<?php
/*
	Question2Answer by Gideon Greenspan and contributors
	http://www.question2answer.org/

	File: qa-include/qa-db-recalc.php
	Description: Database functions for recalculations (clean-up operations)


	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.

	More about this license: http://www.question2answer.org/license.php
*/

	if (!defined('QA_VERSION')) { // don't allow this page to be requested directly from browser
		header('Location: ../');
		exit;
	}

	require_once QA_INCLUDE_DIR.'db/post-create.php';


//	For reindexing pages...

	function qa_db_count_pages()
/*
	Return the number of custom pages currently in the database
*/
	{
		return qa_db_read_one_value(qa_db_query_sub(
			'SELECT COUNT(*) FROM ^pages'
		));
	}


	function qa_db_pages_get_for_reindexing($startpageid, $count)
/*
	Return the information to reindex up to $count pages starting from $startpageid in the database
*/
	{
		return qa_db_read_all_assoc(qa_db_query_sub(
			'SELECT pageid, flags, tags, heading, content FROM ^pages WHERE pageid>=# ORDER BY pageid LIMIT #',
			$startpageid, $count
		), 'pageid');
	}


//	For reindexing posts...

	function qa_db_posts_get_for_reindexing($startpostid, $count)
/*
	Return the information required to reindex up to $count posts starting from $startpostid in the database
*/
	{
		return qa_db_read_all_assoc(qa_db_query_sub(
			"SELECT ^posts.postid, ^posts.title, ^posts.content, ^posts.format, ^posts.tags, ^posts.categoryid, ^posts.type, IF (^posts.type='Q', ^posts.postid, IF(parent.type='Q', parent.postid, grandparent.postid)) AS questionid, ^posts.parentid FROM ^posts LEFT JOIN ^posts AS parent ON ^posts.parentid=parent.postid LEFT JOIN ^posts as grandparent ON parent.parentid=grandparent.postid WHERE ^posts.postid>=# AND ( (^posts.type='Q') OR (^posts.type='A' AND parent.type<=>'Q') OR (^posts.type='C' AND parent.type<=>'Q') OR (^posts.type='C' AND parent.type<=>'A' AND grandparent.type<=>'Q') ) ORDER BY postid LIMIT #",
			$startpostid, $count
		), 'postid');
	}


	function qa_db_prepare_for_reindexing($firstpostid, $lastpostid)
/*
	Prepare posts $firstpostid to $lastpostid for reindexing in the database by removing their prior index entries
*/
	{
		qa_db_query_sub(
			'DELETE FROM ^titlewords WHERE postid>=# AND postid<=#',
			$firstpostid, $lastpostid
		);

		qa_db_query_sub(
			'DELETE FROM ^contentwords WHERE postid>=# AND postid<=#',
			$firstpostid, $lastpostid
		);

		qa_db_query_sub(
			'DELETE FROM ^tagwords WHERE postid>=# AND postid<=#',
			$firstpostid, $lastpostid
		);

		qa_db_query_sub(
			'DELETE FROM ^posttags WHERE postid>=# AND postid<=#',
			$firstpostid, $lastpostid
		);
	}


	function qa_db_truncate_indexes($firstpostid)
/*
	Remove any rows in the database word indexes with postid from $firstpostid upwards
*/
	{
		qa_db_query_sub(
			'DELETE FROM ^titlewords WHERE postid>=#',
			$firstpostid
		);

		qa_db_query_sub(
			'DELETE FROM ^contentwords WHERE postid>=#',
			$firstpostid
		);

		qa_db_query_sub(
			'DELETE FROM ^tagwords WHERE postid>=#',
			$firstpostid
		);

		qa_db_query_sub(
			'DELETE FROM ^posttags WHERE postid>=#',
			$firstpostid
		);
	}


	function qa_db_count_words()
/*
	Return the number of words currently referenced in the database
*/
	{
		return qa_db_read_one_value(qa_db_query_sub(
			'SELECT COUNT(*) FROM ^words'
		));
	}


	function qa_db_words_prepare_for_recounting($startwordid, $count)
/*
	Return the ids of up to $count words in the database starting from $startwordid
*/
	{
		return qa_db_read_all_values(qa_db_query_sub(
			'SELECT wordid FROM ^words WHERE wordid>=# ORDER BY wordid LIMIT #',
			$startwordid, $count
		));
	}


	function qa_db_words_recount($firstwordid, $lastwordid)
/*
	Recalculate the cached counts for words $firstwordid to $lastwordid in the database
*/
	{
		qa_db_query_sub(
			'UPDATE ^words AS x, (SELECT ^words.wordid, COUNT(^titlewords.wordid) AS titlecount FROM ^words LEFT JOIN ^titlewords ON ^titlewords.wordid=^words.wordid WHERE ^words.wordid>=# AND ^words.wordid<=# GROUP BY wordid) AS a SET x.titlecount=a.titlecount WHERE x.wordid=a.wordid',
			$firstwordid, $lastwordid
		);

		qa_db_query_sub(
			'UPDATE ^words AS x, (SELECT ^words.wordid, COUNT(^contentwords.wordid) AS contentcount FROM ^words LEFT JOIN ^contentwords ON ^contentwords.wordid=^words.wordid WHERE ^words.wordid>=# AND ^words.wordid<=# GROUP BY wordid) AS a SET x.contentcount=a.contentcount WHERE x.wordid=a.wordid',
			$firstwordid, $lastwordid
		);

		qa_db_query_sub(
			'UPDATE ^words AS x, (SELECT ^words.wordid, COUNT(^tagwords.wordid) AS tagwordcount FROM ^words LEFT JOIN ^tagwords ON ^tagwords.wordid=^words.wordid WHERE ^words.wordid>=# AND ^words.wordid<=# GROUP BY wordid) AS a SET x.tagwordcount=a.tagwordcount WHERE x.wordid=a.wordid',
			$firstwordid, $lastwordid
		);

		qa_db_query_sub(
			'UPDATE ^words AS x, (SELECT ^words.wordid, COUNT(^posttags.wordid) AS tagcount FROM ^words LEFT JOIN ^posttags ON ^posttags.wordid=^words.wordid WHERE ^words.wordid>=# AND ^words.wordid<=# GROUP BY wordid) AS a SET x.tagcount=a.tagcount WHERE x.wordid=a.wordid',
			$firstwordid, $lastwordid
		);

		qa_db_query_sub(
			'DELETE FROM ^words WHERE wordid>=# AND wordid<=# AND titlecount=0 AND contentcount=0 AND tagwordcount=0 AND tagcount=0',
			$firstwordid, $lastwordid
		);
	}


//	For recalculating numbers of votes and answers for questions...

	function qa_db_posts_get_for_recounting($startpostid, $count)
/*
	Return the ids of up to $count posts in the database starting from $startpostid
*/
	{
		return qa_db_read_all_values(qa_db_query_sub(
			'SELECT postid FROM ^posts WHERE postid>=# ORDER BY postid LIMIT #',
			$startpostid, $count
		));
	}


	function qa_db_posts_votes_recount($firstpostid, $lastpostid)
/*
	Recalculate the cached vote counts for posts $firstpostid to $lastpostid in the database
*/
	{
		qa_db_query_sub(
			'UPDATE ^posts AS x, (SELECT ^posts.postid, COALESCE(SUM(GREATEST(0,^uservotes.vote)),0) AS upvotes, -COALESCE(SUM(LEAST(0,^uservotes.vote)),0) AS downvotes, COALESCE(SUM(IF(^uservotes.flag, 1, 0)),0) AS flagcount FROM ^posts LEFT JOIN ^uservotes ON ^uservotes.postid=^posts.postid WHERE ^posts.postid>=# AND ^posts.postid<=# GROUP BY postid) AS a SET x.upvotes=a.upvotes, x.downvotes=a.downvotes, x.netvotes=a.upvotes-a.downvotes, x.flagcount=a.flagcount WHERE x.postid=a.postid',
			$firstpostid, $lastpostid
		);

		qa_db_hotness_update($firstpostid, $lastpostid);
	}


	function qa_db_posts_answers_recount($firstpostid, $lastpostid)
/*
	Recalculate the cached answer counts for posts $firstpostid to $lastpostid in the database, along with the highest netvotes of any of their answers
*/
	{
		require_once QA_INCLUDE_DIR.'db/hotness.php';

		qa_db_query_sub(
			'UPDATE ^posts AS x, (SELECT parents.postid, COUNT(children.postid) AS acount, COALESCE(GREATEST(MAX(children.netvotes), 0), 0) AS amaxvote FROM ^posts AS parents LEFT JOIN ^posts AS children ON parents.postid=children.parentid AND children.type=\'A\' WHERE parents.postid>=# AND parents.postid<=# GROUP BY postid) AS a SET x.acount=a.acount, x.amaxvote=a.amaxvote WHERE x.postid=a.postid',
			$firstpostid, $lastpostid
		);

		qa_db_hotness_update($firstpostid, $lastpostid);
	}


//	For recalculating user points...

	function qa_db_users_get_for_recalc_points($startuserid, $count)
/*
	Return the ids of up to $count users in the database starting from $startuserid
	If using single sign-on integration, base this on user activity rather than the users table which we don't have
*/
	{
		if (QA_FINAL_EXTERNAL_USERS)
			return qa_db_read_all_values(qa_db_query_sub(
				'SELECT userid FROM ((SELECT DISTINCT userid FROM ^posts WHERE userid>=# ORDER BY userid LIMIT #) UNION (SELECT DISTINCT userid FROM ^uservotes WHERE userid>=# ORDER BY userid LIMIT #)) x ORDER BY userid LIMIT #',
				$startuserid, $count, $startuserid, $count, $count
			));
		else
			return qa_db_read_all_values(qa_db_query_sub(
				'SELECT DISTINCT userid FROM ^users WHERE userid>=# ORDER BY userid LIMIT #',
				$startuserid, $count
			));
	}


	function qa_db_users_recalc_points($firstuserid, $lastuserid)
/*
	Recalculate all userpoints columns for users $firstuserid to $lastuserid in the database
*/
	{
		require_once QA_INCLUDE_DIR.'db/points.php';

		$qa_userpoints_calculations=qa_db_points_calculations();

		qa_db_query_sub(
			'DELETE FROM ^userpoints WHERE userid>=# AND userid<=# AND bonus=0', // delete those with no bonus
			$firstuserid, $lastuserid
		);

		$zeropoints='points=0';
		foreach ($qa_userpoints_calculations as $field => $calculation)
			$zeropoints.=', '.$field.'=0';

		qa_db_query_sub(
			'UPDATE ^userpoints SET '.$zeropoints.' WHERE userid>=# AND userid<=#', // zero out the rest
			$firstuserid, $lastuserid
		);

		if (QA_FINAL_EXTERNAL_USERS)
			qa_db_query_sub(
				'INSERT IGNORE INTO ^userpoints (userid) SELECT DISTINCT userid FROM ^posts WHERE userid>=# AND userid<=# UNION SELECT DISTINCT userid FROM ^uservotes WHERE userid>=# AND userid<=#',
				$firstuserid, $lastuserid, $firstuserid, $lastuserid
			);
		else
			qa_db_query_sub(
				'INSERT IGNORE INTO ^userpoints (userid) SELECT DISTINCT userid FROM ^users WHERE userid>=# AND userid<=#',
				$firstuserid, $lastuserid
			);

		$updatepoints=(int)qa_opt('points_base');

		foreach ($qa_userpoints_calculations as $field => $calculation) {
			qa_db_query_sub(
				'UPDATE ^userpoints, (SELECT userid_src.userid, '.str_replace('~', ' BETWEEN # AND #', $calculation['formula']).' GROUP BY userid) AS results '.
				'SET ^userpoints.'.$field.'=results.'.$field.' WHERE ^userpoints.userid=results.userid',
				$firstuserid, $lastuserid
			);

			$updatepoints.='+('.((int)$calculation['multiple']).'*'.$field.')';
		}

		qa_db_query_sub(
			'UPDATE ^userpoints SET points='.$updatepoints.'+bonus WHERE userid>=# AND userid<=#',
			$firstuserid, $lastuserid
		);
	}


	function qa_db_truncate_userpoints($lastuserid)
/*
	Remove any rows in the userpoints table where userid is greater than $lastuserid
*/
	{
		qa_db_query_sub(
			'DELETE FROM ^userpoints WHERE userid>#',
			$lastuserid
		);
	}


//	For refilling event streams...

	function qa_db_qs_get_for_event_refilling($startpostid, $count)
/*
	Return the ids of up to $count questions in the database starting from $startpostid
*/
	{
		return qa_db_read_all_values(qa_db_query_sub(
			"SELECT postid FROM ^posts WHERE postid>=# AND LEFT(type, 1)='Q' ORDER BY postid LIMIT #",
			$startpostid, $count
		));
	}


//	For recalculating categories...

	function qa_db_posts_get_for_recategorizing($startpostid, $count)
/*
	Return the ids of up to $count posts (including queued/hidden) in the database starting from $startpostid
*/
	{
		return qa_db_read_all_values(qa_db_query_sub(
			"SELECT postid FROM ^posts WHERE postid>=# ORDER BY postid LIMIT #",
			$startpostid, $count
		));
	}


	function qa_db_posts_recalc_categoryid($firstpostid, $lastpostid)
/*
	Recalculate the (exact) categoryid for the posts (including queued/hidden) between $firstpostid and $lastpostid
	in the database, where the category of comments and answers is set by the category of the antecedent question
*/
	{
		qa_db_query_sub(
			"UPDATE ^posts AS x, (SELECT ^posts.postid, IF(LEFT(parent.type, 1)='Q', parent.categoryid, grandparent.categoryid) AS categoryid FROM ^posts LEFT JOIN ^posts AS parent ON ^posts.parentid=parent.postid LEFT JOIN ^posts AS grandparent ON parent.parentid=grandparent.postid WHERE ^posts.postid BETWEEN # AND # AND LEFT(^posts.type, 1)!='Q') AS a SET x.categoryid=a.categoryid WHERE x.postid=a.postid",
			$firstpostid, $lastpostid
		);
	}


	function qa_db_categories_get_for_recalcs($startcategoryid, $count)
/*
	Return the ids of up to $count categories in the database starting from $startcategoryid
*/
	{
		return qa_db_read_all_values(qa_db_query_sub(
			"SELECT categoryid FROM ^categories WHERE categoryid>=# ORDER BY categoryid LIMIT #",
			$startcategoryid, $count
		));
	}


//	For deleting hidden posts...

	function qa_db_posts_get_for_deleting($type, $startpostid=0, $limit=null)
/*
	Return the ids of up to $limit posts of $type that can be deleted from the database (i.e. have no dependents)
*/
	{
		$limitsql=isset($limit) ? (' ORDER BY ^posts.postid LIMIT '.(int)$limit) : '';

		return qa_db_read_all_values(qa_db_query_sub(
			"SELECT ^posts.postid FROM ^posts LEFT JOIN ^posts AS child ON child.parentid=^posts.postid WHERE ^posts.type=$ AND ^posts.postid>=# AND child.postid IS NULL".$limitsql,
			$type.'_HIDDEN', $startpostid
		));
	}


//	For moving blobs between database and disk...

	function qa_db_count_blobs_in_db()
/*
	Return the number of blobs whose content is stored in the database, rather than on disk
*/
	{
		return qa_db_read_one_value(qa_db_query_sub('SELECT COUNT(*) FROM ^blobs WHERE content IS NOT NULL'));
	}


	function qa_db_get_next_blob_in_db($startblobid)
/*
	Return the id, content and format of the first blob whose content is stored in the database starting from $startblobid
*/
	{
		return qa_db_read_one_assoc(qa_db_query_sub(
			'SELECT blobid, content, format FROM ^blobs WHERE blobid>=# AND content IS NOT NULL LIMIT 1',
			$startblobid
		), true);
	}


	function qa_db_count_blobs_on_disk()
/*
	Return the number of blobs whose content is stored on disk, rather than in the database
*/
	{
		return qa_db_read_one_value(qa_db_query_sub('SELECT COUNT(*) FROM ^blobs WHERE content IS NULL'));
	}


	function qa_db_get_next_blob_on_disk($startblobid)
/*
	Return the id and format of the first blob whose content is stored on disk starting from $startblobid
*/
	{
		return qa_db_read_one_assoc(qa_db_query_sub(
			'SELECT blobid, format FROM ^blobs WHERE blobid>=# AND content IS NULL LIMIT 1',
			$startblobid
		), true);
	}


/*
	Omit PHP closing tag to help avoid accidental output
*/
