#include <iostream>
#include<Windows.h>
using namespace std;

VOID WINAPI asyncReading(DWORD code, DWORD nBytes, LPOVERLAPPED lpOV);
VOID WINAPI asyncWrite(DWORD code, DWORD nBytes, LPOVERLAPPED lpOV);
void asynccopy();

const int CLUSTER = 4096;//4 KB
HANDLE infile, outfile;
CHAR** buffers;
int multiplier;
int bytestouse;
OVERLAPPED* OverLapIn, * OverLapOut;//структуры овелапд
LONGLONG counter;
LARGE_INTEGER fileSize;
int main()
{
    asynccopy();
    system("pause");
    return 0;
}
void asynccopy()
{
    puts("Enter filepath. Spaces are not allowed");
    char path[MAX_PATH];
    cin >> path;
    infile = CreateFileA(path, GENERIC_READ, 0, NULL, OPEN_EXISTING, FILE_FLAG_OVERLAPPED| FILE_FLAG_NO_BUFFERING, NULL);
    if (infile == INVALID_HANDLE_VALUE)
        cout << "Error " << GetLastError() << endl;
    else
    {
        puts("File opened successfully");
        puts("Enter filepath where to copy file. Spaces are not allowed");
        char newpath[MAX_PATH];
        cin >> newpath;
        outfile = CreateFileA(newpath, GENERIC_WRITE, 0, NULL, CREATE_ALWAYS,  FILE_FLAG_OVERLAPPED| FILE_FLAG_NO_BUFFERING  , NULL);
        if (outfile == INVALID_HANDLE_VALUE)
            cout << "Error " << GetLastError() << endl;
        else
        {
            puts("File created successfully");
            puts("Enter cluster multipltier and number of overlaps");
            int num_ovrlp;
            cin >> multiplier >> num_ovrlp;
            bytestouse = multiplier * CLUSTER;
            OverLapIn = new OVERLAPPED[num_ovrlp];
            OverLapOut = new OVERLAPPED[num_ovrlp];
            buffers = new CHAR * [num_ovrlp];//буфферы
            for (int i = 0; i < num_ovrlp; i++)
                buffers[i] = new CHAR[bytestouse];
            int clustersInFile;
            LARGE_INTEGER posIn;
            GetFileSizeEx(infile, &fileSize);
            clustersInFile = fileSize.QuadPart / bytestouse;
            if (fileSize.QuadPart % bytestouse != 0)
                clustersInFile++;
            cout << "File Size: " << fileSize.QuadPart << " Bytes" << endl;
            cout << "Copying with given buffer will take " << clustersInFile*2 << " operations"<<endl;;
            posIn.QuadPart = 0;
            DWORD before = GetTickCount64();
            counter = 0;
            for (int i = 0; i < num_ovrlp; i++)
            {
                OverLapIn[i].hEvent = (HANDLE)i;
                OverLapOut[i].hEvent = (HANDLE)i;
                OverLapIn[i].Offset = posIn.LowPart;
                OverLapIn[i].OffsetHigh = posIn.HighPart;
                if (posIn.QuadPart < fileSize.QuadPart)
                    ReadFileEx(infile, buffers[i], bytestouse, &OverLapIn[i],asyncReading);
                posIn.QuadPart += (LONGLONG)bytestouse;
            }
            while (counter < 2 * clustersInFile)
                SleepEx(INFINITE, true);
            DWORD after = GetTickCount64();
            cout << "Copying took " << float(after - before) << " miliseconds /n Overlaps: " << num_ovrlp << " Buffer size per operation (Bytes) : " << bytestouse << endl;
            delete[] OverLapIn;
            delete[]OverLapOut;
            for (int i = 0; i < num_ovrlp; i++)
                delete[] buffers[i];
            delete[] buffers;
            SetFilePointerEx(outfile, fileSize, 0, FILE_BEGIN);
            SetEndOfFile(outfile);
            CloseHandle(outfile);
        }
    }
    CloseHandle(infile);
}
VOID WINAPI asyncReading(DWORD code,DWORD nBytes,LPOVERLAPPED lpOV) {
    ++counter;
    LARGE_INTEGER posIn, posOut;
    DWORD i = (DWORD)(lpOV->hEvent);
    posIn.LowPart = OverLapIn[i].Offset;
    posIn.HighPart = OverLapIn[i].OffsetHigh;
    posOut.QuadPart = posIn.QuadPart;
    OverLapOut[i].Offset = posOut.LowPart;
    OverLapOut[i].OffsetHigh = posOut.HighPart;
    WriteFileEx(outfile, buffers[i], bytestouse, &OverLapOut[i], asyncWrite);
    posIn.QuadPart += bytestouse;
    OverLapIn[i].Offset = posIn.LowPart;
    OverLapIn[i].OffsetHigh = posIn.HighPart;
}
VOID WINAPI asyncWrite(DWORD code, DWORD nBytes, LPOVERLAPPED lpOV) {
    ++counter;
    LARGE_INTEGER posIn;
    DWORD i = (DWORD)(lpOV->hEvent);
    posIn.LowPart = OverLapIn[i].Offset;
    posIn.HighPart = OverLapIn[i].OffsetHigh;
    if (posIn.QuadPart < fileSize.QuadPart)
        ReadFileEx(infile, buffers[i], bytestouse, &OverLapIn[i], asyncReading);
}