/******************************************************************************
 * The MIT License (MIT)
 * 
 * Copyright (c) 2014 Baldur Karlsson
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 ******************************************************************************/

// This project deliberately references only kernel32.dll (ie. not even the CRT)
// so that when inserted into an application it has as small an overhead/impact
// as possible. Ideally it would be present only to be a pass-through hook and
// the first time only to allocate a little, check if this process should be hooked
// and load the renderdoc dll.
//
// The no-CRT restriction causes some awkward bits and pieces but the dll is simple
// enough that it's not a big issue.

#include <windows.h>

#include "renderdocshim.h"

struct CaptureOptions;
typedef void (__cdecl *pRENDERDOC_SetCaptureOptions)(const CaptureOptions *opts);
typedef void (__cdecl *pRENDERDOC_SetLogFile)(const char *logfile);

#if defined(RELEASE)
#define LOGPRINT(txt) do { } while (0)
#else
// define this to something to get logging
//#define LOGPRINT(txt) OutputDebugStringW(txt)
#define LOGPRINT(txt) do { } while (0)
#endif

void CheckHook()
{
	ShimData *data = NULL;

	HANDLE datahandle = OpenFileMappingA(FILE_MAP_READ, FALSE, GLOBAL_HOOK_DATA_NAME);

	if(datahandle == NULL)
	{
		LOGPRINT(L"renderdocshim: can't open global data\n");
		return;
	}

	data = (ShimData *)MapViewOfFile(datahandle, FILE_MAP_READ, 0, 0, sizeof(ShimData));

	if(data == NULL)
	{
		CloseHandle(datahandle);
		LOGPRINT(L"renderdocshim: can't map global data\n");
		return;
	}

	if(data->pathmatchstring[0] == 0 ||
	   data->pathmatchstring[1] == 0 ||
	   data->pathmatchstring[2] == 0 ||
	   data->pathmatchstring[3] == 0)
	{
		LOGPRINT(L"renderdocshim: invalid pathmatchstring: '");
		LOGPRINT(data->pathmatchstring);
		LOGPRINT(L"'\n");

		UnmapViewOfFile(data);
		CloseHandle(datahandle);
		return;
	}

	// no new[], need to use VirtualAlloc
	const int exepathLen = 1024;
	wchar_t *exepath = (wchar_t *)VirtualAlloc(NULL, exepathLen*sizeof(wchar_t), MEM_RESERVE|MEM_COMMIT, PAGE_READWRITE);

	if(exepath)
	{
		// no memset :).
		for(int i=0; i < exepathLen; i++) exepath[i] = 0;

		GetModuleFileNameW(NULL, exepath, exepathLen - 1);

		// no str*cmp functions
		int find = FindStringOrdinal(FIND_FROMSTART, exepath, -1, data->pathmatchstring, -1, TRUE);

		if(find >= 0)
		{
			LOGPRINT(L"renderdocshim: Hooking into '");
			LOGPRINT(exepath);
			LOGPRINT(L"', based on '");
			LOGPRINT(data->pathmatchstring);
			LOGPRINT(L"'\n");

			HMODULE mod = LoadLibraryW(data->rdocpath);

			if(mod)
			{
				pRENDERDOC_SetCaptureOptions setopts = (pRENDERDOC_SetCaptureOptions)GetProcAddress(mod, "RENDERDOC_SetCaptureOptions");
				pRENDERDOC_SetLogFile setlog = (pRENDERDOC_SetLogFile)GetProcAddress(mod, "RENDERDOC_SetLogFile");

				if(setopts)
					setopts( (const CaptureOptions *)data->opts );

				if(setlog && data->log[0])
					setlog( data->log );
			}
		}
		else
		{
			LOGPRINT(L"renderdocshim: NOT Hooking into '");
			LOGPRINT(data->exepath);
			LOGPRINT(L"', based on '");
			LOGPRINT(data->pathmatchstring);
			LOGPRINT(L"'\n");
		}

		VirtualFree(exepath, 0, MEM_RELEASE);
	}
	else
	{
		LOGPRINT(L"renderdocshim: Failed to allocate exepath\n");
	}
	
	UnmapViewOfFile(data);
	CloseHandle(datahandle);
}

DWORD CheckHookThread(LPVOID param)
{
	CheckHook();

	// this makes sure that we remove the reference to the shim dll and unload from
	// the target process. That minimises the impact of having the dll inserted into
	// every process
	FreeLibraryAndExitThread((HMODULE)param, 0);
	return 0;
}

BOOL APIENTRY dll_entry(HMODULE hModule, DWORD ul_reason_for_call, LPVOID lpReserved)
{
	if(ul_reason_for_call == DLL_PROCESS_ATTACH)
	{
		DisableThreadLibraryCalls(hModule);

		// create a thread so that we can perform more complex actions (DllMain must be minimal
		// in size, even this is a bit dodgy).
		CreateThread(NULL, 0, (LPTHREAD_START_ROUTINE)&CheckHookThread, (LPVOID)hModule, 0, NULL);

		// Sleep on this thread a bit, as we want to call CheckHook() before any real work is done.
		// Note it is important we don't try to *synchronise* on CheckHookThread, as that can easily
		// cause deadlocks, crashes, etc.
		Sleep(500);
	}

	return TRUE;
}
