#!/usr/bin/php
<?php

/*
  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 3 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, see <http://www.gnu.org/licenses/>.
*/

const N="\n";

require(__DIR__.'/../site/mustard/include/gurl.php');

setlocale(LC_ALL,getenv('LANG'));

$opts=array(
	'inifp'=>__DIR__.'/../conf/mustard.ini',
	'startinst'=>'mastodon.social',
	'peersfp'=>__DIR__.'/peers',
	'allpeersfp'=>__DIR__.'/peers.all',
	'restore'=>false,
	'excludefp'=>null,
	'timeout'=>5,
	'verbose'=>false,
	'excludedead'=>false,
	'timezone'=>date_default_timezone_get(),
	'ignorelock'=>false
);

$help='peerscrawl.php
 DESCRIPTION
  This program tries to build a fairly complete list of fediverse instances
  exposing the [instance]/api/v1/instance/peers endpoint.
 SYNOPSIS
  peerscrawl.php [options]
 OPTIONS
  -s, --startinst <domain>
   Defines the first instance to crawl.
   DEFAULT: «'.$opts['startinst'].'»
  -p, --peersfp <file>
   Defines the file into which the ordered list of responding instances
   will be saved.
   DEFAULT: «'.$opts['peersfp'].'»
  -a, --allpeersfp <file>
   Defines the file into which the ordered list of all checked instances
   will be saved.
   DEFAULT: «'.$opts['allpeersfp'].'»
  -I, --ignorelock
   Normally, if its lockfile exists, the program exits with an error before
   doing anything. With this option the lockfile is ignored. Please verify
   that the program is not already running before using it.
  -r, --restore
   If peers file already exists on program’s start it will be loaded into
   memory and each instance it contains will be considered “already
   crawled”, thus allowing to “restore an interrupted crawling session”.
  -e, --excludefp <file>
   Defines a file containing exclusion rules: one regular expression per
   line (empty lines are ignored). Any instance matching any defined regex
   will be ignored by the program. Changes made to this file during program
   execution will be taken into account.
  -t, --timeout <seconds>
   Defines the timeout in seconds for every connection attempt.
   DEFAULT: «'.$opts['timeout'].'»
  -T, --timezone <timezone identifier>
   Defines the timezone for displaying localized values for dates and times.
   DEFAULT on this system: «'.$opts['timezone'].'»
   Note: if you want localized format as well set LANG environment variable.
  -L, --tzlist
   List all valid timezones and exit.
  -E, --excludedead
   Exclude instances marked as "Dead" in the database.
  -v, --verbose
   Be more verbose.
  -h, --help
   Show this help text and exit.

  This program comes with ABSOLUTELY NO WARRANTY; for details see the source.
  This is free software, and you are welcome to redistribute it under
  certain conditions; see <http://www.gnu.org/licenses/> for details.'.N;

for ($i=1; $i<$argc; $i++) {
	if (substr($argv[$i],0,1)=='-') {
		switch($argv[$i]) {
			case '-s':
			case '--startinst':
			if ($i+1>=$argc)
				mexit('Option «'.$argv[$i].'» has to be followed by a domain name (use «-h» for more info).'.N,1);
			$i++;
			$opts['startinst']=$argv[$i];
			break;
			case '-p':
			case '--peersfp':
			if ($i+1>=$argc)
				mexit('Option «'.$argv[$i].'» has to be followed by a file’s path (use «-h» for more info).'.N,1);
			$i++;
			$opts['peersfp']=$argv[$i];
			break;
			case '-a':
			case '--allpeersfp':
			if ($i+1>=$argc)
				mexit('Option «'.$argv[$i].'» has to be followed by a file’s path (use «-h» for more info).'.N,1);
			$i++;
			$opts['allpeersfp']=$argv[$i];
			break;
			case '-r':
			case '--restore':
			$opts['restore']=true;
			break;
			case '-I':
			case '--ignorelock':
			$opts['ignorelock']=true;
			break;
			case '-e':
			case '--excludefp':
			if ($i+1>=$argc || !file_exists($argv[$i+1]) || !is_file($argv[$i+1]) || !is_readable($argv[$i+1]))
				mexit('Option «'.$argv[$i].'» has to be followed by an existing, readable file’s path (use «-h» for more info).'.N,1);
			$i++;
			$opts['excludefp']=$argv[$i];
			break;
			case '-t':
			case '--timeout':
			if ($i+1>=$argc || preg_match('/^[0-9]+$/',$argv[$i+1])!==1)
				mexit('Option «'.$argv[$i].'» has to be followed by a number of seconds (use «-h» for more info).'.N,1);
			$i++;
			$opts['timeout']=$argv[$i]+0;
			break;
			case '-T':
			case '--timezone':
			if ($i+1>=$argc || !@date_default_timezone_set($argv[$i+1]))
				mexit('Option «'.$argv[$i].'» has to be followed by a valid timezone identifier (use «-h» for more info).'.N,1);
			$i++;
			$opts['timezone']=$argv[$i];
			break;
			case '-L':
			case '--tzlist':
			$buf=timezone_identifiers_list();
			foreach ($buf as $val)
				gecho($val.N,false,false);
			exit(0);
			break;
			case '-E':
			case '--excludedead':
			$opts['excludedead']=true;
			break;
			case '-v':
			case '--verbose':
			$opts['verbose']=true;
			break;
			case '-h':
			case '--help':
			mexit($help,0);
			break;
			default:
			mexit('Option «'.$argv[$i].'» is unknown (use «-h» for more info).'.N,1);
			break;
		}
	}
}

$lockfp=__DIR__.'/peerscrawl.lock';
if (is_file($lockfp) && !$opts['ignorelock']) {
	echo('Lockfile exists: it seems the program is already running; if you’re sure it’s not true, use «-I» to force execution.'.N);
	exit(2);
}
touch($lockfp);

function mexit($msg,$code) {
	global $link, $lockfp;
	if (isset($link) && $link!==false) mysqli_close($link);
	if (isset($lockfp) && file_exists($lockfp)) unlink($lockfp);
	if ($code==0)
		echo($msg);
	else
		fwrite(STDERR,$msg);
	exit($code);
}

function gecho($msg,$prtime,$iserr) {
	if ($prtime)
		$msg=microdate().' '.$msg;
	if ($iserr)
		fwrite(STDERR,$msg);
	else
		echo($msg);
}

function microdate($time=null) {
	if (is_null($time)) $time=microtime(false);
	$time=explode(' ',$time);
	return(date('Y-m-d H:i:s',$time[1]).'.'.substr($time[0],2));
}

function sortcheckandsave(&$arr,$arrdesc,&$fp) {
	$buc=count($arr);
	$arr=array_unique($arr);
	$auc=count($arr);
	if ($buc!=$auc)	gecho('WARNING: '.$arrdesc.' contained '.($buc-$auc).' duplicates, better check my code ;-)'.N,true,true);
	gecho('Saving ordered '.$arrdesc.' into «'.$fp.'».'.N,true,false);
	sort($arr);
	$f=@fopen($fp,'w');
	if ($f!==false) {
		foreach ($arr as $val)
			fwrite($f,$val.N);
		fclose($f);
	} else {
		gecho('ERROR: couldn’t open «'.$fp.'» for writing.'.N,true,true);
	}
}

function shutdown($dosort) {
	global $opts, $peersf, $allpeersf, $insts, $ainsts, $lockfp;
	if (isset($peersf) && $peersf!==false) @fclose($peersf);
	if (isset($allpeersf) && $allpeersf!==false) @fclose($allpeersf);
	if (isset($lockfp) && file_exists($lockfp)) unlink($lockfp);
	if ($dosort) {
		sortcheckandsave($insts,'list of responding instances',$opts['peersfp']);
		sortcheckandsave($ainsts,'list of all checked instances',$opts['allpeersfp']);
	}
}

// ATTENZIONE: se lo script viene pipato, tipo "script.php | tee script.log",
// la funzione viene eseguita, anche se l'output della stessa non viene mostrato
function signalHandler($signal) {
	echo(N.'I got interrupted (signal: '.$signal.').'.N);
	shutdown(false);
	//touch('KILLED');
	exit(3);
}
//declare(ticks=1);
pcntl_async_signals(true);
pcntl_signal(SIGTERM,'signalHandler');// Termination ('kill' was called)
pcntl_signal(SIGHUP,'signalHandler');// Terminal log-out
pcntl_signal(SIGINT,'signalHandler');// Interrupted (Ctrl-C is pressed)

$deadinsts=array();
if ($opts['excludedead']) {
	$iniarr=@parse_ini_file($opts['inifp'])
		or mexit('ERROR: I couldn’t open «'.$opts['inifp'].'».'.N,2);
	$link=@mysqli_connect($iniarr['db_host'],$iniarr['db_admin_name'],$iniarr['db_admin_password'],$iniarr['db_name'],$iniarr['db_port'],$iniarr['db_socket'])
		or mexit('ERROR: I couldn’t connect to MySQL server: '.mysqli_connect_error().N,2);
	mysqli_set_charset($link,'utf8mb4')
		or mexit('ERROR trying to set MySQL client charset: '.__LINE__.': '.mysqli_error($link).N,2);
	$res=mysqli_query($link,'SELECT URI FROM Instances WHERE Dead=1')
		or mexit('ERROR: '.__LINE__.': '.mysqli_error($link).N,2);
	mysqli_close($link);
	while ($row=mysqli_fetch_assoc($res))
		$deadinsts[]=$row['URI'];
	unset($res);
	gecho('Loaded list of dead instances ('.count($deadinsts).').'.N,true,false);
}

$insts=array();
$ainsts=array();
$exarr=array();

if ($opts['restore']) {
	if (file_exists($opts['peersfp']) && is_file($opts['peersfp']) && is_readable($opts['peersfp'])) {
		gecho('Loading «'.$opts['peersfp'].'».'.N,true,false);
		$insts=file($opts['peersfp'],FILE_IGNORE_NEW_LINES|FILE_SKIP_EMPTY_LINES);
	} else {
		mexit('WARNING: I couldn’t open «'.$opts['peersfp'].'» for reading.'.N,2);
	}
}
$peersf=@fopen($opts['peersfp'],'w');
if (!$peersf) mexit('I could not open «'.$opts['peersfp'].'» in write mode.'.N,2);
$allpeersf=@fopen($opts['allpeersfp'],'w');
if (!$allpeersf) mexit('I could not open «'.$opts['allpeersfp'].'» in write mode.'.N,2);

function isempty($val) {
	if (preg_match('/^\s*$/',$val)===1)
		return(true);
	else
		return(false);
}

function waituntilonline() {
	$url='www.google.com';
	while (false===($f=@fsockopen($url,80,$errno,$errstr,1))) {
		gecho('WARNING: it seems we are offline :-('.N,true,true);
		sleep(5);
	}
	fclose($f);
//	gecho('It seems we are online! :-)'.N,true,false);
}

function updexarr() {
	global $exarr, $opts;
	if (!is_null($opts['excludefp'])) {
		$f=@fopen($opts['excludefp'],'r');
		if ($f!==false) {
			$i=0;
			$exarr=array();
			while (!feof($f)) {
				$i++;
				$line=trim(fgets($f));
				if (!isempty($line)) {
					if (@preg_match($line,'foo')!==false)
						$exarr[]=$line;
					else
						gecho('WARNING: «'.$opts['excludefp'].'», line '.$i.': «'.$line.'» is not a valid regular expression.'.N,true,true);
				}
			}
		} else {
			gecho('WARNING: I could not open «'.$opts['excludefp'].'» for reading.'.N,true,true);
		}
	}
}

function ckexarr($inst) {
	global $exarr;
	foreach ($exarr as $re)
		if (preg_match($re,$inst)===1) return(true);
	return(false);
}

require(__DIR__.'/../site/mustard/include/ghs.php');
require(__DIR__.'/../site/mustard/include/ght.php');

function ismultibyte($s) {
	preg_replace('/./u','.',$s,-1,$c);
	(strlen($s)>$c) ? $r=true : $r=false;
	return($r);
}

function validhostname($url) {
	//$hostname=preg_replace('#/.*#','',$url);
	//$hostname=preg_replace('#:[0-9]+$#','',$hostname);
	if (ismultibyte($hostname)) $hostname=idn_to_ascii($hostname);
	//echo($hostname.N);
	if (strlen($hostname)>253) return(false);
	$labels=explode('.',$hostname);
	foreach($labels as $label) {
		$len=strlen($label);
		if ($len<1 || $len>63) return(false);
		if (preg_match('#^-#',$label)==1) return(false);
		if (preg_match('#-$#',$label)==1) return(false);
		//if (preg_match('#--#',$label)==1) return(false);
		if (preg_match('#^[a-zA-Z0-9-]+$#',$label)!==1) return(false);
	}
	return(true);
}
//$url='www.team.starschlep.com/'; if (validhostname($url)) echo('OK: '.$url.N); else echo('KO: '.$url.N); die();

function crawl($list,$id) {
	global $ainsts, $insts, $deadinsts, $peersf, $allpeersf, $opts, $tini;
	gecho('~~~~~~~ START OF ROUND '.$id.' ~~~~~~~'.N,true,false);
	waituntilonline();
	updexarr();
	foreach ($list as $inst) {
		if (!in_array($inst,$ainsts)) {
			$ainsts[]=$inst;
			fwrite($allpeersf,$inst.N);
		}
	}
	$nlist=array();
	$c=count($list);
	$i=0;
	$rtini=time();
	foreach ($list as $inst) {
		$i++;
		$now=time();
		$rtela=$now-$rtini;
		gecho('>>> '.$inst.N,true,false);
		gecho('@@@ Round '.$id.', '.$i.'/'.$c.': TET: '.ght($now-$tini,null,0).'; ETR of this round: '.ght($rtela/$i*$c-$rtela,null,0).'; using '.ghs(memory_get_usage(true)).' mem. (peak: '.ghs(memory_get_peak_usage(true)).'); '.count($insts).' responding insts; '.count($nlist).' insts in next round list; '.count($ainsts).' total.'.N,true,false);
		gecho('Trying to load «'.$inst.'»’s peers...'.N,true,false);
		$peers=gurl('https://'.$inst.'/api/v1/instance/peers',$opts['timeout']);
		if ($peers['cont']===false) {
			gecho('ERROR: '.$peers['emsg'].N,true,true);
		} else {
			$peers=@json_decode($peers['cont'],true);
			if (!is_array($peers)) {
				gecho('ERROR: $peers is not an array (its type is '.gettype($peers).').'.N,true,true);
			} else {
				gecho('LOADED!'.N,true,false);
				if (in_array($inst,$insts)) {
					gecho('NOTICE: «'.$inst.'» is not a new instance (it was already in $insts).'.N,true,false);
				} else {
					gecho('NEW INSTANCE FOUND: «'.$inst.'».'.N,true,false);
					$insts[]=$inst;
					fwrite($peersf,$inst.N);
				}
				foreach ($peers as $peer) {
					if (!is_string($peer)) {
						gecho('	ERROR: I won’t add this peer to next round list because its name is not a string.'.N,true,true);
					} elseif (!validhostname($peer)) {
						gecho('	ERROR: I won’t add «'.$peer.'» to next round list because it’s not a valid hostname.'.N,true,true);
					} elseif (ckexarr($peer)) {
						gecho('	NOTICE: I won’t add «'.$peer.'» to next round list because its name matches with an exclusion regex.'.N,true,false);
					} elseif (in_array($peer,$ainsts)) {
						if ($opts['verbose'])
							gecho('	NOTICE: I won’t add «'.$peer.'» to next round list because it’s already in $ainsts.'.N,true,false);
					} elseif (in_array($peer,$nlist)) {
						if ($opts['verbose'])
							gecho('	NOTICE: I won’t add «'.$peer.'» to next round list because it’s already in $nlist.'.N,true,false);
					// questo qui sotto diventa ridondante ora che uso $ainsts e lo popolo a inizio funzione
					/*} elseif (in_array($peer,$list)) {
						if ($opts['verbose'])
							gecho('	NOTICE: I won’t add «'.$peer.'» to next round list because it’s already in $list.'.N,true,false);
					// questo qui sotto è sempre stato ridondante
					} elseif (in_array($peer,$insts)) {
						if ($opts['verbose'])
							gecho('	NOTICE: I won’t add «'.$peer.'» to next round list because it’s already in $insts.'.N,true,false);
					}*/
					} elseif ($opts['excludedead'] && in_array($peer,$deadinsts)) {
						gecho('	NOTICE: I won’t add «'.$peer.'» to next round list because it’s DEAD.'.N,true,false);
					} else {
						//EVVIVA!
						gecho('	ADDING PEER «'.$peer.'» to next round list.'.N,true,false);
						$nlist[]=$peer;
					}
				}
			}
		}
	}
	if (count($nlist)>0) {
		unset($list);
		crawl($nlist,$id+1);
	} else {
		gecho('Next round list is empty.'.N,true,false);
	}
	gecho('~~~~~~~ END OF ROUND '.$id.' ~~~~~~~'.N,true,false);
}

$tini=time();
crawl(array($opts['startinst']),1);
gecho('DONE CRAWLING! :-)'.N,true,false);
shutdown(true);
$now=time();
gecho('Crawl started on '.date('Y-m-d H:i:s',$tini).' and ended on '.date('Y-m-d H:i:s',$now).'.'.N,true,false);
gecho(count($ainsts).' URIs checked in '.ght($now-$tini).'; '.count($insts).' responded. Max memory usage: '.ghs(memory_get_peak_usage(true)).N,true,false);
exit(0);

?>