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

#include "mman.h"

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

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(void *addr, size_t len, int prot, int flags, int fildes, 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(fildes) : 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;
}