#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <stdio.h>
#include <errno.h>
#include <process.h>

int __cdecl wmain(int argc, wchar_t** argv)
{
    static const wchar_t* format = L"\nreal\t%ldm%.3fs\nuser\t%ldm%.3fs\nsys\t%ldm%.3fs\n";
    if(argc > 1)
    {
        FILE* out = stdout;
        int argsToShift = 1;
        if((argv[1][0] == L'-') && (towlower(argv[1][1]) == L'p'))
        {
            out = stderr;
            ++argsToShift;
        }
        int argCount = 0;
        // construct argv for the new process
        LPWSTR* argVector = CommandLineToArgvW(GetCommandLine(), &argCount);
        memmove(argVector, &argVector[argsToShift], sizeof(WCHAR*) * (argc - argsToShift));
        argVector[argc - argsToShift] = NULL;
        // spawn it
        HANDLE hProcess = (HANDLE)_wspawnv(P_NOWAIT, argVector[0], argVector);
        LocalFree(argVector);
        if(hProcess == INVALID_HANDLE_VALUE)
        {
#ifdef _DEBUG
            fwprintf(stderr, L"Couldn't launch process. errno = %d\n", errno);
#endif
            return 126;
        }
        // wait for it to exit
        WaitForSingleObject(hProcess, INFINITE);
        DWORD exitCode = 0;
        GetExitCodeProcess(hProcess, &exitCode);
        FILETIME creation, exit, kernel, user;
        // see how long it ran for
        BOOL result = GetProcessTimes(hProcess, &creation, &exit, &kernel, &user);
        CloseHandle(hProcess);
        if(result)
        {
            // calculate the difference between creation and exit
            ULARGE_INTEGER ulCreation = {creation.dwLowDateTime, creation.dwHighDateTime};
            ULARGE_INTEGER ulExit = {exit.dwLowDateTime, exit.dwHighDateTime};
            ULONGLONG total = ulExit.QuadPart - ulCreation.QuadPart;
            ulCreation.QuadPart = total;
            FILETIME elapsed = {ulCreation.LowPart, ulCreation.HighPart};
            // convert it to a systemtime
            SYSTEMTIME sysTimeElapsed = {0};
            FileTimeToSystemTime(&elapsed, &sysTimeElapsed);
            double elapsedSeconds = sysTimeElapsed.wSecond + ((sysTimeElapsed.wMilliseconds) / 1000.);
            // convert user time to systemtime
            SYSTEMTIME userSysTime = {0};
            FileTimeToSystemTime(&user, &userSysTime);
            double userSeconds = userSysTime.wSecond + ((userSysTime.wMilliseconds) / 1000.);
            // convert kernel time
            SYSTEMTIME kernelSysTime = {0};
            FileTimeToSystemTime(&kernel, &kernelSysTime);
            double kernelSeconds = kernelSysTime.wSecond + ((kernelSysTime.wMilliseconds) / 1000.);
            // print the results
            fwprintf(
                out,
                format,
                sysTimeElapsed.wMinute,
                elapsedSeconds,
                userSysTime.wMinute,
                userSeconds,
                kernelSysTime.wMinute,
                kernelSeconds
                );
        }
        else
        {
#ifdef _DEBUG
            fwprintf(stderr, L"Failed to get process times, error %lu\n", GetLastError());
#endif
        }
        return exitCode;
    }
    else
    {
        const wchar_t* usage = L"Usage: time [-p] utility args\n"
                                L"-p\t\tOptional, send output to stderr instead of stdout\n"
                                L"utility\t\tThe command to time\n"
                                L"args\t\tArguments to 'utility'\n";
        fputws(usage, stderr);
        return 1;
    }
    return 0;
}