<?php
# Convert from the old links schema (string->ID) to the new schema (ID->ID)
# This hasn't been thoroughly tested yet.

# The wiki should be put into read-only mode while this script executes

require_once( "commandLine.inc" );
# the below should probably be moved into commandLine.inc at some point
require_once( "../AdminSettings.php" );

$numRows = $tuplesAdded = $numBadLinks = $curRowsRead = 0; #counters etc
$totalTuplesInserted = 0; # total tuples INSERTed into links_temp
$reportCurReadProgress = true; #whether or not to give progress reports while reading IDs from cur table
$curReadReportInterval = 1000; #number of rows between progress reports
$reportLinksConvProgress = true; #whether or not to give progress reports during conversion
$linksConvInsertInterval = 1000; #number of rows between INSERTs and, optionally, reports
$initialRowOffset = 0;
$finalRowOffset = 0; # not used yet; highest row number from links table to process
$createTemporaryTable = 1; # create a temporary table to hold new links table during conv process
$overwriteLinksTable = 1; # overwrite the old links table with the new one

$res = wfQuery( "SELECT COUNT(*) AS count FROM links", DB_WRITE );
$row = wfFetchObject($res);
$numRows = $row->count;
wfFreeResult( $res );

if ( $numRows == 0 ) {
	print "No rows to convert. Updating schema...\n";
	createTempTable();
} else {
	$row = wfFetchObject( $res );
	if ( is_numeric( $row->l_from ) ) {
		print "Schema already converted\n";
		exit;
	}

	# Create a title -> cur_id map
	print "Loading IDs from cur table...";
	wfBufferSQLResults( false );
	$res = wfQuery( "SELECT cur_namespace,cur_title,cur_id FROM cur", DB_WRITE );
	$ids = array();

	while ( $row = wfFetchObject( $res ) ) {
		$title = $row->cur_title;
		if ( $row->cur_namespace ) {
			$title = $wgLang->getNsText( $row->cur_namespace ) . ":$title";
		}
		$ids[$title] = $row->cur_id;
		$curRowsRead++;
		if ($reportCurReadProgress) {
			if (($curRowsRead % $curReadReportInterval) == 0) {
				print "\t$curRowsRead rows of cur table read.\n";	
			}
		}
	}
	wfFreeResult( $res );
	wfBufferSQLResults( true );
	print "Finished loading IDs.\n";
	if ( $createTemporaryTable ) {
		# Create temporary table which will become the new links table.
		createTempTable();
	}
	
	# Now, step through the links table (in chunks of $linksConvInsertInterval rows),
	# convert, and write to the new table.
	print "Processing $numRows rows from links table...\n";
	for ($rowOffset = $initialRowOffset; $rowOffset < $numRows; $rowOffset += $linksConvInsertInterval) {
		$sqlRead = "SELECT * FROM links LIMIT $linksConvInsertInterval OFFSET $rowOffset";
		$res = wfQuery($sqlRead, DB_READ);
		$sqlWrite = array("INSERT IGNORE INTO links_temp(l_from,l_to) VALUES ");
		$tuplesAdded = 0; # no tuples added to INSERT yet
		while ( $row = wfFetchObject($res) ) {
			$fromTitle = $row->l_from;
			if ( array_key_exists( $fromTitle, $ids ) ) { # valid title
				$from = $ids[$fromTitle];
				$to = $row->l_to;
				if ( $tuplesAdded != 0 ) {
					$sqlWrite[] = ",";
				}
				$sqlWrite[] = "($from,$to)";
				$tuplesAdded++;				
			} else { # invalid title
				$numBadLinks++;
			}
		}
		wfFreeResult($res);
		#print "rowOffset: $rowOffset\ttuplesAdded: $tuplesAdded\tnumBadLinks: $numBadLinks\n";
		if ( $tuplesAdded != 0  ) {
			if ($reportLinksConvProgress)
				print "Inserting $tuplesAdded tuples into links_temp...";
			wfQuery( implode("",$sqlWrite) , DB_WRITE );
			$totalTuplesInserted += $tuplesAdded;
			if ($reportLinksConvProgress)
				print " done. Total $totalTuplesInserted tuples inserted.\n";
		}
	}
	print "$totalTuplesInserted valid titles and $numBadLinks invalid titles were processed.\n";
}

if ( $overwriteLinksTable ) {
	$dbConn = Database::newFromParams( $wgDBserver, $wgDBadminuser, $wgDBadminpassword, $wgDBname );
	if (!($dbConn->isOpen())) {
		print "Opening connection to database failed.\n";
		exit;
	}
	# Check for existing links_backup, and delete it if it exists.
	print "Dropping backup links table if it exists...";
	$dbConn->query( "DROP TABLE IF EXISTS links_backup", DB_WRITE);
	print " done.\n";
	
	# Swap in the new table, and move old links table to links_backup
	print "Swapping tables 'links' to 'links_backup'; 'links_temp' to 'links'...";
	$dbConn->query( "RENAME TABLE links TO links_backup, links_temp TO links", DB_WRITE );
	print " done.\n";
	
	$dbConn->close();
	print "Conversion complete. The old table remains at links_backup;\n";
	print "delete at your leisure.\n";
} else {
	print "Conversion complete.\n";
}

function createTempTable() {
	global $wgDBserver, $wgDBadminuser, $wgDBadminpassword, $wgDBname;
	$dbConn = Database::newFromParams( $wgDBserver, $wgDBadminuser, $wgDBadminpassword, $wgDBname );
	
	if (!($dbConn->isOpen())) {
		print "Opening connection to database failed.\n";
		exit;
	}
	
	print "Dropping temporary links table if it exists...";
	$dbConn->query( "DROP TABLE IF EXISTS links_temp", DB_WRITE);
	print " done.\n";
	
	print "Creating temporary links table...";
	$dbConn->query( "CREATE TABLE links_temp (
	  l_from int(8) unsigned NOT NULL default '0',
	  l_to int(8) unsigned NOT NULL default '0',
	  UNIQUE KEY l_from(l_from,l_to),
	  KEY (l_to))", DB_WRITE);
	print " done.\n";
}
?>