/**

 * vim: set ts=4 :

 * =============================================================================

 * SourceMod Team Fortress 2 Extension

 * Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.

 * =============================================================================

 *

 * This program is free software; you can redistribute it and/or modify it under

 * the terms of the GNU General Public License, version 3.0, as published by the

 * Free Software Foundation.

 * 

 * This program is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more

 * details.

 *

 * You should have received a copy of the GNU General Public License along with

 * this program.  If not, see <http://www.gnu.org/licenses/>.

 *

 * As a special exception, AlliedModders LLC gives you permission to link the

 * code of this program (as well as its derivative works) to "Half-Life 2," the

 * "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software

 * by the Valve Corporation.  You must obey the GNU General Public License in

 * all respects for all other code used.  Additionally, AlliedModders LLC grants

 * this exception to all derivative works.  AlliedModders LLC defines further

 * exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),

 * or <http://www.sourcemod.net/license.php>.

 *

 * Version: $Id$

 */

#include "criticals.h"

ISourcePawnEngine *spengine = NULL;

CriticalHitManager g_CriticalHitManager;

IServerGameEnts *gameents = NULL;

int g_returnvalue;

bool CriticalHitManager::CreateCriticalDetour()

{

	if (!g_pGameConf->GetMemSig("CalcCritical", &critical_address) || !critical_address)

	{

		g_pSM->LogError(myself, "Could not locate CalcCritical - Disabling Critical Hit forward");

		return false;

	}

	if (!g_pGameConf->GetOffset("CalcCriticalBackup", (int *)&(critical_restore.bytes)))

	{

		g_pSM->LogError(myself, "Could not locate CalcCriticalBackup - Disabling Critical Hit forward");

		return false;

	}

	/* First, save restore bits */

	for (size_t i=0; i<critical_restore.bytes; i++)

	{

		critical_restore.patch[i] = ((unsigned char *)critical_address)[i];

	}

	critical_callback = spengine->ExecAlloc(100);

	JitWriter wr;

	JitWriter *jit = ≀

	wr.outbase = (jitcode_t)critical_callback;

	wr.outptr = wr.outbase;

	/* Function we are detouring into is

	 *

	 * void CriticalDetour(CTFWeaponBase(void *) *pWeapon)

	 *

	 * push		pWeapon [ecx]

	 */

#if defined PLATFORM_WINDOWS

	IA32_Push_Reg(jit, REG_ECX);

#elif defined PLATFORM_LINUX

	IA32_Push_Rm_Disp8_ESP(jit, 4);

#endif

	jitoffs_t call = IA32_Call_Imm32(jit, 0); 

	IA32_Write_Jump32_Abs(jit, call, (void *)TempDetour);

#if defined PLATFORM_LINUX

	IA32_Add_Rm_Imm8(jit, REG_ESP, 4, MOD_REG);		//add esp, 4

#elif defined PLATFORM_WINDOWS

	IA32_Pop_Reg(jit, REG_ECX);

#endif

	//If TempDetour returns non-zero we want to load something into eax and return this value

	//IA32_Test_Rm_Reg(jit, eax, eax, something);

	jit->write_ubyte(0x85);

	jit->write_ubyte(0xC0);

	//JNZ critical_callback+50

	jit->write_ubyte(0x75); 

	jit->write_ubyte(50-((jit->outptr+1)-jit->outbase));

	/* Patch old bytes in */

	for (size_t i=0; i<critical_restore.bytes; i++)

	{

		jit->write_ubyte(critical_restore.patch[i]);

	}

	/* Return to the original function */

	call = IA32_Jump_Imm32(jit, 0);

	IA32_Write_Jump32_Abs(jit, call, (unsigned char *)critical_address + critical_restore.bytes);

	wr.outbase = (jitcode_t)critical_callback+50;

	wr.outptr = wr.outbase;

	//copy g_returnvalue into eax

	jit->write_ubyte(0xA1);

	jit->write_uint32((jit_uint32_t)&g_returnvalue);

	IA32_Return(jit);

	return true;

}

bool CriticalHitManager::CreateCriticalMeleeDetour()

{

	if (!g_pGameConf->GetMemSig("CalcCriticalMelee", &melee_address) || !melee_address)

	{

		g_pSM->LogError(myself, "Could not locate CalcCriticalMelee - Disabling Critical Hit forward");

		return false;

	}

	if (!g_pGameConf->GetOffset("CalcCriticalMeleeBackup", (int *)&(melee_restore.bytes)))

	{

		g_pSM->LogError(myself, "Could not locate CalcCriticalMeleeBackup - Disabling Critical Hit forward");

		return false;

	}

	/* First, save restore bits */

	for (size_t i=0; i<melee_restore.bytes; i++)

	{

		melee_restore.patch[i] = ((unsigned char *)melee_address)[i];

	}

	melee_callback = spengine->ExecAlloc(100);

	JitWriter wr;

	JitWriter *jit = ≀

	wr.outbase = (jitcode_t)melee_callback;

	wr.outptr = wr.outbase;

	/* Function we are detouring into is

	 *

	 * void CriticalDetour(CTFWeaponBase(void *) *pWeapon)

	 *

	 * push		pWeapon [ecx]

	 */

#if defined PLATFORM_WINDOWS

	IA32_Push_Reg(jit, REG_ECX);

#elif defined PLATFORM_LINUX

	IA32_Push_Rm_Disp8_ESP(jit, 4);

#endif

	jitoffs_t call = IA32_Call_Imm32(jit, 0); 

	IA32_Write_Jump32_Abs(jit, call, (void *)TempDetour);

#if defined PLATFORM_LINUX

	IA32_Add_Rm_Imm8(jit, REG_ESP, 4, MOD_REG);		//add esp, 4

#elif defined PLATFORM_WINDOWS

	IA32_Pop_Reg(jit, REG_ECX);

#endif

	//If TempDetour returns non-zero we want to load something into eax and return this value

	//IA32_Test_Rm_Reg(jit, eax, eax, something);

	jit->write_ubyte(0x85);

	jit->write_ubyte(0xC0);

	//JNZ critical_callback+50

	jit->write_ubyte(0x75); 

	jit->write_ubyte(50-((jit->outptr+1)-jit->outbase));

	/* Patch old bytes in */

	for (size_t i=0; i<melee_restore.bytes; i++)

	{

		jit->write_ubyte(melee_restore.patch[i]);

	}

	/* Return to the original function */

	call = IA32_Jump_Imm32(jit, 0);

	IA32_Write_Jump32_Abs(jit, call, (unsigned char *)melee_address + melee_restore.bytes);

	wr.outbase = (jitcode_t)melee_callback+50;

	wr.outptr = wr.outbase;

	//copy g_returnvalue into eax

	jit->write_ubyte(0xA1);

	jit->write_uint32((jit_uint32_t)&g_returnvalue);

	IA32_Return(jit);

	return true;

}

bool CriticalHitManager::CreateCriticalKnifeDetour()

{

	if (!g_pGameConf->GetMemSig("CalcCriticalKnife", &knife_address) || !knife_address)

	{

		g_pSM->LogError(myself, "Could not locate CalcCriticalKnife - Disabling Critical Hit forward");

		return false;

	}

	if (!g_pGameConf->GetOffset("CalcCriticalMeleeBackup", (int *)&(knife_restore.bytes)))

	{

		g_pSM->LogError(myself, "Could not locate CalcCriticalKnifeBackup - Disabling Critical Hit forward");

		return false;

	}

	/* First, save restore bits */

	for (size_t i=0; i<knife_restore.bytes; i++)

	{

		knife_restore.patch[i] = ((unsigned char *)knife_address)[i];

	}

	knife_callback = spengine->ExecAlloc(100);

	JitWriter wr;

	JitWriter *jit = ≀

	wr.outbase = (jitcode_t)knife_callback;

	wr.outptr = wr.outbase;

	/* Function we are detouring into is

	 *

	 * void CriticalDetour(CTFWeaponBase(void *) *pWeapon)

	 *

	 * push		pWeapon [ecx]

	 */

#if defined PLATFORM_WINDOWS

	IA32_Push_Reg(jit, REG_ECX);

#elif defined PLATFORM_LINUX

	IA32_Push_Rm_Disp8_ESP(jit, 4);

#endif

	jitoffs_t call = IA32_Call_Imm32(jit, 0); 

	IA32_Write_Jump32_Abs(jit, call, (void *)TempDetour);

#if defined PLATFORM_LINUX

	IA32_Add_Rm_Imm8(jit, REG_ESP, 4, MOD_REG);		//add esp, 4

#elif defined PLATFORM_WINDOWS

	IA32_Pop_Reg(jit, REG_ECX);

#endif

	//If TempDetour returns non-zero we want to load something into eax and return this value

	//IA32_Test_Rm_Reg(jit, eax, eax, something);

	jit->write_ubyte(0x85);

	jit->write_ubyte(0xC0);

	//JNZ critical_callback+50

	jit->write_ubyte(0x75); 

	jit->write_ubyte(50-((jit->outptr+1)-jit->outbase));

	/* Patch old bytes in */

	for (size_t i=0; i<knife_restore.bytes; i++)

	{

		jit->write_ubyte(knife_restore.patch[i]);

	}

	/* Return to the original function */

	call = IA32_Jump_Imm32(jit, 0);

	IA32_Write_Jump32_Abs(jit, call, (unsigned char *)knife_address + knife_restore.bytes);

	wr.outbase = (jitcode_t)knife_callback+50;

	wr.outptr = wr.outbase;

	//copy g_returnvalue into eax

	jit->write_ubyte(0xA1);

	jit->write_uint32((jit_uint32_t)&g_returnvalue);

	IA32_Return(jit);

	return true;

}

void CriticalHitManager::EnableCriticalDetour()

{

	if (!detoured)

	{

		DoGatePatch((unsigned char *)critical_address, &critical_callback);

		DoGatePatch((unsigned char *)melee_address, &melee_callback);

		DoGatePatch((unsigned char *)knife_address, &knife_callback);

		detoured = true;

	}

}

void CriticalHitManager::DeleteCriticalDetour()

{

	if (detoured)

	{

		DisableCriticalDetour();

	}

	if (critical_callback)

	{

		/* Free the gate */

		spengine->ExecFree(critical_callback);

		critical_callback = NULL;

	}

	if (melee_callback)

	{

		/* Free the gate */

		spengine->ExecFree(melee_callback);

		melee_callback = NULL;

	}

	if (knife_callback)

	{

		/* Free the gate */

		spengine->ExecFree(knife_callback);

		knife_callback = NULL;

	}

}

bool TempDetour(void *pWeapon)

{

	return g_CriticalHitManager.CriticalDetour(pWeapon);

}

void CriticalHitManager::DisableCriticalDetour()

{

	if (critical_callback)

	{

		/* Remove the patch */

		ApplyPatch(critical_address, 0, &critical_restore, NULL);

		detoured = false;

	}

	if (melee_callback)

	{

		/* Remove the patch */

		ApplyPatch(melee_address, 0, &melee_restore, NULL);

		detoured = false;

	}

	if (melee_callback)

	{

		/* Remove the patch */

		ApplyPatch(knife_address, 0, &knife_restore, NULL);

		detoured = false;

	}

}

int CheckBaseHandle(CBaseHandle &hndl)

{

	if (!hndl.IsValid())

	{

		return -1;

	}

	int index = hndl.GetEntryIndex();

	edict_t *pStoredEdict;

	pStoredEdict = engine->PEntityOfEntIndex(index);

	if (pStoredEdict == NULL)

	{

		return -1;

	}

	IServerEntity *pSE = pStoredEdict->GetIServerEntity();

	if (pSE == NULL)

	{

		return -1;

	}

	if (pSE->GetRefEHandle() != hndl)

	{

		return -1;

	}

	return index;

}

bool CriticalHitManager::CriticalDetour(void *pWeapon)

{

	edict_t *pEdict = gameents->BaseEntityToEdict((CBaseEntity *)pWeapon);

	if (!pEdict)

	{

		g_pSM->LogMessage(myself, "Entity Error");

		return false;

	}

	sm_sendprop_info_t info;

	if (!gamehelpers->FindSendPropInfo(pEdict->GetNetworkable()->GetServerClass()->GetName(), "m_hOwnerEntity", &info))

	{

		g_pSM->LogMessage(myself, "Offset Error");

		return false;

	}

	if (!forward)

	{

		g_pSM->LogMessage(myself, "Invalid Forward");

		return false;

	}

	CBaseHandle &hndl = *(CBaseHandle *)((uint8_t *)pWeapon + info.actual_offset);

	int index = CheckBaseHandle(hndl);

	forward->PushCell(index); //Client index

	forward->PushCell(engine->IndexOfEdict(pEdict)); // Weapon index

	forward->PushString(pEdict->GetClassName()); //Weapon classname

	forward->PushCellByRef(&g_returnvalue); //return value

	cell_t result = 0;

	forward->Execute(&result);

	return !!result;

}