<?php
/**
 * Configuration holder, particularly for multi-wiki sites.
 *
 * 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 is a class for holding configuration settings, particularly for
 * multi-wiki sites.
 *
 * A basic synopsis:
 *
 * Consider a wikifarm having three sites: two production sites, one in English
 * and one in German, and one testing site. You can assign them easy-to-remember
 * identifiers - ISO 639 codes 'en' and 'de' for language wikis, and 'beta' for
 * the testing wiki.
 *
 * You would thus initialize the site configuration by specifying the wiki
 * identifiers:
 *
 * @code
 * $conf = new SiteConfiguration;
 * $conf->wikis = array( 'de', 'en', 'beta' );
 * @endcode
 *
 * When configuring the MediaWiki global settings (the $wg variables),
 * the identifiers will be available to specify settings on a per wiki basis.
 *
 * @code
 * $conf->settings = array(
 *	'wgSomeSetting' => array(
 *
 *		# production:
 *		'de'     => false,
 *		'en'     => false,
 *
 *		# test:
 *		'beta    => true,
 *	),
 * );
 * @endcode
 *
 * With three wikis, that is easy to manage. But what about a farm with
 * hundreds of wikis? Site configuration provides a special keyword named
 * 'default' which is the value used when a wiki is not found. Hence
 * the above code could be written:
 *
 * @code
 * $conf->settings = array(
 *	'wgSomeSetting' => array(
 *
 *		'default' => false,
 *
 *		# Enable feature on test
 *		'beta'    => true,
 *	),
 * );
 * @endcode
 *
 *
 * Since settings can contain arrays, site configuration provides a way
 * to merge an array with the default. This is very useful to avoid
 * repeating settings again and again while still maintaining specific changes
 * on a per wiki basis.
 *
 * @code
 * $conf->settings = array(
 *	'wgMergeSetting' = array(
 *		# Value that will be shared among all wikis:
 *		'default' => array( NS_USER => true ),
 *
 *		# Leading '+' means merging the array of value with the defaults
 *		'+beta' => array( NS_HELP => true ),
 *	),
 * );
 *
 * # Get configuration for the German site:
 * $conf->get( 'wgMergeSetting', 'de' );
 * // --> array( NS_USER => true );
 *
 * # Get configuration for the testing site:
 * $conf->get( 'wgMergeSetting', 'beta' );
 * // --> array( NS_USER => true, NS_HELP => true );
 * @endcode
 *
 * Finally, to load all configuration settings, extract them in global context:
 *
 * @code
 * # Name / identifier of the wiki as set in $conf->wikis
 * $wikiID = 'beta';
 * $globals = $conf->getAll( $wikiID );
 * extract( $globals );
 * @endcode
 *
 * @todo Give examples for,
 * suffixes:
 * $conf->suffixes = array( 'wiki' );
 * localVHosts
 * callbacks!
 */
class SiteConfiguration {

	/**
	 * Array of suffixes, for self::siteFromDB()
	 */
	public $suffixes = array();

	/**
	 * Array of wikis, should be the same as $wgLocalDatabases
	 */
	public $wikis = array();

	/**
	 * The whole array of settings
	 */
	public $settings = array();

	/**
	 * Array of domains that are local and can be handled by the same server
	 */
	public $localVHosts = array();

	/**
	 * Optional callback to load full configuration data.
	 * @var string|array
	 */
	public $fullLoadCallback = null;

	/** Whether or not all data has been loaded */
	public $fullLoadDone = false;

	/**
	 * A callback function that returns an array with the following keys (all
	 * optional):
	 * - suffix: site's suffix
	 * - lang: site's lang
	 * - tags: array of wiki tags
	 * - params: array of parameters to be replaced
	 * The function will receive the SiteConfiguration instance in the first
	 * argument and the wiki in the second one.
	 * if suffix and lang are passed they will be used for the return value of
	 * self::siteFromDB() and self::$suffixes will be ignored
	 *
	 * @var string|array
	 */
	public $siteParamsCallback = null;

	/**
	 * Configuration cache for getConfig()
	 * @var array
	 */
	protected $cfgCache = array();

	/**
	 * Retrieves a configuration setting for a given wiki.
	 * @param string $settingName ID of the setting name to retrieve
	 * @param string $wiki Wiki ID of the wiki in question.
	 * @param string $suffix The suffix of the wiki in question.
	 * @param array $params List of parameters. $.'key' is replaced by $value in all returned data.
	 * @param array $wikiTags The tags assigned to the wiki.
	 * @return mixed The value of the setting requested.
	 */
	public function get( $settingName, $wiki, $suffix = null, $params = array(),
		$wikiTags = array()
	) {
		$params = $this->mergeParams( $wiki, $suffix, $params, $wikiTags );
		return $this->getSetting( $settingName, $wiki, $params );
	}

	/**
	 * Really retrieves a configuration setting for a given wiki.
	 *
	 * @param string $settingName ID of the setting name to retrieve.
	 * @param string $wiki Wiki ID of the wiki in question.
	 * @param array $params Array of parameters.
	 * @return mixed The value of the setting requested.
	 */
	protected function getSetting( $settingName, $wiki, array $params ) {
		$retval = null;
		if ( array_key_exists( $settingName, $this->settings ) ) {
			$thisSetting =& $this->settings[$settingName];
			do {
				// Do individual wiki settings
				if ( array_key_exists( $wiki, $thisSetting ) ) {
					$retval = $thisSetting[$wiki];
					break;
				} elseif ( array_key_exists( "+$wiki", $thisSetting ) && is_array( $thisSetting["+$wiki"] ) ) {
					$retval = $thisSetting["+$wiki"];
				}

				// Do tag settings
				foreach ( $params['tags'] as $tag ) {
					if ( array_key_exists( $tag, $thisSetting ) ) {
						if ( is_array( $retval ) && is_array( $thisSetting[$tag] ) ) {
							$retval = self::arrayMerge( $retval, $thisSetting[$tag] );
						} else {
							$retval = $thisSetting[$tag];
						}
						break 2;
					} elseif ( array_key_exists( "+$tag", $thisSetting ) && is_array( $thisSetting["+$tag"] ) ) {
						if ( $retval === null ) {
							$retval = array();
						}
						$retval = self::arrayMerge( $retval, $thisSetting["+$tag"] );
					}
				}
				// Do suffix settings
				$suffix = $params['suffix'];
				if ( !is_null( $suffix ) ) {
					if ( array_key_exists( $suffix, $thisSetting ) ) {
						if ( is_array( $retval ) && is_array( $thisSetting[$suffix] ) ) {
							$retval = self::arrayMerge( $retval, $thisSetting[$suffix] );
						} else {
							$retval = $thisSetting[$suffix];
						}
						break;
					} elseif ( array_key_exists( "+$suffix", $thisSetting )
						&& is_array( $thisSetting["+$suffix"] )
					) {
						if ( $retval === null ) {
							$retval = array();
						}
						$retval = self::arrayMerge( $retval, $thisSetting["+$suffix"] );
					}
				}

				// Fall back to default.
				if ( array_key_exists( 'default', $thisSetting ) ) {
					if ( is_array( $retval ) && is_array( $thisSetting['default'] ) ) {
						$retval = self::arrayMerge( $retval, $thisSetting['default'] );
					} else {
						$retval = $thisSetting['default'];
					}
					break;
				}
			} while ( false );
		}

		if ( !is_null( $retval ) && count( $params['params'] ) ) {
			foreach ( $params['params'] as $key => $value ) {
				$retval = $this->doReplace( '$' . $key, $value, $retval );
			}
		}
		return $retval;
	}

	/**
	 * Type-safe string replace; won't do replacements on non-strings
	 * private?
	 *
	 * @param string $from
	 * @param string $to
	 * @param string|array $in
	 * @return string
	 */
	function doReplace( $from, $to, $in ) {
		if ( is_string( $in ) ) {
			return str_replace( $from, $to, $in );
		} elseif ( is_array( $in ) ) {
			foreach ( $in as $key => $val ) {
				$in[$key] = $this->doReplace( $from, $to, $val );
			}
			return $in;
		} else {
			return $in;
		}
	}

	/**
	 * Gets all settings for a wiki
	 * @param string $wiki Wiki ID of the wiki in question.
	 * @param string $suffix The suffix of the wiki in question.
	 * @param array $params List of parameters. $.'key' is replaced by $value in all returned data.
	 * @param array $wikiTags The tags assigned to the wiki.
	 * @return array Array of settings requested.
	 */
	public function getAll( $wiki, $suffix = null, $params = array(), $wikiTags = array() ) {
		$params = $this->mergeParams( $wiki, $suffix, $params, $wikiTags );
		$localSettings = array();
		foreach ( $this->settings as $varname => $stuff ) {
			$append = false;
			$var = $varname;
			if ( substr( $varname, 0, 1 ) == '+' ) {
				$append = true;
				$var = substr( $varname, 1 );
			}

			$value = $this->getSetting( $varname, $wiki, $params );
			if ( $append && is_array( $value ) && is_array( $GLOBALS[$var] ) ) {
				$value = self::arrayMerge( $value, $GLOBALS[$var] );
			}
			if ( !is_null( $value ) ) {
				$localSettings[$var] = $value;
			}
		}
		return $localSettings;
	}

	/**
	 * Retrieves a configuration setting for a given wiki, forced to a boolean.
	 * @param string $setting ID of the setting name to retrieve
	 * @param string $wiki Wiki ID of the wiki in question.
	 * @param string $suffix The suffix of the wiki in question.
	 * @param array $wikiTags The tags assigned to the wiki.
	 * @return bool The value of the setting requested.
	 */
	public function getBool( $setting, $wiki, $suffix = null, $wikiTags = array() ) {
		return (bool)$this->get( $setting, $wiki, $suffix, array(), $wikiTags );
	}

	/**
	 * Retrieves an array of local databases
	 *
	 * @return array
	 */
	function &getLocalDatabases() {
		return $this->wikis;
	}

	/**
	 * Retrieves the value of a given setting, and places it in a variable passed by reference.
	 * @param string $setting ID of the setting name to retrieve
	 * @param string $wiki Wiki ID of the wiki in question.
	 * @param string $suffix The suffix of the wiki in question.
	 * @param array $var Reference The variable to insert the value into.
	 * @param array $params List of parameters. $.'key' is replaced by $value in all returned data.
	 * @param array $wikiTags The tags assigned to the wiki.
	 */
	public function extractVar( $setting, $wiki, $suffix, &$var,
		$params = array(), $wikiTags = array()
	) {
		$value = $this->get( $setting, $wiki, $suffix, $params, $wikiTags );
		if ( !is_null( $value ) ) {
			$var = $value;
		}
	}

	/**
	 * Retrieves the value of a given setting, and places it in its corresponding global variable.
	 * @param string $setting ID of the setting name to retrieve
	 * @param string $wiki Wiki ID of the wiki in question.
	 * @param string $suffix The suffix of the wiki in question.
	 * @param array $params List of parameters. $.'key' is replaced by $value in all returned data.
	 * @param array $wikiTags The tags assigned to the wiki.
	 */
	public function extractGlobal( $setting, $wiki, $suffix = null,
		$params = array(), $wikiTags = array()
	) {
		$params = $this->mergeParams( $wiki, $suffix, $params, $wikiTags );
		$this->extractGlobalSetting( $setting, $wiki, $params );
	}

	/**
	 * @param string $setting
	 * @param string $wiki
	 * @param array $params
	 */
	public function extractGlobalSetting( $setting, $wiki, $params ) {
		$value = $this->getSetting( $setting, $wiki, $params );
		if ( !is_null( $value ) ) {
			if ( substr( $setting, 0, 1 ) == '+' && is_array( $value ) ) {
				$setting = substr( $setting, 1 );
				if ( is_array( $GLOBALS[$setting] ) ) {
					$GLOBALS[$setting] = self::arrayMerge( $GLOBALS[$setting], $value );
				} else {
					$GLOBALS[$setting] = $value;
				}
			} else {
				$GLOBALS[$setting] = $value;
			}
		}
	}

	/**
	 * Retrieves the values of all settings, and places them in their corresponding global variables.
	 * @param string $wiki Wiki ID of the wiki in question.
	 * @param string $suffix The suffix of the wiki in question.
	 * @param array $params List of parameters. $.'key' is replaced by $value in all returned data.
	 * @param array $wikiTags The tags assigned to the wiki.
	 */
	public function extractAllGlobals( $wiki, $suffix = null, $params = array(),
		$wikiTags = array()
	) {
		$params = $this->mergeParams( $wiki, $suffix, $params, $wikiTags );
		foreach ( $this->settings as $varName => $setting ) {
			$this->extractGlobalSetting( $varName, $wiki, $params );
		}
	}

	/**
	 * Return specific settings for $wiki
	 * See the documentation of self::$siteParamsCallback for more in-depth
	 * documentation about this function
	 *
	 * @param string $wiki
	 * @return array
	 */
	protected function getWikiParams( $wiki ) {
		static $default = array(
			'suffix' => null,
			'lang' => null,
			'tags' => array(),
			'params' => array(),
		);

		if ( !is_callable( $this->siteParamsCallback ) ) {
			return $default;
		}

		$ret = call_user_func_array( $this->siteParamsCallback, array( $this, $wiki ) );
		# Validate the returned value
		if ( !is_array( $ret ) ) {
			return $default;
		}

		foreach ( $default as $name => $def ) {
			if ( !isset( $ret[$name] ) || ( is_array( $default[$name] ) && !is_array( $ret[$name] ) ) ) {
				$ret[$name] = $default[$name];
			}
		}

		return $ret;
	}

	/**
	 * Merge params between the ones passed to the function and the ones given
	 * by self::$siteParamsCallback for backward compatibility
	 * Values returned by self::getWikiParams() have the priority.
	 *
	 * @param string $wiki Wiki ID of the wiki in question.
	 * @param string $suffix The suffix of the wiki in question.
	 * @param array $params List of parameters. $.'key' is replaced by $value in
	 *   all returned data.
	 * @param array $wikiTags The tags assigned to the wiki.
	 * @return array
	 */
	protected function mergeParams( $wiki, $suffix, array $params, array $wikiTags ) {
		$ret = $this->getWikiParams( $wiki );

		if ( is_null( $ret['suffix'] ) ) {
			$ret['suffix'] = $suffix;
		}

		$ret['tags'] = array_unique( array_merge( $ret['tags'], $wikiTags ) );

		$ret['params'] += $params;

		// Automatically fill that ones if needed
		if ( !isset( $ret['params']['lang'] ) && !is_null( $ret['lang'] ) ) {
			$ret['params']['lang'] = $ret['lang'];
		}
		if ( !isset( $ret['params']['site'] ) && !is_null( $ret['suffix'] ) ) {
			$ret['params']['site'] = $ret['suffix'];
		}

		return $ret;
	}

	/**
	 * Work out the site and language name from a database name
	 * @param string $db
	 *
	 * @return array
	 */
	public function siteFromDB( $db ) {
		// Allow override
		$def = $this->getWikiParams( $db );
		if ( !is_null( $def['suffix'] ) && !is_null( $def['lang'] ) ) {
			return array( $def['suffix'], $def['lang'] );
		}

		$site = null;
		$lang = null;
		foreach ( $this->suffixes as $altSite => $suffix ) {
			if ( $suffix === '' ) {
				$site = '';
				$lang = $db;
				break;
			} elseif ( substr( $db, -strlen( $suffix ) ) == $suffix ) {
				$site = is_numeric( $altSite ) ? $suffix : $altSite;
				$lang = substr( $db, 0, strlen( $db ) - strlen( $suffix ) );
				break;
			}
		}
		$lang = str_replace( '_', '-', $lang );
		return array( $site, $lang );
	}

	/**
	 * Get the resolved (post-setup) configuration of a potentially foreign wiki.
	 * For foreign wikis, this is expensive, and only works if maintenance
	 * scripts are setup to handle the --wiki parameter such as in wiki farms.
	 *
	 * @param string $wiki
	 * @param array|string $settings A setting name or array of setting names
	 * @return mixed|mixed[] Array if $settings is an array, otherwise the value
	 * @throws MWException
	 * @since 1.21
	 */
	public function getConfig( $wiki, $settings ) {
		global $IP;

		$multi = is_array( $settings );
		$settings = (array)$settings;
		if ( $wiki === wfWikiID() ) { // $wiki is this wiki
			$res = array();
			foreach ( $settings as $name ) {
				if ( !preg_match( '/^wg[A-Z]/', $name ) ) {
					throw new MWException( "Variable '$name' does start with 'wg'." );
				} elseif ( !isset( $GLOBALS[$name] ) ) {
					throw new MWException( "Variable '$name' is not set." );
				}
				$res[$name] = $GLOBALS[$name];
			}
		} else { // $wiki is a foreign wiki
			if ( isset( $this->cfgCache[$wiki] ) ) {
				$res = array_intersect_key( $this->cfgCache[$wiki], array_flip( $settings ) );
				if ( count( $res ) == count( $settings ) ) {
					return $multi ? $res : current( $res ); // cache hit
				}
			} elseif ( !in_array( $wiki, $this->wikis ) ) {
				throw new MWException( "No such wiki '$wiki'." );
			} else {
				$this->cfgCache[$wiki] = array();
			}
			$retVal = 1;
			$cmd = wfShellWikiCmd(
				"$IP/maintenance/getConfiguration.php",
				array(
					'--wiki', $wiki,
					'--settings', implode( ' ', $settings ),
					'--format', 'PHP'
				)
			);
			// ulimit5.sh breaks this call
			$data = trim( wfShellExec( $cmd, $retVal, array(), array( 'memory' => 0 ) ) );
			if ( $retVal != 0 || !strlen( $data ) ) {
				throw new MWException( "Failed to run getConfiguration.php." );
			}
			$res = unserialize( $data );
			if ( !is_array( $res ) ) {
				throw new MWException( "Failed to unserialize configuration array." );
			}
			$this->cfgCache[$wiki] = $this->cfgCache[$wiki] + $res;
		}

		return $multi ? $res : current( $res );
	}

	/**
	 * Returns true if the given vhost is handled locally.
	 * @param string $vhost
	 * @return bool
	 */
	public function isLocalVHost( $vhost ) {
		return in_array( $vhost, $this->localVHosts );
	}

	/**
	 * Merge multiple arrays together.
	 * On encountering duplicate keys, merge the two, but ONLY if they're arrays.
	 * PHP's array_merge_recursive() merges ANY duplicate values into arrays,
	 * which is not fun
	 *
	 * @param array $array1
	 *
	 * @return array
	 */
	static function arrayMerge( $array1/* ... */ ) {
		$out = $array1;
		$argsCount = func_num_args();
		for ( $i = 1; $i < $argsCount; $i++ ) {
			foreach ( func_get_arg( $i ) as $key => $value ) {
				if ( isset( $out[$key] ) && is_array( $out[$key] ) && is_array( $value ) ) {
					$out[$key] = self::arrayMerge( $out[$key], $value );
				} elseif ( !isset( $out[$key] ) || !$out[$key] && !is_numeric( $key ) ) {
					// Values that evaluate to true given precedence, for the
					// primary purpose of merging permissions arrays.
					$out[$key] = $value;
				} elseif ( is_numeric( $key ) ) {
					$out[] = $value;
				}
			}
		}

		return $out;
	}

	public function loadFullData() {
		if ( $this->fullLoadCallback && !$this->fullLoadDone ) {
			call_user_func( $this->fullLoadCallback, $this );
			$this->fullLoadDone = true;
		}
	}
}