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date.c
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date.c
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#include "date.h"
/*return values:
1-12 - actual month
13 - sometihg wrong */
static unsigned char retrieveMonth (char *s) {
//make everything lower case
for (char *aux = s; *aux != '\0'; ++aux) {
if (!(*aux >= 'a' && *aux <= 'z')) {
*aux += ULDIFF;
}
}
if (!strcmp(s, "january")) return 1;
if (!strcmp(s, "february")) return 2;
if (!strcmp(s, "march")) return 3;
if (!strcmp(s, "april")) return 4;
if (!strcmp(s, "may")) return 5;
if (!strcmp(s, "june")) return 6;
if (!strcmp(s, "july")) return 7;
if (!strcmp(s, "august")) return 8;
if (!strcmp(s, "september")) return 9;
if (!strcmp(s, "october")) return 10;
if (!strcmp(s, "novemer")) return 11;
if (!strcmp(s, "december")) return 12;
return 13;
}
/*return values:
0 - everything ok
1 - incorrect format
try to retrieve day/month/year */
static int checkDate (char *s, TDate *date) {
if (!s) return 1;
date->day = (unsigned char) atoi(s);
s = strtok(NULL, "/");
if (!s) return 1;
//if month is given by name retrieve it
//else retrieve number
if (*s < '0' || *s > '9') {
date->month = retrieveMonth(s);
} else {
date->month = (unsigned char) atoi(s);
}
s = strtok(NULL, "/");
if (!s) return 1;
date->year = atoi(s);
return 0;
}
/*return values
0 - everything ok
1 - incorrect format
try to retrieve hour:min:sec */
static int checkHour (char *s, TDate *date) {
char *aux = strtok(s, ":");
if (!aux) return 1;
date->hour = (unsigned char) atoi(aux);
aux = strtok(NULL, ":");
if (!aux) return 1;
date->minute = (unsigned char) atoi(aux);
aux = strtok(NULL, ":");
if (!aux) return 1;
date->second = (unsigned char) atoi(aux);
return 0;
}
static int absVal (int x) {
return (x < 0) ? -x : x;
}
/*return values
0 - everything ok
1 - wrong limits
checks if given date is valid */
static int checkLimits (TDate *date) {
if (date->hour > 23) return 1;
if (date->minute > 59 || date->second > 59) return 1;
if (date->month < 1 || date->month > 12) return 1;
if (date->day > 31) {
return 1;
} else if (date->day > 30 && (date->month % 2) == 0) {
return 1;
} else if (date->month == 2) {
if (absVal(date->year) % 4 == 1 && date->day > 29) {
return 1;
} else if (date->day > 28) {
return 1;
}
}
return 0;
}
TDate * parse (char *s) {
char *aux = strtok(s, "/"), *hour = NULL;
if (!aux) return NULL;
//check if first field is of format hour:min:sec
//if so then keep it for later parsing
if (strchr(aux, ':') != NULL) {
hour = aux;
aux = strtok(NULL, "/");
}
TDate *date = (TDate *) calloc(1, sizeof(TDate));
if (!date) return NULL;
if (checkDate(aux, date) == 1) {
free(date);
return NULL;
}
if (hour != NULL && checkHour(hour, date) == 1) {
free(date);
return NULL;
}
if (checkLimits(date) == 1) {
free(date);
return NULL;
}
return date;
}
TDate * currentDate (TDate *update) {
time_t rawtime; //no of second
struct tm *actualTime; //structure from which TDate will be built
//get raw time - no of second from 1/01/1970 (most probably)
time(&rawtime);
//get local time from
actualTime = localtime(&rawtime);
//if adress is given then update it, else create new TDate
TDate *present = update;
if (!present) {
present = (TDate *) malloc(sizeof(TDate));
if (!present) return NULL;
}
//convert values
present->year = 1900 + actualTime->tm_year;
present->month = 1 + actualTime->tm_mon;
present->day = actualTime->tm_mday;
present->hour = actualTime->tm_hour;
present->minute = actualTime->tm_min;
present->second = actualTime->tm_sec;
return present;
}
double toJulian (TDate *date) {
int a = (14 - date->month) / 12;
int y = date->year + 4800 - a;
int m = date->month + 12 * a - 3;
double jvalue = date->day + (153 * m + 2) / 5;
jvalue += 365 * y + y / 4 - y / 100 + y / 400 - 32045;
jvalue += ((double) date->hour - 2) / 24;
jvalue += (double) date->minute / 1440;
jvalue += (double) date->second / 86400;
return jvalue;
}
TDateDiff * tdiff (double jv1, double jv2) {
TDateDiff * diff = calloc(1, sizeof(TDateDiff));
if (!diff) return NULL;
//calculate difference
jv1 -= jv2;
//retrive number of second from fraction part
diff->second = (int) ((jv1 - (int) jv1) * 86400);
//number of days
diff->day = (int) jv1;
//calculate number of weeks and keep number of remaining days
diff->week = diff->day / 7;
diff->day %= 7;
//find number of hours
diff->hour = diff->second / 3600;
//eliminate hours, and keep remaining second, from that find minute
diff->second %= 3600;
diff->minute = diff->second / 60;
//eliminate minute and then keep remaining second
diff->second %= 60;
return diff;
}
void decreaseDiff (TDateDiff *diff) {
if (diff->second != 0) {
--diff->second;
} else if (diff->minute != 0) {
--diff->minute;
diff->second = 59;
} else if (diff->hour != 0) {
--diff->hour;
diff->minute = 59;
diff->second = 59;
} else if (diff->day != 0) {
--diff->day;
diff->hour = 23;
diff->minute = 59;
diff->second = 59;
} else if (diff->week != 0) {
--diff->week;
diff->day = 6;
diff->hour = 23;
diff->minute = 59;
diff->second = 59;
}
}