<?php
error_reporting(E_ALL | E_STRICT);

define('START_TIME'            , microtime(TRUE));
define('CHECK_POINT'           , 'chash.pos');

// Hashes needed to complete a "block"
$GLOBALS['block_size']          = 100;
$GLOBALS['none_increment']      = (1 / pow(10, 20));

// Hashing algorythm
$GLOBALS['hash_algo']           = MHASH_SHA256;

// Automatic saving interval in seconds
$GLOBALS['flush_file_time']     = 30;

/*
 * How long (in seconds) to try to find a proper hash until the best root hash
 * is taken.
 */
$GLOBALS['restart_search_time'] = 1800;

// Hashes per call
$GLOBALS['hash_cycles'] = 5;

// Total restarts
$GLOBALS['total_restarts'] = 0;

// Found hashes
$GLOBALS['found_hashes'] = array(0 => 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
	$hash = mhash($GLOBALS['hash_algo'], $str);

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

/**
 * Multiple-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	$hash	The generated hash
 */
function multipleHashString ($str) {
	// Generate hash from given hash
	$hash = hashString($str);

	// Now over-hash it
	for ($idx = 0; $idx < ($GLOBALS['hash_cycles'] - 1); $idx++) {
		// Over-hash the given hash
		$hash = hashString($hash);
	} // END - for

	// 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 propability array with 256 zeros
	$propability = array_fill(0, 256, 0);

	// 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));

		// Debug message
		//* NOISY-DEBUG: */ print 'part1=' . $part1 . ',part2=' . $part2 . PHP_EOL;

		/*
		 * 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 % $part2;
		} elseif (($part2 > $part1) && ($part1 > 0)) {
			// 'part2' is larger than 'part1'
			$mod = $part2 % $part1;
		}

		// $mod is now mostly a small number so try to "improve" it
		//* NOISY-DEBUG: */ print 'mod[' . gettype($mod) . ']=' . $mod . ' - BEFORE!' . PHP_EOL;
		$mod = (int) round(sqrt($mod * ($part1 + $part2 + $mod ^ 7) / 3));
		//* NOISY-DEBUG: */ print 'mod[' . gettype($mod) . ']=' . $mod . ' - AFTER!' . PHP_EOL;

		// Make sure it is valid
		assert($mod >= 0);
		assert($mod <= 255);

		// "Invert" the result against 255 as zeros are not good for later calculations
		$mod = 255 - $mod;

		// Add it to propability array for debugging
		$propability[$mod]++;

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

	// Debug propability array
	$cnt = 0;
	foreach ($propability as $value) {
		// Is the value larger than one, means the number has been found at least once?
		if ($value > 0) {
			// Then count it
			$cnt++;
		} // END - if
	} // END - foreach

	// Debug message
	//* NOISY-DEBUG: */ print('cnt=' . $cnt . '/' . strlen($hash1) / 2 . PHP_EOL);

	// 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));
	} // END - for

	// And return it
	return $sum;
}

/**
 * Calculates new nonce
 *
 * @return	void
 */
function calculateNonce () {
	// Linear incrementation
	$GLOBALS['nonce'] += $GLOBALS['none_increment'];
}

/**
 * Writes/flushes check-point file
 *
 * @param	$hash	Modula hash (or hash to save)
 * @return	void
 */
function flushCheckPointFile ($hash) {
	// Display message
	print ('FLUSHING: Writing ' . count($GLOBALS['found_hashes']) . ' blocks ...' . PHP_EOL);

	// Start timer
	$timer = microtime(TRUE);

	// Flush data
	file_put_contents(
		CHECK_POINT,
		$GLOBALS['total_blocks'] . ':' .
		$GLOBALS['total_reward'] . ':' .
		$GLOBALS['total_hashes'] . ':' .
		$GLOBALS['total_found'] . ':' .
		$GLOBALS['total_restarts'] . ':' .
		$GLOBALS['hash_cycles'] . ':' .
		base64_encode((float) $GLOBALS['nonce']) . ':' .
		$hash . ':' .
		$GLOBALS['root_hash'] . ':' .
		base64_encode(gzcompress(json_encode($GLOBALS['found_hashes'])))
	);

	// Set time
	$GLOBALS['time_flush'] = microtime(TRUE);
	print ('FLUSHING: Took ' . ($GLOBALS['time_flush'] - $timer) . ' seconds.' . PHP_EOL);
}

/**
 * Adds a found hash and flushes the checkpoint file
 *
 * @param	$hash	Hash to save
 */
function addFoundHash ($hash) {
	// Increment counter
	$GLOBALS['total_found']++;

	// Add hash to array
	array_push($GLOBALS['found_hashes'][$GLOBALS['total_blocks']], array(
		'modula_hash'  => $GLOBALS['modula_hash'],
		'genesis_hash' => $GLOBALS['genesis_hash'],
		'root_hash'    => $GLOBALS['root_hash'],
		'nonce'        => (float) $GLOBALS['nonce'],
		'iter'         => $GLOBALS['iteration'],
		'hashes_block' => $GLOBALS['hashes_block'],
		'hash_cycles'  => $GLOBALS['hash_cycles'],
		'nonce_hash'   => $hash
	));

	// Found hash:
	print ('FOUND: hash=' . $hash . ',nonce=' . $GLOBALS['nonce'] . ',total_found=' . $GLOBALS['total_found'] . PHP_EOL);

	// Set time as a new hash was found
	$GLOBALS['found_time'] = microtime(TRUE);

	// Flush check-point file after new hash is found
	flushCheckPointFile($hash);

	// Use nonceHash as next modula hash
	setModulaHash($hash);
}

/**
 * Initializes nonce
 *
 * @return	void
 */
function initNonce () {
	$GLOBALS['nonce'] = 1 / (mt_rand() ^ pi());
	print (__FUNCTION__ . ': nonce=' . $GLOBALS['nonce'] . PHP_EOL);
}

/**
 * Sets modula hash and calculates sum of it
 *
 * @param	$hash	Hash to set as "modula hash"
 * @return	void
 */
function setModulaHash ($hash) {
	$GLOBALS['modula_hash'] = $hash;
	$GLOBALS['sum_modula']  = calculateSumFromHash($GLOBALS['modula_hash']);
}

/*
 * 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.
 */
$gensisHashes = array(
	// A famous quote from Deus Ex 2 - Invisible War
	multiplehashString('"Informations must be free." - AI Helios from Deus Ex'),
	// My name + URL of my first StatusNet instance
	multipleHashString('Roland Haeder, https://status.mxchange.org'),
	// A famous quote from Linus Torwalds
	multipleHashString('"Software is like sex. Its better when its free." - Linus Torwalds'),
	// Well ...
	multipleHashString('September 11 is a big lie.'),

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

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

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

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

// Calulcate modula hash
setModulaHash(multipleHashString(modulaHash($sqrtHashes[0], $sqrtHashes[1])));

// This is also the "genesis" hash and first root hash
$GLOBALS['genesis_hash'] = $GLOBALS['modula_hash'];
$GLOBALS['root_hash']    = $GLOBALS['modula_hash'];

// Output results
print ('hashes=' . print_r($gensisHashes, TRUE));
print ('modulaHashes=' . print_r($modulaHashes, TRUE));
print ('sqrtHashes=' . print_r($sqrtHashes, TRUE));
print ('modulaHash=' . $GLOBALS['modula_hash'] . PHP_EOL);

// Total reward + hashes
$GLOBALS['total_reward']   = 0;
$GLOBALS['total_hashes']   = 0;
$GLOBALS['total_found']    = 0;
$GLOBALS['total_blocks']   = 0;
$GLOBALS['found_time']     = microtime(TRUE);

// 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) == 10);

	// 1st element is nonce, 2nd hash, 3rd found hashes
	$GLOBALS['total_blocks']   = $data[0];
	$GLOBALS['total_reward']   = $data[1];
	$GLOBALS['total_hashes']   = $data[2];
	$GLOBALS['total_found']    = $data[3];
	$GLOBALS['total_restarts'] = $data[4];
	$GLOBALS['hash_cycles']    = intval($data[5]);
	$GLOBALS['nonce']          = (float) base64_decode($data[6]);
	$GLOBALS['root_hash']      = $data[8];
	$GLOBALS['found_hashes']   = json_decode(gzuncompress(base64_decode($data[9])));

	// Set modula hash
	setModulaHash($data[7]);
} else {
	// Create nonce (small)
	initNonce();
}

// Output again
print ('modulaHash=' . $GLOBALS['modula_hash'] . PHP_EOL);
print ('nonce=' . $GLOBALS['nonce'] . PHP_EOL);
print ('found=' . count($GLOBALS['found_hashes'][$GLOBALS['total_blocks']]) . PHP_EOL);

// Start "mining"
while (TRUE) {
	// Init hash-per-block counter and hashrate
	$GLOBALS['hashes_block'] = 0;
	$hashrate = 0;

	// Wait for block_size iterations (= found hashes). This is one block
	$timeBlock   = microtime(TRUE);
	$timeDisplay = $timeBlock;
	$GLOBALS['time_flush'] = $timeBlock;

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

	while (count($GLOBALS['found_hashes'][$GLOBALS['total_blocks']]) <= $GLOBALS['block_size']) {
		// Create hash from modulaHash ("genesis hash") and nonce
		$nonceHash = multipleHashString($GLOBALS['nonce'] . $GLOBALS['modula_hash']);

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

		// Init counter
		$GLOBALS['iteration'] = 0;
		$GLOBALS['iteration_second'] = 0;

		// Now start the "mining" ...
		$timeHash = microtime(TRUE);
		while ($sumNonce < $GLOBALS['sum_modula']) {
			// Calculate new nonce
			calculateNonce();

			// And hash again
			$nonceHash = multipleHashString($GLOBALS['nonce'] . $GLOBALS['modula_hash']);

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

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

			// Calculate hashrate/sec
			$hashrate = 1 / $testTime * $GLOBALS['iteration_second'] * $GLOBALS['hash_cycles'];

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

				// Reset timer
				$timeDisplay = microtime(TRUE);
				$GLOBALS['iteration_second']  = 0;
			} // END - if

			// Time spend from last flush
			$testTime = abs(microtime(TRUE) - $GLOBALS['time_flush']);

			// Only once per 10 seconds
			if ($testTime >= $GLOBALS['flush_file_time']) {
				// Flush check-point file
				flushCheckPointFile($GLOBALS['modula_hash']);
			} // END - if

			// Time spend from last found block
			$testTime = abs(microtime(TRUE) - $GLOBALS['found_time']);

			// Is the last found time to far away?
			if ($testTime >= $GLOBALS['restart_search_time']) {
				// Count up restart
				$GLOBALS['total_restarts']++;

				// Output message
				print('total_restarts=' . $GLOBALS['total_restarts'] . ' - Restarting ...');

				// Count all root (genesis) hashes
				$rootHashes = array();
				foreach ($GLOBALS['found_hashes'] as $block) {
					// "Walk" through all blocks
					foreach ($block as $hash) {
						if (!isset($hash['root_hash'])) {
							// Bad file
							die('INCONSISTENCY: hash=' . print_r($hash, TRUE));
						} // END - if

						if (isset($rootHashes[$hash['root_hash']])) {
							// Count up
							$rootHashes[$hash['root_hash']]++;
						} else {
							// First entry found
							$rootHashes[$hash['root_hash']] = 1;
						}
					} // END - foreach
				} // END - foreach

				// Find best root hash
				$bestRootHash = '';
				$bestRootCount = 0;
				foreach ($rootHashes as $hash => $count) {
					// Debug message
					//* NOISY-DEBUG: */ print ('hash=' . $hash . ',count=' . $count . ',bestRootHash=' . $bestRootHash . ',bestRootCount=' . $bestRootCount . PHP_EOL);

					// Is a better one found?
					if ($count > $bestRootCount) {
						// Remember it
						$bestRootHash  = $hash;
						$bestRootCount = $count;
					} // END - if
				} // END - foreach

				// Output message
				print ('bestRootHash=' . $bestRootHash . ',bestRootCount=' . $bestRootCount . PHP_EOL);

				// Search for latest best root hash
				foreach ($GLOBALS['found_hashes'] as $block) {
					// "Walk" through whole block and search for first appearance of best root hash
					foreach ($block as $idx => $hash) {
						// Is the root hash there?
						if ($hash['root_hash'] == $bestRootHash) {
							// Set found modula hash as new root and current modula hash
							$GLOBALS['root_hash']   = $hash['nonce_hash'];
							setModulaHash($hash['nonce_hash']);
							print ('idx=' . $idx . ',modulaHash=' . $GLOBALS['root_hash'] . ' - Is now new root hash!' . PHP_EOL);

							// Reset "found time" (when a hash was found)
							$GLOBALS['found_time'] = microtime(TRUE);

							// Re-initialize nonce
							initNonce();

							// Abort search
							break;
						} // END - if
					} // END - for
				} // END - foreach
			} // END - if

			// Next round
			$GLOBALS['iteration']++;
			$GLOBALS['iteration_second']++;
			//print ('nonce=' . $GLOBALS['nonce'] . ',iteration=' . $GLOBALS['iteration'] . PHP_EOL);
			//print ('nonceHash=' . $nonceHash . PHP_EOL);
			//print ('sumNonce=' . $sumNonce . PHP_EOL);
			//print ('sumModula=' . $GLOBALS['sum_modula'] . PHP_EOL);
		} // END - while

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

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

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

		// Add amount of hashes per block (multiple-hash)
		$GLOBALS['hashes_block'] += $GLOBALS['iteration'] * $GLOBALS['hash_cycles'] + $GLOBALS['hash_cycles'];

		// Push found hash
		addFoundHash($nonceHash);
	} // END - while

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

	// Calculate reward
	$reward = abs($timeBlock - $timeBadHashes) / $hashrate * $GLOBALS['hashes_block'] / $GLOBALS['block_size'] * 1000;
	print ('timeBlock=' . $timeBlock . ',timeBadHashes=' . $timeBadHashes . ',hashesPerBlock=' . $GLOBALS['hashes_block'] .',reward=' . $reward . PHP_EOL);

	// Block completed
	$GLOBALS['total_hashes'] += $GLOBALS['hashes_block'];
	$GLOBALS['total_blocks']++;
	$GLOBALS['hashes_block'] = 0;

	// Init next block
	$GLOBALS['found_hashes'][$GLOBALS['total_blocks']] = array();

	// Calculate new nonce
	calculateNonce();

	// Add reward to total
	$GLOBALS['total_reward'] += $reward;

	// Calculate average block value
	$blockValue = $GLOBALS['total_reward'] / $GLOBALS['total_blocks'] * $GLOBALS['total_hashes'] / ($GLOBALS['block_size'] * $GLOBALS['total_blocks']);

	// Calculate reward per hour (= 3600 seconds)
	$rewardPerHour = $GLOBALS['total_reward'] / abs(microtime(TRUE) - START_TIME) * 3600;

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

// [EOF]
?>