// Copyright (C) 2003-2008 Dolphin Project.

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, version 2.0.

// 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 2.0 for more details.

// A copy of the GPL 2.0 should have been included with the program.
// If not, see http://www.gnu.org/licenses/

// Official SVN repository and contact information can be found at
// http://code.google.com/p/dolphin-emu/

#include <string.h>
#ifdef _WIN32
#include <windows.h>
#else
#include <dlfcn.h>
#include <stdio.h>
#endif

#include "Common.h"
#include "FileUtil.h"
#include "StringUtil.h"
#include "DynamicLibrary.h"

DynamicLibrary::DynamicLibrary()
{
	library = 0;
}

std::string GetLastErrorAsString()
{
#ifdef _WIN32
	LPVOID lpMsgBuf = 0;
	DWORD error = GetLastError();
	FormatMessage( 
		FORMAT_MESSAGE_ALLOCATE_BUFFER | FORMAT_MESSAGE_FROM_SYSTEM,
		NULL,
		error,
		MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
		(LPTSTR) &lpMsgBuf,
		0, NULL);
	std::string s;
	if (lpMsgBuf)
	{
		s = ((char *)lpMsgBuf);
		LocalFree(lpMsgBuf);
	} else {
		s = StringFromFormat("(unknown error %08x)", error);
	}
	return s;
#else
        static std::string errstr;
        char *tmp = dlerror();
        if (tmp)
            errstr = tmp;
        
        return errstr;
#endif
}

// Loading means loading the dll with LoadLibrary() to get an instance to the dll.
// This is done when Dolphin is started to determine which dlls are good, and
// before opening the Config and Debugging windows from Plugin.cpp and
// before opening the dll for running the emulation in Video_...cpp in Core.
// Since this is fairly slow, TODO: think about implementing some sort of cache.
int DynamicLibrary::Load(const char* filename)
{
	if (!filename || strlen(filename) == 0)
	{
		LOG(MASTER_LOG, "Missing filename of dynamic library to load");
                PanicAlert("Missing filename of dynamic library to load");
		return 0;
	}
	LOG(MASTER_LOG, "Trying to load library %s", filename);
	if (IsLoaded())
	{
		LOG(MASTER_LOG, "Trying to load already loaded library %s", filename);
		return 2;
	}

#ifdef _WIN32
	library = LoadLibrary(filename);
#else
	library = dlopen(filename, RTLD_NOW | RTLD_LOCAL);
#endif
        
	if (!library)
	{
		LOG(MASTER_LOG, "Error loading DLL %s: %s", filename, GetLastErrorAsString().c_str());
		PanicAlert("Error loading DLL %s: %s\n", filename, GetLastErrorAsString().c_str());
		return 0;
	}

	library_file = filename;
	return 1;
}


int DynamicLibrary::Unload()
{
    int retval;
    if (!IsLoaded()) {
        PanicAlert("Error unloading DLL %s: not loaded", library_file.c_str());
        return 0;
    }
        
#ifdef _WIN32
	retval = FreeLibrary(library);
#else
    retval = dlclose(library)?0:1;
#endif
    if (!retval) {
        PanicAlert("Error unloading DLL %s: %s", library_file.c_str(),
                   GetLastErrorAsString().c_str());
    }
    library = 0;
    return retval;
}


void* DynamicLibrary::Get(const char* funcname) const
{
	void* retval;
	if (!library)
	{
		PanicAlert("Can't find function %s - Library not loaded.");
		return NULL;
	}
#ifdef _WIN32
	retval = GetProcAddress(library, funcname);
#else
	retval = dlsym(library, funcname);
#endif

	if (!retval) {
		LOG(MASTER_LOG, "Symbol %s missing in %s (error: %s)\n", funcname, library_file.c_str(), GetLastErrorAsString().c_str());
		PanicAlert("Symbol %s missing in %s (error: %s)\n", funcname, library_file.c_str(), GetLastErrorAsString().c_str());
	}

	return retval;
}