//===== Copyright © 1996-2005, Valve Corporation, All rights reserved. ======//
//
// Purpose: 
//
//===========================================================================//
#if defined( _WIN32 ) && !defined( _X360 )
#include <windows.h>
#endif

#if !defined( DONT_PROTECT_FILEIO_FUNCTIONS )
#define DONT_PROTECT_FILEIO_FUNCTIONS // for protected_things.h
#endif

#if defined( PROTECTED_THINGS_ENABLE )
#undef PROTECTED_THINGS_ENABLE // from protected_things.h
#endif

#include <stdio.h>
#include "interface.h"
#include "basetypes.h"
#include "tier0/dbg.h"
#include <string.h>
#include <stdlib.h>
#include "tier1/strtools.h"
#include "tier0/icommandline.h"
#include "tier0/dbg.h"
#include "tier0/threadtools.h"
#ifdef _WIN32
#include <direct.h> // getcwd
#elif defined _LINUX || defined __APPLE__
#define _getcwd getcwd
#endif
#if defined( _X360 )
#include "xbox/xbox_win32stubs.h"
#endif

// memdbgon must be the last include file in a .cpp file!!!
#include "tier0/memdbgon.h"

#if !defined COMPILER_MSVC && !defined HMODULE
#define HMODULE void *
#endif

// ------------------------------------------------------------------------------------ //
// InterfaceReg.
// ------------------------------------------------------------------------------------ //
InterfaceReg *s_pInterfaceRegs = NULL;

InterfaceReg::InterfaceReg( InstantiateInterfaceFn fn, const char *pName ) :
	m_pName(pName)
{
	m_CreateFn = fn;
	m_pNext = s_pInterfaceRegs;
	s_pInterfaceRegs = this;
}

// ------------------------------------------------------------------------------------ //
// CreateInterface.
// This is the primary exported function by a dll, referenced by name via dynamic binding
// that exposes an opqaue function pointer to the interface.
// ------------------------------------------------------------------------------------ //
void* CreateInterface( const char *pName, int *pReturnCode )
{
	InterfaceReg *pCur;
	
	for (pCur=s_pInterfaceRegs; pCur; pCur=pCur->m_pNext)
	{
		if (strcmp(pCur->m_pName, pName) == 0)
		{
			if (pReturnCode)
			{
				*pReturnCode = IFACE_OK;
			}
			return pCur->m_CreateFn();
		}
	}
	
	if (pReturnCode)
	{
		*pReturnCode = IFACE_FAILED;
	}
	return NULL;	
}


#if defined _LINUX || defined __APPLE__
// Linux doesn't have this function so this emulates its functionality
void *GetModuleHandle(const char *name)
{
	void *handle;

	if( name == NULL )
	{
		// hmm, how can this be handled under linux....
		// is it even needed?
		return NULL;
	}

    if( (handle=dlopen(name, RTLD_NOW))==NULL)
    {
            printf("DLOPEN Error:%s\n",dlerror());
            // couldn't open this file
            return NULL;
    }

	// read "man dlopen" for details
	// in short dlopen() inc a ref count
	// so dec the ref count by performing the close
	dlclose(handle);
	return handle;
}
#endif

#if defined( _WIN32 ) && !defined( _X360 )
#define WIN32_LEAN_AND_MEAN
#include "windows.h"
#endif

bool Sys_IsDebuggerPresent()
{
	return Plat_IsInDebugSession();
}

struct ThreadedLoadLibaryContext_t
{
	const char *m_pLibraryName;
	HMODULE m_hLibrary;
};

//-----------------------------------------------------------------------------
// Purpose: get the interface for the specified module and version
// Input  : 
// Output : 
//-----------------------------------------------------------------------------
bool Sys_LoadInterface(
	const char *pModuleName,
	const char *pInterfaceVersionName,
	HMODULE *pOutModule,
	void **pOutInterface )
{
	HMODULE pMod = Plat_LoadModule( pModuleName );
	if ( !pMod )
		return false;

	CreateInterfaceFn fn = Plat_GetModuleInterfaceFactory( pMod );
	if ( !fn )
	{
		Plat_UnloadModule( pMod );
		return false;
	}

	*pOutInterface = fn( pInterfaceVersionName, NULL );
	if ( !( *pOutInterface ) )
	{
		Plat_UnloadModule( pMod );
		return false;
	}

	if ( pOutModule )
		*pOutModule = pMod;

	return true;
}

//-----------------------------------------------------------------------------
// Purpose: Place this as a singleton at module scope (e.g.) and use it to get the factory from the specified module name.  
// 
// When the singleton goes out of scope (.dll unload if at module scope),
//  then it'll call Sys_UnloadModule on the module so that the refcount is decremented 
//  and the .dll actually can unload from memory.
//-----------------------------------------------------------------------------
CDllDemandLoader::CDllDemandLoader( char const *pchModuleName ) : 
	m_pchModuleName( pchModuleName ), 
	m_hModule( 0 ),
	m_bLoadAttempted( false )
{
}

CDllDemandLoader::~CDllDemandLoader()
{
	Unload();
}

CreateInterfaceFn CDllDemandLoader::GetFactory()
{
	if ( !m_hModule && !m_bLoadAttempted )
	{
		m_bLoadAttempted = true;
		m_hModule = Plat_LoadModule( m_pchModuleName );
	}

	if ( !m_hModule )
	{
		return NULL;
	}

	return Plat_GetModuleInterfaceFactory( m_hModule );
}

void CDllDemandLoader::Unload()
{
	if ( m_hModule )
	{
		Plat_UnloadModule( m_hModule );
		m_hModule = 0;
	}
}