ) {
                        $this->mCacheControl['s-maxage'] = $this->getParameter( 'smaxage' );
                }
                if ( !isset( $this->mCacheControl['max-age'] ) ) {
                        $this->mCacheControl['max-age'] = $this->getParameter( 'maxage' );
                }

                if ( !$this->mCacheControl['s-maxage'] && !$this->mCacheControl['max-age'] ) {
                        // Public cache not requested
                        // Sending a Vary header in this case is harmless, and protects us
                        // against conditional calls of setCacheMaxAge().
                        $response->header( 'Cache-Control: private' );
                        return;
                }

                $this->mCacheControl['public'] = true;

                // Send an Expires header
                $maxAge = min( $this->mCacheControl['s-maxage'], $this->mCacheControl['max-age'] );
                $expiryUnixTime = ( $maxAge == 0 ? 1 : time() + $maxAge );
                $response->header( 'Expires: ' . wfTimestamp( TS_RFC2822, $expiryUnixTime ) );

                // Construct the Cache-Control header
                $ccHeader = '';
                $separator = '';
                foreach ( $this->mCacheControl as $name => $value ) {
                        if ( is_bool( $value ) ) {
                                if ( $value ) {
                                        $ccHeader .= $separator . $name;
                                        $separator = ', ';
                                }
                        } else {
                                $ccHeader .= $separator . "$name=$value";
                                $separator = ', ';
                        }
                }

                $response->header( "Cache-Control: $ccHeader" );
        }

        /**
         * Replace the result data with the information about an exception.
         * Returns the error code
         * @param $e Exception
         * @return string
         */
        protected function substituteResultWithError( $e ) {
                global $wgShowHostnames;

                $result = $this->getResult();
                // Printer may not be initialized if the extractRequestParams() fails for the main module
                if ( !isset( $this->mPrinter ) ) {
                        // The printer has not been created yet. Try to manually get formatter value.
                        $value = $this->getRequest()->getVal( 'format', self::API_DEFAULT_FORMAT );
                        if ( !$this->mModuleMgr->isDefined( $value, 'format' ) ) {
                                $value = self::API_DEFAULT_FORMAT;
                        }

                        $this->mPrinter = $this->createPrinterByName( $value );
                        if ( $this->mPrinter->getNeedsRawData() ) {
                                $result->setRawMode();
                        }
                }

                if ( $e instanceof UsageException ) {
                        // User entered incorrect parameters - print usage screen
                        $errMessage = $e->getMessageArray();

                        // Only print the help message when this is for the developer, not runtime
                        if ( $this->mPrinter->getWantsHelp() || $this->mAction == 'help' ) {
                                ApiResult::setContent( $errMessage, $this->makeHelpMsg() );
                        }
                } else {
                        global $wgShowSQLErrors, $wgShowExceptionDetails;
                        // Something is seriously wrong
                        if ( ( $e instanceof DBQueryError ) && !$wgShowSQLErrors ) {
                                $info = 'Database query error';
                        } else {
                                $info = "Exception Caught: {$e->getMessage()}";
                        }

                        $errMessage = array(
                                'code' => 'internal_api_error_' . get_class( $e ),
                                'info' => $info,
                        );
                        ApiResult::setContent( $errMessage, $wgShowExceptionDetails ? "\n\n{$e->getTraceAsString()}\n\n" : '' );
                }

                // Remember all the warnings to re-add them later
                $oldResult = $result->getData();
                $warnings = isset( $oldResult['warnings'] ) ? $oldResult['warnings'] : null;

                $result->reset();
                $result->disableSizeCheck();
                // Re-add the id
                $requestid = $this->getParameter( 'requestid' );
                if ( !is_null( $requestid ) ) {
                        $result->addValue( null, 'requestid', $requestid );
                }
                if ( $wgShowHostnames ) {
                        // servedby is especially useful when debugging errors
                        $result->addValue( null, 'servedby', wfHostName() );
                }
                if ( $warnings !== null ) {
                        $result->addValue( null, 'warnings', $warnings );
                }

                $result->addValue( null, 'error', $errMessage );

                return $errMessage['code'];
        }

        /**
         * Set up for the execution.
         * @return array
         */
        protected function setupExecuteAction() {
                global $wgShowHostnames;

                // First add the id to the top element
                $result = $this->getResult();
                $requestid = $this->getParameter( 'requestid' );
                if ( !is_null( $requestid ) ) {
                        $result->addValue( null, 'requestid', $requestid );
                }

                if ( $wgShowHostnames ) {
                        $servedby = $this->getParameter( 'servedby' );
                        if ( $servedby ) {
                                $result->addValue( null, 'servedby', wfHostName() );
                        }
                }

                $params = $this->extractRequestParams();

                $this->mAction = $params['action'];

                if ( !is_string( $this->mAction ) ) {
                        $this->dieUsage( 'The API requires a valid action parameter', 'unknown_action' );
                }

                return $params;
        }

        /**
         * Set up the module for response
         * @return ApiBase The module that will handle this action
         */
        protected function setupModule() {
                // Instantiate the module requested by the user
                $module = $this->mModuleMgr->getModule( $this->mAction, 'action' );
                if ( $module === null ) {
                        $this->dieUsage( 'The API requires a valid action parameter', 'unknown_action' );
                }
                $moduleParams = $module->extractRequestParams();

                // Die if token required, but not provided (unless there is a gettoken parameter)
                if ( isset( $moduleParams['gettoken'] ) ) {
                        $gettoken = $moduleParams['gettoken'];
                } else {
                        $gettoken = false;
                }

                $salt = $module->getTokenSalt();
                if ( $salt !== false && !$gettoken ) {
                        if ( !isset( $moduleParams['token'] ) ) {
                                $this->dieUsageMsg( array( 'missingparam', 'token' ) );
                        } else {
                                if ( !$this->getUser()->matchEditToken( $moduleParams['token'], $salt, $this->getContext()->getRequest() ) ) {
                                        $this->dieUsageMsg( 'sessionfailure' );
                                }
                        }
                }
                return $module;
        }

        /**
         * Check the max lag if necessary
         * @param $module ApiBase object: Api module being used
         * @param array $params an array containing the request parameters.
         * @return boolean True on success, false should exit immediately
         */
        protected function checkMaxLag( $module, $params ) {
                if ( $module->shouldCheckMaxlag() && isset( $params['maxlag'] ) ) {
                        // Check for maxlag
                        global $wgShowHostnames;
                        $maxLag = $params['maxlag'];
                        list( $host, $lag ) = wfGetLB()->getMaxLag();
                        if ( $lag > $maxLag ) {
                                $response = $this->getRequest()->response();

                                $response->header( 'Retry-After: ' . max( intval( $maxLag ), 5 ) );
                                $response->header( 'X-Database-Lag: ' . intval( $lag ) );

                                if ( $wgShowHostnames ) {
                                        $this->dieUsage( "Waiting for $host: $lag seconds lagged", 'maxlag' );
                                } else {
                                        $this->dieUsage( "Waiting for a database server: $lag seconds lagged", 'maxlag' );
                                }
                                return false;
                        }
                }
                return true;
        }

        /**
         * Check for sufficient permissions to execute
         * @param $module ApiBase An Api module
         */
        protected function checkExecutePermissions( $module ) {
                $user = $this->getUser();
                if ( $module->isReadMode() && !User::isEveryoneAllowed( 'read' ) &&
                        !$user->isAllowed( 'read' ) )
                {
                        $this->dieUsageMsg( 'readrequired' );
                }
                if ( $module->isWriteMode() ) {
                        if ( !$this->mEnableWrite ) {
                                $this->dieUsageMsg( 'writedisabled' );
                        }
                        if ( !$user->isAllowed( 'writeapi' ) ) {
                                $this->dieUsageMsg( 'writerequired' );
                        }
                        if ( wfReadOnly() ) {
                                $this->dieReadOnly();
                        }
                }

                // Allow extensions to stop execution for arbitrary reasons.
                $message = false;
                if ( !wfRunHooks( 'ApiCheckCanExecute', array( $module, $user, &$message ) ) ) {
                        $this->dieUsageMsg( $message );
                }
        }

        /**
         * Check POST for external response and setup result printer
         * @param $module ApiBase An Api module
         * @param array $params an array with the request parameters
         */
        protected function setupExternalResponse( $module, $params ) {
                if ( !$this->getRequest()->wasPosted() && $module->mustBePosted() ) {
                        // Module requires POST. GET request might still be allowed
                        // if $wgDebugApi is true, otherwise fail.
                        $this->dieUsageMsgOrDebug( array( 'mustbeposted', $this->mAction ) );
                }

                // See if custom printer is used
                $this->mPrinter = $module->getCustomPrinter();
                if ( is_null( $this->mPrinter ) ) {
                        // Create an appropriate printer
                        $this->mPrinter = $this->createPrinterByName( $params['format'] );
                }

                if ( $this->mPrinter->getNeedsRawData() ) {
                        $this->getResult()->setRawMode();
                }
        }

        /**
         * Execute the actual module, without any error handling
         */
        protected function executeAction() {
                $params = $this->setupExecuteAction();
                $module = $this->setupModule();
                $this->mModule = $module;

                $this->checkExecutePermissions( $module );

                if ( !$this->checkMaxLag( $module, $params ) ) {
                        return;
                }

                if ( !$this->mInternalMode ) {
                        $this->setupExternalResponse( $module, $params );
                }

                // Execute
                $module->profileIn();
                $module->execute();
                wfRunHooks( 'APIAfterExecute', array( &$module ) );
                $module->profileOut();

                $this->reportUnusedParams();

                if ( !$this->mInternalMode ) {
                        //append Debug information
                        MWDebug::appendDebugInfoToApiResult( $this->getContext(), $this->getResult() );

                        // Print result data
                        $this->printResult( false );
                }
        }

        /**
         * Log the preceding request
         * @param $time Time in seconds
         */
        protected function logRequest( $time ) {
                $request = $this->getRequest();
                $milliseconds = $time === null ? '?' : round( $time * 1000 );
                $s = 'API' .
                        ' ' . $request->getMethod() .
                        ' ' . wfUrlencode( str_replace( ' ', '_', $this->getUser()->getName() ) ) .
                        ' ' . $request->getIP() .
                        ' T=' . $milliseconds . 'ms';
                foreach ( $this->getParamsUsed() as $name ) {
                        $value = $request->getVal( $name );
                        if ( $value === null ) {
                                continue;
                        }
                        $s .= ' ' . $name . '=';
                        if ( strlen( $value ) > 256 ) {
                                $encValue = $this->encodeRequestLogValue( substr( $value, 0, 256 ) );
                                $s .= $encValue . '[...]';
                        } else {
                                $s .= $this->encodeRequestLogValue( $value );
                        }
                }
                $s .= "\n";
                wfDebugLog( 'api', $s, false );
        }

        /**
         * Encode a value in a format suitable for a space-separated log line.
         */
        protected function encodeRequestLogValue( $s ) {
                static $table;
                if ( !$table ) {
                        $chars = ';@$!*(),/:';
                        for ( $i = 0; $i < strlen( $chars ); $i++ ) {
                                $table[rawurlencode( $chars[$i] )] = $chars[$i];
                        }
                }
                return strtr( rawurlencode( $s ), $table );
        }

        /**
         * Get the request parameters used in the course of the preceding execute() request
         */
        protected function getParamsUsed() {
                return array_keys( $this->mParamsUsed );
        }

        /**
         * Get a request value, and register the fact that it was used, for logging.
         */
        public function getVal( $name, $default = null ) {
                $this->mParamsUsed[$name] = true;
                return $this->getRequest()->getVal( $name, $default );
        }

        /**
         * Get a boolean request value, and register the fact that the parameter
         * was used, for logging.
         */
        public function getCheck( $name ) {
                $this->mParamsUsed[$name] = true;
                return $this->getRequest()->getCheck( $name );
        }

        /**
         * Get a request upload, and register the fact that it was used, for logging.
         *
         * @since 1.21
         * @param string $name Parameter name
         * @return WebRequestUpload
         */
        public function getUpload( $name ) {
                $this->mParamsUsed[$name] = true;
                return $this->getRequest()->getUpload( $name );
        }

        /**
         * Report unused parameters, so the client gets a hint in case it gave us parameters we don't know,
         * for example in case of spelling mistakes or a missing 'g' prefix for generators.
         */
        protected function reportUnusedParams() {
                $paramsUsed = $this->getParamsUsed();
                $allParams = $this->getRequest()->getValueNames();

                if ( !$this->mInternalMode ) {
                        // Printer has not yet executed; don't warn that its parameters are unused
                        $printerParams = array_map(
                                array( $this->mPrinter, 'encodeParamName' ),
                                array_keys( $this->mPrinter->getFinalParams() ?: array() )
                        );
                        $unusedParams = array_diff( $allParams, $paramsUsed, $printerParams );
                } else {
                        $unusedParams = array_diff( $allParams, $paramsUsed );
                }

                if ( count( $unusedParams ) ) {
                        $s = count( $unusedParams ) > 1 ? 's' : '';
                        $this->setWarning( "Unrecognized parameter$s: '" . implode( $unusedParams, "', '" ) . "'" );
                }
        }

        /**
         * Print results using the current printer
         *
         * @param $isError bool
         */
        protected function printResult( $isError ) {
                global $wgDebugAPI;
                if ( $wgDebugAPI !== false ) {
                        $this->setWarning( 'SECURITY WARNING: $wgDebugAPI is enabled' );
                }

                $this->getResult()->cleanUpUTF8();
                $printer = $this->mPrinter;
                $printer->profileIn();

                /**
                 * If the help message is requested in the default (xmlfm) format,
                 * tell the printer not to escape ampersands so that our links do
                 * not break.
                 */
                $isHelp = $isError || $this->mAction == 'help';
                $printer->setUnescapeAmps( $isHelp && $printer->getFormat() == 'XML' && $printer->getIsHtml() );

                $printer->initPrinter( $isHelp );

                $printer->execute();
                $printer->closePrinter();
                $printer->profileOut();
        }

        /**
         * @return bool
         */
        public function isReadMode() {
                return false;
        }

        /**
         * See ApiBase for description.
         *
         * @return array
         */
        public function getAllowedParams() {
                return array(
                        'format' => array(
                                ApiBase::PARAM_DFLT => ApiMain::API_DEFAULT_FORMAT,
                                ApiBase::PARAM_TYPE => $this->mModuleMgr->getNames( 'format' )
                        ),
                        'action' => array(
                                ApiBase::PARAM_DFLT => 'help',
                                ApiBase::PARAM_TYPE => $this->mModuleMgr->getNames( 'action' )
                        ),
                        'maxlag' => array(
                                ApiBase::PARAM_TYPE => 'integer'
                        ),
                        'smaxage' => array(
                                ApiBase::PARAM_TYPE => 'integer',
                                ApiBase::PARAM_DFLT => 0
                        ),
                        'maxage' => array(
                                ApiBase::PARAM_TYPE => 'integer',
                                ApiBase::PARAM_DFLT => 0
                        ),
                        'requestid' => null,
                        'servedby' => false,
                        'origin' => null,
                );
        }

        /**
         * See ApiBase for description.
         *
         * @return array
         */
        public function getParamDescription() {
                return array(
                        'format' => 'The format of the output',
                        'action' => 'What action you would like to perform. See below for module help',
                        'maxlag' => array(
                                'Maximum lag can be used when MediaWiki is installed on a database replicated cluster.',
                                'To save actions causing any more site replication lag, this parameter can make the client',
                                'wait until the replication lag is less than the specified value.',
                                'In case of a replag error, error code "maxlag" is returned, with the message like',
                                '"Waiting for $host: $lag seconds lagged\n".',
                                'See https://www.mediawiki.org/wiki/Manual:Maxlag_parameter for more information',
                        ),
                        'smaxage' => 'Set the s-maxage header to this many seconds. Errors are never cached',
                        'maxage' => 'Set the max-age header to this many seconds. Errors are never cached',
                        'requestid' => 'Request ID to distinguish requests. This will just be output back to you',
                        'servedby' => 'Include the hostname that served the request in the results. Unconditionally shown on error',
                        'origin' => array(
                                'When accessing the API using a cross-domain AJAX request (CORS), set this to the originating domain.',
                                'This must be included in any pre-flight request, and therefore must be part of the request URI (not the POST body).',
                                'This must match one of the origins in the Origin: header exactly, so it has to be set to something like http://en.wikipedia.org or https://meta.wikimedia.org .',
                                'If this parameter does not match the Origin: header, a 403 response will be returned.',
                                'If this parameter matches the Origin: header and the origin is whitelisted, an Access-Control-Allow-Origin header will be set.',
                        ),
                );
        }

        /**
         * See ApiBase for description.
         *
         * @return array
         */
        public function getDescription() {
                return array(
                        '',
                        '',
                        '**********************************************************************************************************',
                        '**                                                                                                      **',
                        '**                      This is an auto-generated MediaWiki API documentation page                      **',
                        '**                                                                                                      **',
                        '**                                     Documentation and Examples:                                      **',
                        '**                                  https://www.mediawiki.org/wiki/API                                  **',
                        '**                                                                                                      **',
                        '**********************************************************************************************************',
                        '',
                        'Status:                All features shown on this page should be working, but the API',
                        '                       is still in active development, and may change at any time.',
                        '                       Make sure to monitor our mailing list for any updates',
                        '',
                        'Erroneous requests:    When erroneous requests are sent to the API, a HTTP header will be sent',
                        '                       with the key "MediaWiki-API-Error" and then both the value of the',
                        '                       header and the error code sent back will be set to the same value',
                        '',
                        '                       In the case of an invalid action being passed, these will have a value',
                        '                       of "unknown_action"',
                        '',
                        '                       For more information see https://www.mediawiki.org/wiki/API:Errors_and_warnings',
                        '',
                        'Documentation:         https://www.mediawiki.org/wiki/API:Main_page',
                        'FAQ                    https://www.mediawiki.org/wiki/API:FAQ',
                        'Mailing list:          https://lists.wikimedia.org/mailman/listinfo/mediawiki-api',
                        'Api Announcements:     https://lists.wikimedia.org/mailman/listinfo/mediawiki-api-announce',
                        'Bugs & Requests:       https://bugzilla.wikimedia.org/buglist.cgi?component=API&bug_status=NEW&bug_status=ASSIGNED&bug_status=REOPENED&order=bugs.delta_ts',
                        '',
                        '',
                        '',
                        '',
                        '',
                );
        }

        /**
         * @return array
         */
        public function getPossibleErrors() {
                return array_merge( parent::getPossibleErrors(), array(
                        array( 'readonlytext' ),
                        array( 'code' => 'unknown_format', 'info' => 'Unrecognized format: format' ),
                        array( 'code' => 'unknown_action', 'info' => 'The API requires a valid action parameter' ),
                        array( 'code' => 'maxlag', 'info' => 'Waiting for host: x seconds lagged' ),
                        array( 'code' => 'maxlag', 'info' => 'Waiting for a database server: x seconds lagged' ),
                ) );
        }

        /**
         * Returns an array of strings with credits for the API
         * @return array
         */
        protected function getCredits() {
                return array(
                        'API developers:',
                        '    Roan Kattouw "<Firstname>.<Lastname>@gmail.com" (lead developer Sep 2007-2009)',
                        '    Victor Vasiliev - vasilvv @ gmail . com',
                        '    Bryan Tong Minh - bryan . tongminh @ gmail . com',
                        '    Sam Reed - sam @ reedyboy . net',
                        '    Yuri Astrakhan "<Firstname><Lastname>@gmail.com" (creator, lead developer Sep 2006-Sep 2007, 2012-present)',
                        '',
                        'Please send your comments, suggestions and questions to mediawiki-api@lists.wikimedia.org',
                        'or file a bug report at https://bugzilla.wikimedia.org/'
                );
        }

        /**
         * Sets whether the pretty-printer should format *bold* and $italics$
         *
         * @param $help bool
         */
        public function setHelp( $help = true ) {
                $this->mPrinter->setHelp( $help );
        }

        /**
         * Override the parent to generate help messages for all available modules.
         *
         * @return string
         */
        public function makeHelpMsg() {
                global $wgMemc, $wgAPICacheHelpTimeout;
                $this->setHelp();
                // Get help text from cache if present
                $key = wfMemcKey( 'apihelp', $this->getModuleName(),
                        SpecialVersion::getVersion( 'nodb' ) );
                if ( $wgAPICacheHelpTimeout > 0 ) {
                        $cached = $wgMemc->get( $key );
                        if ( $cached ) {
                                return $cached;
                        }
                }
                $retval = $this->reallyMakeHelpMsg();
                if ( $wgAPICacheHelpTimeout > 0 ) {
                        $wgMemc->set( $key, $retval, $wgAPICacheHelpTimeout );
                }
                return $retval;
        }

        /**
         * @return mixed|string
         */
        public function reallyMakeHelpMsg() {
                $this->setHelp();

                // Use parent to make default message for the main module
                $msg = parent::makeHelpMsg();

                $astriks = str_repeat( '*** ', 14 );
                $msg .= "\n\n$astriks Modules  $astriks\n\n";

                foreach ( $this->mModuleMgr->getNames( 'action' ) as $name ) {
                        $module = $this->mModuleMgr->getModule( $name );
                        $msg .= self::makeHelpMsgHeader( $module, 'action' );

                        $msg2 = $module->makeHelpMsg();
                        if ( $msg2 !== false ) {
                                $msg .= $msg2;
                        }
                        $msg .= "\n";
                }

                $msg .= "\n$astriks Permissions $astriks\n\n";
                foreach ( self::$mRights as $right => $rightMsg ) {
                        $groups = User::getGroupsWithPermission( $right );
                        $msg .= "* " . $right . " *\n  " . wfMsgReplaceArgs( $rightMsg['msg'], $rightMsg['params'] ) .
                                                "\nGranted to:\n  " . str_replace( '*', 'all', implode( ', ', $groups ) ) . "\n\n";
                }

                $msg .= "\n$astriks Formats  $astriks\n\n";
                foreach ( $this->mModuleMgr->getNames( 'format' ) as $name ) {
                        $module = $this->mModuleMgr->getModule( $name );
                        $msg .= self::makeHelpMsgHeader( $module, 'format' );
                        $msg2 = $module->makeHelpMsg();
                        if ( $msg2 !== false ) {
                                $msg .= $msg2;
                        }
                        $msg .= "\n";
                }

                $msg .= "\n*** Credits: ***\n   " . implode( "\n   ", $this->getCredits() ) . "\n";

                return $msg;
        }

        /**
         * @param $module ApiBase
         * @param string $paramName What type of request is this? e.g. action, query, list, prop, meta, format
         * @return string
         */
        public static function makeHelpMsgHeader( $module, $paramName ) {
                $modulePrefix = $module->getModulePrefix();
                if ( strval( $modulePrefix ) !== '' ) {
                        $modulePrefix = "($modulePrefix) ";
                }

                return "* $paramName={$module->getModuleName()} $modulePrefix*";
        }

        private $mCanApiHighLimits = null;

        /**
         * Check whether the current user is allowed to use high limits
         * @return bool
         */
        public function canApiHighLimits() {
                if ( !isset( $this->mCanApiHighLimits ) ) {
                        $this->mCanApiHighLimits = $this->getUser()->isAllowed( 'apihighlimits' );
                }

                return $this->mCanApiHighLimits;
        }

        /**
         * Check whether the user wants us to show version information in the API help
         * @return bool
         * @deprecated since 1.21, always returns false
         */
        public function getShowVersions() {
                wfDeprecated( __METHOD__, '1.21' );
                return false;
        }

        /**
         * Overrides to return this instance's module manager.
         * @return ApiModuleManager
         */
        public function getModuleManager() {
                return $this->mModuleMgr;
        }

        /**
         * Add or overwrite a module in this ApiMain instance. Intended for use by extending
         * classes who wish to add their own modules to their lexicon or override the
         * behavior of inherent ones.
         *
         * @deprecated since 1.21, Use getModuleManager()->addModule() instead.
         * @param string $name The identifier for this module.
         * @param $class ApiBase The class where this module is implemented.
         */
        protected function addModule( $name, $class ) {
                $this->getModuleManager()->addModule( $name, 'action', $class );
        }

        /**
         * Add or overwrite an output format for this ApiMain. Intended for use by extending
         * classes who wish to add to or modify current formatters.
         *
         * @deprecated since 1.21, Use getModuleManager()->addModule() instead.
         * @param string $name The identifier for this format.
         * @param $class ApiFormatBase The class implementing this format.
         */
        protected function addFormat( $name, $class ) {
                $this->getModuleManager()->addModule( $name, 'format', $class );
        }

        /**
         * Get the array mapping module names to class names
         * @deprecated since 1.21, Use getModuleManager()'s methods instead.
         * @return array
         */
        function getModules() {
                return $this->getModuleManager()->getNamesWithClasses( 'action' );
        }

        /**
         * Returns the list of supported formats in form ( 'format' => 'ClassName' )
         *
         * @since 1.18
         * @deprecated since 1.21, Use getModuleManager()'s methods instead.
         * @return array
         */
        public function getFormats() {
                return $this->getModuleManager()->getNamesWithClasses( 'format' );
        }
}

/**
 * This exception will be thrown when dieUsage is called to stop module execution.
 * The exception handling code will print a help screen explaining how this API may be used.
 *
 * @ingroup API
 */
class UsageException extends MWException {

        private $mCodestr;

        /**
         * @var null|array
         */
        private $mExtraData;

        /**
         * @param $message string
         * @param $codestr string
         * @param $code int
         * @param $extradata array|null
         */
        public function __construct( $message, $codestr, $code = 0, $extradata = null ) {
                parent::__construct( $message, $code );
                $this->mCodestr = $codestr;
                $this->mExtraData = $extradata;
        }

        /**
         * @return string
         */
        public function getCodeString() {
                return $this->mCodestr;
        }

        /**
         * @return array
         */
        public function getMessageArray() {
                $result = array(
                        'code' => $this->mCodestr,
                        'info' => $this->getMessage()
                );
                if ( is_array( $this->mExtraData ) ) {
                        $result = array_merge( $result, $this->mExtraData );
                }
                return $result;
        }

        /**
         * @return string
         */
        public function __toString() {
                return "{$this->getCodeString()}: {$this->getMessage()}";
        }
}