/*
  * vertex_cover.cpp :		Source c++ code solving "Optimal Vertex Cover Problem"
  * Implemented by : 		Psallidas Fotis( using naxos project implemented by Nikos Pothitos)
  * std code :			std06170
  * Project Reference:		Logic Programming Project 5.0
  *
  */

#include <naxos.h>
#include <iostream>
#include <fstream>
#include <sstream>
#include <cstdlib>

extern "C"{
	#include <sys/stat.h>
	#include <unistd.h>
	#include <sys/wait.h>
}
using namespace std;
using namespace naxos;



 template <class T>
 std::string to_string (const T& t) { 								/* convert numbers to strings */
	std::stringstream ss;
	ss << t;
	return ss.str();
 }
	int
main (int argc, char *argv[])
{
	try  {
		NsProblemManager  pm;
		NsIntVarArray  Var;
		int* optimal=NULL;
		bool  firstSolItem;
		struct stat statbuf;
		ofstream file;
		//  Checking input arguments.

		if ( argc != 3  &&  argc != 4 )   {

			cerr << "Correct syntax is:\t" << argv[0]
				<< " <nodes_number> <density> [<seed>]\n";
			return  1;
		}

		//  Passing the number of nodes.
		int        N = atoi(argv[1]);

		//  Passing the density.
		int  density = atoi(argv[2]);

		//  Setting the seed.
		if ( argc  ==  4 )
			srand( atoi(argv[3]) );


		//  Creating for each node `i' the array `graph_edge[i-1]', which
		//   contains the numbers (`j') of the nodes connected to `i'.

		NsDeque< NsDeque<NsInt> >  graph_edge;
		int  i, j;

		for (i=1;  i <= N;  ++i)    {

			graph_edge.push_back( NsDeque<NsInt>() );

			for (j=i+1;  j <= N;  ++j)    {

				if ( 100 * (rand()/(RAND_MAX+1.0))  <=  density )
					graph_edge[ i-1 ].push_back( j );
			}
		}


		//  Printing the graph representation.

		bool  firstEdge = true;

		cout << "G = [";

		for (i=1;  i <= N;  ++i)    {
			for (j=0;  j < (signed int)graph_edge[i-1].size();  ++j)    {

				if ( firstEdge )
					firstEdge  =  false;
				else
					cout << ", ";

				cout << i << " - " << graph_edge[i-1][j];
			}
		}

		cout << "]\n";


		/* Create Variables List */
		for (i=1;  i <= N;  ++i) {
			Var.push_back( NsIntVar(pm, 0, 1) );
		}
		/* Add Constraints */
		for (i=1;  i <= N;  ++i){
			for (j=0;  (unsigned)j < graph_edge[i-1].size();  ++j)
				pm.add( NsAbs(Var[i-1] + Var[graph_edge[i-1][j]-1]) >= 1);
		}
		pm.addGoal( new NsgLabeling(Var) );
		pm.minimize(NsSum(Var));
		optimal = new int[N];
		while (pm.nextSolution() != false){
			for(i = 0 ; i < N ; i++){
				if(Var[i].value()==1)
				optimal[i]=1;
				else
				optimal[i]=0;
			}
		}
		firstSolItem = true;
		cout<<"Optimal Vetrex Cover: [";
		for(i = 0 ; i < N; i++){	
			if(optimal[i]==1){
				if ( firstSolItem ) firstSolItem  =  false;
				else		 cout << ", ";
				cout<<i+1;
			}
		}
		cout<<"]"<<endl;

		/* Make the optimal graph visible */
#if defined (__linux) || defined (linux)
		string *filename;
		filename = new string();
		*filename = "solution.txt";
		int k = 1;
		while( lstat(filename->c_str(),&statbuf) != -1 ){
			*filename = "solution" + to_string<int>(k) + ".txt";
			k++;
		}
		file.open(filename->c_str());
		firstEdge = true;
		file << "G = [";
		for (i=1;  i <= N;  ++i)    {
			for (j=0;  j < (signed int)graph_edge[i-1].size();  ++j)    {

				if ( firstEdge )
					firstEdge  =  false;
				else
					file << ", ";

				file << i << " - " << graph_edge[i-1][j];
			}
		}
		file << "]\n";
		firstSolItem = true;
		file<<"C = [";
		for(i = 0 ; i < N; i++){	
			if(optimal[i]==1){
				if ( firstSolItem ) firstSolItem  =  false;
				else		 file << ", ";
				file<<i+1;
			}
		}
		file<<"]"<<endl;
		file.close();
		string output_filename = "v" + to_string(N) + ".png";
		int fd[2],status;
		pid_t pid,pid2,pid3;
		pid = fork();
		switch(pid){
			case 0:
				if(pipe(fd) == -1){
					cerr<<"Pipe error"<<endl;
					exit(EXIT_FAILURE);
				}
				pid2 = fork();
				if(pid2 == 0){
					close(fd[1]);
					dup2(fd[0],0);
					close(fd[0]);
					execlp("/home/users/pothitos/graphviz/graph2png","graph2png",to_string<int>(N).c_str(),output_filename.c_str(),NULL);
					perror("Execlp error");
					exit(EXIT_FAILURE);
				}else{
					close(fd[0]);
					dup2(fd[1],1);
					close(fd[1]);
					execlp("/bin/cat","cat",filename->c_str(),NULL);
					perror("Execlp error");
					exit(EXIT_FAILURE);
				}
			case -1:
				exit(EXIT_FAILURE);
			default:
				wait(&status);
		}
		pid3 = fork();
		switch(pid3){
			case 0:
				execlp("/usr/bin/X11/eog","eog",output_filename.c_str(),NULL);
				perror("Execlp error");
				exit(EXIT_FAILURE);
			case -1:
				cerr<<"Internal error"<<endl;
				exit(EXIT_FAILURE);
			default:
				wait(&status);
		}
#endif
	}  catch (exception& exc)  {

		cerr << exc.what() << "\n";

	}  catch (...)  {

		cerr << "Unknown exception" << "\n";
	}
}