/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifdef _WIN32
#include <windows.h>
#include <wincrypt.h>
#include "pathhash.h"


/**
 * Converts a binary sequence into a hex string
 *
 * @param hash      The binary data sequence
 * @param hashSize  The size of the binary data sequence
 * @param hexString A buffer to store the hex string, must be of
 *                  size 2 * @hashSize
*/
static void
BinaryDataToHexString(const BYTE *hash, DWORD &hashSize,
                      LPWSTR hexString)
{
    WCHAR *p = hexString;
    for (DWORD i = 0; i < hashSize; ++i)
    {
        wsprintfW(p, L"%.2x", hash[i]);
        p += 2;
    }
}

/**
 * Calculates an MD5 hash for the given input binary data
 *
 * @param  data     Any sequence of bytes
 * @param  dataSize The number of bytes inside @data
 * @param  hash     Output buffer to store hash, must be freed by the caller
 * @param  hashSize The number of bytes in the output buffer
 * @return TRUE on success
*/
static BOOL
CalculateMD5(const char *data, DWORD dataSize,
             BYTE **hash, DWORD &hashSize)
{
    HCRYPTPROV hProv = 0;
    HCRYPTHASH hHash = 0;

    if (!CryptAcquireContext(&hProv, nullptr, nullptr, PROV_RSA_FULL,
                             CRYPT_VERIFYCONTEXT))
    {
        if (NTE_BAD_KEYSET != GetLastError())
        {
            return FALSE;
        }

        // Maybe it doesn't exist, try to create it.
        if (!CryptAcquireContext(&hProv, nullptr, nullptr, PROV_RSA_FULL,
                                 CRYPT_VERIFYCONTEXT | CRYPT_NEWKEYSET))
        {
            return FALSE;
        }
    }

    if (!CryptCreateHash(hProv, CALG_MD5, 0, 0, &hHash))
    {
        return FALSE;
    }

    if (!CryptHashData(hHash, reinterpret_cast<const BYTE*>(data),
                       dataSize, 0))
    {
        return FALSE;
    }

    DWORD dwCount = sizeof(DWORD);
    if (!CryptGetHashParam(hHash, HP_HASHSIZE, (BYTE *)&hashSize,
                           &dwCount, 0))
    {
        return FALSE;
    }

    *hash = new BYTE[hashSize];
    ZeroMemory(*hash, hashSize);
    if (!CryptGetHashParam(hHash, HP_HASHVAL, *hash, &hashSize, 0))
    {
        return FALSE;
    }

    if (hHash)
    {
        CryptDestroyHash(hHash);
    }

    if (hProv)
    {
        CryptReleaseContext(hProv,0);
    }

    return TRUE;
}

/**
 * Converts a file path into a unique registry location for cert storage
 *
 * @param  filePath     The input file path to get a registry path from
 * @param  registryPath A buffer to write the registry path to, must
 *                      be of size in WCHARs MAX_PATH + 1
 * @return TRUE if successful
*/
BOOL
CalculateRegistryPathFromFilePath(const LPCWSTR filePath,
                                  LPWSTR registryPath)
{
    size_t filePathLen = wcslen(filePath);
    if (!filePathLen)
    {
        return FALSE;
    }

    // If the file path ends in a slash, ignore that character
    if (filePath[filePathLen -1] == L'\\' ||
            filePath[filePathLen - 1] == L'/')
    {
        filePathLen--;
    }

    // Copy in the full path into our own buffer.
    // Copying in the extra slash is OK because we calculate the hash
    // based on the filePathLen which excludes the slash.
    // +2 to account for the possibly trailing slash and the null terminator.
    WCHAR *lowercasePath = new WCHAR[filePathLen + 2];
    memset(lowercasePath, 0, (filePathLen + 2) * sizeof(WCHAR));
    wcsncpy(lowercasePath, filePath, filePathLen + 1);
    _wcslwr(lowercasePath);

    BYTE *hash;
    DWORD hashSize = 0;
    if (!CalculateMD5(reinterpret_cast<const char*>(lowercasePath),
                      filePathLen * 2,
                      &hash, hashSize))
    {
        delete[] lowercasePath;
        return FALSE;
    }
    delete[] lowercasePath;

    LPCWSTR baseRegPath = L"SOFTWARE\\LibreOffice\\MaintenanceService\\";
    wcsncpy(registryPath, baseRegPath, MAX_PATH);
    BinaryDataToHexString(hash, hashSize,
                          registryPath + wcslen(baseRegPath));
    delete[] hash;
    return TRUE;
}
#endif