/* Rand.c, modified slighly for use in ices, 980120 <eel@musiknet.se> */
/*****************************************************************************
 *    rand.c : write a randomization of files or stdin or parms to stdout
 *    Usage:
 *        blah | rand
 *        rand -f <file>
 *        rand <parms to be randomized>
 * 	
 *     Copyright (C) 1998 Erik Greenwald <br0ke@math.smsu.edu>
 * 
 *     This program is free software; you can redistribute it and/or modify
 *     it under the terms of the GNU General Public License as published by
 *     the Free Software Foundation; either version 2 of the License, or
 *     (at your option) any later version.
 *
 *     This program is distributed in the hope that it will be useful,
 *     but WITHOUT ANY WARRANTY; without even the implied warranty of
 *     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *     GNU General Public License for more details.
 *
 *     You should have received a copy of the GNU General Public License
 *     along with this program; if not, write to the Free Software
 *     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 ******************************************************************************/

/* NOTE: the method I'm using to get a random number LOOKS ineffecient. But
 * that's on purpose. random number generators tend to make the most 
 * significant bits the most random, and teh least significant the least
 * random, to generate the optimal spread across the entire range. When a
 * modulus is used to extract the number inside of the range, it takes the 
 * LEAST significant bits, which are the least random. When a plain old slow
 * division is done, it takes the MOST significant bits. This isn't a serious
 * speed loss because % calls a div opcode anyways.       
 */

#include "definitions.h"

/* Private data structures */
#define LINE 0
static unsigned char method;

/*** struct for the linked lists ***/
struct ll
{
	char *data;
	struct ll *next;
};

/* Private function declarations */
static void scramble (FILE *fp, FILE *out);

/* Public function definitions */

void 
rand_file (FILE *fp, FILE *out)
{
  method = LINE;	/* default to LINE method */	
  scramble (fp, out);
}

/* Private function definitions */

/*** scramble function, for files */
static void 
scramble (FILE *fp, FILE *out)
{
	char *line_storage = NULL, **table = NULL;
	struct ll *llist = NULL, *ptr = NULL;
	int size = 0, n = 0, x = 0;
	
	srand (ices_util_get_random ());
	
	llist = malloc (sizeof (struct ll));
	llist->data = NULL;
	ptr = llist;
	
	line_storage = (char *) malloc (sizeof (char) * 1024 + 2);
	
	/*** make linked list     ***/
	if (method == LINE) {
		while (fgets (line_storage, 1024, fp)) {
			struct ll *x = malloc (sizeof (struct ll));
			x->data = malloc (strlen (line_storage) * sizeof (char) + 2);
			memcpy (x->data, line_storage, strlen (line_storage) * sizeof (char) + 1);
			x->data[strlen (x->data) - 1] = 0;
			x->next = NULL;
			ptr->next = x;
			ptr = x;
			size++;
		}
	}
	
	/*** make table from list ***/
	table = malloc (size * sizeof (void *));
	ptr = llist->next;
	for (x = 0; x < size; x++) {
		table[x] = ptr->data;
		ptr = ptr->next;
	}
	
	
	/* shuffle it  (thanks to Dr Shade) */
	n = size;
	
	while (n > 1) {
		int d = (int)((double)size * rand() / (RAND_MAX + 1.0));
		char *temp = table[d];
		table[d] = table[n-1];
		table[n-1] = temp;
		--n;
	}
	
	/*** print it   ***/
	while (size) {
		fprintf (out, "%s\n", table[size - 1]);
		size--;
	}
	
	/*** delete the linked list and clean up ***/
	
	ptr = llist->next;
	while (ptr) {
		free (llist);
		llist = ptr;
		ptr =ptr->next;
	}
	
	free (line_storage);
	return;
}