/* START LIBRARY DESCRIPTION *********************************************
FLOAT.LIB
	Copyright (c) 2006, Avtech Electrosystems Ltd.

DESCRIPTION:
	Functions that deal with strings and floating point numbers.

SUPPORT LIB'S:
END DESCRIPTION **********************************************************/


#include <string.h>
#include <ctype.h>
#include <math.h>
#include <glib/gprintf.h>
#include "globals.h"
#include "string_utils.h"

void Float_To_Text(int decimal_digits,float number_in, gchar ** text_out)
{
	g_assert (*text_out == NULL);

	if (fabs(number_in)<1.1*smallest_allowed_number) {
		if (number_in<0.0) {
			*text_out = g_strdup_printf("-0.%0*d",decimal_digits,0);
		} else {
			*text_out = g_strdup_printf("0.%0*d",decimal_digits,0);
		}
		return;
	}

	*text_out = g_strdup_printf("%.*e", decimal_digits, number_in);
}


int String_trim_excess_digits(char *parameter)
{
	/* this function takes a parameter like "1.2345678901234567890" and reduces it to "1.234567" */
	/* so that atof() will work properly */

	gchar* new_string = g_strdup(parameter);
	memset(new_string, 0, strlen(parameter));

	int i;
	int j;
	int sig_digits;	/* number of significant digits so far */
	long exp_power;		/* append an exponent of this power */
	int sign;			/* is the exponent negative? */
	int start_of_exponent;	/* location of exponent */

	i=0;	/* location in input string */
	j=0;	/* location in output string */
	sig_digits=0;
	exp_power=0;
	sign=NO;

#define max_sig_dig 8

	if (!(isdigit(parameter[0]) || parameter[0]=='+' || parameter[0]=='-' || parameter[0]=='.')) {
		return OK;
	}

	/* take care of sign */
	if (parameter[0]=='+' || parameter[0]=='-') {
		new_string[j]=parameter[i];
		++i;
		++j;
	}

	/* leave in leading zeros */
	while (parameter[i]=='0') {
		new_string[j]=parameter[i];
		++i;
		++j;
	}

	/* leave in up to 8 pre-decimal significant digits */
	while (isdigit(parameter[i]) && sig_digits<max_sig_dig) {
		new_string[j]=parameter[i];
		++i;
		++j;
		++sig_digits;
	}

	/* if there are remaining digits, truncate and add exponent, and then return immediately */
	while (isdigit(parameter[i]) && sig_digits==max_sig_dig) {
		++i;
		++exp_power;
	}
	if (exp_power>0) {
		strcat(new_string+j,"e");

		//replaced itoa (non standard) with sprintf
		char temp[64];
		memset(temp, 0, 64);
		sprintf(temp, "%ld", exp_power);

		strcat(new_string,temp);

		strcpy(parameter,new_string);
		if (exp_power<38) {
			return OK;
		} else {
			return OutOfRange;
		}
	}

	/* leave in decimal point */
	if (parameter[i]=='.') {
		new_string[j]=parameter[i];
		++i;
		++j;
	}

	/* leave in post-decimal zeros if no significant digits yet */
	while (parameter[i]=='0' && sig_digits==0) {
		new_string[j]=parameter[i];
		++i;
		++j;
	}

	/* leave in up to 8 post-decimal significant digits */
	while (isdigit(parameter[i]) && sig_digits<max_sig_dig) {
		new_string[j]=parameter[i];
		++i;
		++j;
		++sig_digits;
	}

	/* skip extraneous post-decimal digits */
	while (isdigit(parameter[i]) && sig_digits==max_sig_dig) {
		++i;
	}

	if (parameter[i]=='e') {
		new_string[j]=parameter[i];
		++i;
		++j;

		if (parameter[i]=='+') {
			sign=NO;
			new_string[j]=parameter[i];
			++i;
			++j;
		} else if (parameter[i]=='-') {
			sign=YES;
			new_string[j]=parameter[i];
			++i;
			++j;
		}

		if (i<strlen(parameter) && isdigit(parameter[i])) {
			start_of_exponent=j;
			new_string[j]=parameter[i];
			++i;
			++j;
		}

		while (i<strlen(parameter) && isdigit(parameter[i])) {
			new_string[j]=parameter[i];
			++i;
			++j;
		}

		new_string[j]=0;
		exp_power=atol(new_string+start_of_exponent);

		if (exp_power>37 && sign==NO) {
			g_free(new_string);
			return OutOfRange;
		}
		if (exp_power>37 && sign==YES) {
			strcpy(new_string,"0.0");
		}
	}

	new_string[j]=0;

	strcpy(parameter,new_string);
	g_free(new_string);
	return OK;
}


/*----------------------------------------------------------------------------------------------------------*/
gboolean String_is_it_numeric(char *parameter) {

	GRegex *numeric_regex = g_regex_new (	"\\s*[+-]?(\\d*\\.\\d+|\\d+(\\.\\d*)?)\\s*(e\\s*[+-]?\\d+)?\\s*", 
					     	G_REGEX_CASELESS,
					     	0,
						NULL);

	return g_regex_match (numeric_regex, parameter, 0, NULL);
}