<?php
error_reporting(E_ALL | E_STRICT);

define('HASH_ALGO', MHASH_RIPEMD320);
define('BLOCK_SIZE', 100);
define('NONCE_INCREMENT', 0.0000000000000001);
define('START_TIME', microtime(TRUE));
define('CHECK_POINT', 'chash.pos');

// Found hashes
$foundHashes = array();

/**
 * Continued-hashing
 *
 * @author		Roland Haeder <roland@mxchange.org>
 * @copyright	Copyright (c) 2013 by Core Developer Team
 * @license		See LICENSE (public-domain)
 */

/**
 * Calculates a simple but stronger hash from given string. No salts are being
 * added here.
 *
 * @param	$str	The string to be hashed
 * @return	$hash	The hash from string $str
 */
function hashString ($str) {
	// Calculate strong hash from given string
	$hash = mhash(HASH_ALGO, $str);

	// Return it hexadecimal-encoded
	return bin2hex($hash);
}

/**
 * Double-hashes given string. This is done by hashing the given string and
 * then hashing the generated hash again.
 *
 * @param	$str	The string to be hashed 4 times
 * @return	$hash	The generated hash
 */
function doubleHashString ($str) {
	// Generate hash from given hash
	$hash = hashString(hashString($str));

	// Return it
	return $hash;
}

/**
 * Calculates a "modula-hash" based given two hashes.
 *
 * @param	$hash1	Hash 1
 * @param	$hash2	Hash 2
 */
function modulaHash ($hash1, $hash2) {
	// Both must have same length
	assert(strlen($hash1) === strlen($hash2));

	// Init new hash
	$modulaHash = '';

	// "Walk" trough first hash and get every 2 byte of both hashes
	for ($idx = 0; $idx < strlen($hash1); $idx += 2) {
		// Init modula value
		$mod = 0;

		// Get both hash parts and convert to ASCII number
		$part1 = hexdec(substr($hash1, $idx, 2));
		$part2 = hexdec(substr($hash2, $idx, 2));

		/*
		 * If part1 is larget part2, part1 is divident and vise-versa. But don't do it
		 * if one is zero
		 */
		if (($part1 > $part2) && ($part2 > 0)) {
			// 'part1' is larger than 'part2'
			$mod = $part1 % $part2;
		} elseif (($part1 < $part2) && ($part1 > 0)) {
			// 'part2' is larger than 'part1'
			$mod = $part2 % $part1;
		}

		// "Invert" the result against 255
		$mod = 255 - $mod;

		// Encode to hex, pre-pad it with zeros and add to new hash
		$modulaHash .= padHex($mod);
	} // END - for

	// Modula hash must have same length as input hash
	assert(strlen($modulaHash) === strlen($hash1));

	// Return modula hash
	return $modulaHash;
}

/**
 * Calculates a "sqrt-hash" based given two hashes and single-hash it
 *
 * @param	$hash1	Hash 1
 * @param	$hash2	Hash 2
 */
function sqrtHash ($hash1, $hash2) {
	// Both must have same length
	assert(strlen($hash1) === strlen($hash2));

	// Init new hash
	$sqrtHash = '';

	// "Walk" trough first hash and get every 2 byte of both hashes
	for ($idx = 0; $idx < strlen($hash1); $idx += 2) {
		// Init modula value
		$mod = 0;

		// Get both hash parts and convert to ASCII number
		$part1 = hexdec(substr($hash1, $idx, 2));
		$part2 = hexdec(substr($hash2, $idx, 2));

		// Calculate square root of both parts being multiplied and round up, then "invert" it against 255
		$sqrt = intval(255 - ceil(sqrt($part1 * $part2)));

		// Encode to hex, pre-pad it with zeros and add to new hash
		$sqrtHash .= padHex($sqrt);
	} // END - for

	// "sqrt-hash" must have same length as input hash
	assert(strlen($sqrtHash) === strlen($hash1));

	// Hash reversed "sqrt-hash" again and return it
	return hashString(strrev($sqrtHash));
}

/**
 * Converts a number between 0 and 255 into a zero-padded hexadecimal string
 *
 * @param	$num	Number between 0 and 255
 * @return	$hex	Hexadecimal string, padded with zeros
 */
function padHex ($num) {
	// Must be a integer number and between 0 and 255
	assert(is_int($num));
	assert($num >= 0);
	assert($num <= 255);

	// Convert it
	$hex = str_pad(dechex($num), 2, '0', STR_PAD_LEFT);

	// ... and return it
	return $hex;
}

/**
 * Calculates sum from given hash
 *
 * @param	$hash	Hash to calculate sum from
 * @return	$sum	Sum from given hash
 */
function calculateSumFromHash ($hash) {
	// Everything starts with zero ...
	$sum = 0;

	// Loop through hash
	for ($idx = 0; $idx < (strlen($hash) / 2); $idx++) {
		// And add it
		$sum = $sum + (hexdec(substr($hash, $idx, 2)) * $idx & 256);
	} // END - for

	// And return it
	return $sum;
}

/**
 * Calculates new nonce
 *
 * @param	$nonce		Old nonce to be used
 * @return	$newNonce	New nonce
 */
function calculateNonce ($nonce) {
	// Linear incrementation
	$newNonce = $nonce + NONCE_INCREMENT;

	// Return new value
	return $newNonce;
}

/*
 * Calculate "genesis" hashes, please note that these "genesis strings" are now
 * known to the public as you can read them here in source code and therefore I
 * will not use them for the real genesis hashes.
 */
$hashes = array(
	// A famous quote from Deus Ex 2 - Invisible War
	doublehashString('"Informations must be free." - AI Helios from Deus Ex'),
	// My name + URL of my first StatusNet instance
	doubleHashString('Roland Haeder, https://status.mxchange.org'),
	// A famous quote from Linus Torwalds
	doubleHashString('"Software is like sex. Its better when its free." - Linus Torwalds'),
	// Possible truth ;-)
	doubleHashString('September 11 is a big lie.'),

	// GNU is not Uni*
	doubleHashString('GNU is Not Uni*.'),
	// WINE is not an emulator
	doubleHashString('WINE Is Not an Emulator.'),
	// FlightGear - Fly free!
	doubleHashString('FlightGear - Fly free!'),
	// Linus Torwalds Quote
	doubleHashString('Your code is shit.. your argument is shit.'),
);

// Calculate "modula hash" from 1st/4th and 2nd/3rd
$modulaHashes = array(
	// "Block" 0
	modulaHash($hashes[0], $hashes[3]),
	modulaHash($hashes[1], $hashes[2]),

	// "Block" 1
	modulaHash($hashes[4], $hashes[7]),
	modulaHash($hashes[5], $hashes[6]),
);

// Calculate "sqrt hash"
$sqrtHashes = array(
	sqrtHash($modulaHashes[0], $modulaHashes[1]),
	sqrtHash($modulaHashes[2], $modulaHashes[3])
);

// Calulcate modula hash
$modulaHash = doubleHashString(modulaHash($sqrtHashes[0], $sqrtHashes[1]));

// This is also the "genesis hash"
$genesisHash = $modulaHash;

// Output results
print ('hashes=' . print_r($hashes, TRUE));
print ('modulaHashes=' . print_r($modulaHashes, TRUE));
print ('sqrtHashes=' . print_r($sqrtHashes, TRUE));
print ('modulaHash=' . $modulaHash . PHP_EOL);

// Total reward + hashes
$totalReward = 0;
$totalHashes = 0;
$totalBlocks = 0;

// Is the check point there?
if (is_readable(CHECK_POINT)) {
	// Then load it
	$checkPoint = file_get_contents(CHECK_POINT);

	// Explode it
	$data = explode(':', $checkPoint);

	// Assert on count
	assert(count($data) == 3);

	// 1st element is nonce, 2nd hash, 3rd found hashes
	$nonce       = base64_decode($data[0]);
	$modulaHash  = $data[1];
	$foundHashes = unserialize(base64_decode($data[2]));
} else {
	// Create nonce (small)
	$nonce = 1 / mt_rand();
}

// Output again
print ('modulaHash=' . $modulaHash . PHP_EOL);
print ('nonce=' . $nonce . PHP_EOL);
print ('found=' . count($foundHashes) . PHP_EOL);

// Start "mining"
while (TRUE) {
	// Init hash-per-block counter and hashrate
	$hashesPerBlock = 0;
	$hashrate = 0;

	// Wait for BLOCK_SIZE iterations (= found hashes). This is one block
	$timeBlock   = microtime(TRUE);
	$timeDisplay = $timeBlock;
	$timeFlush   = $timeBlock;

	// Time waited for a good block again (no iteration)
	$timeBadHashes = 0;

	while (count($foundHashes) <= BLOCK_SIZE) {
		// Create hash from modulaHash ("genesis hash") and nonce
		$nonceHash = doubleHashString($modulaHash . $nonce);

		// Calculate sums
		$sumNonce  = calculateSumFromHash($nonceHash);
		$sumModula = calculateSumFromHash($modulaHash);

		// Init counter
		$iter = 0;
		$iterSecond = 0;

		// Now start the "mining" ...
		$timeHash = microtime(TRUE);
		while ($sumNonce >= $sumModula) {
			// Calculate new nonce
			$nonce = calculateNonce($nonce);

			// And hash again
			$nonceHash = doubleHashString($modulaHash . $nonce);

			// Calculate sums
			$sumNonce  = calculateSumFromHash($nonceHash);

			// Time spend in loop
			$testTime = abs(microtime(TRUE) - $timeDisplay);

			// Calculate hashrate/sec
			$hashrate = 1 / $testTime * $iterSecond * 2;

			// Only every second
			if ($testTime >= 1) {
				// Display hash rate
				print ('hashrate=' . $hashrate . ' hashes/sec,iterSecond=' . $iterSecond . ' iterations/sec' . PHP_EOL);

				// Reset timer
				$timeDisplay = microtime(TRUE);
				$iterSecond  = 0;
			} // END - if

			// Time spend from last flush
			$testTime = abs(microtime(TRUE) - $timeFlush);

			// Only once per 10 seconds
			if ($testTime >= 10) {
				// Display message
				print ('FLUSHING: ' . count($foundHashes) . ' total found.' . PHP_EOL);

				// Write check-point
				file_put_contents(CHECK_POINT, base64_encode($nonce) . ':' . $modulaHash . ':' . base64_encode(serialize($foundHashes)));

				$timeFlush = microtime(TRUE);
			} // END - if

			// Next round
			$iter++;
			$iterSecond++;
			//print ('nonce=' . $nonce . ',iter=' . $iter . PHP_EOL);
			//print ('nonceHash=' . $nonceHash . PHP_EOL);
			//print ('sumNonce=' . $sumNonce . PHP_EOL);
			//print ('sumModula=' . $sumModula . PHP_EOL);
		} // END - while

		// If the iteration is zero, then no hash is found
		if ($iter == 0) {
			// Bad hash found
			$timeBadHashes += abs(microtime(TRUE) - $timeHash);

			// And next round
			//print('BAD:nonce=' . $nonce . PHP_EOL);

			// Nothing found, so calculate new nonce
			$nonce = calculateNonce($nonce);
			continue;
		} // END - if

		// Add amount of hashes per block (double-hash)
		$hashesPerBlock += $iter * 2 + 2;

		// Push found hash
		array_push($foundHashes, array(
			'modula_hash'  => $modulaHash,
			'genesis_hash' => $genesisHash,
			'nonce'        => $nonce,
			'iter'         => $iter,
			'hashes_block' => $hashesPerBlock,
			'nonce_hash'   => $nonceHash
		));

		// Found hash:
		print ('FOUND: nonceHash=' . $nonceHash . ',nonce=' . $nonce . ',iter=' . $iter . PHP_EOL);


		// Use nonceHash as next modula hash
		$modulaHash = $nonceHash;
	} // END - while

	// Time taken for one block
	$timeBlock = abs(microtime(TRUE) - $timeBlock);

	// Calculate reward
	$reward = abs($timeBlock - $timeBadHashes) / $hashrate * $hashesPerBlock / BLOCK_SIZE * 1000;
	print ('timeBlock=' . $timeBlock . ',timeBadHashes=' . $timeBadHashes . ',hashesPerBlock=' . $hashesPerBlock .',reward=' . $reward . PHP_EOL);

	// Block completed
	$totalHashes += $hashesPerBlock;
	$totalBlocks++;
	$hashesPerBlock = 0;
	$foundHashes = array();

	// Calculate new nonce
	$nonce = calculateNonce($nonce);

	// Add reward to total
	$totalReward += $reward;

	// Calculate average block value
	$blockValue = $totalReward / $totalBlocks * $totalHashes / (BLOCK_SIZE * $totalBlocks);

	// Calculate reward per hour (= 3600 seconds)
	$rewardPerHour = $totalReward / abs(microtime(TRUE) - START_TIME) * 3600;

	print ('totalReward=' . $totalReward . ',blockValue=' . $blockValue . ',rewardPerHour=' . $rewardPerHour . PHP_EOL);
} // END - while

// [EOF]
?>