#include <stdio.h>      
#include "freq-list.h"

#define increment_freq(n) (n)->freq++

static char *new_word(char *w) {
  char *tmp;
  if ( (tmp = (char *) malloc(strlen(w)+1)) == NULL) {
    fprintf(stderr, "Out of memory.\n");
    exit(-1);
  }
  return strcpy(tmp, w);
}

static struct freq *new_node(char *word, int freq) {
  struct freq *n = (struct freq *) malloc(sizeof (struct freq));

  if (n == NULL) {
    fprintf(stderr, "Out of memory.\n");
    exit(-1);
  }
  n->word = word;
  n->freq = freq;
  n->next = NULL;

  return n;
}

/* This is a constant now     */
/* freq_list fl_empty = NULL; */

freq_list new_freq_list() {
  return new_node((char *)NULL, -1);
}
  
static freq_list fl_add(char *word, int freq, freq_list fl) {
  struct freq *n;
  char *wordcopy = new_word(word);

  n = new_node(wordcopy, freq);
  n->next = fl;

  return n;
}

struct freq *fl_lookup(char *word, freq_list fl) {
  if ( (fl == NULL) || (strcmp(word, fl->word) == 0) )
    return fl;
  else
    return fl_lookup(word, fl->next);
}
  
void fl_foreach(void (*fn)(char *, int), freq_list fl) {
  struct freq *tmp;

  for (tmp = fl; tmp != NULL; tmp = tmp->next)
    (*fn)(tmp->word, tmp->freq);
}

freq_list fl_insert(char *word, freq_list fl) {
  struct freq *tmp = fl_lookup(word, fl);

  if (tmp == NULL)
    return fl_add(word, 1, fl);
  else
    return increment_freq(tmp), fl;
}

freq_list fl_destroy(struct freq *fl) {
  free(fl->word);
  fl_destroy(fl->next);
  free(fl);
  return fl_empty;
}