/*******************************************************************************
 * Copyright (c) 2015-2018 Skymind, Inc.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Apache License, Version 2.0 which is available at
 * https://www.apache.org/licenses/LICENSE-2.0.
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 *
 * SPDX-License-Identifier: Apache-2.0
 ******************************************************************************/

// mmap for win32 platform using win32 api
//
// https://code.google.com/p/mman-win32/
//

#ifndef _SYS_MMAN_H_
#define _SYS_MMAN_H_

#include <windows.h>
#include <errno.h>
#include <io.h>

#ifndef FILE_MAP_EXECUTE
#define FILE_MAP_EXECUTE    0x0020
#endif /* FILE_MAP_EXECUTE */

#ifndef _WIN32_WINNT		// Allow use of features specific to Windows XP or later.
#define _WIN32_WINNT 0x0501	// Change this to the appropriate value to target other versions of Windows.
#endif

/* All the headers include this file. */
#ifndef _MSC_VER
#include <_mingw.h>
#endif

/* Determine offset type */
#include <stdint.h>
#if defined(_WIN64)
typedef int64_t OffsetType;
#else
typedef uint32_t OffsetType;
#endif

#include <sys/types.h>

#ifdef __cplusplus
extern "C" {
#endif

#define PROT_NONE       0
#define PROT_READ       1
#define PROT_WRITE      2
#define PROT_EXEC       4

#define MAP_FILE        0
#define MAP_SHARED      1
#define MAP_PRIVATE     2
#define MAP_TYPE        0xf
#define MAP_FIXED       0x10
#define MAP_ANONYMOUS   0x20
#define MAP_ANON        MAP_ANONYMOUS

#define MAP_FAILED      ((void *)-1)

/* Flags for msync. */
#define MS_ASYNC        1
#define MS_SYNC         2
#define MS_INVALIDATE   4

void _mmap(Nd4jLong* result, size_t length, const char *fileName);
void*   mmap(void *addr, size_t len, int prot, int flags, int fildes, OffsetType off);
int     munmap(void *addr, size_t len);
int     _mprotect(void *addr, size_t len, int prot);
int     msync(void *addr, size_t len, int flags);
int     mlock(const void *addr, size_t len);
int     munlock(const void *addr, size_t len);

#ifdef __cplusplus
}
#endif

static int __map_mman_error(const DWORD err, const int deferr)
{
    if (err == 0)
        return 0;
    //TODO: implement
    return err;
}

static DWORD __map_mmap_prot_page(const int prot)
{
    DWORD protect = 0;

    if (prot == PROT_NONE)
        return protect;

    if ((prot & PROT_EXEC) != 0)
    {
        protect = ((prot & PROT_WRITE) != 0) ?
                  PAGE_EXECUTE_READWRITE : PAGE_EXECUTE_READ;
    }
    else
    {
        protect = ((prot & PROT_WRITE) != 0) ?
                  PAGE_READWRITE : PAGE_READONLY;
    }

    return protect;
}

static DWORD __map_mmap_prot_file(const int prot)
{
    DWORD desiredAccess = 0;

    if (prot == PROT_NONE)
        return desiredAccess;

    if ((prot & PROT_READ) != 0)
        desiredAccess |= FILE_MAP_READ;
    if ((prot & PROT_WRITE) != 0)
        desiredAccess |= FILE_MAP_WRITE;
    if ((prot & PROT_EXEC) != 0)
        desiredAccess |= FILE_MAP_EXECUTE;

    return desiredAccess;
}

void _mmap(Nd4jLong* result, size_t length, const char *fileName) {
    HANDLE fm, h;

    void * map = MAP_FAILED;
    OffsetType off  = 0;
    int prot = PROT_READ | PROT_WRITE;

    // we need to convert long path (probably) to short pat (actually)
    // it's Windows API, in the middle of 2018!
    auto sz = GetShortPathName(fileName, nullptr, 0);

    auto shortName = new TCHAR[sz];
    GetShortPathName(fileName, shortName, sz);

    delete[] shortName;

#ifdef _MSC_VER
    #pragma warning(push)
    #pragma warning(disable: 4293)
#endif

    const DWORD dwFileOffsetLow = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                                  (DWORD)off : (DWORD)(off & 0xFFFFFFFFL);
    const DWORD dwFileOffsetHigh = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                                   (DWORD)0 : (DWORD)((off >> 32) & 0xFFFFFFFFL);
    const DWORD protect = __map_mmap_prot_page(prot);
    const DWORD desiredAccess = __map_mmap_prot_file(prot);

    const OffsetType maxSize = off + (OffsetType) length;

    const DWORD dwMaxSizeLow = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                               (DWORD)maxSize : (DWORD)(maxSize & 0xFFFFFFFFL);
    const DWORD dwMaxSizeHigh = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                                (DWORD)0 : (DWORD)((maxSize >> 32) & 0xFFFFFFFFL);

#ifdef _MSC_VER
    #pragma warning(pop)
#endif

    h = CreateFile(shortName, GENERIC_READ | GENERIC_WRITE, FILE_SHARE_WRITE | FILE_SHARE_READ, nullptr, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, nullptr);

    if (h == INVALID_HANDLE_VALUE) {
        errno = __map_mman_error(GetLastError(), EPERM);
        nd4j_printf("Error code: %i\n", (int) errno);
        throw std::runtime_error("CreateFile failed");
    }

    fm = CreateFileMapping(h, NULL, protect, dwMaxSizeHigh, dwMaxSizeLow, NULL);

    if (fm == NULL)
    {
        errno = __map_mman_error(GetLastError(), EPERM);
        throw std::runtime_error("CreateFileMapping failed");
    }

    map = MapViewOfFile(fm, desiredAccess, dwFileOffsetHigh, dwFileOffsetLow, length);

    CloseHandle(fm);

    if (map == NULL)
    {
        errno = __map_mman_error(GetLastError(), EPERM);
        throw std::runtime_error("MapViewOfFile failed");
    }

    result[0] = reinterpret_cast<Nd4jLong>(map);
    result[1] = reinterpret_cast<Nd4jLong>(h);
}

void* mmap(void *addr, size_t len, int prot, int flags, int files, OffsetType off)
{
    HANDLE fm, h;

    void * map = MAP_FAILED;

#ifdef _MSC_VER
    #pragma warning(push)
#pragma warning(disable: 4293)
#endif

    const DWORD dwFileOffsetLow = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                                  (DWORD)off : (DWORD)(off & 0xFFFFFFFFL);
    const DWORD dwFileOffsetHigh = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                                   (DWORD)0 : (DWORD)((off >> 32) & 0xFFFFFFFFL);
    const DWORD protect = __map_mmap_prot_page(prot);
    const DWORD desiredAccess = __map_mmap_prot_file(prot);

    const OffsetType maxSize = off + (OffsetType)len;

    const DWORD dwMaxSizeLow = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                               (DWORD)maxSize : (DWORD)(maxSize & 0xFFFFFFFFL);
    const DWORD dwMaxSizeHigh = (sizeof(OffsetType) <= sizeof(DWORD)) ?
                                (DWORD)0 : (DWORD)((maxSize >> 32) & 0xFFFFFFFFL);

#ifdef _MSC_VER
#pragma warning(pop)
#endif

    errno = 0;

    if (len == 0
        /* Unsupported flag combinations */
        || (flags & MAP_FIXED) != 0
        /* Usupported protection combinations */
        || prot == PROT_EXEC)
    {
        errno = EINVAL;
        return MAP_FAILED;
    }

    h = ((flags & MAP_ANONYMOUS) == 0) ?
        (HANDLE)_get_osfhandle(files) : INVALID_HANDLE_VALUE;


    if ((flags & MAP_ANONYMOUS) == 0 && h == INVALID_HANDLE_VALUE)
    {
        errno = EBADF;
        return MAP_FAILED;
    }

    fm = CreateFileMapping(h, NULL, protect, dwMaxSizeHigh, dwMaxSizeLow, NULL);

    if (fm == NULL)
    {
        errno = __map_mman_error(GetLastError(), EPERM);
        return MAP_FAILED;
    }

    map = MapViewOfFile(fm, desiredAccess, dwFileOffsetHigh, dwFileOffsetLow, len);

    CloseHandle(fm);

    if (map == NULL)
    {
        errno = __map_mman_error(GetLastError(), EPERM);
        return MAP_FAILED;
    }

    return map;
}

int munmap(void *addr, size_t len)
{
    if (UnmapViewOfFile(addr))
        return 0;

    errno =  __map_mman_error(GetLastError(), EPERM);

    return -1;
}

int _mprotect(void *addr, size_t len, int prot)
{
    DWORD newProtect = __map_mmap_prot_page(prot);
    DWORD oldProtect = 0;

    if (VirtualProtect(addr, len, newProtect, &oldProtect))
        return 0;

    errno =  __map_mman_error(GetLastError(), EPERM);

    return -1;
}

int msync(void *addr, size_t len, int flags)

{
    if (FlushViewOfFile(addr, len))
        return 0;

    errno =  __map_mman_error(GetLastError(), EPERM);

    return -1;
}

int mlock(const void *addr, size_t len)
{
    if (VirtualLock((LPVOID)addr, len))
        return 0;

    errno =  __map_mman_error(GetLastError(), EPERM);

    return -1;
}

int munlock(const void *addr, size_t len)
{
    if (VirtualUnlock((LPVOID)addr, len))
        return 0;

    errno =  __map_mman_error(GetLastError(), EPERM);

    return -1;
}


#endif //PROJECT_MMAN_H
