/*
 * Name:     CInstrFactory
 * Author:   Martin Perner, 0725782, 535
 * E-Mail:   e0725782@student.tuwien.ac.at
 * Purpose:  Factory for creating Instruction from shared libraries
 * Date:     29.04.2009
 */

#include "CInstrFactory.hpp"

using namespace std;

/**
 * Name:    loadFromLib
 * Purpose: loads a command from the given library file

 * Parameter: std::string lib  location of the library file

 * Preconditions:  lib references to a valid library
 */
Iinstr* CInstrFactory::loadFromLib(string lib)
{
	Iinstr* (*create_instruction)();

	// load a Instruction from library
	void* instruction = dlopen(lib.c_str(), RTLD_LAZY);
	if (!instruction) {
		cerr << "Cannot load library: " << dlerror() << endl;
		exit(EXIT_FAILURE);
	}

	// load the symbols
	void* create = dlsym(instruction, "create_instruction");
	void* destroy = dlsym(instruction, "destroy_instruction");

	if (!create || !destroy) {
		cerr << "Cannot load symbols: " << dlerror() << endl;
		dlclose(instruction);
		exit(EXIT_FAILURE);
	}

	memcpy(&create_instruction, &create, sizeof(create)); 

	Iinstr* instructionPointer = create_instruction();

	m_libStore.insert(make_pair(instruction, instructionPointer));

	return instructionPointer;
}

/**
 * Name:    getNextInstruction
 * Purpose: returns a pointer to a command

 * Returns: Pointer to the loaded command

 * Throw:  string
 * Preconditions:  a command is left to load
 */
Iinstr* CInstrFactory::getNextInstr()
{
	if(m_files.size() >= 1) {
		Iinstr* instruction;
		instruction = loadFromLib(m_files[0]);
		m_files.erase(m_files.begin());
		return instruction;
	}
	else {
		throw string("No more instruction left!");
	}
}


/**
 * Name:    searchLibsInDir
 * Purpose: finds librarys in the given directory

 * Returns: number of found librarays

 * Parameters: std::string dir  Directory where the libraries are located
 * Throw:  string
 * Postconditions: all files with a trailing '.so' are ready to be used
 */
size_t CInstrFactory::searchLibsInDir(string dir)
{
	DIR *dp;

	if((dp  = opendir(dir.c_str())) == NULL) {
		stringstream errmsg;
		errmsg << "Error(" << errno << ") opening " << dir << endl;
		throw errmsg.str();
	}
	struct dirent *dirp;
	while ((dirp = readdir(dp)) != NULL) {
		string file = dirp->d_name;
		if(file.size() >= 3) {
			file = file.substr(file.size()-3);
			std::transform(file.begin(), file.end(), file.begin(), ::tolower);
			if(file == ".so") {
				m_files.push_back(dir+"/"+string(dirp->d_name));
			}
		}
	}
	closedir(dp);
	return m_files.size();
}

/**
 * Name:    getNumFiles
 * Purpose: returns the number of librarys left

 * Returns: size_t number of files left
 */
size_t CInstrFactory::getNumFiles()
{
	return m_files.size();
}

void CInstrFactory::loadLibsIntoMap(map<short, Iinstr*>& instr, string dir)
{
#ifdef DEBUG
		cout << "Loaded " << this->searchLibsInDir(dir) << " Libraryfiles" << endl;
#else
		this->searchLibsInDir(dir);
#endif
		while(this->getNumFiles() >= 1) {
			Iinstr* pinstr = this->getNextInstr();
			instr.insert(make_pair(pinstr->getOpcode(),pinstr));
#ifdef DEBUG
			cout << "found: " << pinstr->getName() << " its opcode is : " << pinstr->getOpcode() << endl;
#endif
		}
}


/**
 * Name:    ~CInstrFactory
 * Purpose: Destructor of the Object
 */
CInstrFactory::~CInstrFactory()
{
	void (*destroy_instruction)(Iinstr*);

	while(!m_libStore.empty()) {
		void* destroy = dlsym(m_libStore.begin()->first, "destroy_instruction");
		memcpy(&destroy_instruction, &destroy, sizeof(destroy)); 
		destroy_instruction(m_libStore.begin()->second);
		dlclose(m_libStore.begin()->first);
		m_libStore.erase(m_libStore.begin());
	}
}