#include "stdafx.h"
#include "SiaCommon.h"
#include <ttmath/ttmath.h>
#include <Wincrypt.h>

NS_BEGIN(Sia)
NS_BEGIN(Api)

String AFX_EXT_API GenerateSha256(const String& str)
{
	String ret;
	HCRYPTPROV hCryptProv = 0;
	HCRYPTHASH hHash = 0;
	BOOL ok = CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_AES, 0);
	ok = ok && CryptCreateHash(hCryptProv, CALG_SHA_256, 0, 0, &hHash);
	ok = ok && CryptHashData(hHash, reinterpret_cast<const BYTE*>(&str[0]), str.length() * sizeof(TCHAR), 0);
	if (ok)
	{
		DWORD dwHashLen;
		DWORD dwCount = sizeof(DWORD);
		if (CryptGetHashParam(hHash, HP_HASHSIZE, reinterpret_cast<BYTE *>(&dwHashLen), &dwCount, 0))
		{
			std::vector<unsigned char> hash(dwHashLen);
			if (CryptGetHashParam(hHash, HP_HASHVAL, reinterpret_cast<BYTE *>(&hash[0]), &dwHashLen, 0))
			{
				std::ostringstream ss;
				ss << std::hex << std::uppercase << std::setfill('0');
				for (int c : hash)
				{
					ss << std::setw(2) << c;
				}
				std::string s = ss.str();
				ret = CA2W(s.c_str()).m_psz;
			}
		}
	}
	
	if (hHash) CryptDestroyHash(hHash);
	if (hCryptProv) CryptReleaseContext(hCryptProv, 0);

	return ret;
}

NS_END(2)