// compile: gcc generate-packets-all.c
// execute: ./a.out [-n packetsize]
// summary:
// generates all permutations of length n; taken to be received by a single 
// node or via a single "hop" packets are generated based
// on the sending of a single ordered packet, and are permuted based on the
// sending probability p of the network; s (sample) controls how many times this
// sending process is simulated; using -i initializes the packet to the proper ordering
// each time.  The STDOUT may be captured and measured using measure-order.c:
//
// ./gen-packets-all.x -n | ./measure-order.x 
//
// Output format:
//
// numNodes(or hops) numPackets numSuccessfulRuns(or data sets) 
// foreach S numSuccessfulRuns
//   foreach N numHodes
//     nodeNumber: orderPacketsReceived
//

#include <stdio.h>
#include <stdlib.h>

#define MARKED          -1
#define _SINGLE_NODE     0
#define _NUM_PACKETS     5

// so we can use cmdline flags
int NUM_PACKETS=_NUM_PACKETS,SINGLE_NODE=_SINGLE_NODE;

// prints array
void print_array( int* array, int size )
{ int i;
  for (i = 0; i < size; i++)
      printf("%d ", array[i]);
  printf("\n");
}

// recursively creates permutation ina systematic way - when the
// permutation is created, the function evaluates the it
void makePermutation ( int* permutation, int curr_size, int* choices )
{ int i;
  if ( NUM_PACKETS > curr_size )
  { for (i=0; i < NUM_PACKETS; i++) 
    { if ( MARKED != choices[i] )
      { permutation[curr_size++] = i; choices[i] = MARKED;
        makePermutation(permutation, curr_size, choices);
        choices[i] = i; curr_size--;}
    }
  } 
  else {
    printf("%d: ",SINGLE_NODE);
    print_array(permutation,NUM_PACKETS);  
  }
}

// takes argument processing out of main
void processArgs( int argc, char** argv )
{ int i;
  extern char *optarg;
  extern int optind, optopt;
  /* command line flag stuff */
  while ((i = getopt(argc, argv, "n:")) != -1)
  {   switch(i)
      {case 'n':
          NUM_PACKETS = atoi(optarg);
          break;
       case ':': /* n, p, or s without operand */
          exit (EXIT_FAILURE);
          break;
       case '?':
          exit (EXIT_FAILURE);
          break;
      }
  }
}

int main( int argc, char** argv ) 
{ int i, *inputPermutation, *permutation, total_permutations=1;
  processArgs(argc,argv);
  //output first line of output
  for (i=1;i<=NUM_PACKETS;i++) total_permutations *= i;
  printf("%d %d %d // numNodes(or hops) numPackets numSuccessfulRuns(or data sets)\n",1,NUM_PACKETS,total_permutations);
  inputPermutation = (int*)malloc(sizeof(int)*NUM_PACKETS); 
  permutation = (int*)malloc(sizeof(int)*NUM_PACKETS); 
  /* init */
  for (i=0;i<NUM_PACKETS;i++)
      inputPermutation[i] = i;  // init initial permutation in perfect order
  /* initial call to permute items */ 
  makePermutation(permutation, 0, inputPermutation); 
  return EXIT_SUCCESS;
}