/*
	Projet d'algorithmique et programmation 2013-2014
	(cours de C.Matthieu et J.Stern)
	Alex AUVOLAT, Mendes OULAMARA

	Sujet : Algorithme de Bron-Kerbosch pour Maximum-Clique
	(cf maxclique.pdf)
*/

#include <stdlib.h>

#include "sets.h"
#include "graph.h"

/*
	max_clique calculates the maximum clique in a graph. Arguments :
	- g : the graph where the clique is looked for
	- k : the clique we are currently examining
	- c : the graph nodes we can potentially add to the clique
	- a : the nodes we can actually add to the clique
	- mc : a pointer to the set containing the maximum clique found until now
	Returns nothing (result is in *mc).
*/
void max_clique_a(const graph g, set k, set c, set *mc) {
	if (is_set_empty(c)) {
		if (set_size(k) > set_size(*mc)) {
			delete_set(*mc);
			*mc = copy_set(k);
			printf("Found new max clique: "); dump_set(*mc); fflush(stdout);
		}
	} else {
		set cc = copy_set(c);
		while (!(is_set_empty(cc))) {
			int x = elt_of_set(cc);
			set_remove_ip(x, cc);

			set k2 = set_add(x, k);
			set c2 = set_inter(c, graph_neighbours(g, x));
			max_clique_a(g,k2, c2, mc);
			delete_set(k2);
			delete_set(c2);
		}
		delete_set(cc);
	}
}


void max_clique_b(const graph g, set k, set c, set a, set *mc) {
	if (is_set_empty(c)) {
		if (set_size(k) > set_size(*mc)) {
			delete_set(*mc);
			*mc = copy_set(k);
			printf("Found new max clique: "); dump_set(*mc); fflush(stdout);
		}
	} else {
	    	set at = copy_set a;
		while (!(is_set_empty(a2))) {
			int x = elt_of_set(at);
			set_remove_ip(x, at);

			set k2 = set_add(x, k);
			set c2 = set_inter(c, graph_neighbours(g, x));
			set a2 = set_inter(at,  graph_neighbours(g, x));
			
			max_clique_a(g,k2, c2, a2, mc);
			delete_set(k2);
			delete_set(c2);
			delete_set(a2);
		}
		delete_set(at);
	}
}

// Driver

void usage(char *pname) {
	printf("\nUsage:\n\t%s [options] [<graph file>]\n\n", pname);
	printf("Available options:\n");
	printf("\n    -d\n\tRead input in DIMACS format\n");
	printf("\n    -o <file.dot>\n\tDump graph in graphwiz .dot format\n");
	printf("\n    -h, --help\n\tShow this help page\n");
	exit(1);
}

int main(int argc, char **argv) {
	int i;
	int dimacs = 0;
	char *filename = "-";
	char *dump = NULL;

	for (i = 1; i < argc; i++) {
		if (!strcmp(argv[i], "-d")) {
			dimacs = 1;
		} else if (!strcmp(argv[i], "-o")) {
			if (++i == argc) usage(argv[0]);
			dump = argv[i];
		} else if (argv[i][0] == '-') {
			usage(argv[0]);
		} else {
			filename = argv[i];
		}
	}

	FILE *f = stdin;
	if (strcmp(filename, "-")) {
		f = fopen(filename, "r");
		if (f == NULL) {
			fprintf(stderr, "Error: could not open file %s\n", filename);
			return 1;
		}
	}
	graph g = (dimacs ? load_graph_dimacs(f) : load_graph(f));
	if (g == NULL) {
		fprintf(stderr, "Error loading file %s\n", filename);
		return 1;
	}
	fclose(f);

	if (dump != NULL) {
		f = fopen(dump, "w");
		if (f == NULL) {
			fprintf(stderr, "Error: could not open file %s for writing\n", dump);
			return 1;
		}
		dump_graphviz(g, f);
		fclose(f);
	}

	// do stuff with graph
	set max_clique = empty_set(g->N);
	set init_s = full_set(g->N);
	set init_k = empty_set(g->N);
	max_clique_a(g, init_k, init_s, &max_clique);
	printf("Max clique: "); dump_set(max_clique);

	delete_graph(g);
	return 0;
}