/* This file has the implementation of the function for bubble sort. */
/* Include guards + include statements. */
#ifndef BINARY_SEARCH_C
#define BINARY_SEARCH_C
#include <stdlib.h>
#include <string.h>
#include "binary_search.h"
#endif /* BINARY_SEARCH_C */

/* Note that if the comparison function is NULL, the array pointer is NULL or the search value is NULL, then the function will quit. */
/* Note that the comparison function should return 1 if the second argument is larger than the first, zero if they're both equal and -1 otherwise. */
/* The array's length should be passed in the length argument. */
/* Size should match a single object's size, and should be > 0. */
/* The function returns BINARY_SEARCH_INDEX_NOT_FOUND on error or not found, otherwise will return the index of the value. */
int binary_search(void *array, void *value, int (*comparison_function)(const void*, const void*), const int length, size_t size) {
	/* Local variables. */
	int index_left, index_right, current_index;

	/* Sanity check. */
	if (array == NULL || value == NULL || comparison_function == NULL || size <= 0 || length <= 0)
		return BINARY_SEARCH_INDEX_NOT_FOUND;

	/* Input values are correct, commence the search. */
	/* Set the initial index values. */
	index_left = 0;
	index_right = length - 1;
	/* Loop and search. */
	while (index_left <= index_right) {
		/* Calculate the current index. */
		current_index = (index_left + index_right) / 2;
		/* Check if we've found the number. */
		if (comparison_function(array + (current_index * size), value) == BINARY_SEARCH_COMPARISON_EQUAL_TO)
			return current_index;
		/* Check if smaller/larger and continue accordingly. */
		if (comparison_function(array + (current_index * size), value) == BINARY_SEARCH_COMPARISON_LESS_THAN)
			index_left = current_index + 1;
		else
			index_right = current_index - 1;
	}

	/* Search failed! */
	return BINARY_SEARCH_INDEX_NOT_FOUND;
}