/*
	This file is part of cpp-ethereum.

	cpp-ethereum 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.

	cpp-ethereum 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 cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file fuzzHelper.cpp
 * @author Dimitry Khokhlov <winsvega@mail.ru>
 * @date 2015
 */

#include "fuzzHelper.h"

#include <chrono>
#include <boost/random.hpp>
#include <boost/filesystem/path.hpp>
#include <libevmcore/Instruction.h>

namespace dev
{
namespace test
{

boost::random::mt19937 RandomCode::gen;
boostIntDistrib RandomCode::opCodeDist = boostIntDistrib (0, 255);
boostIntDistrib RandomCode::opLengDist = boostIntDistrib (1, 32);
boostIntDistrib RandomCode::uniIntDist = boostIntDistrib (0, 0x7fffffff);
boostUint64Distrib RandomCode::uInt64Dist = boostUint64Distrib (0, std::numeric_limits<uint64_t>::max());

boostIntGenerator RandomCode::randOpCodeGen = boostIntGenerator(gen, opCodeDist);
boostIntGenerator RandomCode::randOpLengGen = boostIntGenerator(gen, opLengDist);
boostIntGenerator RandomCode::randUniIntGen = boostIntGenerator(gen, uniIntDist);
boostUInt64Generator RandomCode::randUInt64Gen = boostUInt64Generator(gen, uInt64Dist);

int RandomCode::recursiveRLP(std::string& _result, int _depth, std::string& _debug)
{
	bool genValidRlp = true;
	int bugProbability = randUniIntGen() % 100;
	if (bugProbability < 80)
		genValidRlp = false;

	if (_depth > 1)
	{
		//create rlp blocks
		int size = 1 + randUniIntGen() % 4;
		for (auto i = 0; i < size; i++)
		{
			std::string blockstr;
			std::string blockDebug;
			recursiveRLP(blockstr, _depth - 1, blockDebug);
			_result += blockstr;
			_debug += blockDebug;
		}

		//make rlp header
		int length = _result.size() / 2;
		std::string header;
		int rtype = 0;
		int rnd = randUniIntGen() % 100;
		if (rnd < 10)
		{
			//make header as array
			if (length <= 55)
			{
				header = toCompactHex(128 + length);
				rtype = 1;
			}
			else
			{
				std::string hexlength = toCompactHex(length);
				header = toCompactHex(183 + hexlength.size() / 2) + hexlength;
				rtype = 2;
			}
		}
		else
		{
			//make header as list
			if (length <= 55)
			{
				header = toCompactHex(192 + length);
				rtype = 3;
			}
			else
			{
				std::string hexlength = toCompactHex(length, HexPrefix::DontAdd, 1);
				header = toCompactHex(247 + hexlength.size() / 2) + hexlength;
				rtype = 4;
			}
		}
		_result = header + _result;
		_debug = "[" + header + "(" + toString(length) + "){" + toString(rtype) + "}]" + _debug;
		return _result.size() / 2;
	}
	if (_depth == 1)
	{
		bool genbug = false;
		bool genbug2 = false;
		int bugProbability = randUniIntGen() % 100;
		if (bugProbability < 50 && !genValidRlp)
			genbug = true;
		bugProbability = randUniIntGen() % 100;   //more randomness
		if (bugProbability < 50 && !genValidRlp)
			genbug2 = true;

		std::string emptyZeros = genValidRlp ? "" : genbug ? "00" : "";
		std::string emptyZeros2 = genValidRlp ? "" : genbug2 ? "00" : "";

		int rnd = randUniIntGen() % 5;
		switch (rnd)
		{
		case 0:
		{
			//single byte [0x00, 0x7f]
			std::string rlp = emptyZeros + toCompactHex(genbug ? randUniIntGen() % 255 : randUniIntGen() % 128, HexPrefix::DontAdd, 1);
			_result.insert(0, rlp);
			_debug.insert(0, "[" + rlp + "]");
			return 1;
		}
		case 1:
		{
			//string 0-55 [0x80, 0xb7] + string
			int len = genbug ? randUniIntGen() % 255 : randUniIntGen() % 55;
			std::string hex = rndByteSequence(len);
			if (len == 1)
			if (genValidRlp && fromHex(hex)[0] < 128)
				hex = toCompactHex((u64)128);

			_result.insert(0, toCompactHex(128 + len) + emptyZeros + hex);
			_debug.insert(0, "[" + toCompactHex(128 + len) + "(" + toString(len) + ")]" + emptyZeros + hex);
			return len + 1;
		}
		case 2:
		{
			//string more 55 [0xb8, 0xbf] + length + string
			int len = randUniIntGen() % 100;
			if (len < 56 && genValidRlp)
				len = 56;

			std::string hex = rndByteSequence(len);
			std::string hexlen = emptyZeros2 + toCompactHex(len, HexPrefix::DontAdd, 1);
			std::string rlpblock = toCompactHex(183 + hexlen.size() / 2) + hexlen + emptyZeros + hex;
			_debug.insert(0, "[" + toCompactHex(183 + hexlen.size() / 2) + hexlen + "(" + toString(len) + "){2}]" + emptyZeros + hex);
			_result.insert(0, rlpblock);
			return rlpblock.size() / 2;
		}
		case 3:
		{
			//list 0-55 [0xc0, 0xf7] + data
			int len = genbug ? randUniIntGen() % 255 : randUniIntGen() % 55;
			std::string hex = emptyZeros + rndByteSequence(len);
			_result.insert(0, toCompactHex(192 + len) + hex);
			_debug.insert(0, "[" + toCompactHex(192 + len) + "(" + toString(len) + "){3}]" + hex);
			return len + 1;
		}
		case 4:
		{
			//list more 55 [0xf8, 0xff] + length + data
			int len = randUniIntGen() % 100;
			if (len < 56 && genValidRlp)
				len = 56;
			std::string hexlen = emptyZeros2 + toCompactHex(len, HexPrefix::DontAdd, 1);
			std::string rlpblock = toCompactHex(247 + hexlen.size() / 2) + hexlen + emptyZeros + rndByteSequence(len);
			_debug.insert(0, "[" + toCompactHex(247 + hexlen.size() / 2) + hexlen + "(" + toString(len) + "){4}]" + emptyZeros + rndByteSequence(len));
			_result.insert(0, rlpblock);
			return rlpblock.size() / 2;
		}
		}
	}
	return 0;
}

std::string RandomCode::rndRLPSequence(int _depth, std::string& _debug)
{
	refreshSeed();
	std::string hash;
	_depth = std::min(std::max(1, _depth), 7); //limit depth to avoid overkill
	recursiveRLP(hash, _depth, _debug);
	return hash;
}

std::string RandomCode::rndByteSequence(int _length, SizeStrictness _sizeType)
{
	refreshSeed();
	std::string hash = "";
	_length = (_sizeType == SizeStrictness::Strict) ? std::max(0, _length) : randomUniInt() % _length;
	for (auto i = 0; i < _length; i++)
	{
		uint8_t byte = randOpCodeGen();
		hash += toCompactHex(byte, HexPrefix::DontAdd, 1);
	}
	return hash;
}

//generate smart random code
std::string RandomCode::generate(int _maxOpNumber, RandomCodeOptions _options)
{
	refreshSeed();
	std::string code;

	//random opCode amount
	boostIntDistrib sizeDist (0, _maxOpNumber);
	boostIntGenerator rndSizeGen(gen, sizeDist);
	int size = (int)rndSizeGen();

	boostWeightGenerator randOpCodeWeight (gen, _options.opCodeProbability);
	bool weightsDefined = _options.opCodeProbability.probabilities().size() == 255;

	for (auto i = 0; i < size; i++)
	{
		uint8_t opcode = weightsDefined ? randOpCodeWeight() : randOpCodeGen();
		dev::eth::InstructionInfo info = dev::eth::instructionInfo((dev::eth::Instruction) opcode);

		if (info.name.find("INVALID_INSTRUCTION") != std::string::npos)
		{
			//Byte code is yet not implemented
			if (_options.useUndefinedOpCodes == false)
			{
				i--;
				continue;
			}
		}
		else
		{
			if (info.name.find("PUSH") != std::string::npos)
				code += toCompactHex(opcode);
			code += fillArguments((dev::eth::Instruction) opcode, _options);
		}

		if (info.name.find("PUSH") == std::string::npos)
		{
			std::string byte = toCompactHex(opcode);
			code += (byte == "") ? "00" : byte;
		}
	}
	return code;
}

std::string RandomCode::randomUniIntHex(u256 _maxVal)
{
	if (_maxVal == 0)
		_maxVal = std::numeric_limits<uint64_t>::max();
	refreshSeed();
	int rand = randUniIntGen() % 100;
	if (rand < 50)
		return "0x" + toCompactHex((u256)randUniIntGen() % _maxVal);
	return "0x" + toCompactHex((u256)randUInt64Gen() % _maxVal);
}

int RandomCode::randomUniInt()
{
	refreshSeed();
	return (int)randUniIntGen();
}

void RandomCode::refreshSeed()
{
	auto now = std::chrono::steady_clock::now().time_since_epoch();
	auto timeSinceEpoch = std::chrono::duration_cast<std::chrono::nanoseconds>(now).count();
	gen.seed(static_cast<unsigned int>(timeSinceEpoch));
}

std::string RandomCode::getPushCode(std::string const& _hex)
{
	int length = _hex.length() / 2;
	int pushCode = 96 + length - 1;
	return toCompactHex(pushCode) + _hex;
}

std::string RandomCode::getPushCode(int _value)
{
	std::string hexString = toCompactHex(_value);
	return getPushCode(hexString);
}

std::string RandomCode::fillArguments(dev::eth::Instruction _opcode, RandomCodeOptions const& _options)
{
	dev::eth::InstructionInfo info = dev::eth::instructionInfo(_opcode);

	std::string code;
	bool smart = false;
	unsigned num = info.args;
	int rand = randUniIntGen() % 100;
	if (rand < _options.smartCodeProbability)
		smart = true;

	if (smart)
	{
		//PUSH1 ... PUSH32
		if (dev::eth::Instruction::PUSH1 <= _opcode && _opcode <= dev::eth::Instruction::PUSH32)
		{
		  code += rndByteSequence(int(_opcode) - int(dev::eth::Instruction::PUSH1) + 1);
		  return code;
		}

		//SWAP1 ... SWAP16 || DUP1 ... DUP16
		bool isSWAP = (dev::eth::Instruction::SWAP1 <= _opcode && _opcode <= dev::eth::Instruction::SWAP16);
		bool isDUP = (dev::eth::Instruction::DUP1 <= _opcode && _opcode <= dev::eth::Instruction::DUP16);

		if (isSWAP || isDUP)
		{
			int times = 0;
			if (isSWAP)
				times = int(_opcode) - int(dev::eth::Instruction::SWAP1) + 2;
			else
			if (isDUP)
				times = int(_opcode) - int(dev::eth::Instruction::DUP1) + 1;

			for (int i = 0; i < times; i ++)
				code += getPushCode(randUniIntGen() % 32);

			return code;
		}

		switch (_opcode)
		{
		case dev::eth::Instruction::CREATE:
			//(CREATE value mem1 mem2)
			code += getPushCode(randUniIntGen() % 128);  //memlen1
			code += getPushCode(randUniIntGen() % 32);   //memlen1
			code += getPushCode(randUniIntGen());		 //value
		break;
		case dev::eth::Instruction::CALL:
		case dev::eth::Instruction::CALLCODE:
			//(CALL gaslimit address value memstart1 memlen1 memstart2 memlen2)
			//(CALLCODE gaslimit address value memstart1 memlen1 memstart2 memlen2)
			code += getPushCode(randUniIntGen() % 128);  //memlen2
			code += getPushCode(randUniIntGen() % 32);  //memstart2
			code += getPushCode(randUniIntGen() % 128);  //memlen1
			code += getPushCode(randUniIntGen() % 32);  //memlen1
			code += getPushCode(randUniIntGen());		//value
			code += getPushCode(toString(_options.getRandomAddress()));//address
			code += getPushCode(randUniIntGen());		//gaslimit
		break;
		case dev::eth::Instruction::SUICIDE: //(SUICIDE address)
			code += getPushCode(toString(_options.getRandomAddress()));
		break;
		case dev::eth::Instruction::RETURN:  //(RETURN memlen1 memlen2)
			code += getPushCode(randUniIntGen() % 128);  //memlen1
			code += getPushCode(randUniIntGen() % 32);  //memlen1
		break;
		default:
			smart = false;
		}
	}

	if (smart == false)
	for (unsigned i = 0; i < num; i++)
	{
		//generate random parameters
		int length = randOpLengGen();
		code += getPushCode(rndByteSequence(length));
	}
	return code;
}


//Ramdom Code Options
RandomCodeOptions::RandomCodeOptions() : useUndefinedOpCodes(false), smartCodeProbability(50)
{
	//each op code with same weight-probability
	for (auto i = 0; i < 255; i++)
		mapWeights.insert(std::pair<int, int>(i, 50));
	setWeights();
}

void RandomCodeOptions::setWeight(dev::eth::Instruction _opCode, int _weight)
{
	mapWeights.at((int)_opCode) = _weight;
	setWeights();
}

void RandomCodeOptions::addAddress(dev::Address const& _address)
{
	addressList.push_back(_address);
}

dev::Address RandomCodeOptions::getRandomAddress() const
{
	if (addressList.size() > 0)
	{
		int index = RandomCode::randomUniInt() % addressList.size();
		return addressList[index];
	}
	return Address(RandomCode::rndByteSequence(20));
}

void RandomCodeOptions::setWeights()
{
	std::vector<int> weights;
	for (auto const& element: mapWeights)
		weights.push_back(element.second);
	opCodeProbability = boostDescreteDistrib(weights);
}


BOOST_AUTO_TEST_SUITE(RandomCodeTests)

BOOST_AUTO_TEST_CASE(rndCode)
{
	std::string code;
	std::cerr << "Testing Random Code: ";
	try
	{
		code = dev::test::RandomCode::generate(10);
	}
	catch(...)
	{
		BOOST_ERROR("Exception thrown when generating random code!");
	}
	std::cerr << code;
}

BOOST_AUTO_TEST_SUITE_END()

}
}