<?php
################################################################################################
# The goal of this program is to create a collection of primes.
# Primes will be collected into a sqlite3 database.
#
# This program is designed to run until it encounters an error, crashes, or you kill it.
#
# Authors: Dax Mickelson, Ryan Malloy
#
# Note: This PHP file will require the GMP libraries which don't come installed typically by default.
# I've only ever ran this program using PHP's CLI and not via Apache or some other PHP interpreter, FYI.
################################################################################################


################################################################################################
###  User Adjustable Values
################################################################################################
/* Point $DocRoot to where the program and db exists.*/
$DocRoot = ".";
$DBname = "prime.db";

/* Set the timezone.  (Used for output to the log.txt file.) */
date_default_timezone_set('America/Denver');

$database = "$DocRoot/$DBname";

/* Status Check */
$StatusCheck = 54321;
$Counter = 0;
################################################################################################

/*
declare(ticks=1);

$pid = pcntl_fork();
if ($pid == -1) {
     die("could not fork");
} else if ($pid) {
     exit(); // we are the parent
} else {
     // we are the child
}

// detatch from the controlling terminal
if (posix_setsid() == -1) {
    die("could not detach from terminal");
}

// setup signal handlers
pcntl_signal(SIGTERM, "sig_handler");
pcntl_signal(SIGHUP, "sig_handler");
pcntl_signal(SIGINT, "sig_handler");
*/
if(is_file("$DocRoot/NumberToTest.txt"))
{
	$StartingString = file_get_contents("$DocRoot/NumberToTest.txt");
}
else
{
	$StartingString = "3";
}

$two = gmp_init("2",10);
$NumberToTest = gmp_init("$StartingString",10);
print ("StartingNumber: $StartingString\n");
$Prime = gmp_init("2",10);

$db = new SQLite3($database);

/* Time to test for primality */
while(is_resource($NumberToTest))
{
/*
First a quick test using gmp_prob_prime, however, it seems many numbers are reported "probable" so I don't know if it is worth the time to do this step.
0 = composite
1 = probable prime
2 = definite prime
*/
	$Reps = 25; /* What depth level do you want gmp_prob_prime to run to?  Deeper means more accurate (10 is the default). */
	$QuickTest = gmp_prob_prime($NumberToTest,$Reps);
	if($QuickTest == 0) { $IsPrime = 0; }
	if($QuickTest == 2) { $IsPrime = 1; }
	if($QuickTest == 1)
	{
/*
If we get to here then gmp_prob_prime isn't sure whether the $NumberToTest is prime or not.
Give gmp_prob_prime the benefit of the doubt and assume the number is prime. If the following tests$
not prime then this value will be what is used.
*/
		$IsPrime = 1;
/*
Take the number being tested, $NumberToTest, and find it's sqrt, $x.  Then do a query of the databa$
for all the prime numbers 2 <= $x.  Then for each of these numbers, $PrimeNumber do the following:
If $PrimeNumber > $x set $IsPrime to 1 else divide it into $NumberToTest.  If there is no remainder$
factor of $NumberToTest) set $IsPrime to 0, else take the next number until the list is exhausted a$
*/
		$sql="SELECT thenumber FROM Number WHERE thenumber <= " . gmp_strval(gmp_add(gmp_sqrt($NumberToTest),1));
		$result = $db->query($sql) or die ("\nSelect failed: $sql\n" . $db->error . "\n");
/* Loop through the whole list of found primes <= sgrt($NumberToTest) */
		while($row = $result->fetchArray())
		{
			$Prime = $row['thenumber'];
/* Error occurs here.  gmp_mod() errors cuz -2147483648 isn't a valid gmp Resource.  Is the $Prime assignment f'ing up? */
			if(0 == gmp_cmp(gmp_mod($NumberToTest,$Prime),0)) /* If $NumberToTest/$Prime has no remainder then $NumberToTest isn't prime. */
			{
				$IsPrime = 0;
				break;
			}
		}
	}
/* If prime add this new prime to our prime list. */
	if(1 == $IsPrime)
	{
/*
Add $NumberToTest to database.
*/
		$sql = "INSERT INTO Number (thenumber) VALUES (" . gmp_strval($NumberToTest) . ")";
		$db->query($sql) or die ("\nInsert failed: $sql\n" . $db->error . "\n");
	}
/*
Prep for the next number to test by incrementing by 2 and saving this to NumberToTest.txt (in case the program crashes we can start here next time).
*/
	$Counter = $Counter % $StatusCheck;
	if(0 == $Counter)
	{
		write_wwi();
	}
	$Counter++;
	$NumberToTest = gmp_add($NumberToTest,$two);
}

if(!(is_resource($NumberToTest)))
{
	print "\nNumberToTest is no longer a resource.\n";
	print "NumberToTest: $NumberToTest\n";
}

function write_wwi()
{
	global $NumberToTest;
	@unlink("NumberToTest.txt");
	file_put_contents("NumberToTest.txt", gmp_strval($NumberToTest));
	print date("Y-m-d H:i:s") . " --> NumberToTest = " . gmp_strval($NumberToTest) . "\n";
echo "NumberToTest as a Resource: " . $NumberToTest . "\n";
}

function sig_handler($signo)
{
	switch ($signo)
	{
		case SIGINT:
			write_wwi();
			print "SIGINT";
			exit;
			break;
		case SIGTERM:
		/* handle shutdown tasks */
			write_wwi();
			print "SIGTERM";
			exit;
			break;
		case SIGHUP:
		/* handle restart tasks */
			print "SIGHUP";
			write_wwi();
			break;
		default:
		/* handle all other signals */
	}
}