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#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <sys/types.h>
#include <time.h>
#include <stdlib.h>
#include <ctype.h>
#include "tztable.h"
/*it's not case sensitive
returns the offset
returns -1 if it doesn't find it*/
int findintable(char *what){
for(size_t i = 0; i < TZTABLE_LENGHT; i++){
if((strcasecmp(what, tz_table[i].zn)) == 0){
return tz_table[i].offset;
}
}
return -1;
}
/*parses H or H:M (24hs)
returns 0 on success, -1 if it's not a valid time*/
int strtimetoint(const char *whattimeisit, davidtime *out) {
if (whattimeisit == NULL || out == NULL) return -1;
char *end;
long hour = strtol(whattimeisit, &end, 10);
if (end == whattimeisit) return -1;
long minutes = 0;
if (*end == ':') {
const char *mstart = end + 1;
minutes = strtol(mstart, &end, 10);
if (end == mstart) return -1;
}
if (*end != '\0') return -1;
if (hour < 0 || hour > 23 || minutes < 0 || minutes > 59) return -1;
out->hour = (int)hour;
out->minutes = (int)minutes;
return 0;
}
char* gethhmm(char* buffer, size_t max_size) {
time_t raw_time;
struct tm* time_info;
time(&raw_time);
time_info = localtime(&raw_time);
strftime(buffer, max_size, "%H:%M", time_info);
return buffer;
}
int gettimeandstuff(void){
time_t rawtime = time(NULL);
struct tm utc = *gmtime(&rawtime); /*copy, gmtime uses a static buffer*/
utc.tm_isdst = -1;
time_t gmt = mktime(&utc);
return difftime(rawtime, gmt) / 60;
}
/*tozone = 0 time is in zone, print it as local time
tozone = 1 time is local time, print it in zone
returns 0 ok -1 zone not found and -2 if invalid time*/
int convert(char *timey, char *zone, int tozone){
int offset = gettimeandstuff();
//tmzn hour --> utc00 --> local time
int zntime = findintable(zone);
if(zntime == -1)return -1;
davidtime eugh;
if(strtimetoint(timey, &eugh) == -1) return -2;
int mins = eugh.hour * 60 + eugh.minutes;
int total = tozone ? mins - offset + zntime : mins - zntime + offset; //ok this is better yeah
int day = 0;
while (total < 0){
total += 1440; day--;
}
while (total >= 1440){
total -= 1440; day++;
}
printf("%02d:%02d", total / 60, total % 60);
if(day) printf(" %+dd", day);
printf("\n");
return 0;
}
/*takes in a single argument
and returns whatever timezones allign with the input*/
int convert2(char *timey){
/*it should fist get the offset between local time and input
it should probably round up to ~5 minutes so multiples of 5
input is like 7:32 rounds down to 7:30
finds the closest match, on many matches it just presents the first in the list*/
int localoffset = gettimeandstuff();
davidtime hi;
if(strtimetoint(timey, &hi) == -1) return -2;
char nowstr[16];
davidtime now;
gethhmm(nowstr, sizeof(nowstr));
strtimetoint(nowstr, &now);
int inmins = hi.hour * 60 + hi.minutes;
int nowmins = now.hour * 60 + now.minutes;
inmins -= inmins % 5; /*round down to multiples of 5*/
nowmins -= nowmins % 5;
//offset of the zone that has the input as its current time
int target = localoffset + (inmins - nowmins);
int best = -1, bestdist = 1441;
for(size_t i = 0; i < TZTABLE_LENGHT; i++){
//distance on the 24h clock so +13 and -11 count as the same time
int d = ((tz_table[i].offset - target) % 1440 + 1440) % 1440;
if(d > 720) d = 1440 - d;
if(d < bestdist){
bestdist = d;
best = (int)i;
}
}
if(best == -1) return -1;
int off = tz_table[best].offset;
printf("%s (UTC%c%02d:%02d)\n", tz_table[best].zn, off < 0 ? '-' : '+', abs(off) / 60, abs(off) % 60);
return 0;
}
int main (int argc, char **argv){
if((argc <= 1) || (argc > 3)){
printf("%s: usage: %s [TIME (24hs)] [ZONE]\ne.g: %s 7:15 est\n\nalso get relative times like %s [ZONE]\ne.g: %s est\n\nor find which zone has a given time right now like %s [TIME (24hs)]\ne.g: %s 17:00\n", argv[0], argv[0], argv[0], argv[0], argv[0], argv[0], argv[0]);
exit(1);
}
char timestr[16];
gethhmm(timestr, sizeof(timestr));
if (argc == 2) {
if (isdigit((unsigned char)argv[1][0])) {
int res2 = convert2(argv[1]);
if (res2 == -2) {
printf("%s: invalid time, use 24hs format like 7:15\n", argv[0]);
return 1;
}
if (res2 == -1) {
printf("%s: no time zones to match against\n", argv[0]);
return 1;
}
return 0;
}
if (convert(timestr, argv[1], 1) == -1) {
printf("%s: time zone not found, did you write it correctly?\n", argv[0]);
return 1;
}
return 0;
}
int res = convert(argv[1], argv[2], 0);
if (res == -1) {
printf("%s: time zone not found, did you write it correctly?\n", argv[0]);
return 1;
}
if (res == -2) {
printf("%s: invalid time, use 24hs format like 7:15\n", argv[0]);
return 1;
}
return 0;
}
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