Merge "Add function to clear mPreparedEdit, to use in cases of mutable content"

[lhc/web/wiklou.git] / includes / api / ApiBase.php

<?php
/**
 *
 *
 * Created on Sep 5, 2006
 *
 * Copyright © 2006, 2010 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
 */

/**
 * This abstract class implements many basic API functions, and is the base of
 * all API classes.
 * The class functions are divided into several areas of functionality:
 *
 * Module parameters: Derived classes can define getAllowedParams() to specify
 *    which parameters to expect, how to parse and validate them.
 *
 * Profiling: various methods to allow keeping tabs on various tasks and their
 *    time costs
 *
 * Self-documentation: code to allow the API to document its own state
 *
 * @ingroup API
 */
abstract class ApiBase extends ContextSource {

        // These constants allow modules to specify exactly how to treat incoming parameters.

        const PARAM_DFLT = 0; // Default value of the parameter
        const PARAM_ISMULTI = 1; // Boolean, do we accept more than one item for this parameter (e.g.: titles)?
        const PARAM_TYPE = 2; // Can be either a string type (e.g.: 'integer') or an array of allowed values
        const PARAM_MAX = 3; // Max value allowed for a parameter. Only applies if TYPE='integer'
        const PARAM_MAX2 = 4; // Max value allowed for a parameter for bots and sysops. Only applies if TYPE='integer'
        const PARAM_MIN = 5; // Lowest value allowed for a parameter. Only applies if TYPE='integer'
        const PARAM_ALLOW_DUPLICATES = 6; // Boolean, do we allow the same value to be set more than once when ISMULTI=true
        const PARAM_DEPRECATED = 7; // Boolean, is the parameter deprecated (will show a warning)
        /// @since 1.17
        const PARAM_REQUIRED = 8; // Boolean, is the parameter required?
        /// @since 1.17
        const PARAM_RANGE_ENFORCE = 9; // Boolean, if MIN/MAX are set, enforce (die) these? Only applies if TYPE='integer' Use with extreme caution

        const PROP_ROOT = 'ROOT'; // Name of property group that is on the root element of the result, i.e. not part of a list
        const PROP_LIST = 'LIST'; // Boolean, is the result multiple items? Defaults to true for query modules, to false for other modules
        const PROP_TYPE = 0; // Type of the property, uses same format as PARAM_TYPE
        const PROP_NULLABLE = 1; // Boolean, can the property be not included in the result? Defaults to false

        const LIMIT_BIG1 = 500; // Fast query, std user limit
        const LIMIT_BIG2 = 5000; // Fast query, bot/sysop limit
        const LIMIT_SML1 = 50; // Slow query, std user limit
        const LIMIT_SML2 = 500; // Slow query, bot/sysop limit

        /**
         * getAllowedParams() flag: When set, the result could take longer to generate,
         * but should be more thorough. E.g. get the list of generators for ApiSandBox extension
         * @since 1.21
         */
        const GET_VALUES_FOR_HELP = 1;

        private $mMainModule, $mModuleName, $mModulePrefix;
        private $mSlaveDB = null;
        private $mParamCache = array();

        /**
         * Constructor
         * @param $mainModule ApiMain object
         * @param string $moduleName Name of this module
         * @param string $modulePrefix Prefix to use for parameter names
         */
        public function __construct( $mainModule, $moduleName, $modulePrefix = '' ) {
                $this->mMainModule = $mainModule;
                $this->mModuleName = $moduleName;
                $this->mModulePrefix = $modulePrefix;

                if ( !$this->isMain() ) {
                        $this->setContext( $mainModule->getContext() );
                }
        }

        /*****************************************************************************
         * ABSTRACT METHODS                                                          *
         *****************************************************************************/

        /**
         * Evaluates the parameters, performs the requested query, and sets up
         * the result. Concrete implementations of ApiBase must override this
         * method to provide whatever functionality their module offers.
         * Implementations must not produce any output on their own and are not
         * expected to handle any errors.
         *
         * The execute() method will be invoked directly by ApiMain immediately
         * before the result of the module is output. Aside from the
         * constructor, implementations should assume that no other methods
         * will be called externally on the module before the result is
         * processed.
         *
         * The result data should be stored in the ApiResult object available
         * through getResult().
         */
        abstract public function execute();

        /**
         * Returns a string that identifies the version of the extending class.
         * Typically includes the class name, the svn revision, timestamp, and
         * last author. Usually done with SVN's Id keyword
         * @return string
         * @deprecated since 1.21, version string is no longer supported
         */
        public function getVersion() {
                wfDeprecated( __METHOD__, '1.21' );

                return '';
        }

        /**
         * Get the name of the module being executed by this instance
         * @return string
         */
        public function getModuleName() {
                return $this->mModuleName;
        }

        /**
         * Get the module manager, or null if this module has no sub-modules
         * @since 1.21
         * @return ApiModuleManager
         */
        public function getModuleManager() {
                return null;
        }

        /**
         * Get parameter prefix (usually two letters or an empty string).
         * @return string
         */
        public function getModulePrefix() {
                return $this->mModulePrefix;
        }

        /**
         * Get the name of the module as shown in the profiler log
         *
         * @param $db DatabaseBase|bool
         *
         * @return string
         */
        public function getModuleProfileName( $db = false ) {
                if ( $db ) {
                        return 'API:' . $this->mModuleName . '-DB';
                } else {
                        return 'API:' . $this->mModuleName;
                }
        }

        /**
         * Get the main module
         * @return ApiMain object
         */
        public function getMain() {
                return $this->mMainModule;
        }

        /**
         * Returns true if this module is the main module ($this === $this->mMainModule),
         * false otherwise.
         * @return bool
         */
        public function isMain() {
                return $this === $this->mMainModule;
        }

        /**
         * Get the result object
         * @return ApiResult
         */
        public function getResult() {
                // Main module has getResult() method overridden
                // Safety - avoid infinite loop:
                if ( $this->isMain() ) {
                        ApiBase::dieDebug( __METHOD__, 'base method was called on main module. ' );
                }

                return $this->getMain()->getResult();
        }

        /**
         * Get the result data array (read-only)
         * @return array
         */
        public function getResultData() {
                return $this->getResult()->getData();
        }

        /**
         * Create a new RequestContext object to use e.g. for calls to other parts
         * the software.
         * The object will have the WebRequest and the User object set to the ones
         * used in this instance.
         *
         * @deprecated since 1.19 use getContext to get the current context
         * @return DerivativeContext
         */
        public function createContext() {
                wfDeprecated( __METHOD__, '1.19' );

                return new DerivativeContext( $this->getContext() );
        }

        /**
         * Set warning section for this module. Users should monitor this
         * section to notice any changes in API. Multiple calls to this
         * function will result in the warning messages being separated by
         * newlines
         * @param string $warning Warning message
         */
        public function setWarning( $warning ) {
                $result = $this->getResult();
                $data = $result->getData();
                $moduleName = $this->getModuleName();
                if ( isset( $data['warnings'][$moduleName] ) ) {
                        // Don't add duplicate warnings
                        $oldWarning = $data['warnings'][$moduleName]['*'];
                        $warnPos = strpos( $oldWarning, $warning );
                        // If $warning was found in $oldWarning, check if it starts at 0 or after "\n"
                        if ( $warnPos !== false && ( $warnPos === 0 || $oldWarning[$warnPos - 1] === "\n" ) ) {
                                // Check if $warning is followed by "\n" or the end of the $oldWarning
                                $warnPos += strlen( $warning );
                                if ( strlen( $oldWarning ) <= $warnPos || $oldWarning[$warnPos] === "\n" ) {
                                        return;
                                }
                        }
                        // If there is a warning already, append it to the existing one
                        $warning = "$oldWarning\n$warning";
                }
                $msg = array();
                ApiResult::setContent( $msg, $warning );
                $result->disableSizeCheck();
                $result->addValue( 'warnings', $moduleName,
                        $msg, ApiResult::OVERRIDE | ApiResult::ADD_ON_TOP );
                $result->enableSizeCheck();
        }

        /**
         * If the module may only be used with a certain format module,
         * it should override this method to return an instance of that formatter.
         * A value of null means the default format will be used.
         * @return mixed instance of a derived class of ApiFormatBase, or null
         */
        public function getCustomPrinter() {
                return null;
        }

        /**
         * Generates help message for this module, or false if there is no description
         * @return mixed string or false
         */
        public function makeHelpMsg() {
                static $lnPrfx = "\n  ";

                $msg = $this->getFinalDescription();

                if ( $msg !== false ) {

                        if ( !is_array( $msg ) ) {
                                $msg = array(
                                        $msg
                                );
                        }
                        $msg = $lnPrfx . implode( $lnPrfx, $msg ) . "\n";

                        $msg .= $this->makeHelpArrayToString( $lnPrfx, false, $this->getHelpUrls() );

                        if ( $this->isReadMode() ) {
                                $msg .= "\nThis module requires read rights";
                        }
                        if ( $this->isWriteMode() ) {
                                $msg .= "\nThis module requires write rights";
                        }
                        if ( $this->mustBePosted() ) {
                                $msg .= "\nThis module only accepts POST requests";
                        }
                        if ( $this->isReadMode() || $this->isWriteMode() ||
                                $this->mustBePosted()
                        ) {
                                $msg .= "\n";
                        }

                        // Parameters
                        $paramsMsg = $this->makeHelpMsgParameters();
                        if ( $paramsMsg !== false ) {
                                $msg .= "Parameters:\n$paramsMsg";
                        }

                        $examples = $this->getExamples();
                        if ( $examples ) {
                                if ( !is_array( $examples ) ) {
                                        $examples = array(
                                                $examples
                                        );
                                }
                                $msg .= "Example" . ( count( $examples ) > 1 ? 's' : '' ) . ":\n";
                                foreach ( $examples as $k => $v ) {
                                        if ( is_numeric( $k ) ) {
                                                $msg .= "  $v\n";
                                        } else {
                                                if ( is_array( $v ) ) {
                                                        $msgExample = implode( "\n", array_map( array( $this, 'indentExampleText' ), $v ) );
                                                } else {
                                                        $msgExample = "  $v";
                                                }
                                                $msgExample .= ":";
                                                $msg .= wordwrap( $msgExample, 100, "\n" ) . "\n    $k\n";
                                        }
                                }
                        }
                }

                return $msg;
        }

        /**
         * @param $item string
         * @return string
         */
        private function indentExampleText( $item ) {
                return "  " . $item;
        }

        /**
         * @param string $prefix Text to split output items
         * @param string $title What is being output
         * @param $input string|array
         * @return string
         */
        protected function makeHelpArrayToString( $prefix, $title, $input ) {
                if ( $input === false ) {
                        return '';
                }
                if ( !is_array( $input ) ) {
                        $input = array( $input );
                }

                if ( count( $input ) > 0 ) {
                        if ( $title ) {
                                $msg = $title . ( count( $input ) > 1 ? 's' : '' ) . ":\n  ";
                        } else {
                                $msg = '  ';
                        }
                        $msg .= implode( $prefix, $input ) . "\n";

                        return $msg;
                }

                return '';
        }

        /**
         * Generates the parameter descriptions for this module, to be displayed in the
         * module's help.
         * @return string or false
         */
        public function makeHelpMsgParameters() {
                $params = $this->getFinalParams( ApiBase::GET_VALUES_FOR_HELP );
                if ( $params ) {

                        $paramsDescription = $this->getFinalParamDescription();
                        $msg = '';
                        $paramPrefix = "\n" . str_repeat( ' ', 24 );
                        $descWordwrap = "\n" . str_repeat( ' ', 28 );
                        foreach ( $params as $paramName => $paramSettings ) {
                                $desc = isset( $paramsDescription[$paramName] ) ? $paramsDescription[$paramName] : '';
                                if ( is_array( $desc ) ) {
                                        $desc = implode( $paramPrefix, $desc );
                                }

                                //handle shorthand
                                if ( !is_array( $paramSettings ) ) {
                                        $paramSettings = array(
                                                self::PARAM_DFLT => $paramSettings,
                                        );
                                }

                                //handle missing type
                                if ( !isset( $paramSettings[ApiBase::PARAM_TYPE] ) ) {
                                        $dflt = isset( $paramSettings[ApiBase::PARAM_DFLT] ) ? $paramSettings[ApiBase::PARAM_DFLT] : null;
                                        if ( is_bool( $dflt ) ) {
                                                $paramSettings[ApiBase::PARAM_TYPE] = 'boolean';
                                        } elseif ( is_string( $dflt ) || is_null( $dflt ) ) {
                                                $paramSettings[ApiBase::PARAM_TYPE] = 'string';
                                        } elseif ( is_int( $dflt ) ) {
                                                $paramSettings[ApiBase::PARAM_TYPE] = 'integer';
                                        }
                                }

                                if ( isset( $paramSettings[self::PARAM_DEPRECATED] ) && $paramSettings[self::PARAM_DEPRECATED] ) {
                                        $desc = "DEPRECATED! $desc";
                                }

                                if ( isset( $paramSettings[self::PARAM_REQUIRED] ) && $paramSettings[self::PARAM_REQUIRED] ) {
                                        $desc .= $paramPrefix . "This parameter is required";
                                }

                                $type = isset( $paramSettings[self::PARAM_TYPE] ) ? $paramSettings[self::PARAM_TYPE] : null;
                                if ( isset( $type ) ) {
                                        $hintPipeSeparated = true;
                                        $multi = isset( $paramSettings[self::PARAM_ISMULTI] ) ? $paramSettings[self::PARAM_ISMULTI] : false;
                                        if ( $multi ) {
                                                $prompt = 'Values (separate with \'|\'): ';
                                        } else {
                                                $prompt = 'One value: ';
                                        }

                                        if ( is_array( $type ) ) {
                                                $choices = array();
                                                $nothingPrompt = '';
                                                foreach ( $type as $t ) {
                                                        if ( $t === '' ) {
                                                                $nothingPrompt = 'Can be empty, or ';
                                                        } else {
                                                                $choices[] = $t;
                                                        }
                                                }
                                                $desc .= $paramPrefix . $nothingPrompt . $prompt;
                                                $choicesstring = implode( ', ', $choices );
                                                $desc .= wordwrap( $choicesstring, 100, $descWordwrap );
                                                $hintPipeSeparated = false;
                                        } else {
                                                switch ( $type ) {
                                                        case 'namespace':
                                                                // Special handling because namespaces are type-limited, yet they are not given
                                                                $desc .= $paramPrefix . $prompt;
                                                                $desc .= wordwrap( implode( ', ', MWNamespace::getValidNamespaces() ),
                                                                        100, $descWordwrap );
                                                                $hintPipeSeparated = false;
                                                                break;
                                                        case 'limit':
                                                                $desc .= $paramPrefix . "No more than {$paramSettings[self::PARAM_MAX]}";
                                                                if ( isset( $paramSettings[self::PARAM_MAX2] ) ) {
                                                                        $desc .= " ({$paramSettings[self::PARAM_MAX2]} for bots)";
                                                                }
                                                                $desc .= ' allowed';
                                                                break;
                                                        case 'integer':
                                                                $s = $multi ? 's' : '';
                                                                $hasMin = isset( $paramSettings[self::PARAM_MIN] );
                                                                $hasMax = isset( $paramSettings[self::PARAM_MAX] );
                                                                if ( $hasMin || $hasMax ) {
                                                                        if ( !$hasMax ) {
                                                                                $intRangeStr = "The value$s must be no less than {$paramSettings[self::PARAM_MIN]}";
                                                                        } elseif ( !$hasMin ) {
                                                                                $intRangeStr = "The value$s must be no more than {$paramSettings[self::PARAM_MAX]}";
                                                                        } else {
                                                                                $intRangeStr = "The value$s must be between {$paramSettings[self::PARAM_MIN]} and {$paramSettings[self::PARAM_MAX]}";
                                                                        }

                                                                        $desc .= $paramPrefix . $intRangeStr;
                                                                }
                                                                break;
                                                        case 'upload':
                                                                $desc .= $paramPrefix . "Must be posted as a file upload using multipart/form-data";
                                                                break;
                                                }
                                        }

                                        if ( $multi ) {
                                                if ( $hintPipeSeparated ) {
                                                        $desc .= $paramPrefix . "Separate values with '|'";
                                                }

                                                $isArray = is_array( $type );
                                                if ( !$isArray
                                                        || $isArray && count( $type ) > self::LIMIT_SML1
                                                ) {
                                                        $desc .= $paramPrefix . "Maximum number of values " .
                                                                self::LIMIT_SML1 . " (" . self::LIMIT_SML2 . " for bots)";
                                                }
                                        }
                                }

                                $default = isset( $paramSettings[self::PARAM_DFLT] ) ? $paramSettings[self::PARAM_DFLT] : null;
                                if ( !is_null( $default ) && $default !== false ) {
                                        $desc .= $paramPrefix . "Default: $default";
                                }

                                $msg .= sprintf( "  %-19s - %s\n", $this->encodeParamName( $paramName ), $desc );
                        }

                        return $msg;
                } else {
                        return false;
                }
        }

        /**
         * Returns the description string for this module
         * @return mixed string or array of strings
         */
        protected function getDescription() {
                return false;
        }

        /**
         * Returns usage examples for this module. Return false if no examples are available.
         * @return bool|string|array
         */
        protected function getExamples() {
                return false;
        }

        /**
         * Returns an array of allowed parameters (parameter name) => (default
         * value) or (parameter name) => (array with PARAM_* constants as keys)
         * Don't call this function directly: use getFinalParams() to allow
         * hooks to modify parameters as needed.
         *
         * Some derived classes may choose to handle an integer $flags parameter
         * in the overriding methods. Callers of this method can pass zero or
         * more OR-ed flags like GET_VALUES_FOR_HELP.
         *
         * @return array|bool
         */
        protected function getAllowedParams( /* $flags = 0 */ ) {
                // int $flags is not declared because it causes "Strict standards"
                // warning. Most derived classes do not implement it.
                return false;
        }

        /**
         * Returns an array of parameter descriptions.
         * Don't call this function directly: use getFinalParamDescription() to
         * allow hooks to modify descriptions as needed.
         * @return array|bool False on no parameter descriptions
         */
        protected function getParamDescription() {
                return false;
        }

        /**
         * Get final list of parameters, after hooks have had a chance to
         * tweak it as needed.
         *
         * @param int $flags Zero or more flags like GET_VALUES_FOR_HELP
         * @return array|Bool False on no parameters
         * @since 1.21 $flags param added
         */
        public function getFinalParams( $flags = 0 ) {
                $params = $this->getAllowedParams( $flags );
                wfRunHooks( 'APIGetAllowedParams', array( &$this, &$params, $flags ) );

                return $params;
        }

        /**
         * Get final parameter descriptions, after hooks have had a chance to tweak it as
         * needed.
         *
         * @return array|bool False on no parameter descriptions
         */
        public function getFinalParamDescription() {
                $desc = $this->getParamDescription();
                wfRunHooks( 'APIGetParamDescription', array( &$this, &$desc ) );

                return $desc;
        }

        /**
         * Returns possible properties in the result, grouped by the value of the prop parameter
         * that shows them.
         *
         * Properties that are shown always are in a group with empty string as a key.
         * Properties that can be shown by several values of prop are included multiple times.
         * If some properties are part of a list and some are on the root object (see ApiQueryQueryPage),
         * those on the root object are under the key PROP_ROOT.
         * The array can also contain a boolean under the key PROP_LIST,
         * indicating whether the result is a list.
         *
         * Don't call this function directly: use getFinalResultProperties() to
         * allow hooks to modify descriptions as needed.
         *
         * @return array|bool False on no properties
         */
        protected function getResultProperties() {
                return false;
        }

        /**
         * Get final possible result properties, after hooks have had a chance to tweak it as
         * needed.
         *
         * @return array
         */
        public function getFinalResultProperties() {
                $properties = $this->getResultProperties();
                wfRunHooks( 'APIGetResultProperties', array( $this, &$properties ) );

                return $properties;
        }

        /**
         * Add token properties to the array used by getResultProperties,
         * based on a token functions mapping.
         */
        protected static function addTokenProperties( &$props, $tokenFunctions ) {
                foreach ( array_keys( $tokenFunctions ) as $token ) {
                        $props[''][$token . 'token'] = array(
                                ApiBase::PROP_TYPE => 'string',
                                ApiBase::PROP_NULLABLE => true
                        );
                }
        }

        /**
         * Get final module description, after hooks have had a chance to tweak it as
         * needed.
         *
         * @return array|bool False on no parameters
         */
        public function getFinalDescription() {
                $desc = $this->getDescription();
                wfRunHooks( 'APIGetDescription', array( &$this, &$desc ) );

                return $desc;
        }

        /**
         * This method mangles parameter name based on the prefix supplied to the constructor.
         * Override this method to change parameter name during runtime
         * @param string $paramName Parameter name
         * @return string Prefixed parameter name
         */
        public function encodeParamName( $paramName ) {
                return $this->mModulePrefix . $paramName;
        }

        /**
         * Using getAllowedParams(), this function makes an array of the values
         * provided by the user, with key being the name of the variable, and
         * value - validated value from user or default. limits will not be
         * parsed if $parseLimit is set to false; use this when the max
         * limit is not definitive yet, e.g. when getting revisions.
         * @param $parseLimit Boolean: true by default
         * @return array
         */
        public function extractRequestParams( $parseLimit = true ) {
                // Cache parameters, for performance and to avoid bug 24564.
                if ( !isset( $this->mParamCache[$parseLimit] ) ) {
                        $params = $this->getFinalParams();
                        $results = array();

                        if ( $params ) { // getFinalParams() can return false
                                foreach ( $params as $paramName => $paramSettings ) {
                                        $results[$paramName] = $this->getParameterFromSettings(
                                                $paramName, $paramSettings, $parseLimit );
                                }
                        }
                        $this->mParamCache[$parseLimit] = $results;
                }

                return $this->mParamCache[$parseLimit];
        }

        /**
         * Get a value for the given parameter
         * @param string $paramName Parameter name
         * @param bool $parseLimit see extractRequestParams()
         * @return mixed Parameter value
         */
        protected function getParameter( $paramName, $parseLimit = true ) {
                $params = $this->getFinalParams();
                $paramSettings = $params[$paramName];

                return $this->getParameterFromSettings( $paramName, $paramSettings, $parseLimit );
        }

        /**
         * Die if none or more than one of a certain set of parameters is set and not false.
         * @param array $params of parameter names
         */
        public function requireOnlyOneParameter( $params ) {
                $required = func_get_args();
                array_shift( $required );
                $p = $this->getModulePrefix();

                $intersection = array_intersect( array_keys( array_filter( $params,
                        array( $this, "parameterNotEmpty" ) ) ), $required );

                if ( count( $intersection ) > 1 ) {
                        $this->dieUsage( "The parameters {$p}" . implode( ", {$p}", $intersection ) . ' can not be used together', 'invalidparammix' );
                } elseif ( count( $intersection ) == 0 ) {
                        $this->dieUsage( "One of the parameters {$p}" . implode( ", {$p}", $required ) . ' is required', 'missingparam' );
                }
        }

        /**
         * Generates the possible errors requireOnlyOneParameter() can die with
         *
         * @param $params array
         * @return array
         */
        public function getRequireOnlyOneParameterErrorMessages( $params ) {
                $p = $this->getModulePrefix();
                $params = implode( ", {$p}", $params );

                return array(
                        array( 'code' => "{$p}missingparam", 'info' => "One of the parameters {$p}{$params} is required" ),
                        array( 'code' => "{$p}invalidparammix", 'info' => "The parameters {$p}{$params} can not be used together" )
                );
        }

        /**
         * Die if more than one of a certain set of parameters is set and not false.
         *
         * @param $params array
         */
        public function requireMaxOneParameter( $params ) {
                $required = func_get_args();
                array_shift( $required );
                $p = $this->getModulePrefix();

                $intersection = array_intersect( array_keys( array_filter( $params,
                        array( $this, "parameterNotEmpty" ) ) ), $required );

                if ( count( $intersection ) > 1 ) {
                        $this->dieUsage( "The parameters {$p}" . implode( ", {$p}", $intersection ) . ' can not be used together', 'invalidparammix' );
                }
        }

        /**
         * Generates the possible error requireMaxOneParameter() can die with
         *
         * @param $params array
         * @return array
         */
        public function getRequireMaxOneParameterErrorMessages( $params ) {
                $p = $this->getModulePrefix();
                $params = implode( ", {$p}", $params );

                return array(
                        array( 'code' => "{$p}invalidparammix", 'info' => "The parameters {$p}{$params} can not be used together" )
                );
        }

        /**
         * @param $params array
         * @param bool|string $load Whether load the object's state from the database:
         *        - false: don't load (if the pageid is given, it will still be loaded)
         *        - 'fromdb': load from a slave database
         *        - 'fromdbmaster': load from the master database
         * @return WikiPage
         */
        public function getTitleOrPageId( $params, $load = false ) {
                $this->requireOnlyOneParameter( $params, 'title', 'pageid' );

                $pageObj = null;
                if ( isset( $params['title'] ) ) {
                        $titleObj = Title::newFromText( $params['title'] );
                        if ( !$titleObj || $titleObj->isExternal() ) {
                                $this->dieUsageMsg( array( 'invalidtitle', $params['title'] ) );
                        }
                        if ( !$titleObj->canExist() ) {
                                $this->dieUsage( "Namespace doesn't allow actual pages", 'pagecannotexist' );
                        }
                        $pageObj = WikiPage::factory( $titleObj );
                        if ( $load !== false ) {
                                $pageObj->loadPageData( $load );
                        }
                } elseif ( isset( $params['pageid'] ) ) {
                        if ( $load === false ) {
                                $load = 'fromdb';
                        }
                        $pageObj = WikiPage::newFromID( $params['pageid'], $load );
                        if ( !$pageObj ) {
                                $this->dieUsageMsg( array( 'nosuchpageid', $params['pageid'] ) );
                        }
                }

                return $pageObj;
        }

        /**
         * @return array
         */
        public function getTitleOrPageIdErrorMessage() {
                return array_merge(
                        $this->getRequireOnlyOneParameterErrorMessages( array( 'title', 'pageid' ) ),
                        array(
                                array( 'invalidtitle', 'title' ),
                                array( 'nosuchpageid', 'pageid' ),
                        )
                );
        }

        /**
         * Callback function used in requireOnlyOneParameter to check whether required parameters are set
         *
         * @param  $x object Parameter to check is not null/false
         * @return bool
         */
        private function parameterNotEmpty( $x ) {
                return !is_null( $x ) && $x !== false;
        }

        /**
         * @deprecated since 1.17 use MWNamespace::getValidNamespaces()
         *
         * @return array
         */
        public static function getValidNamespaces() {
                wfDeprecated( __METHOD__, '1.17' );

                return MWNamespace::getValidNamespaces();
        }

        /**
         * Return true if we're to watch the page, false if not, null if no change.
         * @param string $watchlist Valid values: 'watch', 'unwatch', 'preferences', 'nochange'
         * @param $titleObj Title the page under consideration
         * @param string $userOption The user option to consider when $watchlist=preferences.
         *    If not set will use watchdefault always and watchcreations if $titleObj doesn't exist.
         * @return bool
         */
        protected function getWatchlistValue( $watchlist, $titleObj, $userOption = null ) {

                $userWatching = $this->getUser()->isWatched( $titleObj, WatchedItem::IGNORE_USER_RIGHTS );

                switch ( $watchlist ) {
                        case 'watch':
                                return true;

                        case 'unwatch':
                                return false;

                        case 'preferences':
                                # If the user is already watching, don't bother checking
                                if ( $userWatching ) {
                                        return true;
                                }
                                # If no user option was passed, use watchdefault and watchcreations
                                if ( is_null( $userOption ) ) {
                                        return $this->getUser()->getBoolOption( 'watchdefault' ) ||
                                                $this->getUser()->getBoolOption( 'watchcreations' ) && !$titleObj->exists();
                                }

                                # Watch the article based on the user preference
                                return $this->getUser()->getBoolOption( $userOption );

                        case 'nochange':
                                return $userWatching;

                        default:
                                return $userWatching;
                }
        }

        /**
         * Set a watch (or unwatch) based the based on a watchlist parameter.
         * @param string $watch Valid values: 'watch', 'unwatch', 'preferences', 'nochange'
         * @param $titleObj Title the article's title to change
         * @param string $userOption The user option to consider when $watch=preferences
         */
        protected function setWatch( $watch, $titleObj, $userOption = null ) {
                $value = $this->getWatchlistValue( $watch, $titleObj, $userOption );
                if ( $value === null ) {
                        return;
                }

                WatchAction::doWatchOrUnwatch( $value, $titleObj, $this->getUser() );
        }

        /**
         * Using the settings determine the value for the given parameter
         *
         * @param string $paramName parameter name
         * @param array|mixed $paramSettings default value or an array of settings
         *  using PARAM_* constants.
         * @param $parseLimit Boolean: parse limit?
         * @return mixed Parameter value
         */
        protected function getParameterFromSettings( $paramName, $paramSettings, $parseLimit ) {
                // Some classes may decide to change parameter names
                $encParamName = $this->encodeParamName( $paramName );

                if ( !is_array( $paramSettings ) ) {
                        $default = $paramSettings;
                        $multi = false;
                        $type = gettype( $paramSettings );
                        $dupes = false;
                        $deprecated = false;
                        $required = false;
                } else {
                        $default = isset( $paramSettings[self::PARAM_DFLT] ) ? $paramSettings[self::PARAM_DFLT] : null;
                        $multi = isset( $paramSettings[self::PARAM_ISMULTI] ) ? $paramSettings[self::PARAM_ISMULTI] : false;
                        $type = isset( $paramSettings[self::PARAM_TYPE] ) ? $paramSettings[self::PARAM_TYPE] : null;
                        $dupes = isset( $paramSettings[self::PARAM_ALLOW_DUPLICATES] ) ? $paramSettings[self::PARAM_ALLOW_DUPLICATES] : false;
                        $deprecated = isset( $paramSettings[self::PARAM_DEPRECATED] ) ? $paramSettings[self::PARAM_DEPRECATED] : false;
                        $required = isset( $paramSettings[self::PARAM_REQUIRED] ) ? $paramSettings[self::PARAM_REQUIRED] : false;

                        // When type is not given, and no choices, the type is the same as $default
                        if ( !isset( $type ) ) {
                                if ( isset( $default ) ) {
                                        $type = gettype( $default );
                                } else {
                                        $type = 'NULL'; // allow everything
                                }
                        }
                }

                if ( $type == 'boolean' ) {
                        if ( isset( $default ) && $default !== false ) {
                                // Having a default value of anything other than 'false' is not allowed
                                ApiBase::dieDebug( __METHOD__, "Boolean param $encParamName's default is set to '$default'. Boolean parameters must default to false." );
                        }

                        $value = $this->getMain()->getCheck( $encParamName );
                } elseif ( $type == 'upload' ) {
                        if ( isset( $default ) ) {
                                // Having a default value is not allowed
                                ApiBase::dieDebug( __METHOD__, "File upload param $encParamName's default is set to '$default'. File upload parameters may not have a default." );
                        }
                        if ( $multi ) {
                                ApiBase::dieDebug( __METHOD__, "Multi-values not supported for $encParamName" );
                        }
                        $value = $this->getMain()->getUpload( $encParamName );
                        if ( !$value->exists() ) {
                                // This will get the value without trying to normalize it
                                // (because trying to normalize a large binary file
                                // accidentally uploaded as a field fails spectacularly)
                                $value = $this->getMain()->getRequest()->unsetVal( $encParamName );
                                if ( $value !== null ) {
                                        $this->dieUsage(
                                                "File upload param $encParamName is not a file upload; " .
                                                "be sure to use multipart/form-data for your POST and include " .
                                                "a filename in the Content-Disposition header.",
                                                "badupload_{$encParamName}"
                                        );
                                }
                        }
                } else {
                        $value = $this->getMain()->getVal( $encParamName, $default );

                        if ( isset( $value ) && $type == 'namespace' ) {
                                $type = MWNamespace::getValidNamespaces();
                        }
                }

                if ( isset( $value ) && ( $multi || is_array( $type ) ) ) {
                        $value = $this->parseMultiValue( $encParamName, $value, $multi, is_array( $type ) ? $type : null );
                }

                // More validation only when choices were not given
                // choices were validated in parseMultiValue()
                if ( isset( $value ) ) {
                        if ( !is_array( $type ) ) {
                                switch ( $type ) {
                                        case 'NULL': // nothing to do
                                                break;
                                        case 'string':
                                                if ( $required && $value === '' ) {
                                                        $this->dieUsageMsg( array( 'missingparam', $paramName ) );
                                                }
                                                break;
                                        case 'integer': // Force everything using intval() and optionally validate limits
                                                $min = isset( $paramSettings[self::PARAM_MIN] ) ? $paramSettings[self::PARAM_MIN] : null;
                                                $max = isset( $paramSettings[self::PARAM_MAX] ) ? $paramSettings[self::PARAM_MAX] : null;
                                                $enforceLimits = isset( $paramSettings[self::PARAM_RANGE_ENFORCE] )
                                                        ? $paramSettings[self::PARAM_RANGE_ENFORCE] : false;

                                                if ( is_array( $value ) ) {
                                                        $value = array_map( 'intval', $value );
                                                        if ( !is_null( $min ) || !is_null( $max ) ) {
                                                                foreach ( $value as &$v ) {
                                                                        $this->validateLimit( $paramName, $v, $min, $max, null, $enforceLimits );
                                                                }
                                                        }
                                                } else {
                                                        $value = intval( $value );
                                                        if ( !is_null( $min ) || !is_null( $max ) ) {
                                                                $this->validateLimit( $paramName, $value, $min, $max, null, $enforceLimits );
                                                        }
                                                }
                                                break;
                                        case 'limit':
                                                if ( !$parseLimit ) {
                                                        // Don't do any validation whatsoever
                                                        break;
                                                }
                                                if ( !isset( $paramSettings[self::PARAM_MAX] ) || !isset( $paramSettings[self::PARAM_MAX2] ) ) {
                                                        ApiBase::dieDebug( __METHOD__, "MAX1 or MAX2 are not defined for the limit $encParamName" );
                                                }
                                                if ( $multi ) {
                                                        ApiBase::dieDebug( __METHOD__, "Multi-values not supported for $encParamName" );
                                                }
                                                $min = isset( $paramSettings[self::PARAM_MIN] ) ? $paramSettings[self::PARAM_MIN] : 0;
                                                if ( $value == 'max' ) {
                                                        $value = $this->getMain()->canApiHighLimits() ? $paramSettings[self::PARAM_MAX2] : $paramSettings[self::PARAM_MAX];
                                                        $this->getResult()->setParsedLimit( $this->getModuleName(), $value );
                                                } else {
                                                        $value = intval( $value );
                                                        $this->validateLimit( $paramName, $value, $min, $paramSettings[self::PARAM_MAX], $paramSettings[self::PARAM_MAX2] );
                                                }
                                                break;
                                        case 'boolean':
                                                if ( $multi ) {
                                                        ApiBase::dieDebug( __METHOD__, "Multi-values not supported for $encParamName" );
                                                }
                                                break;
                                        case 'timestamp':
                                                if ( is_array( $value ) ) {
                                                        foreach ( $value as $key => $val ) {
                                                                $value[$key] = $this->validateTimestamp( $val, $encParamName );
                                                        }
                                                } else {
                                                        $value = $this->validateTimestamp( $value, $encParamName );
                                                }
                                                break;
                                        case 'user':
                                                if ( is_array( $value ) ) {
                                                        foreach ( $value as $key => $val ) {
                                                                $value[$key] = $this->validateUser( $val, $encParamName );
                                                        }
                                                } else {
                                                        $value = $this->validateUser( $value, $encParamName );
                                                }
                                                break;
                                        case 'upload': // nothing to do
                                                break;
                                        default:
                                                ApiBase::dieDebug( __METHOD__, "Param $encParamName's type is unknown - $type" );
                                }
                        }

                        // Throw out duplicates if requested
                        if ( !$dupes && is_array( $value ) ) {
                                $value = array_unique( $value );
                        }

                        // Set a warning if a deprecated parameter has been passed
                        if ( $deprecated && $value !== false ) {
                                $this->setWarning( "The $encParamName parameter has been deprecated." );
                        }
                } elseif ( $required ) {
                        $this->dieUsageMsg( array( 'missingparam', $paramName ) );
                }

                return $value;
        }

        /**
         * Return an array of values that were given in a 'a|b|c' notation,
         * after it optionally validates them against the list allowed values.
         *
         * @param string $valueName The name of the parameter (for error
         *  reporting)
         * @param $value mixed The value being parsed
         * @param bool $allowMultiple Can $value contain more than one value
         *  separated by '|'?
         * @param $allowedValues mixed An array of values to check against. If
         *  null, all values are accepted.
         * @return mixed (allowMultiple ? an_array_of_values : a_single_value)
         */
        protected function parseMultiValue( $valueName, $value, $allowMultiple, $allowedValues ) {
                if ( trim( $value ) === '' && $allowMultiple ) {
                        return array();
                }

                // This is a bit awkward, but we want to avoid calling canApiHighLimits() because it unstubs $wgUser
                $valuesList = explode( '|', $value, self::LIMIT_SML2 + 1 );
                $sizeLimit = count( $valuesList ) > self::LIMIT_SML1 && $this->mMainModule->canApiHighLimits() ?
                        self::LIMIT_SML2 : self::LIMIT_SML1;

                if ( self::truncateArray( $valuesList, $sizeLimit ) ) {
                        $this->setWarning( "Too many values supplied for parameter '$valueName': the limit is $sizeLimit" );
                }

                if ( !$allowMultiple && count( $valuesList ) != 1 ) {
                        // Bug 33482 - Allow entries with | in them for non-multiple values
                        if ( in_array( $value, $allowedValues, true ) ) {
                                return $value;
                        }

                        $possibleValues = is_array( $allowedValues ) ? "of '" . implode( "', '", $allowedValues ) . "'" : '';
                        $this->dieUsage( "Only one $possibleValues is allowed for parameter '$valueName'", "multival_$valueName" );
                }

                if ( is_array( $allowedValues ) ) {
                        // Check for unknown values
                        $unknown = array_diff( $valuesList, $allowedValues );
                        if ( count( $unknown ) ) {
                                if ( $allowMultiple ) {
                                        $s = count( $unknown ) > 1 ? 's' : '';
                                        $vals = implode( ", ", $unknown );
                                        $this->setWarning( "Unrecognized value$s for parameter '$valueName': $vals" );
                                } else {
                                        $this->dieUsage( "Unrecognized value for parameter '$valueName': {$valuesList[0]}", "unknown_$valueName" );
                                }
                        }
                        // Now throw them out
                        $valuesList = array_intersect( $valuesList, $allowedValues );
                }

                return $allowMultiple ? $valuesList : $valuesList[0];
        }

        /**
         * Validate the value against the minimum and user/bot maximum limits.
         * Prints usage info on failure.
         * @param string $paramName Parameter name
         * @param int $value Parameter value
         * @param int|null $min Minimum value
         * @param int|null $max Maximum value for users
         * @param int $botMax Maximum value for sysops/bots
         * @param $enforceLimits Boolean Whether to enforce (die) if value is outside limits
         */
        function validateLimit( $paramName, &$value, $min, $max, $botMax = null, $enforceLimits = false ) {
                if ( !is_null( $min ) && $value < $min ) {

                        $msg = $this->encodeParamName( $paramName ) . " may not be less than $min (set to $value)";
                        $this->warnOrDie( $msg, $enforceLimits );
                        $value = $min;
                }

                // Minimum is always validated, whereas maximum is checked only if not running in internal call mode
                if ( $this->getMain()->isInternalMode() ) {
                        return;
                }

                // Optimization: do not check user's bot status unless really needed -- skips db query
                // assumes $botMax >= $max
                if ( !is_null( $max ) && $value > $max ) {
                        if ( !is_null( $botMax ) && $this->getMain()->canApiHighLimits() ) {
                                if ( $value > $botMax ) {
                                        $msg = $this->encodeParamName( $paramName ) . " may not be over $botMax (set to $value) for bots or sysops";
                                        $this->warnOrDie( $msg, $enforceLimits );
                                        $value = $botMax;
                                }
                        } else {
                                $msg = $this->encodeParamName( $paramName ) . " may not be over $max (set to $value) for users";
                                $this->warnOrDie( $msg, $enforceLimits );
                                $value = $max;
                        }
                }
        }

        /**
         * Validate and normalize of parameters of type 'timestamp'
         * @param string $value Parameter value
         * @param string $encParamName Parameter name
         * @return string Validated and normalized parameter
         */
        function validateTimestamp( $value, $encParamName ) {
                $unixTimestamp = wfTimestamp( TS_UNIX, $value );
                if ( $unixTimestamp === false ) {
                        $this->dieUsage( "Invalid value '$value' for timestamp parameter $encParamName", "badtimestamp_{$encParamName}" );
                }

                return wfTimestamp( TS_MW, $unixTimestamp );
        }

        /**
         * Validate and normalize of parameters of type 'user'
         * @param string $value Parameter value
         * @param string $encParamName Parameter name
         * @return string Validated and normalized parameter
         */
        private function validateUser( $value, $encParamName ) {
                $title = Title::makeTitleSafe( NS_USER, $value );
                if ( $title === null ) {
                        $this->dieUsage( "Invalid value '$value' for user parameter $encParamName", "baduser_{$encParamName}" );
                }

                return $title->getText();
        }

        /**
         * Adds a warning to the output, else dies
         *
         * @param  $msg String Message to show as a warning, or error message if dying
         * @param  $enforceLimits Boolean Whether this is an enforce (die)
         */
        private function warnOrDie( $msg, $enforceLimits = false ) {
                if ( $enforceLimits ) {
                        $this->dieUsage( $msg, 'integeroutofrange' );
                } else {
                        $this->setWarning( $msg );
                }
        }

        /**
         * Truncate an array to a certain length.
         * @param array $arr Array to truncate
         * @param int $limit Maximum length
         * @return bool True if the array was truncated, false otherwise
         */
        public static function truncateArray( &$arr, $limit ) {
                $modified = false;
                while ( count( $arr ) > $limit ) {
                        array_pop( $arr );
                        $modified = true;
                }

                return $modified;
        }

        /**
         * Throw a UsageException, which will (if uncaught) call the main module's
         * error handler and die with an error message.
         *
         * @param string $description One-line human-readable description of the
         *   error condition, e.g., "The API requires a valid action parameter"
         * @param string $errorCode Brief, arbitrary, stable string to allow easy
         *   automated identification of the error, e.g., 'unknown_action'
         * @param int $httpRespCode HTTP response code
         * @param array $extradata Data to add to the "<error>" element; array in ApiResult format
         * @throws UsageException
         */
        public function dieUsage( $description, $errorCode, $httpRespCode = 0, $extradata = null ) {
                Profiler::instance()->close();
                throw new UsageException( $description, $this->encodeParamName( $errorCode ), $httpRespCode, $extradata );
        }

        /**
         * Throw a UsageException based on the errors in the Status object.
         *
         * @since 1.22
         * @param Status $status Status object
         * @throws UsageException
         */
        public function dieStatus( $status ) {
                if ( $status->isGood() ) {
                        throw new MWException( 'Successful status passed to ApiBase::dieStatus' );
                }

                $errors = $status->getErrorsArray();
                if ( !$errors ) {
                        // No errors? Assume the warnings should be treated as errors
                        $errors = $status->getWarningsArray();
                }
                if ( !$errors ) {
                        // Still no errors? Punt
                        $errors = array( array( 'unknownerror-nocode' ) );
                }

                // Cannot use dieUsageMsg() because extensions might return custom
                // error messages.
                if ( $errors[0] instanceof Message ) {
                        $msg = $errors[0];
                        $code = $msg->getKey();
                } else {
                        $code = array_shift( $errors[0] );
                        $msg = wfMessage( $code, $errors[0] );
                }
                if ( isset( ApiBase::$messageMap[$code] ) ) {
                        // Translate message to code, for backwards compatability
                        $code = ApiBase::$messageMap[$code]['code'];
                }
                $this->dieUsage( $msg->inLanguage( 'en' )->useDatabase( false )->plain(), $code );
        }

        /**
         * Array that maps message keys to error messages. $1 and friends are replaced.
         */
        public static $messageMap = array(
                // This one MUST be present, or dieUsageMsg() will recurse infinitely
                'unknownerror' => array( 'code' => 'unknownerror', 'info' => "Unknown error: \"\$1\"" ),
                'unknownerror-nocode' => array( 'code' => 'unknownerror', 'info' => 'Unknown error' ),

                // Messages from Title::getUserPermissionsErrors()
                'ns-specialprotected' => array( 'code' => 'unsupportednamespace', 'info' => "Pages in the Special namespace can't be edited" ),
                'protectedinterface' => array( 'code' => 'protectednamespace-interface', 'info' => "You're not allowed to edit interface messages" ),
                'namespaceprotected' => array( 'code' => 'protectednamespace', 'info' => "You're not allowed to edit pages in the \"\$1\" namespace" ),
                'customcssprotected' => array( 'code' => 'customcssprotected', 'info' => "You're not allowed to edit custom CSS pages" ),
                'customjsprotected' => array( 'code' => 'customjsprotected', 'info' => "You're not allowed to edit custom JavaScript pages" ),
                'cascadeprotected' => array( 'code' => 'cascadeprotected', 'info' => "The page you're trying to edit is protected because it's included in a cascade-protected page" ),
                'protectedpagetext' => array( 'code' => 'protectedpage', 'info' => "The \"\$1\" right is required to edit this page" ),
                'protect-cantedit' => array( 'code' => 'cantedit', 'info' => "You can't protect this page because you can't edit it" ),
                'badaccess-group0' => array( 'code' => 'permissiondenied', 'info' => "Permission denied" ), // Generic permission denied message
                'badaccess-groups' => array( 'code' => 'permissiondenied', 'info' => "Permission denied" ),
                'titleprotected' => array( 'code' => 'protectedtitle', 'info' => "This title has been protected from creation" ),
                'nocreate-loggedin' => array( 'code' => 'cantcreate', 'info' => "You don't have permission to create new pages" ),
                'nocreatetext' => array( 'code' => 'cantcreate-anon', 'info' => "Anonymous users can't create new pages" ),
                'movenologintext' => array( 'code' => 'cantmove-anon', 'info' => "Anonymous users can't move pages" ),
                'movenotallowed' => array( 'code' => 'cantmove', 'info' => "You don't have permission to move pages" ),
                'confirmedittext' => array( 'code' => 'confirmemail', 'info' => "You must confirm your email address before you can edit" ),
                'blockedtext' => array( 'code' => 'blocked', 'info' => "You have been blocked from editing" ),
                'autoblockedtext' => array( 'code' => 'autoblocked', 'info' => "Your IP address has been blocked automatically, because it was used by a blocked user" ),

                // Miscellaneous interface messages
                'actionthrottledtext' => array( 'code' => 'ratelimited', 'info' => "You've exceeded your rate limit. Please wait some time and try again" ),
                'alreadyrolled' => array( 'code' => 'alreadyrolled', 'info' => "The page you tried to rollback was already rolled back" ),
                'cantrollback' => array( 'code' => 'onlyauthor', 'info' => "The page you tried to rollback only has one author" ),
                'readonlytext' => array( 'code' => 'readonly', 'info' => "The wiki is currently in read-only mode" ),
                'sessionfailure' => array( 'code' => 'badtoken', 'info' => "Invalid token" ),
                'cannotdelete' => array( 'code' => 'cantdelete', 'info' => "Couldn't delete \"\$1\". Maybe it was deleted already by someone else" ),
                'notanarticle' => array( 'code' => 'missingtitle', 'info' => "The page you requested doesn't exist" ),
                'selfmove' => array( 'code' => 'selfmove', 'info' => "Can't move a page to itself" ),
                'immobile_namespace' => array( 'code' => 'immobilenamespace', 'info' => "You tried to move pages from or to a namespace that is protected from moving" ),
                'articleexists' => array( 'code' => 'articleexists', 'info' => "The destination article already exists and is not a redirect to the source article" ),
                'protectedpage' => array( 'code' => 'protectedpage', 'info' => "You don't have permission to perform this move" ),
                'hookaborted' => array( 'code' => 'hookaborted', 'info' => "The modification you tried to make was aborted by an extension hook" ),
                'cantmove-titleprotected' => array( 'code' => 'protectedtitle', 'info' => "The destination article has been protected from creation" ),
                'imagenocrossnamespace' => array( 'code' => 'nonfilenamespace', 'info' => "Can't move a file to a non-file namespace" ),
                'imagetypemismatch' => array( 'code' => 'filetypemismatch', 'info' => "The new file extension doesn't match its type" ),
                // 'badarticleerror' => shouldn't happen
                // 'badtitletext' => shouldn't happen
                'ip_range_invalid' => array( 'code' => 'invalidrange', 'info' => "Invalid IP range" ),
                'range_block_disabled' => array( 'code' => 'rangedisabled', 'info' => "Blocking IP ranges has been disabled" ),
                'nosuchusershort' => array( 'code' => 'nosuchuser', 'info' => "The user you specified doesn't exist" ),
                'badipaddress' => array( 'code' => 'invalidip', 'info' => "Invalid IP address specified" ),
                'ipb_expiry_invalid' => array( 'code' => 'invalidexpiry', 'info' => "Invalid expiry time" ),
                'ipb_already_blocked' => array( 'code' => 'alreadyblocked', 'info' => "The user you tried to block was already blocked" ),
                'ipb_blocked_as_range' => array( 'code' => 'blockedasrange', 'info' => "IP address \"\$1\" was blocked as part of range \"\$2\". You can't unblock the IP individually, but you can unblock the range as a whole." ),
                'ipb_cant_unblock' => array( 'code' => 'cantunblock', 'info' => "The block you specified was not found. It may have been unblocked already" ),
                'mailnologin' => array( 'code' => 'cantsend', 'info' => "You are not logged in, you do not have a confirmed email address, or you are not allowed to send email to other users, so you cannot send email" ),
                'ipbblocked' => array( 'code' => 'ipbblocked', 'info' => 'You cannot block or unblock users while you are yourself blocked' ),
                'ipbnounblockself' => array( 'code' => 'ipbnounblockself', 'info' => 'You are not allowed to unblock yourself' ),
                'usermaildisabled' => array( 'code' => 'usermaildisabled', 'info' => "User email has been disabled" ),
                'blockedemailuser' => array( 'code' => 'blockedfrommail', 'info' => "You have been blocked from sending email" ),
                'notarget' => array( 'code' => 'notarget', 'info' => "You have not specified a valid target for this action" ),
                'noemail' => array( 'code' => 'noemail', 'info' => "The user has not specified a valid email address, or has chosen not to receive email from other users" ),
                'rcpatroldisabled' => array( 'code' => 'patroldisabled', 'info' => "Patrolling is disabled on this wiki" ),
                'markedaspatrollederror-noautopatrol' => array( 'code' => 'noautopatrol', 'info' => "You don't have permission to patrol your own changes" ),
                'delete-toobig' => array( 'code' => 'bigdelete', 'info' => "You can't delete this page because it has more than \$1 revisions" ),
                'movenotallowedfile' => array( 'code' => 'cantmovefile', 'info' => "You don't have permission to move files" ),
                'userrights-no-interwiki' => array( 'code' => 'nointerwikiuserrights', 'info' => "You don't have permission to change user rights on other wikis" ),
                'userrights-nodatabase' => array( 'code' => 'nosuchdatabase', 'info' => "Database \"\$1\" does not exist or is not local" ),
                'nouserspecified' => array( 'code' => 'invaliduser', 'info' => "Invalid username \"\$1\"" ),
                'noname' => array( 'code' => 'invaliduser', 'info' => "Invalid username \"\$1\"" ),
                'summaryrequired' => array( 'code' => 'summaryrequired', 'info' => 'Summary required' ),
                'import-rootpage-invalid' => array( 'code' => 'import-rootpage-invalid', 'info' => 'Root page is an invalid title' ),
                'import-rootpage-nosubpage' => array( 'code' => 'import-rootpage-nosubpage', 'info' => 'Namespace "$1" of the root page does not allow subpages' ),

                // API-specific messages
                'readrequired' => array( 'code' => 'readapidenied', 'info' => "You need read permission to use this module" ),
                'writedisabled' => array( 'code' => 'noapiwrite', 'info' => "Editing of this wiki through the API is disabled. Make sure the \$wgEnableWriteAPI=true; statement is included in the wiki's LocalSettings.php file" ),
                'writerequired' => array( 'code' => 'writeapidenied', 'info' => "You're not allowed to edit this wiki through the API" ),
                'missingparam' => array( 'code' => 'no$1', 'info' => "The \$1 parameter must be set" ),
                'invalidtitle' => array( 'code' => 'invalidtitle', 'info' => "Bad title \"\$1\"" ),
                'nosuchpageid' => array( 'code' => 'nosuchpageid', 'info' => "There is no page with ID \$1" ),
                'nosuchrevid' => array( 'code' => 'nosuchrevid', 'info' => "There is no revision with ID \$1" ),
                'nosuchuser' => array( 'code' => 'nosuchuser', 'info' => "User \"\$1\" doesn't exist" ),
                'invaliduser' => array( 'code' => 'invaliduser', 'info' => "Invalid username \"\$1\"" ),
                'invalidexpiry' => array( 'code' => 'invalidexpiry', 'info' => "Invalid expiry time \"\$1\"" ),
                'pastexpiry' => array( 'code' => 'pastexpiry', 'info' => "Expiry time \"\$1\" is in the past" ),
                'create-titleexists' => array( 'code' => 'create-titleexists', 'info' => "Existing titles can't be protected with 'create'" ),
                'missingtitle-createonly' => array( 'code' => 'missingtitle-createonly', 'info' => "Missing titles can only be protected with 'create'" ),
                'cantblock' => array( 'code' => 'cantblock', 'info' => "You don't have permission to block users" ),
                'canthide' => array( 'code' => 'canthide', 'info' => "You don't have permission to hide user names from the block log" ),
                'cantblock-email' => array( 'code' => 'cantblock-email', 'info' => "You don't have permission to block users from sending email through the wiki" ),
                'unblock-notarget' => array( 'code' => 'notarget', 'info' => "Either the id or the user parameter must be set" ),
                'unblock-idanduser' => array( 'code' => 'idanduser', 'info' => "The id and user parameters can't be used together" ),
                'cantunblock' => array( 'code' => 'permissiondenied', 'info' => "You don't have permission to unblock users" ),
                'cannotundelete' => array( 'code' => 'cantundelete', 'info' => "Couldn't undelete: the requested revisions may not exist, or may have been undeleted already" ),
                'permdenied-undelete' => array( 'code' => 'permissiondenied', 'info' => "You don't have permission to restore deleted revisions" ),
                'createonly-exists' => array( 'code' => 'articleexists', 'info' => "The article you tried to create has been created already" ),
                'nocreate-missing' => array( 'code' => 'missingtitle', 'info' => "The article you tried to edit doesn't exist" ),
                'nosuchrcid' => array( 'code' => 'nosuchrcid', 'info' => "There is no change with rcid \"\$1\"" ),
                'protect-invalidaction' => array( 'code' => 'protect-invalidaction', 'info' => "Invalid protection type \"\$1\"" ),
                'protect-invalidlevel' => array( 'code' => 'protect-invalidlevel', 'info' => "Invalid protection level \"\$1\"" ),
                'toofewexpiries' => array( 'code' => 'toofewexpiries', 'info' => "\$1 expiry timestamps were provided where \$2 were needed" ),
                'cantimport' => array( 'code' => 'cantimport', 'info' => "You don't have permission to import pages" ),
                'cantimport-upload' => array( 'code' => 'cantimport-upload', 'info' => "You don't have permission to import uploaded pages" ),
                'importnofile' => array( 'code' => 'nofile', 'info' => "You didn't upload a file" ),
                'importuploaderrorsize' => array( 'code' => 'filetoobig', 'info' => 'The file you uploaded is bigger than the maximum upload size' ),
                'importuploaderrorpartial' => array( 'code' => 'partialupload', 'info' => 'The file was only partially uploaded' ),
                'importuploaderrortemp' => array( 'code' => 'notempdir', 'info' => 'The temporary upload directory is missing' ),
                'importcantopen' => array( 'code' => 'cantopenfile', 'info' => "Couldn't open the uploaded file" ),
                'import-noarticle' => array( 'code' => 'badinterwiki', 'info' => 'Invalid interwiki title specified' ),
                'importbadinterwiki' => array( 'code' => 'badinterwiki', 'info' => 'Invalid interwiki title specified' ),
                'import-unknownerror' => array( 'code' => 'import-unknownerror', 'info' => "Unknown error on import: \"\$1\"" ),
                'cantoverwrite-sharedfile' => array( 'code' => 'cantoverwrite-sharedfile', 'info' => 'The target file exists on a shared repository and you do not have permission to override it' ),
                'sharedfile-exists' => array( 'code' => 'fileexists-sharedrepo-perm', 'info' => 'The target file exists on a shared repository. Use the ignorewarnings parameter to override it.' ),
                'mustbeposted' => array( 'code' => 'mustbeposted', 'info' => "The \$1 module requires a POST request" ),
                'show' => array( 'code' => 'show', 'info' => 'Incorrect parameter - mutually exclusive values may not be supplied' ),
                'specialpage-cantexecute' => array( 'code' => 'specialpage-cantexecute', 'info' => "You don't have permission to view the results of this special page" ),
                'invalidoldimage' => array( 'code' => 'invalidoldimage', 'info' => 'The oldimage parameter has invalid format' ),
                'nodeleteablefile' => array( 'code' => 'nodeleteablefile', 'info' => 'No such old version of the file' ),
                'fileexists-forbidden' => array( 'code' => 'fileexists-forbidden', 'info' => 'A file with name "$1" already exists, and cannot be overwritten.' ),
                'fileexists-shared-forbidden' => array( 'code' => 'fileexists-shared-forbidden', 'info' => 'A file with name "$1" already exists in the shared file repository, and cannot be overwritten.' ),
                'filerevert-badversion' => array( 'code' => 'filerevert-badversion', 'info' => 'There is no previous local version of this file with the provided timestamp.' ),

                // ApiEditPage messages
                'noimageredirect-anon' => array( 'code' => 'noimageredirect-anon', 'info' => "Anonymous users can't create image redirects" ),
                'noimageredirect-logged' => array( 'code' => 'noimageredirect', 'info' => "You don't have permission to create image redirects" ),
                'spamdetected' => array( 'code' => 'spamdetected', 'info' => "Your edit was refused because it contained a spam fragment: \"\$1\"" ),
                'contenttoobig' => array( 'code' => 'contenttoobig', 'info' => "The content you supplied exceeds the article size limit of \$1 kilobytes" ),
                'noedit-anon' => array( 'code' => 'noedit-anon', 'info' => "Anonymous users can't edit pages" ),
                'noedit' => array( 'code' => 'noedit', 'info' => "You don't have permission to edit pages" ),
                'wasdeleted' => array( 'code' => 'pagedeleted', 'info' => "The page has been deleted since you fetched its timestamp" ),
                'blankpage' => array( 'code' => 'emptypage', 'info' => "Creating new, empty pages is not allowed" ),
                'editconflict' => array( 'code' => 'editconflict', 'info' => "Edit conflict detected" ),
                'hashcheckfailed' => array( 'code' => 'badmd5', 'info' => "The supplied MD5 hash was incorrect" ),
                'missingtext' => array( 'code' => 'notext', 'info' => "One of the text, appendtext, prependtext and undo parameters must be set" ),
                'emptynewsection' => array( 'code' => 'emptynewsection', 'info' => 'Creating empty new sections is not possible.' ),
                'revwrongpage' => array( 'code' => 'revwrongpage', 'info' => "r\$1 is not a revision of \"\$2\"" ),
                'undo-failure' => array( 'code' => 'undofailure', 'info' => 'Undo failed due to conflicting intermediate edits' ),

                // Messages from WikiPage::doEit()
                'edit-hook-aborted' => array( 'code' => 'edit-hook-aborted', 'info' => "Your edit was aborted by an ArticleSave hook" ),
                'edit-gone-missing' => array( 'code' => 'edit-gone-missing', 'info' => "The page you tried to edit doesn't seem to exist anymore" ),
                'edit-conflict' => array( 'code' => 'editconflict', 'info' => "Edit conflict detected" ),
                'edit-already-exists' => array( 'code' => 'edit-already-exists', 'info' => "It seems the page you tried to create already exist" ),

                // uploadMsgs
                'invalid-file-key' => array( 'code' => 'invalid-file-key', 'info' => 'Not a valid file key' ),
                'nouploadmodule' => array( 'code' => 'nouploadmodule', 'info' => 'No upload module set' ),
                'uploaddisabled' => array( 'code' => 'uploaddisabled', 'info' => 'Uploads are not enabled. Make sure $wgEnableUploads is set to true in LocalSettings.php and the PHP ini setting file_uploads is true' ),
                'copyuploaddisabled' => array( 'code' => 'copyuploaddisabled', 'info' => 'Uploads by URL is not enabled. Make sure $wgAllowCopyUploads is set to true in LocalSettings.php.' ),
                'copyuploadbaddomain' => array( 'code' => 'copyuploadbaddomain', 'info' => 'Uploads by URL are not allowed from this domain.' ),
                'copyuploadbadurl' => array( 'code' => 'copyuploadbadurl', 'info' => 'Upload not allowed from this URL.' ),

                'filename-tooshort' => array( 'code' => 'filename-tooshort', 'info' => 'The filename is too short' ),
                'filename-toolong' => array( 'code' => 'filename-toolong', 'info' => 'The filename is too long' ),
                'illegal-filename' => array( 'code' => 'illegal-filename', 'info' => 'The filename is not allowed' ),
                'filetype-missing' => array( 'code' => 'filetype-missing', 'info' => 'The file is missing an extension' ),

                'mustbeloggedin' => array( 'code' => 'mustbeloggedin', 'info' => 'You must be logged in to $1.' )
        );

        /**
         * Helper function for readonly errors
         */
        public function dieReadOnly() {
                $parsed = $this->parseMsg( array( 'readonlytext' ) );
                $this->dieUsage( $parsed['info'], $parsed['code'], /* http error */ 0,
                        array( 'readonlyreason' => wfReadOnlyReason() ) );
        }

        /**
         * Output the error message related to a certain array
         * @param $error (array|string) Element of a getUserPermissionsErrors()-style array
         */
        public function dieUsageMsg( $error ) {
                # most of the time we send a 1 element, so we might as well send it as
                # a string and make this an array here.
                if ( is_string( $error ) ) {
                        $error = array( $error );
                }
                $parsed = $this->parseMsg( $error );
                $this->dieUsage( $parsed['info'], $parsed['code'] );
        }

        /**
         * Will only set a warning instead of failing if the global $wgDebugAPI
         * is set to true. Otherwise behaves exactly as dieUsageMsg().
         * @param $error (array|string) Element of a getUserPermissionsErrors()-style array
         * @since 1.21
         */
        public function dieUsageMsgOrDebug( $error ) {
                global $wgDebugAPI;
                if ( $wgDebugAPI !== true ) {
                        $this->dieUsageMsg( $error );
                } else {
                        if ( is_string( $error ) ) {
                                $error = array( $error );
                        }
                        $parsed = $this->parseMsg( $error );
                        $this->setWarning( '$wgDebugAPI: ' . $parsed['code']
                                . ' - ' . $parsed['info'] );
                }
        }

        /**
         * Die with the $prefix.'badcontinue' error. This call is common enough to make it into the base method.
         * @param $condition boolean will only die if this value is true
         * @since 1.21
         */
        protected function dieContinueUsageIf( $condition ) {
                if ( $condition ) {
                        $this->dieUsage(
                                'Invalid continue param. You should pass the original value returned by the previous query',
                                'badcontinue' );
                }
        }

        /**
         * Return the error message related to a certain array
         * @param array $error Element of a getUserPermissionsErrors()-style array
         * @return array('code' => code, 'info' => info)
         */
        public function parseMsg( $error ) {
                $error = (array)$error; // It seems strings sometimes make their way in here
                $key = array_shift( $error );

                // Check whether the error array was nested
                // array( array( <code>, <params> ), array( <another_code>, <params> ) )
                if ( is_array( $key ) ) {
                        $error = $key;
                        $key = array_shift( $error );
                }

                if ( isset( self::$messageMap[$key] ) ) {
                        return array(
                                'code' => wfMsgReplaceArgs( self::$messageMap[$key]['code'], $error ),
                                'info' => wfMsgReplaceArgs( self::$messageMap[$key]['info'], $error )
                        );
                }

                // If the key isn't present, throw an "unknown error"
                return $this->parseMsg( array( 'unknownerror', $key ) );
        }

        /**
         * Internal code errors should be reported with this method
         * @param string $method Method or function name
         * @param string $message Error message
         */
        protected static function dieDebug( $method, $message ) {
                throw new MWException( "Internal error in $method: $message" );
        }

        /**
         * Indicates if this module needs maxlag to be checked
         * @return bool
         */
        public function shouldCheckMaxlag() {
                return true;
        }

        /**
         * Indicates whether this module requires read rights
         * @return bool
         */
        public function isReadMode() {
                return true;
        }

        /**
         * Indicates whether this module requires write mode
         * @return bool
         */
        public function isWriteMode() {
                return false;
        }

        /**
         * Indicates whether this module must be called with a POST request
         * @return bool
         */
        public function mustBePosted() {
                return false;
        }

        /**
         * Returns whether this module requires a token to execute
         * It is used to show possible errors in action=paraminfo
         * see bug 25248
         * @return bool
         */
        public function needsToken() {
                return false;
        }

        /**
         * Returns the token salt if there is one,
         * '' if the module doesn't require a salt,
         * else false if the module doesn't need a token
         * You have also to override needsToken()
         * Value is passed to User::getEditToken
         * @return bool|string|array
         */
        public function getTokenSalt() {
                return false;
        }

        /**
         * Gets the user for whom to get the watchlist
         *
         * @param $params array
         * @return User
         */
        public function getWatchlistUser( $params ) {
                if ( !is_null( $params['owner'] ) && !is_null( $params['token'] ) ) {
                        $user = User::newFromName( $params['owner'], false );
                        if ( !( $user && $user->getId() ) ) {
                                $this->dieUsage( 'Specified user does not exist', 'bad_wlowner' );
                        }
                        $token = $user->getOption( 'watchlisttoken' );
                        if ( $token == '' || $token != $params['token'] ) {
                                $this->dieUsage( 'Incorrect watchlist token provided -- please set a correct token in Special:Preferences', 'bad_wltoken' );
                        }
                } else {
                        if ( !$this->getUser()->isLoggedIn() ) {
                                $this->dieUsage( 'You must be logged-in to have a watchlist', 'notloggedin' );
                        }
                        if ( !$this->getUser()->isAllowed( 'viewmywatchlist' ) ) {
                                $this->dieUsage( 'You don\'t have permission to view your watchlist', 'permissiondenied' );
                        }
                        $user = $this->getUser();
                }

                return $user;
        }

        /**
         * @return bool|string|array Returns a false if the module has no help url, else returns a (array of) string
         */
        public function getHelpUrls() {
                return false;
        }

        /**
         * Returns a list of all possible errors returned by the module
         *
         * Don't call this function directly: use getFinalPossibleErrors() to allow
         * hooks to modify parameters as needed.
         *
         * @return array in the format of array( key, param1, param2, ... ) or array( 'code' => ..., 'info' => ... )
         */
        public function getPossibleErrors() {
                $ret = array();

                $params = $this->getFinalParams();
                if ( $params ) {
                        foreach ( $params as $paramName => $paramSettings ) {
                                if ( isset( $paramSettings[ApiBase::PARAM_REQUIRED] ) && $paramSettings[ApiBase::PARAM_REQUIRED] ) {
                                        $ret[] = array( 'missingparam', $paramName );
                                }
                        }
                        if ( array_key_exists( 'continue', $params ) ) {
                                $ret[] = array(
                                        'code' => 'badcontinue',
                                        'info' => 'Invalid continue param. You should pass the original value returned by the previous query'
                                );
                        }
                }

                if ( $this->mustBePosted() ) {
                        $ret[] = array( 'mustbeposted', $this->getModuleName() );
                }

                if ( $this->isReadMode() ) {
                        $ret[] = array( 'readrequired' );
                }

                if ( $this->isWriteMode() ) {
                        $ret[] = array( 'writerequired' );
                        $ret[] = array( 'writedisabled' );
                }

                if ( $this->needsToken() ) {
                        if ( !isset( $params['token'][ApiBase::PARAM_REQUIRED] )
                                || !$params['token'][ApiBase::PARAM_REQUIRED]
                        ) {
                                // Add token as possible missing parameter, if not already done
                                $ret[] = array( 'missingparam', 'token' );
                        }
                        $ret[] = array( 'sessionfailure' );
                }

                return $ret;
        }

        /**
         * Get final list of possible errors, after hooks have had a chance to
         * tweak it as needed.
         *
         * @return array
         * @since 1.22
         */
        public function getFinalPossibleErrors() {
                $possibleErrors = $this->getPossibleErrors();
                wfRunHooks( 'APIGetPossibleErrors', array( $this, &$possibleErrors ) );

                return $possibleErrors;
        }

        /**
         * Parses a list of errors into a standardised format
         * @param array $errors List of errors. Items can be in the for array( key, param1, param2, ... ) or array( 'code' => ..., 'info' => ... )
         * @return array Parsed list of errors with items in the form array( 'code' => ..., 'info' => ... )
         */
        public function parseErrors( $errors ) {
                $ret = array();

                foreach ( $errors as $row ) {
                        if ( isset( $row['code'] ) && isset( $row['info'] ) ) {
                                $ret[] = $row;
                        } else {
                                $ret[] = $this->parseMsg( $row );
                        }
                }

                return $ret;
        }

        /**
         * Profiling: total module execution time
         */
        private $mTimeIn = 0, $mModuleTime = 0;

        /**
         * Start module profiling
         */
        public function profileIn() {
                if ( $this->mTimeIn !== 0 ) {
                        ApiBase::dieDebug( __METHOD__, 'called twice without calling profileOut()' );
                }
                $this->mTimeIn = microtime( true );
                wfProfileIn( $this->getModuleProfileName() );
        }

        /**
         * End module profiling
         */
        public function profileOut() {
                if ( $this->mTimeIn === 0 ) {
                        ApiBase::dieDebug( __METHOD__, 'called without calling profileIn() first' );
                }
                if ( $this->mDBTimeIn !== 0 ) {
                        ApiBase::dieDebug( __METHOD__, 'must be called after database profiling is done with profileDBOut()' );
                }

                $this->mModuleTime += microtime( true ) - $this->mTimeIn;
                $this->mTimeIn = 0;
                wfProfileOut( $this->getModuleProfileName() );
        }

        /**
         * When modules crash, sometimes it is needed to do a profileOut() regardless
         * of the profiling state the module was in. This method does such cleanup.
         */
        public function safeProfileOut() {
                if ( $this->mTimeIn !== 0 ) {
                        if ( $this->mDBTimeIn !== 0 ) {
                                $this->profileDBOut();
                        }
                        $this->profileOut();
                }
        }

        /**
         * Total time the module was executed
         * @return float
         */
        public function getProfileTime() {
                if ( $this->mTimeIn !== 0 ) {
                        ApiBase::dieDebug( __METHOD__, 'called without calling profileOut() first' );
                }

                return $this->mModuleTime;
        }

        /**
         * Profiling: database execution time
         */
        private $mDBTimeIn = 0, $mDBTime = 0;

        /**
         * Start module profiling
         */
        public function profileDBIn() {
                if ( $this->mTimeIn === 0 ) {
                        ApiBase::dieDebug( __METHOD__, 'must be called while profiling the entire module with profileIn()' );
                }
                if ( $this->mDBTimeIn !== 0 ) {
                        ApiBase::dieDebug( __METHOD__, 'called twice without calling profileDBOut()' );
                }
                $this->mDBTimeIn = microtime( true );
                wfProfileIn( $this->getModuleProfileName( true ) );
        }

        /**
         * End database profiling
         */
        public function profileDBOut() {
                if ( $this->mTimeIn === 0 ) {
                        ApiBase::dieDebug( __METHOD__, 'must be called while profiling the entire module with profileIn()' );
                }
                if ( $this->mDBTimeIn === 0 ) {
                        ApiBase::dieDebug( __METHOD__, 'called without calling profileDBIn() first' );
                }

                $time = microtime( true ) - $this->mDBTimeIn;
                $this->mDBTimeIn = 0;

                $this->mDBTime += $time;
                $this->getMain()->mDBTime += $time;
                wfProfileOut( $this->getModuleProfileName( true ) );
        }

        /**
         * Total time the module used the database
         * @return float
         */
        public function getProfileDBTime() {
                if ( $this->mDBTimeIn !== 0 ) {
                        ApiBase::dieDebug( __METHOD__, 'called without calling profileDBOut() first' );
                }

                return $this->mDBTime;
        }

        /**
         * Gets a default slave database connection object
         * @return DatabaseBase
         */
        protected function getDB() {
                if ( !isset( $this->mSlaveDB ) ) {
                        $this->profileDBIn();
                        $this->mSlaveDB = wfGetDB( DB_SLAVE, 'api' );
                        $this->profileDBOut();
                }

                return $this->mSlaveDB;
        }

        /**
         * Debugging function that prints a value and an optional backtrace
         * @param $value mixed Value to print
         * @param string $name Description of the printed value
         * @param bool $backtrace If true, print a backtrace
         */
        public static function debugPrint( $value, $name = 'unknown', $backtrace = false ) {
                print "\n\n<pre><b>Debugging value '$name':</b>\n\n";
                var_export( $value );
                if ( $backtrace ) {
                        print "\n" . wfBacktrace();
                }
                print "\n</pre>\n";
        }
}