<?php

/*
 * Created on Sep 7, 2006
 *
 * API for MediaWiki 1.8+
 *
 * Copyright (C) 2006 Yuri Astrakhan <Firstname><Lastname>@gmail.com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 * http://www.gnu.org/copyleft/gpl.html
 */

if (!defined('MEDIAWIKI')) {
	// Eclipse helper - will be ignored in production
	require_once ('ApiBase.php');
}

/**
 * This is a base class for all Query modules.
 * It provides some common functionality such as constructing various SQL queries.
 *
 * @ingroup API
 */
abstract class ApiQueryBase extends ApiBase {

	private $mQueryModule, $mDb, $tables, $where, $fields, $options, $join_conds;

	public function __construct($query, $moduleName, $paramPrefix = '') {
		parent :: __construct($query->getMain(), $moduleName, $paramPrefix);
		$this->mQueryModule = $query;
		$this->mDb = null;
		$this->resetQueryParams();
	}

	/**
	 * Blank the internal arrays with query parameters
	 */
	protected function resetQueryParams() {
		$this->tables = array ();
		$this->where = array ();
		$this->fields = array ();
		$this->options = array ();
		$this->join_conds = array ();
	}

	/**
	 * Add a set of tables to the internal array
	 * @param mixed $tables Table name or array of table names
	 * @param mixed $alias Table alias, or null for no alias. Cannot be used with multiple tables
	 */
	protected function addTables($tables, $alias = null) {
		if (is_array($tables)) {
			if (!is_null($alias))
				ApiBase :: dieDebug(__METHOD__, 'Multiple table aliases not supported');
			$this->tables = array_merge($this->tables, $tables);
		} else {
			if (!is_null($alias))
				$tables = $this->getAliasedName($tables, $alias);
			$this->tables[] = $tables;
		}
	}
	
	/**
	 * Get the SQL for a table name with alias
	 * @param string $table Table name
	 * @param string $alias Alias
	 * @return string SQL
	 */
	protected function getAliasedName($table, $alias) {
		return $this->getDB()->tableName($table) . ' ' . $alias;
	}
	
	/**
	 * Add a set of JOIN conditions to the internal array
	 *
	 * JOIN conditions are formatted as array( tablename => array(jointype, conditions)
	 * e.g. array('page' => array('LEFT JOIN', 'page_id=rev_page'))
	 * @param array $join_conds JOIN conditions
	 */
	protected function addJoinConds($join_conds) {
		if(!is_array($join_conds))
			ApiBase::dieDebug(__METHOD__, 'Join conditions have to be arrays');
		$this->join_conds = array_merge($this->join_conds, $join_conds);
	}

	/**
	 * Add a set of fields to select to the internal array
	 * @param mixed $value Field name or array of field names
	 */
	protected function addFields($value) {
		if (is_array($value))
			$this->fields = array_merge($this->fields, $value);
		else
			$this->fields[] = $value;
	}

	/**
	 * Same as addFields(), but add the fields only if a condition is met
	 * @param mixed $value See addFields()
	 * @param bool $condition If false, do nothing
	 * @return bool $condition
	 */
	protected function addFieldsIf($value, $condition) {
		if ($condition) {
			$this->addFields($value);
			return true;
		}
		return false;
	}

	/**
	 * Add a set of WHERE clauses to the internal array.
	 * Clauses can be formatted as 'foo=bar' or array('foo' => 'bar'),
	 * the latter only works if the value is a constant (i.e. not another field)
	 *
	 * If $value is an empty array, this function does nothing.
	 *
	 * For example, array('foo=bar', 'baz' => 3, 'bla' => 'foo') translates
	 * to "foo=bar AND baz='3' AND bla='foo'"
	 * @param mixed $value String or array
	 */
	protected function addWhere($value) {
		if (is_array($value)) {
			// Sanity check: don't insert empty arrays,
			// Database::makeList() chokes on them
			if ( count( $value ) )
				$this->where = array_merge($this->where, $value);
		}
		else
			$this->where[] = $value;
	}

	/**
	 * Same as addWhere(), but add the WHERE clauses only if a condition is met
	 * @param mixed $value See addWhere()
	 * @param bool $condition If false, do nothing
	 * @return bool $condition
	 */
	protected function addWhereIf($value, $condition) {
		if ($condition) {
			$this->addWhere($value);
			return true;
		}
		return false;
	}

	/**
	 * Equivalent to addWhere(array($field => $value))
	 * @param string $field Field name
	 * @param string $value Value; ignored if null or empty array;
	 */
	protected function addWhereFld($field, $value) {
		// Use count() to its full documented capabilities to simultaneously 
		// test for null, empty array or empty countable object
		if ( count( $value ) )
			$this->where[$field] = $value;
	}

	/**
	 * Add a WHERE clause corresponding to a range, and an ORDER BY
	 * clause to sort in the right direction
	 * @param string $field Field name
	 * @param string $dir If 'newer', sort in ascending order, otherwise sort in descending order
	 * @param string $start Value to start the list at. If $dir == 'newer' this is the lower boundary, otherwise it's the upper boundary
	 * @param string $end Value to end the list at. If $dir == 'newer' this is the upper boundary, otherwise it's the lower boundary
	 */
	protected function addWhereRange($field, $dir, $start, $end) {
		$isDirNewer = ($dir === 'newer');
		$after = ($isDirNewer ? '>=' : '<=');
		$before = ($isDirNewer ? '<=' : '>=');
		$db = $this->getDB();

		if (!is_null($start))
			$this->addWhere($field . $after . $db->addQuotes($start));

		if (!is_null($end))
			$this->addWhere($field . $before . $db->addQuotes($end));

		$order = $field . ($isDirNewer ? '' : ' DESC');
		if (!isset($this->options['ORDER BY']))
			$this->addOption('ORDER BY', $order);
		else
			$this->addOption('ORDER BY', $this->options['ORDER BY'] . ', ' . $order);
	}

	/**
	 * Add an option such as LIMIT or USE INDEX
	 * @param string $name Option name
	 * @param string $value Option value
	 */
	protected function addOption($name, $value = null) {
		if (is_null($value))
			$this->options[] = $name;
		else
			$this->options[$name] = $value;
	}

	/**
	 * Execute a SELECT query based on the values in the internal arrays
	 * @param string $method Function the query should be attributed to. You should usually use __METHOD__ here
	 * @return ResultWrapper
	 */
	protected function select($method) {

		// getDB has its own profileDBIn/Out calls
		$db = $this->getDB();

		$this->profileDBIn();
		$res = $db->select($this->tables, $this->fields, $this->where, $method, $this->options, $this->join_conds);
		$this->profileDBOut();

		return $res;
	}

	/**
	 * Estimate the row count for the SELECT query that would be run if we
	 * called select() right now, and check if it's acceptable.
	 * @return bool true if acceptable, false otherwise
	 */
	protected function checkRowCount() {
		$db = $this->getDB();
		$this->profileDBIn();
		$rowcount = $db->estimateRowCount($this->tables, $this->fields, $this->where, __METHOD__, $this->options);
		$this->profileDBOut();

		global $wgAPIMaxDBRows;
		if($rowcount > $wgAPIMaxDBRows)
			return false;
		return true;
	}

	/**
	 * Add information (title and namespace) about a Title object to a result array
	 * @param array $arr Result array à la ApiResult
	 * @param Title $title Title object
	 * @param string $prefix Module prefix
	 */
	public static function addTitleInfo(&$arr, $title, $prefix='') {
		$arr[$prefix . 'ns'] = intval($title->getNamespace());
		$arr[$prefix . 'title'] = $title->getPrefixedText();
	}

	/**
	 * Override this method to request extra fields from the pageSet
	 * using $pageSet->requestField('fieldName')
	 * @param ApiPageSet $pageSet
	 */
	public function requestExtraData($pageSet) {
	}

	/**
	 * Get the main Query module
	 * @return ApiQuery
	 */
	public function getQuery() {
		return $this->mQueryModule;
	}

	/**
	 * Add a sub-element under the page element with the given page ID
	 * @param int $pageId Page ID
	 * @param array $data Data array à la ApiResult 
	 */
	protected function addPageSubItems($pageId, $data) {
		$result = $this->getResult();
		$result->setIndexedTagName($data, $this->getModulePrefix());
		$result->addValue(array ('query', 'pages', intval($pageId)),
			$this->getModuleName(),
			$data);
	}

	/**
	 * Set a query-continue value
	 * @param $paramName Parameter name
	 * @param $paramValue Parameter value
	 */
	protected function setContinueEnumParameter($paramName, $paramValue) {

		$paramName = $this->encodeParamName($paramName);
		$msg = array( $paramName => $paramValue );
		$this->getResult()->addValue('query-continue', $this->getModuleName(), $msg);
	}

	/**
	 * Get the Query database connection (readonly)
	 * @return Database
	 */
	protected function getDB() {
		if (is_null($this->mDb))
			$this->mDb = $this->getQuery()->getDB();
		return $this->mDb;
	}

	/**
	 * Selects the query database connection with the given name.
	 * If no such connection has been requested before, it will be created.
	 * Subsequent calls with the same $name will return the same connection
	 * as the first, regardless of $db or $groups new values.
	 * @param string $name Name to assign to the database connection
	 * @param int $db One of the DB_* constants
	 * @param array $groups Query groups
	 * @return Database 
	 */
	public function selectNamedDB($name, $db, $groups) {
		$this->mDb = $this->getQuery()->getNamedDB($name, $db, $groups);
	}

	/**
	 * Get the PageSet object to work on
	 * @return ApiPageSet
	 */
	protected function getPageSet() {
		return $this->getQuery()->getPageSet();
	}

	/**
	 * Convert a title to a DB key
	 * @param string $title Page title with spaces
	 * @return string Page title with underscores
	 */
	public function titleToKey($title) {
		# Don't throw an error if we got an empty string
		if(trim($title) == '')
			return '';
		$t = Title::newFromText($title);
		if(!$t)
			$this->dieUsageMsg(array('invalidtitle', $title));
		return $t->getPrefixedDbKey();
	}

	/**
	 * The inverse of titleToKey()
	 * @param string $key Page title with underscores
	 * @return string Page title with spaces
	 */
	public function keyToTitle($key) {
		# Don't throw an error if we got an empty string
		if(trim($key) == '')
			return '';
		$t = Title::newFromDbKey($key);
		# This really shouldn't happen but we gotta check anyway
		if(!$t)
			$this->dieUsageMsg(array('invalidtitle', $key));
		return $t->getPrefixedText();
	}
	
	/**
	 * An alternative to titleToKey() that doesn't trim trailing spaces
	 * @param string $titlePart Title part with spaces
	 * @return string Title part with underscores
	 */
	public function titlePartToKey($titlePart) {
		return substr($this->titleToKey($titlePart . 'x'), 0, -1);
	}
	
	/**
	 * An alternative to keyToTitle() that doesn't trim trailing spaces
	 * @param string $keyPart Key part with spaces
	 * @return string Key part with underscores
	 */
	public function keyPartToTitle($keyPart) {
		return substr($this->keyToTitle($keyPart . 'x'), 0, -1);
	}

	/**
	 * Get version string for use in the API help output
	 * @return string
	 */
	public static function getBaseVersion() {
		return __CLASS__ . ': $Id: ApiQueryBase.php 44461 2008-12-11 19:11:11Z ialex $';
	}
}

/**
 * @ingroup API
 */
abstract class ApiQueryGeneratorBase extends ApiQueryBase {

	private $mIsGenerator;

	public function __construct($query, $moduleName, $paramPrefix = '') {
		parent :: __construct($query, $moduleName, $paramPrefix);
		$this->mIsGenerator = false;
	}

	/**
	 * Switch this module to generator mode. By default, generator mode is
	 * switched off and the module acts like a normal query module.
	 */
	public function setGeneratorMode() {
		$this->mIsGenerator = true;
	}

	/**
	 * Overrides base class to prepend 'g' to every generator parameter
	 */
	public function encodeParamName($paramName) {
		if ($this->mIsGenerator)
			return 'g' . parent :: encodeParamName($paramName);
		else
			return parent :: encodeParamName($paramName);
	}

	/**
	 * Execute this module as a generator
	 * @param $resultPageSet PageSet: All output should be appended to this object
	 */
	public abstract function executeGenerator($resultPageSet);
}
