#include <stdio.h>
#include <stdint.h>
#include <string.h>

//#pragma warning( push )
//#pragma warning( disable : 4668)
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <psapi.h>
//#pragma warning( pop )

static void* faddrs[6];
char fnames[] = "DirectInput8Create\0" "DllCanUnloadNow\0" "DllGetClassObject\0" \
"DllRegisterServer\0" "DllUnregisterServer\0" "GetdfDIJoystick\0" "\3";

/*[[nodiscard]]*/ size_t next_name(char *names[])
{
	size_t len = 0;
	while(names != NULL) {
		if(**names == '\0') { (*names)++; break; }
		else if(**names == '\3') break;
		(*names)++; len++;
	}

	return len;
}

HMODULE init_faddrs(void)
{
	HMODULE h = LoadLibrary("C:\\Windows\\SysWOW64\\dinput8.dll"); // perhaps i should ship my own original dinput8.dll and proxy from a renamed copy but uhhhh no
	if (h == NULL) goto init_end;
	
	char* fname = fnames;
	size_t i = 0;
	do {
		faddrs[i] = (void*)GetProcAddress(h, fname);
		i++;
	} while(next_name(&fname));


init_end:
	return h;
}

HMODULE hodll = NULL;


/*void* sigscan(const char* pattern, const char* mask)
{
	HMODULE module = GetModuleHandle(NULL);
	if(module == NULL) return NULL;

	MODULEINFO minfo;
	if(GetModuleInformation(GetCurrentProcess(), module, &minfo, sizeof(minfo)) == 0) return NULL;
	
	size_t len = strlen(mask);
	unsigned char* addr = (unsigned char*)minfo.lpBaseOfDll;
	for(DWORD i = 0; i < minfo.SizeOfImage - (len-1); i++)
	{
		for(size_t j = 0; j < len; j++)
		{
			if(addr[i + j] == (unsigned char)(pattern[j]) && (unsigned char)(mask[j]) != '?')
			{
				if(j == (len-1))
					return (void*)(addr + i);
			}
			else
				break;
			
		}
	}
	
	return NULL;
}*/

/*
void* GetStackBaseFromTEB(void)
{
#if defined(_WIN64)
	return (void*)__readgsqword(0x08);
#elif defined(_WIN32)
	return (void*)__readfsdword(0x04);
#endif
}
*/

void* GetEntryPointOfHostProcess(void)
{
	HMODULE module = GetModuleHandle(NULL);
	if(module == NULL) return NULL;

	MODULEINFO minfo;
	if(GetModuleInformation(GetCurrentProcess(), module, &minfo, sizeof(minfo)) == 0) return NULL;
	return minfo.EntryPoint;
}

void* PD2_EBP = NULL;
uint8_t writeback[5] = { 0 };
void* retaddr = NULL;

#pragma pack(push, 4)
typedef struct _Patch {
	uint8_t* writeback;
	uint8_t NOPs; // to keep alignment, unsure if actually needed but would be nice if the debugger suddenly didn't re-disassemble everything incorrectly after the patch
	void* addr;
	void (*func)(void);
} Patch;
#pragma pack(pop)

void PatchCALL(Patch* patch, BOOL UnVProtect)
{
	if(UnVProtect) {
		DWORD _;
		if(VirtualProtect(patch->addr, 5 + patch->NOPs, PAGE_EXECUTE_READWRITE, &_) == 0) {
			char err[64] = { '\0' };
			snprintf(err, 64, "%lu", GetLastError());
			MessageBox(GetCurrentProcess(), err, NULL, MB_OK);
			return;
		}
	}
}

void PatchGame(void* addr, void (*func)(void))
{
	DWORD _;
	if(VirtualProtect(addr, 5, PAGE_EXECUTE_READWRITE, &_) == 0)
	{
		char err[64] = { '\0' };
		snprintf(err, 64, "%lu", GetLastError());
		MessageBox(GetCurrentProcess(), err, NULL, MB_OK);
		return;
	}
	uint8_t oinst[5] = { 0 };
	memcpy_s(oinst, sizeof(*oinst) * 5, addr, 5);
	uint8_t patched[5] = { 0xE9, 0x00, 0x00, 0x00, 0x00 };
	((int32_t*)(patched + 1))[0] = (uintptr_t)func - ((uintptr_t)addr + 1 + sizeof(uintptr_t)); // math assumes patching over a jmp or call, not that it really matters
	memcpy_s(addr, 5, patched, 5);
	memcpy_s(writeback, 5, oinst, 5); // magic global that hopefully works
}

void __declspec(naked) GetEBPWithinGame(void)
{
	__asm {
		pushad
	}
	__asm {
		mov PD2_EBP, ebp
	}
	memcpy_s(retaddr, 5, writeback, 5);
	__asm {
		popad
		push retaddr
		ret
	}
}

BOOL WINAPI DllMain(/*[[maybe_unused]]*/ HINSTANCE h_dll, DWORD fwdReason, LPVOID lpvReserved)
{
	switch(fwdReason)
	{
		case DLL_PROCESS_ATTACH:
		hodll = init_faddrs();
		if(hodll == NULL) return FALSE;
		retaddr = GetEntryPointOfHostProcess();
		PatchGame(retaddr, &GetEBPWithinGame);
		break;

		case DLL_THREAD_ATTACH:
		// [[fallthrough]];
		case DLL_THREAD_DETACH:
		break;
		
		case DLL_PROCESS_DETACH:
		if(lpvReserved != NULL) break;
		if(hodll != NULL) FreeLibrary(hodll);
		break;
	}
	
	return TRUE;
}