//********************************** Banshee Engine (www.banshee3d.com) **************************************************//
//**************** Copyright (c) 2016 Marko Pintera (marko.pintera@gmail.com). All rights reserved. **********************//
#include "Utility/BsDynLib.h"
#include "Error/BsException.h"

#if BS_PLATFORM == BS_PLATFORM_WIN32
	#define WIN32_LEAN_AND_MEAN
	#if !defined(NOMINMAX) && defined(_MSC_VER)
		#define NOMINMAX // required to stop windows.h messing up std::min
	#endif
	#include <windows.h>
#endif

#if BS_PLATFORM == BS_PLATFORM_OSX
	#include <dlfcn.h>
#endif

namespace bs
{

#if BS_PLATFORM == BS_PLATFORM_LINUX
	const char* DynLib::EXTENSION = "so";
#elif BS_PLATFORM == BS_PLATFORM_OSX
	const char* DynLib::EXTENSION = "dylib";
#elif BS_PLATFORM == BS_PLATFORM_WIN32
	const char* DynLib::EXTENSION = "dll";
#else
	#error Unhandled platform
#endif

	DynLib::DynLib(const String& name)
	{
		mName = name;
		m_hInst = nullptr;

		load();
	}

	DynLib::~DynLib()
	{
	}

	void DynLib::load()
	{
		if (m_hInst)
			return;

		m_hInst = (DYNLIB_HANDLE)DYNLIB_LOAD(mName.c_str());

		if (!m_hInst)
		{
			BS_EXCEPT(InternalErrorException,
				"Could not load dynamic library " + mName +
				".  System Error: " + dynlibError());
		}
	}

	void DynLib::unload()
	{
		if (!m_hInst)
			return;

		if (DYNLIB_UNLOAD(m_hInst))
		{
			BS_EXCEPT(InternalErrorException,
				"Could not unload dynamic library " + mName +
				".  System Error: " + dynlibError());
		}
	}

	void* DynLib::getSymbol(const String& strName) const
	{
		if (!m_hInst)
			return nullptr;

		return (void*)DYNLIB_GETSYM(m_hInst, strName.c_str());
	}

	String DynLib::dynlibError()
	{
#if BS_PLATFORM == BS_PLATFORM_WIN32
		LPVOID lpMsgBuf;
		FormatMessage(
			FORMAT_MESSAGE_ALLOCATE_BUFFER |
			FORMAT_MESSAGE_FROM_SYSTEM |
			FORMAT_MESSAGE_IGNORE_INSERTS,
			NULL,
			GetLastError(),
			MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT),
			(LPTSTR)&lpMsgBuf,
			0,
			NULL
		);
		String ret = (char*)lpMsgBuf;
		// Free the buffer.
		LocalFree(lpMsgBuf);
		return ret;
#elif BS_PLATFORM == BS_PLATFORM_LINUX || BS_PLATFORM == BS_PLATFORM_OSX
		return String(dlerror());
#else
		return String("");
#endif
	}
}