#include "kwic.h"
#include "noise_word_storage.h"

#define MAX_WORDS 3
static char **word_list;
static int word_list_length;
static int num_words;

/* internal state invariant
* 1. word_list[0..word_list_length-1] is allocated
* 2. word_list[0..num_words-1] contains pointers to null-terminated C strings
* 3. word_list[0..num_words-1] is sorted in ascending order
*/

/**
@purpose
Initialize the module.
Return the appropriate KWIC status code.
@preconditions
none
*/
int ns_init(void)
{
	// create an empty word_list with default space
	word_list_length = MAX_WORDS;
	num_words = 0;
	word_list = calloc(word_list_length,sizeof(char *));
	if (word_list == NULL) {
		return KW_MEMORY_ERROR;
	} else {
		return KW_SUCCESS;
	}
}

/**
@purpose
Add word to the currently stored list of words.
if not enough memory is available to store word
	return KW_MEMORY_ERROR
else
	return KW_SUCCESS
@preconditions
word is a legal C string
ns_init has been called and returned KW_SUCCESS
*/
int ns_add_word(char *word)
{
	int insert_position,i,n;

	// if word_list is full, double its size
	if (num_words >= word_list_length) {
		word_list_length *= 2;
		word_list = realloc(word_list, word_list_length*sizeof(char*));
		if (word_list == NULL) {
			return KW_MEMORY_ERROR;
		}
	}
	printf("%d %d\n",word_list_length,num_words);

	// find position to insert word
	for (insert_position = 0;
	 insert_position < num_words;
	  insert_position++) {
		printf("%d\n",insert_position);
		n = strcasecmp(word,word_list[insert_position]);
		if (n == 0) { // already in word_list: ignore
			return KW_SUCCESS;
		} else if (n < 0) { // insert position found
			break;
		}
	}

	// shift word_list[i..num_words-1] to the right
	num_words++;
	for (i = num_words-1; i > insert_position; i--) {
		printf("%d\n",i);
		word_list[i] = word_list[i-1];
	}

	// insert word in place
	word_list[insert_position] = malloc(strlen(word)+1);
	if (word_list[insert_position] == NULL) {
		return KW_MEMORY_ERROR;
	}
	strcpy(word_list[insert_position],word);

	return KW_SUCCESS;
}

/**
@purpose
Return 1 if word is in the currently stored list and 0 otherwise.
When searching, the comparisons must be case insensitive.
For example, "aaa" and "aAa" are considered equal.
@preconditions
word is a legal C string
ns_init has been called and returned KW_SUCCESS
*/
int ns_find_word(const char *word)
{
        int high,low,mid,compare;

	low = 0;
	high = num_words - 1;
        while (low <= high) {
                mid = (low+high)/2;
		printf("%d %d %d\n",low,mid,high);
                compare = strcasecmp(word,word_list[mid]);
                if (compare < 0)
                        high = mid-1;
                else if (compare == 0)
                        return 1;
                else
                        low = mid+1;
        }
        return 0;
}