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<?php
/**
* SemanticScuttle - your social bookmark manager.
*
* PHP version 5.
*
* @category Bookmarking
* @package SemanticScuttle
* @author Christian Weiske <cweiske@cweiske.de>
* @license GPL http://www.gnu.org/licenses/gpl.html
* @link http://sourceforge.net/projects/semanticscuttle
*/
/**
* SemanticScuttle voting system.
*
* Each registered user in SemanticScuttle may vote
* for or against a bookmark, counting +1 or -1.
* The sum of all votes determines the "voting" of a bookmark.
* Every user is equal in voting. Each vote is tied to a user.
*
* @internal
* Votes are saved in a separate "votes" table.
* Additionally to that, the voting and number of votes
* of a bookmark is also stored in the bookmarks table.
* This is done to make sure lookups are really fast, since
* every bookmark in a list shows its voting.
*
* @category Bookmarking
* @package SemanticScuttle
* @author Christian Weiske <cweiske@cweiske.de>
* @license GPL http://www.gnu.org/licenses/gpl.html
* @link http://sourceforge.net/projects/semanticscuttle
*/
class SemanticScuttle_Service_Vote extends SemanticScuttle_DbService
{
/**
* Returns the single service instance
*
* @param sql_db $db Database object
*
* @return SemanticScuttle_Service_Vote
*/
public static function getInstance($db)
{
static $instance;
if (!isset($instance)) {
$instance = new self($db);
}
return $instance;
}
/**
* Create a new instance.
*
* @param sql_db $db Database object
*/
protected function __construct($db)
{
$this->db = $db;
$this->tablename = $GLOBALS['tableprefix'] . 'votes';
}
/**
* Returns the sum of votes for the given bookmark.
*
* @internal
* Uses the "votes" table to retrieve the votes, which
* has high costs. It is more efficient to get the sum of
* all votes for a bookmark from the bookmarks table,
* field bVoting.
*
* @param integer $bookmark Bookmark ID
*
* @return integer Vote (can be positive, 0 or negative)
*/
public function getVoting($bookmark)
{
$query = 'SELECT SUM(vote) as sum FROM ' . $this->getTableName()
. ' WHERE bid = "' . $this->db->sql_escape($bookmark) . '"';
if (!($dbres = $this->db->sql_query_limit($query, 1, 0))) {
message_die(
GENERAL_ERROR, 'Could not get voting',
'', __LINE__, __FILE__, $query, $this->db
);
//FIXME: throw exception
}
$row = $this->db->sql_fetchrow($dbres);
$this->db->sql_freeresult($dbres);
return (int)$row['sum'];
}//public function getVoting(..)
/**
* Returns the number of users that voted for or
* against the given bookmark.
*
* @internal
* This method uses the votes table to calculate the
* number of votes for a bookmark. In normal life, it
* is more efficient to use the "bVotes" field in the
* bookmarks table.
*
* @param integer $bookmark Bookmark ID
*
* @return integer Number of votes
*/
public function getVotes($bookmark)
{
$query = 'SELECT COUNT(vote) as count FROM '
. $this->getTableName()
. ' WHERE bid = "' . $this->db->sql_escape($bookmark) . '"';
if (!($dbres = $this->db->sql_query_limit($query, 1, 0))) {
message_die(
GENERAL_ERROR, 'Could not get vote count',
'', __LINE__, __FILE__, $query, $this->db
);
//FIXME: throw exception
}
$row = $this->db->sql_fetchrow($dbres);
$this->db->sql_freeresult($dbres);
return (int)$row['count'];
}
/**
* Returns if the user has already voted for
* the given bookmark.
*
* @param integer $bookmark Bookmark ID
* @param integer $user User ID
*
* @return boolean True if the user has already voted
*/
public function hasVoted($bookmark, $user)
{
$query = 'SELECT COUNT(vote) as count FROM '
. $this->getTableName()
. ' WHERE'
. ' bid = "' . $this->db->sql_escape($bookmark) . '"'
. ' AND uid = "' . $this->db->sql_escape($user) . '"';
if (!($dbres = $this->db->sql_query_limit($query, 1, 0))) {
message_die(
GENERAL_ERROR, 'Could not get vote count',
'', __LINE__, __FILE__, $query, $this->db
);
//FIXME: throw exception
}
$row = $this->db->sql_fetchrow($dbres);
$this->db->sql_freeresult($dbres);
return (int)$row['count'] == 1;
}
/**
* Returns the actual vote the given user
* gave the bookmark.
*
* @param integer $bookmark Bookmark ID
* @param integer $user User ID
*
* @return integer Either 1 or -1, null when not voted.
*/
public function getVote($bookmark, $user)
{
$query = 'SELECT vote FROM ' . $this->getTableName()
. ' WHERE'
. ' bid = "' . $this->db->sql_escape($bookmark) . '"'
. ' AND uid = "' . $this->db->sql_escape($user) . '"';
if (!($dbres = $this->db->sql_query_limit($query, 1, 0))) {
message_die(
GENERAL_ERROR, 'Could not get vote count',
'', __LINE__, __FILE__, $query, $this->db
);
//FIXME: throw exception
}
$row = $this->db->sql_fetchrow($dbres);
$this->db->sql_freeresult($dbres);
if (!$row) {
return null;
}
return $row['vote'];
}
/**
* Let a user vote for the bookmark.
*
* @internal
* We check if voting is enabled or not,
* and if the user has already voted.
* It is up to the calling code to make sure
* the user is authorized to vote.
*
* @param integer $bookmark Bookmark ID
* @param integer $user User ID
* @param integer $vote 1 or -1
*
* @return boolean True if the vote was saved,
* false if there was a problem
* (i.e. already voted)
*/
public function vote($bookmark, $user, $vote = 1)
{
if ($GLOBALS['enableVoting'] == false) {
return false;
}
if ($vote != -1 && $vote != 1) {
return false;
}
if ($this->hasVoted($bookmark, $user)) {
$this->removeVote($bookmark, $user);
}
$res = $this->db->sql_query(
'INSERT INTO ' . $this->getTableName()
. ' SET'
. ' bid = ' . (int)$bookmark
. ',uid = ' . (int)$user
. ',vote = ' . (int)$vote
);
//FIXME: check for sql error
$this->db->sql_freeresult($res);
//update bookmark table
$bm = SemanticScuttle_Service_Factory::get('Bookmark');
$res = $this->db->sql_query(
$sql='UPDATE ' . $bm->getTableName()
. ' SET bVoting = bVoting + ' . (int)$vote
. ' , bVotes = bVotes + 1'
. ' WHERE bId = ' . (int)$bookmark
);
$this->db->sql_freeresult($res);
return true;
}
/**
* Removes a vote from the database
*
* @param integer $bookmark Bookmark ID
* @param integer $user User ID
*
* @return boolean True if all went well, false if not
*/
protected function removeVote($bookmark, $user)
{
$vote = $this->getVote($bookmark, $user);
if ($vote === null) {
return false;
}
//remove from votes table
$query = 'DELETE FROM ' . $this->getTableName()
. ' WHERE bId = ' . (int)$bookmark
. ' AND uId = ' . (int)$user;
$this->db->sql_query($query);
//change voting sum in bookmarks table
$bm = SemanticScuttle_Service_Factory::get('Bookmark');
$res = $this->db->sql_query(
$sql='UPDATE ' . $bm->getTableName()
. ' SET bVoting = bVoting - ' . (int)$vote
. ' , bVotes = bVotes - 1'
. ' WHERE bId = ' . (int)$bookmark
);
$this->db->sql_freeresult($res);
return true;
}
/**
* Re-calculates all votings for all bookmarks
* and updates the voting values in the bookmarks
* table.
* This is mainly meant to be an administrative method
* to fix a broken database.
*
* @return void
*/
public function rewriteVotings()
{
$bm = SemanticScuttle_Service_Factory::get('Bookmark');
$query = 'UPDATE ' . $bm->getTableName() . ' as B SET bVoting = '
. '(SELECT SUM(vote) FROM ' . $this->getTableName() . ' as V'
. ' WHERE V.bId = B.bId GROUP BY bid)'
. ', bVotes = '
. '(SELECT COUNT(vote) FROM ' . $this->getTableName() . ' as V'
. ' WHERE V.bId = B.bId GROUP BY bid)';
$this->db->sql_query($query);
}
/**
* Delete all votes from the database table.
* Used in unit tests.
*
* @return void
*/
public function deleteAll()
{
$query = 'TRUNCATE TABLE `'. $this->getTableName() .'`';
$this->db->sql_query($query);
}
}
?>
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