/* Most of it stolen from Pierre Beyssac's bing */

/* $Id: util.c 377 2007-03-12 20:48:05Z bortz $ */

#include "echoping.h"

#define STATES 32

#include <time.h>
#include <ctype.h>

char           *
random_string(unsigned length)
{

	char           *state = (char *) malloc(sizeof(char) * STATES);
	char           *result = (char *) malloc(length + 1);
	int             i, number;
	unsigned        seed = (unsigned) time((time_t *) NULL);

	/* printf ("Seed is %u\n", seed); */

	/* Initialize random generator */
	(void) initstate(seed, state, STATES);

	for (i = 0; i < length; i++) {
		number = (random() % 94) + 33;
		/* printf ("Number for %d is %d\n", i, number); */
		result[i] = (char) number;
	}
	result[length] = '\0';

	/* printf ("Result is %s\n", result); */

	return result;

}

char           *
to_upper(char *input)
{
	int             c;
	char           *result;
	result = (char *) malloc(strlen(input));
	for (c = 0; c < strlen(input); c++)
		result[c] = toupper((int)input[c]);
	result[strlen(input)] = '\0';
	return result;
}

/*
 * tvsub -- Subtract 2 timeval structs:  out = out - in. Out is assumed to be
 * >= in. Comes from the bing program. 
 */
void
tvsub(out, in)
	struct timeval *out, *in;
{
	if ((out->tv_usec -= in->tv_usec) < 0) {
		--out->tv_sec;
		out->tv_usec += 1000000;
	}
	out->tv_sec -= in->tv_sec;
}

/* tvadd -- Adds 2 timeval structs:  out = out + in. */
void
tvadd(out, in)
	struct timeval *out, *in;
{
	if ((out->tv_usec += in->tv_usec) >= 1000000) {
		++out->tv_sec;
		out->tv_usec -= 1000000;
	}
	out->tv_sec += in->tv_sec;
}

/* tvavg -- Averages a timeval struct */
void
tvavg(out, number)
	struct timeval *out;
	int             number;
{
	double          result;
	/* 
	 * out->tv_sec = out->tv_sec/number; out->tv_usec =
	 * out->tv_usec/number; 
	 */
	result = (1000000 * out->tv_sec + out->tv_usec) / number;
	/* printf ("Result of average is %f\n", result) */ ;
	out->tv_sec = (long) (result / 1000000);
	out->tv_usec = (long) (result - (out->tv_sec * 1000000));
}

/* tvstddev -- Computes the standard deviation of a set of results */
void
tvstddev(out, number, average, results)
	struct timeval *out;
	int             number;
	struct timeval  average;
	struct result  *results;
{
	int             i;
	struct timeval  result = null_timeval;
	struct timeval  avg = null_timeval;
#ifdef DEBUG
	struct timeval  var = null_timeval;
#endif
	struct timeval  large, small;
	double          d_offset, d_square, d_variance = 0;
	*out = null_timeval;
	for (i = 0; i < number; i++) {
		if (results[i].valid == 1) {
			result = results[i].timevalue;
#ifdef DEBUG
			printf("DEBUG: Value is %f (average is %f)\n", tv2double
			       (result), tv2double(average));
#endif
			avg = average;
			if (tvcmp(&result, &avg) == -1) {
				small = result;
				large = avg;
			} else {
				large = result;
				small = avg;
			}
			tvsub(&large, &small);
#ifdef DEBUG
			printf("abs offset is %f\n", tv2double(large));
#endif
			d_offset = tv2double(large);
			d_square = d_offset * d_offset;
			d_variance += d_square;
#ifdef DEBUG
			printf("variance is now %f\n", tv2double(var));
#endif
		}
	}
	result = double2tv(sqrt(d_variance / (double) number));
	out->tv_sec = result.tv_sec;
	out->tv_usec = result.tv_usec;
}


 /* tvstddevavg -- Computes the average of values within a set of results where the
  * sample is within the given number of standard deviations from the average */
/* TODO: IWBN to return the number of excluded outliers */
void
tvstddevavg(out, number, average, results, n_stddev)
	struct timeval *out;	/* contains std dev on entry */
	int             number;
	struct timeval  average;
	struct result  *results;
	double          n_stddev;
{
	int             i, valid = 0;
	struct timeval  result;	/* working value */
	struct timeval  var = null_timeval;	/* result accumulator */
	double          x;
	double          maxdev = tv2double(*out) * n_stddev;

	if (tvcmp(out, &null_timeval) == 0) {
		/* if the SD is 0 then we just return the average */
		*out = average;
		return;
	}

	for (i = 0; i < number; i++) {
		if (results[i].valid == 1) {
			result = results[i].timevalue;
			tvsub(&result, &average);
			/* printf ("value is %f (stddev is %f)\n", tv2double
			 * (result), tv2double (stddev)); */
			/* ensure that result (difference to average) is absolute
			 * value */
			if (tvcmp(&result, &null_timeval) == -1) {
				result = average;
				tvsub(&result, &results[i].timevalue);
			}
			x = tv2double(result);
			/* printf("value is %g maxdev %g\n",x,maxdev); */
			if (x <= maxdev) {
				/* deviation is less than stddev */
				tvadd(&var, &results[i].timevalue);
				valid++;
			} else {
				/* printf("dropped\n"); */
			}
		}
	}
	/* printf ("total is %f in %d samples\n", tv2double (var), valid); */
	if (valid > 0) {
		*out = double2tv(tv2double(var) / valid);
	} else {
		*out = null_timeval;
	}

}

/* tvcmp -- Compares two timeval structs */
int
tvcmp(left, right)
	struct timeval *left, *right;
{
	if (left->tv_sec < right->tv_sec) {
		return -1;
	}
	if (left->tv_sec > right->tv_sec) {
		return 1;
	}
	if (left->tv_usec < right->tv_usec) {
		return -1;
	}
	if (left->tv_usec > right->tv_usec) {
		return 1;
	}
	return 0;

}

/* tvmin */
void
tvmin(champion, challenger)
	struct timeval *champion, *challenger;
{
	if (tvcmp(champion, challenger) == 1) {
		champion->tv_sec = challenger->tv_sec;
		champion->tv_usec = challenger->tv_usec;
	}
}

/* tvmax */
void
tvmax(champion, challenger)
	struct timeval *champion, *challenger;
{
	if (tvcmp(champion, challenger) == -1) {
		champion->tv_sec = challenger->tv_sec;
		champion->tv_usec = challenger->tv_usec;
	}
}

double
tv2double(tv)
	struct timeval  tv;
{
	double          result;
	result =
	    (((((double) tv.tv_sec) * 1000000.0) + (double) tv.tv_usec) / 1000000.0);
	/* printf ("Double is %9.3f\n", result); */
	return result;
}

struct timeval
double2tv(x)
	double          x;
{
	struct timeval  result;
	result.tv_sec = (int) (x);
	result.tv_usec = (int) ((x - result.tv_sec) * 1000000);
	return result;
}