/* jaccard-sort-hash: Program to calculate Jaccard similarity using sorted vectors of hashes.
   James S. Plank
   CS494/CS594 - Advanced Algorithms and Programming
   October, 2017
 */

#include <string>
#include <cstring>
#include <stdint.h>
#include <sys/time.h>
#include <fstream>
#include <vector>
#include <list>
#include <cmath>
#include <algorithm>
#include <map>
#include <set>
#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <openssl/md5.h>

using namespace std;

void usage(const string s)
{
    fprintf(stderr, "usage: jaccard-sort-hash files\n");
    if (s != "") fprintf(stderr, "%s\n", s.c_str()); 
    exit(1);
}

int main(int argc, char **argv)
{
  vector < vector <unsigned long long> > sets;
  unsigned char md5_buf[16]; 
  unsigned long long ull;
  ifstream f;
  string s;
  int i, j, ip, jp;
  double Intersection;
  double Total;
  double Union;

  if (argc == 1) usage("");

  /* Read the data sets and store the hashes into vectors. */

  sets.resize(argc-1);
  for (i = 1; i < argc; i++) {
    f.clear();
    f.open(argv[i]);
    if (f.fail()) { perror(argv[i]); exit(1); }
    while (getline(f, s)) {
      MD5((const unsigned char *) s.c_str(), s.size(), md5_buf);
      memcpy(&ull, md5_buf, sizeof(unsigned long long));
      sets[i-1].push_back(ull);
    }
    f.close();
  }
  /* Sort the vectors. */

  for (i = 0; i < sets.size(); i++) sort(sets[i].begin(), sets[i].end());

  /* For each pair of sets, calculate the Jaccard similarity directly. */

  for (i = 0; i < sets.size(); i++) {
    for (j = 0; j < sets.size(); j++) {
      Total = sets[i].size() + sets[j].size();
      Intersection = 0;
      ip = 0;
      jp = 0;
      while (ip < sets[i].size() && jp < sets[j].size()) {
        if (sets[i][ip] == sets[j][jp]) {
          Intersection++;
          ip++;
          jp++;
        } else if (sets[i][ip] < sets[j][jp]) {
          ip++;
        } else {
          jp++;
        }
      }
      Union = Total - Intersection;
      printf("%-30s %-30s %.6lf\n", argv[i+1], argv[j+1], Intersection / Union);
    }
  }
  exit(1);
}