/* wordcount-incomplete.c */

#include <stdio.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <unistd.h>
#include <errno.h>
#include <time.h>
#include <string.h>
#include <fcntl.h>


/* function prototypes */
int child( char * word, int fd );
void parent( int children, int child_pids[], char *argv[] );

int main( int argc, char *argv[] )
{
  int i, children;

  if ( argc < 3 )
  {
    fprintf( stderr, "USAGE: %s <filename> <words> ...\n", argv[0] );
    return EXIT_FAILURE;
  }

  printf( "PARENT: opening %s....\n", argv[1] );

  int fd = open( argv[1], O_RDONLY );
     /* maybe use fopen() instead here... */

  if ( fd < 0 )   /* if ( fd == -1 ) */
  {
    fprintf( stderr, "ERROR: errno is %d\n", errno );
    perror( "error opening file" );
    return EXIT_FAILURE;
  }

  int child_pids[100]; /* TO DO: use calloc() and argc */

  /* cycle through argv[2] thru the end argv[argc-1] */
  for ( i = 2 ; i < argc ; i++ )
  {
    pid_t z = fork();

    if ( z < 0 ) {
      perror( "fork() failed" );
      return EXIT_FAILURE;
    }

    if ( z == 0 ) {
      int word_count = child( argv[i], fd );
      exit( word_count );   /* return result to parent */
    }

    child_pids[i-2] = z;  /* parent stores each child's pid */
  }

  parent( argc - 2, child_pids, argv );
        /* child_pids[0] <==> argv[2] */
        /* child_pids[1] <==> argv[3] etc. */

  return EXIT_SUCCESS;
}

/* each child process counts its word */
int child( char * word, int fd )
{
  int count = 0;
  printf( "CHILD: I'm counting \"%s\" occurrences\n", word );

  /* TO DO: read through the file specified by fd and count */


  return count;
}

void parent( int children, int child_pids[], char *argv[] )
{
  int status;  /* return status from a child process */
  pid_t child_pid;

  printf( "PARENT: I'm waiting for my children to report results.\n" );
  int size_of_array = children;

  while ( children > 0 )
  {
    /* wait until a child process exits */
    child_pid = wait( &status );  /* BLOCK */

    children--;

    printf( "PARENT: child %d terminated...", child_pid );

    if ( WIFSIGNALED( status ) )    /* core dump or kill or kill -9 */
    {
      printf( "abnormally\n" );
    }
    else if ( WIFEXITED( status ) )   /* child called return or exit() */
    {
      int rc = WEXITSTATUS( status );
      printf( "successfully with exit status %d\n", rc );
      /* find child_pid in the array: */
      int j = 0;
      while ( j < size_of_array )
      {
        if ( child_pid == child_pids[j] )
        {
          break;
        }
        j++;
      }

      printf( "PARENT: child counted \"%s\"\n", argv[j+2] );
    }

    printf( "PARENT: %d children to go...\n", children );
  }

  printf( "PARENT: All of my children are awake!\n" );
}