/* Copyright 2005 Daniel Cer (daniel.cer@cs.colorado.edu)

This work is licensed under the Creative Commons Attribution-NonCommercial-
ShareAlike License. To view a copy of this license, visit 
http://creativecommons.org/licenses/by-nc-sa/2.5/ or send a letter to 
Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 
94105, USA.
*/

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

#define INBUF_SZ 1024

char **read_entries(char *file_name, size_t *entries_N);
void free_entries(char **entries, int entries_N);
int cmp_entries(const void *entry_a, const void *entry_b);

int main(int argc, char *argv[]) { char *term, *file_name; char **entries;
  size_t entries_N, entry_id; char **search_result;

  if (argc != 3) {
    fprintf(stderr, "Usage:\n\t%s (search term) (file with list of terms)\n",
      argv[0]);
    return -1;
  }

  term = argv[1]; file_name = argv[2];

  /* read in the entries */
  if (!(entries = read_entries(file_name, &entries_N))) { 
    fprintf(stderr, "Can't open \"%s\": %s\n", file_name, strerror(errno));
    return -1; 
  }

  /* find the first match / check to see if there are any matches */
  if (!(search_result = lfind(&term, entries, &entries_N, sizeof(char **), 
    cmp_entries))) { fprintf(stderr, "Search term not found.\n"); return -2; }

  /* locate all of the remaining matches */
  for (entry_id=0,entries_N--; search_result; search_result = 
    lfind(&term, search_result+1, &entries_N, sizeof(char **), cmp_entries)) { 
    entries_N+=entry_id;entry_id=search_result-entries;entries_N-=entry_id;
    printf("found match on line: %d\n", entry_id+1);
  } free(entries);

  return 0; 
}

/* read_entries() - reads in a file from disk, storing each line in the
*  file as a separate string, and then returns an array of said strings.
*  It also sets the value pointed to by *entries_N to be the array's length 
*  (/number of lines in the file).
*/
char **read_entries(char *file_name, size_t *entries_N){ FILE *fh; int i;
  char **entries; char inbuf[INBUF_SZ];

  if (!(fh = fopen(file_name, "r+"))) return NULL;

  /* find out how many entries we have */
  for (i = 0; fgets(inbuf, INBUF_SZ, fh); i++); *entries_N = i;
 
  /* alloc memory for the array of pointers to the entry strings */ 
  if (!(entries=malloc(sizeof(char *)*(*entries_N)))){fclose(fh); return NULL;}

  fseek(fh, 0, SEEK_SET);

  /* read in the entries */
  for (i = 0; fgets(inbuf, INBUF_SZ, fh); i++) { int entry_len;
    entry_len = strlen(inbuf);
    if (inbuf[entry_len-1] == '\n') { inbuf[--entry_len] = '\0'; }
    if (!(entries[i] = malloc(sizeof(char)*(entry_len+1)))) {
      free_entries(entries, i); return NULL;      
    }
    
    strcpy(entries[i], inbuf);
  }
  fclose(fh);
  return entries;
}

/* free_entries() - release the memory allocated for an array of strings */
void free_entries(char **entries, int entries_N) { int i;
  for (i = 0; i < entries_N; i++) free(entries[i]); free(entries); 
}

/* cmp_entries() - helper routine for lfind. note that strcmp
 * can't be used directly since we want to compare strings given
 * by pointers to strings (i.e. pointers to pointers to characters)
 * rather than just standard C strings.
 */
int cmp_entries(const void *entry_a, const void *entry_b) {
  return strcmp(*(char **)entry_a, *(char **)entry_b);
}