<?php
$files = 'Thu Dec 11 17:53:01 PST 2008    a@facebook.com    b@facebook.com
Thu Dec 11 17:53:02 PST 2008    b@facebook.com    a@facebook.com
Thu Dec 11 17:53:03 PST 2008    a@facebook.com    e@facebook.com
Thu Dec 11 17:53:04 PST 2008    e@facebook.com    a@facebook.com
Thu Dec 11 17:53:05 PST 2008    e@facebook.com    d@facebook.com
Thu Dec 11 17:53:06 PST 2008    d@facebook.com    e@facebook.com
Thu Dec 11 17:53:04 PST 2008    d@facebook.com    a@facebook.com
Thu Dec 11 17:53:04 PST 2008    a@facebook.com    d@facebook.com
Thu Dec 11 17:53:04 PST 2008    b@facebook.com    d@facebook.com
Thu Dec 11 17:53:04 PST 2008    d@facebook.com    b@facebook.com
Thu Dec 11 17:53:04 PST 2008    b@facebook.com    c@facebook.com
Thu Dec 11 17:53:04 PST 2008    c@facebook.com    b@facebook.com
';

$file = 'Thu Dec 11 17:53:01 PST 2008    a@facebook.com    b@facebook.com
Thu Dec 11 17:53:02 PST 2008    b@facebook.com    a@facebook.com
Thu Dec 11 17:53:03 PST 2008    a@facebook.com    c@facebook.com
Thu Dec 11 17:53:04 PST 2008    c@facebook.com    a@facebook.com
Thu Dec 11 17:53:05 PST 2008    b@facebook.com    c@facebook.com
Thu Dec 11 17:53:06 PST 2008    c@facebook.com    b@facebook.com
Thu Dec 11 17:53:07 PST 2008    d@facebook.com    e@facebook.com
Thu Dec 11 17:53:08 PST 2008    e@facebook.com    d@facebook.com
Thu Dec 11 17:53:09 PST 2008    d@facebook.com    f@facebook.com
Thu Dec 11 17:53:10 PST 2008    f@facebook.com    d@facebook.com
Thu Dec 11 17:53:11 PST 2008    e@facebook.com    f@facebook.com
Thu Dec 11 17:53:12 PST 2008    f@facebook.com    e@facebook.com
';

$logs = explode("\n", $file);

$interaction = array();
foreach( $logs as $key )
{
	if( preg_match( '/(.*?)\\s+([\\w-+]+(?:\\.[\\w-+]+)*@(?:[\\w-]+\\.)+[a-zA-Z]{2,7})\\s+([\\w-+]+(?:\\.[\\w-+]+)*@(?:[\\w-]+\\.)+[a-zA-Z]{2,7})/i', $key, $matches ) )
	{
		if( empty( $interaction[ $matches[2] ] ) ) $interaction[ $matches[2] ] = array( $matches[2] );

		$interaction[ $matches[2] ][ $matches[3] ] = $matches[3];
	}
}

$clusters = $count = array();
$i = 0;

foreach( $interaction as $key => $value )
{
	if( count( $value ) < 3 )
	{
		unset( $interaction[ $key ] );
	}

	foreach( $value as $keys )
	{
		if( empty( $interaction[ $keys ] ) || count( $interaction[ $keys ] ) < 3 )
		{
			unset( $interaction[ $key ][ $keys ] );
		}
	}

	$clusters[ $key ] = array();

	unset( $value[0] );

	$clusters[ $key ] = buildClusterTree( $value, array( $key ), $key, 0, $key );
}

$clusterArray = array();
foreach( $count as $key => $value )
{
	$clusterArray[ $key ] = $value[ $key ];

	foreach( $value as $keys => $values )
	{
		$counts[ $key ][ $keys ] = $keys;
	}
}

$finalClusters = $location = array();
$i = 0;
foreach( $clusterArray as $key => $value )
{
	if( $value >= 2 )
	{
		$finalClusters[ $i ] = $counts[$key];

		foreach( $counts[$key] as $keys )
		{
			$location[ $keys ][ $i ] = $i;
		}
	}

	++$i;
}

$heighest = 0;

$amount = array();
foreach( $location as $key => $value )
{
	foreach( $value as $keys => $values )
	{
		$amount[$key][ count( $finalClusters[ $values ] ) ] = $values;
	}
}

$finalCl = array();

function maxValue( $array )
{
	$max = current( $array );

	foreach( $array as $key => $value )
	{
		if( $value > $max )
		{
			$max = $value;
		}
	}

	return $max;
}


foreach( $amount as $key => $value )
{
	$max = maxValue( array_flip( $value ) );

	foreach( $value as $amounts => $id )
	{
		if( $amounts == $max )
		{
			$finalCl[ $id ][ $key ] = $key;
		}
	}
}

foreach( $finalCl as $key => $value )
{
	sort( $value );
	if( count( $value ) < 3 )
	{
		unset( $finalCl[ $key ] );
	} else {
		echo implode( ',', $value ) . "\n";
	}
}

function buildClusterTree( $cluster, $ignore, $parent, $depth, $initial )
{
	global $interaction, $count;

	$clusters = array();

	foreach( $cluster as $key => $value )
	{
		if( in_array( $value, $ignore ) === false  )
		{
			$ignore[] = $value;
			$clusters[ $value ] = buildClusterTree( $interaction[$value], $ignore, $key, ++$depth, $initial );
		} else {
			if( $parent != $value ) $clusters[ $value ] = array();

			if( empty( $count[ $initial ][ $value ] ) ) $count[ $initial ][ $value ] = 1; else $count[ $initial ][ $value ]++;
		}
	}

	return $clusters;
}