#include <cstdlib>
#include "EncryptEngine.h"
#include "base/base64.h"

using std::string;
using Jumpeleon::DataType;

EncryptEngine* EncryptEngine::instance = nullptr;

std::string offsets[7] = { "1", "2", "3", "4", "5", "6", "7" };

bool EncryptEngine::init()
{
	instance = new EncryptEngine();

	strcpy((char*)instance->key, "12345678");
	
	return true;
}

EncryptEngine* EncryptEngine::getInstance()
{
	if (!instance)
		init();

	return instance;
}

void EncryptEngine::destroyInstance()
{
	delete instance;
}

string EncryptEngine::encrypt(int number, DataType type)
{
	//creating string with value data
	string tempStr;
	sprintf((char*) tempStr.c_str(), "%d", number);

	xxtea_long dataLen = strlen(tempStr.c_str());

	//create pointer to uchar for xxtea algorithm
	unsigned char* data = new unsigned char[dataLen];

	//copy data from temp string to uchar pointer
	strcpy((char*) data, tempStr.c_str());

	//length of returned result from xxtea_encrypt
	xxtea_long retLen = 0;

	//encrypt data with key
	unsigned char* result = xxtea_encrypt(data, dataLen, key, keyLen, &retLen);

	//encode data with base64 encoding for avoid special-characters
	char* b64enc = nullptr;
	retLen = cocos2d::base64Encode(result, retLen, &b64enc);

	//return result in string
	return std::string(b64enc) + offsets[(int)type];
}

int EncryptEngine::decrypt(string tempStr, DataType type)
{
	//validation
	if (tempStr.length() < 6)
		return 0;
	auto end = tempStr.substr(tempStr.length() - 6, 6);
	if (end != offsets[(int)type])
		return 0;

	tempStr.erase(tempStr.length() - 6, 6);

	//same like in encrypt
	xxtea_long dataLen = tempStr.length();
	unsigned char* data = new unsigned char[dataLen];
	strcpy((char*)data, tempStr.c_str());

	//decode data with base64 decoding for get actual encrypted data
	unsigned char* b64dec = nullptr;
	xxtea_long retLen = cocos2d::base64Decode(data, dataLen, &b64dec);

	//return 0 if decode is failed
	if (b64dec == NULL)
		return 0;

	//decrypt data with key
	unsigned char* result = xxtea_decrypt((unsigned char*) b64dec, retLen, key, keyLen, &retLen);

	//return 0 if decrypt is failed
	if (result == NULL)
		return 0;

	//return result in int
	return atoi((char*)result);
}