#    _____ ___  ____     ____  _____ ____ ____  _____ _____ 
#   |_   _/ _ \|  _ \   / ___|| ____/ ___|  _ \| ____|_   _|
#     | || | | | |_) |  \___ \|  _|| |   | |_) |  _|   | |
#     | || |_| |  __/    ___) | |__| |___|  _ <| |___  | |
#     |_| \___/|_|      |____/|_____\____|_| \_\_____| |_|


#   see https://github.com/byt3bl33d3r/OffensiveNim/blob/master/src/pop_bin.nim
#   see https://github.com/byt3bl33d3r/OffensiveNim/blob/master/src/shellcode_bin.nim
import os
import system

const
  MEM_COMMIT = 0x1000
  MEM_RESERVE = 0x2000
  PAGE_EXECUTE_READWRITE = 0x40

type
    HANDLE* = int
    HWND* = HANDLE
    UINT* = int32
    LPCSTR* = cstring

proc MessageBox*(hWnd: HWND, lpText: LPCSTR, lpCaption: LPCSTR, uType: UINT): int32 
  {.discardable, stdcall, dynlib: "user32", importc: "MessageBoxA".}

MessageBox(0, "Hello, world !", "Nim is Powerful", 0)



#    LPVOID VirtualAllocEx(
#      [in]           HANDLE hProcess,
#      [in, optional] LPVOID lpAddress, BUT IF NULL: automatically calculated
#      [in]           SIZE_T dwSize,    is an int? size in bytes of memory region. "The size of the region of memory to allocate, in bytes."
#      [in]           DWORD  flAllocationType,      see https://learn.microsoft.com/en-us/windows/win32/api/memoryapi/nf-memoryapi-virtualallocex
#      [in]           DWORD  flProtect
#    );

# proc NimVirtualAllocEx*(hWnd: HWND, lpAddress: pointer, dwSize: LPCSTR, uType: UINT): int32 
#  {.discardable, stdcall, dynlib: "user32", importc: "VirtualAllocEx".}


# Declare the VirtualAlloc function from Windows API
proc VirtualAlloc*(addr: pointer void, size: csize_t, allocType: cuint, protect: cuint): pointer cvoid {.importwinapi: "VirtualAlloc".}

# Declare a simple function that will be loaded into the allocated memory
proc helloWorld() =
  echo "Hello, World from allocated memory!"

# Main procedure
proc main(): int =
  # Calculate the size needed for the function
  let codeSize = procSize(helloWorld)

  # Allocate memory using VirtualAlloc
  let allocatedMemory = VirtualAlloc(nil, codeSize, MEM_COMMIT or MEM_RESERVE, PAGE_EXECUTE_READWRITE)
  if allocatedMemory == nil:
    echo "Failed to allocate memory."
    return 1  # Return an error code

  # Copy the function code to the allocated memory
  memcpy(allocatedMemory, addr(helloWorld), codeSize)

  # Cast the allocated memory to a function pointer
  let funcPointer: proc() {.cdecl.} = cast[proc()](allocatedMemory)

  # Execute the function in the allocated memory
  funcPointer()

  # Deallocate the memory (optional)
  os.free(allocatedMemory)

  return 0  # Return 0 to indicate successful execution

when isMainModule:
  main()