/* 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/. */

#include "servicebase.hxx"
#include "windowsHelper.hxx"

// Shared code between applications and updater.exe

/**
 * Verifies if 2 files are byte for byte equivalent.
 *
 * @param  file1Path   The first file to verify.
 * @param  file2Path   The second file to verify.
 * @param  sameContent Out parameter, TRUE if the files are equal
 * @return TRUE If there was no error checking the files.
 */
BOOL
VerifySameFiles(LPCWSTR file1Path, LPCWSTR file2Path, BOOL &sameContent)
{
    sameContent = FALSE;
    AutoHandle file1(CreateFileW(file1Path, GENERIC_READ, FILE_SHARE_READ,
                                 nullptr, OPEN_EXISTING, 0, nullptr));
    if (file1 == INVALID_HANDLE_VALUE)
    {
        return FALSE;
    }
    AutoHandle file2(CreateFileW(file2Path, GENERIC_READ, FILE_SHARE_READ,
                                 nullptr, OPEN_EXISTING, 0, nullptr));
    if (file2 == INVALID_HANDLE_VALUE)
    {
        return FALSE;
    }

    DWORD fileSize1 = GetFileSize(file1.get(), nullptr);
    DWORD fileSize2 = GetFileSize(file2.get(), nullptr);
    if (INVALID_FILE_SIZE == fileSize1 || INVALID_FILE_SIZE == fileSize2)
    {
        return FALSE;
    }

    if (fileSize1 != fileSize2)
    {
        // sameContent is already set to FALSE
        return TRUE;
    }

    char buf1[COMPARE_BLOCKSIZE];
    char buf2[COMPARE_BLOCKSIZE];
    DWORD numBlocks = fileSize1 / COMPARE_BLOCKSIZE;
    DWORD leftOver = fileSize1 % COMPARE_BLOCKSIZE;
    DWORD readAmount;
    for (DWORD i = 0; i < numBlocks; i++)
    {
        if (!ReadFile(file1.get(), buf1, COMPARE_BLOCKSIZE, &readAmount, nullptr) ||
                readAmount != COMPARE_BLOCKSIZE)
        {
            return FALSE;
        }

        if (!ReadFile(file2.get(), buf2, COMPARE_BLOCKSIZE, &readAmount, nullptr) ||
                readAmount != COMPARE_BLOCKSIZE)
        {
            return FALSE;
        }

        if (memcmp(buf1, buf2, COMPARE_BLOCKSIZE))
        {
            // sameContent is already set to FALSE
            return TRUE;
        }
    }

    if (leftOver)
    {
        if (!ReadFile(file1.get(), buf1, leftOver, &readAmount, nullptr) ||
                readAmount != leftOver)
        {
            return FALSE;
        }

        if (!ReadFile(file2.get(), buf2, leftOver, &readAmount, nullptr) ||
                readAmount != leftOver)
        {
            return FALSE;
        }

        if (memcmp(buf1, buf2, leftOver))
        {
            // sameContent is already set to FALSE
            return TRUE;
        }
    }

    sameContent = TRUE;
    return TRUE;
}