/*
*	DSFML - SFML Library wrapper for the D programming language.
*	Copyright (C) 2008 Julien Dagorn (sirjulio13@gmail.com)
*	Copyright (C) 2010 Andreas Hollandt
*
*	This software is provided 'as-is', without any express or
*	implied warranty. In no event will the authors be held
*	liable for any damages arising from the use of this software.
*
*	Permission is granted to anyone to use this software for any purpose,
*	including commercial applications, and to alter it and redistribute
*	it freely, subject to the following restrictions:
*
*	1.  The origin of this software must not be misrepresented;
*		you must not claim that you wrote the original software.
*		If you use this software in a product, an acknowledgment
*		in the product documentation would be appreciated but
*		is not required.
*
*	2.  Altered source versions must be plainly marked as such,
*		and must not be misrepresented as being the original software.
*
*	3.  This notice may not be removed or altered from any
*		source distribution.
*/

module dsfml.system.dllloader;

import dsfml.system.stringutil;

version (Tango)
{
	import tango.io.Console;
	import tango.sys.SharedLib;
}
else
{
	import std.stdio;
	
	version (Windows)
	{
		import std.c.windows.windows;
		alias HMODULE MODULEHANDLE; 
	}
	version (linux)
	{
		import std.c.linux.linux;
		alias void* MODULEHANDLE;
		
		const int RTLD_NOW = 0x00002;
		const int RTLD_GLOBAL = 0x00100;
	}
}

static this()
{
	version (Tango)
	{
		SharedLib.throwExceptions = false;
	}
}

private void report(string msg, string lib, string symb)
{
	string str = "Loading error. Reason : " ~ msg ~ " (library : " ~ lib ~ ", symbol : " ~ symb ~ ")";
	version (Tango)
	{
		Cerr(str).newline; 
	}
	else
	{
		stderr.writeln(str);
	}
}


/**
*	Simple Dll loader.
*/
class DllLoader
{  
	static DllLoader load(string library)
	{
		version (Windows)
		{
			string libraryName = library ~ ".dll";
		}
		version (linux)
		{
			string libraryName = "lib" ~ library ~ ".so";
		}
		
		if (libraryName in alreadyLoaded)
		{
			return alreadyLoaded[libraryName];
		}
		else
		{
			DllLoader temp = new DllLoader(libraryName);
			alreadyLoaded[libraryName] = temp;
			return temp;
		}		
	}
	
	~this()
	{
		close();
	}

	void* getSymbol(string symbolName)
	{
		void* symb;
		version (Tango)
		{
			symb = m_lib.getSymbol(toStringz(symbolName));
		}
		else
		{				
			version (Windows)
			{
				symb = GetProcAddress(m_lib, toStringz(symbolName));
			}
			version (linux)
			{
				symb = dlsym(m_lib, toStringz(symbolName));
			}
		}
	
		if (symb is null)
			report( "Symbol cannot be found in specified library", m_libPath, symbolName);
			
		return symb;
	}

	void close()
	{
		version (Tango)
		{
			m_lib.unload();
		}
		else
		{
			version (Windows)
			{
				FreeLibrary(m_lib);
			}
			version (linux)
			{
				dlclose(m_lib);
			}
			alreadyLoaded.remove(this.m_libPath);
		}
	}

private:
	this(string libraryPath)
	{
		m_libPath = libraryPath;
		
		version (Tango)
		{
			m_lib = SharedLib.load(libraryPath);
		}
		else
		{
			version (Windows)
			{
				m_lib = LoadLibraryA(toStringz(libraryPath));
			}
			version (linux)
			{
				m_lib = dlopen(toStringz(libraryPath), RTLD_NOW | RTLD_GLOBAL);
			}
		}
		if (m_lib is null)
			report("Cannot open library", m_libPath, null);
	}
	
	version (Tango)
	{
		SharedLib m_lib;
	}
	else
	{
		MODULEHANDLE m_lib; 
	}
	
	static DllLoader[string] alreadyLoaded;
	string m_libPath;
}