timezone.cpp

/*
  PsychoPlug
  ESP8266 based remote outlet with standalone timer and MQTT integration
  
  Copyright (C) 2017  Earle F. Philhower, III

  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 3 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, see <http://www.gnu.org/licenses/>.
*/

#ifndef TEST_TIMEZONE
#include <Arduino.h>
#include <TimeLib.h>
#include "timezone.h"
//#include "log.h"

#include "tz.h"

typedef struct tm {
  uint8_t tm_sec; 
  uint8_t tm_min; 
  uint8_t tm_hour; 
  uint8_t tm_wday;
  uint8_t tm_mday;
  uint8_t tm_mon; 
  uint16_t tm_year;
  uint8_t tm_isdst;
} tm;


time_t mktime(struct tm *tm)
{
  tmElements_t tme;
  tme.Second = tm->tm_sec;
  tme.Minute = tm->tm_min; 
  tme.Hour = tm->tm_hour; 
  tme.Wday = tm->tm_wday+1;   // day of week, sunday is day 1
  tme.Day = tm->tm_mday;
  tme.Month = tm->tm_mon+1;  // Jan = 1 in tme, 0 in tm
  tme.Year = (uint8_t)(tm->tm_year - 70); // offset from 1970; 
  time_t t = makeTime(tme); // convert time elements into time_t
  return t;
  
}

struct tm *gmtime_r(const time_t *timep, struct tm *tm)
{
  tmElements_t tme;
  breakTime(*timep, tme); // break time_t into elements
  tm->tm_sec = tme.Second;
  tm->tm_min = tme.Minute;
  tm->tm_hour = tme.Hour;
  tm->tm_wday = tme.Wday-1; // Sun=0 in tm, 1 in tme
  tm->tm_mday = tme.Day;
  tm->tm_mon = tme.Month-1; // Jan=0 in tm, 1 in tme
  tm->tm_year = tme.Year + 70; // 0=1900 in tm, 1970 in tme
  return tm;
}

#else
#include <stdint.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>

#define ICACHE_RODATA_ATTR
#define PSTR
#include "tz.h"

#define memcpy_P memcpy
#define snprintf_P snprintf
#define strlcpy strncpy
#define strncpy_P strncpy
#define LogPrintf printf
#define SECS_PER_MIN (60)
#define SECS_PER_HOUR (60*60)
#define SECS_PER_DAY (60*60*24)
#endif


char *GetNextTZ(bool reset, char *buff, char buffLen)
{
	static uint16_t idxTZ = 0;
	static uint16_t idxLink = 0;
	if (reset) {
		idxLink = 0;
		idxTZ = 0;
	}

  const int tzcount = sizeof(mtimezone)/sizeof(mtimezone[0]);
  const int linkcount = sizeof(link)/sizeof(link[0]);
	if (idxTZ < tzcount) {
    timezone_t l;
    memcpy_P(&l, &mtimezone[idxTZ], sizeof(l));
		strlcpy(buff + l.zoneNameFromPrev,l.zonename, buffLen - l.zoneNameFromPrev);
		idxTZ++;
		return buff;
	} else if (idxLink < linkcount) {
    link_t l;
    memcpy_P(&l, &link[idxLink], sizeof(l));
    strlcpy(buff + l.zoneNameFromPrev,  l.zonename, buffLen - l.zoneNameFromPrev);
		idxLink++;
		return buff;
	} else {
		return NULL;
	}
}

int FindTZName(const char *tzname)
{
	char buff[64];
  const int tzcount = sizeof(mtimezone)/sizeof(mtimezone[0]);
  const int linkcount = sizeof(link)/sizeof(link[0]);
	for (int i=0; i < tzcount; i++) {
    timezone_t l;
    memcpy_P(&l, &mtimezone[i], sizeof(l));
		strlcpy(buff + l.zoneNameFromPrev,  l.zonename, sizeof(buff) - l.zoneNameFromPrev);
		if (!strcmp(buff, tzname)) return i;
	}
	for (int i=0; i < linkcount; i++) {
    link_t l;
    memcpy_P(&l, &link[i], sizeof(l));
		strlcpy(buff + l.zoneNameFromPrev,  l.zonename, sizeof(buff) - l.zoneNameFromPrev);
		if (!strcmp(buff, tzname)) return link[i].timezone;
	}
	return -1;
}

static timezone_t myTimezone;    // Which timezone are we in?
static time_t utcOffsetSecs = 0; // Unadjusted UTC offset
static bool useDSTRule = false;  // Does the current TZ need DST handling?
static uint16_t dstYear = 1900;  // What year the cached computations below are falid for
static time_t dstChangeAtUTC[2]; // UTC time when the offset below takes effect
static time_t dstOffsetSecs[2];  // Delta from default UTC offset to apply
static char timezoneStr[16];     // Human readable string w/format specifiers for DST/non-DST
static char dstString[2][4];     // Format specifier replacement

void UpdateDSTInfo(time_t whenUTC)
{
  const int ruleCount = sizeof(rules)/sizeof(rules[0]);
	rule_t dstRule[2];
	struct tm t;
	int ruleIdx;

//  LogPrintf("+UpdateDSTInfo(%ld)\n", (long)whenUTC);

	ruleIdx = 0;
	for (int i=0; i<ruleCount && ruleIdx < 2; i++) {
    rule_t rule;
    memcpy_P(&rule, &rules[i],sizeof(rule));
		if (rule.name == myTimezone.rule) { //mtimezone[timezoneNum].rule) {
			memcpy(dstRule+ruleIdx, &rule, sizeof(rule));
			ruleIdx++;
		}
	}
	if (ruleIdx != 2) {
		// Something weird, we don't understand if there's only one
		useDSTRule = false;
		return;
	}

  strlcpy(dstString[0], dstRule[0].fmtstr, sizeof(dstString[0]));
  strlcpy(dstString[1], dstRule[1].fmtstr, sizeof(dstString[1]));

  gmtime_r(&whenUTC, &t);
  
	int curYear = 1900 + t.tm_year;
	dstYear = curYear;
//  LogPrintf(" UpdateDSTInfo year=%d\n", dstYear);
  
	// Calculate the time when each rule will fire this year
	for (int i=0; i<2; i++) {
		memset(&t, sizeof(t), 0);
		t.tm_year = curYear - 1900;
		t.tm_mon = dstRule[i].month;
		t.tm_mday = 1;
		t.tm_isdst = 0;
		t.tm_hour = 0;
		t.tm_min = 0;
		t.tm_sec = 0;
		time_t at = mktime(&t);
//    LogPrintf(" UpdateDSTInfo: t.tm_year = %d, at = %ld\n", (int)t.tm_year, (long)at);
		// Fill in the wday, yday field
    gmtime_r(&at, &t);
		// Now we have "t" which has the UTC time for day 1 of the month.
		// Adjust to the proper day mechanically.  Could be optimized
		switch (dstRule[i].daytrig) {
			case SUN_GTEQ:
			case SUN_LAST:
				while (0!=t.tm_wday) {t.tm_wday = (t.tm_wday+1)%7; t.tm_mday++; at += SECS_PER_DAY; }
				break;
			case MON_GTEQ:
			case MON_LAST:
				while (1!=t.tm_wday) {t.tm_wday = (t.tm_wday+1)%7; t.tm_mday++; at += SECS_PER_DAY; }
				break;
			case TUE_GTEQ:
			case TUE_LAST:
				while (2!=t.tm_wday) {t.tm_wday = (t.tm_wday+1)%7; t.tm_mday++; at += SECS_PER_DAY; }
				break;
			case WED_GTEQ:
			case WED_LAST:
				while (3!=t.tm_wday) {t.tm_wday = (t.tm_wday+1)%7; t.tm_mday++; at += SECS_PER_DAY; }
				break;
			case THU_GTEQ:
			case THU_LAST:
				while (4!=t.tm_wday) {t.tm_wday = (t.tm_wday+1)%7; t.tm_mday++; at += SECS_PER_DAY; }
				break;
			case FRI_GTEQ:
			case FRI_LAST:
				while (5!=t.tm_wday) {t.tm_wday = (t.tm_wday+1)%7; t.tm_mday++; at += SECS_PER_DAY; }
				break;
			case SAT_GTEQ:
			case SAT_LAST:
				while (6!=t.tm_wday) {t.tm_wday = (t.tm_wday+1)%7; t.tm_mday++; at += SECS_PER_DAY; }
				break;

			case GIVEN_DAY:  // Simplest, update day and recalc AT
				t.tm_mday = dstRule[i].daynum;
				at = mktime(&t);
				break;
		}
		switch (dstRule[i].daytrig) {
			case SUN_GTEQ:
			case MON_GTEQ:
			case TUE_GTEQ:
			case WED_GTEQ:
			case THU_GTEQ:
			case FRI_GTEQ:
			case SAT_GTEQ:
				while (t.tm_mday < dstRule[i].daynum) { t.tm_mday += 7; at += SECS_PER_DAY * 7; }
				break;
			case SUN_LAST:
			case MON_LAST:
			case TUE_LAST:
			case WED_LAST:
			case THU_LAST:
			case FRI_LAST:
			case SAT_LAST:
				// Go to the next month and work backwards
				while (t.tm_mon == dstRule[i].month) {
					at += 7 * SECS_PER_DAY;
          gmtime_r(&at, &t);
				}
				at -= 7 * SECS_PER_DAY; // Back one week
        gmtime_r(&at, &t);
				break;
		}
		// Now at == t == day of the event
		int secToFire = abs(dstRule[i].athr) * SECS_PER_HOUR + dstRule[i].atmin * SECS_PER_MIN;
		if (dstRule[i].athr<0) secToFire = -secToFire;
		at += secToFire; 
		
		// Now see where this time is relative to and adjust appropriately.
		int dstoffsecs = abs(dstRule[i].offsethrs) * 3600 + dstRule[i].offsetmins;
		if (dstRule[i].offsethrs<0) dstoffsecs = -dstoffsecs;
		int otherdstoffsecs = abs(dstRule[i?0:1].offsethrs) * 3600 + dstRule[i?0:1].offsetmins;
		if (dstRule[i?0:1].offsethrs<0) otherdstoffsecs = -otherdstoffsecs;
		switch(dstRule[i].atref) {
			case ATREF_U:
				// Relative to UTC, so no change needed
				break;
			case ATREF_S:
				// Relative to unadjusted local time (no DST jiggery)
				at -= utcOffsetSecs;
				break;
			case ATREF_W:
				// Relative to wall time (local adjusted by DST)...by the *other* rule!
				at -= utcOffsetSecs;
				at -= otherdstoffsecs;
				break;
		}
    gmtime_r(&at, &t);
		dstChangeAtUTC[i] = at;
		dstOffsetSecs[i] = dstoffsecs;
//    LogPrintf(" UpdateDSTInfo: dstChangeAtUTC[%d] = %ld\n", i, (long)dstChangeAtUTC[i]);
//    LogPrintf(" UpdateDSTInfo: dstOffsetSecs[%d] = %ld\n", i, (long)dstOffsetSecs[i]);
	}
//  LogPrintf("-UpdateDSTInfo()\n");
}



bool SetTZ(const char *tzName)
{
  bool ret = true;

	int timezoneNum = FindTZName(tzName);
	if (timezoneNum<0) {
//	  LogPrintf("SetTZ: Unable to find timezone named '%s', using UTC\n", tzName);
	  timezoneNum = FindTZName("UTC"); // Default to UTC/GMT
    ret = false;
	}

  memcpy_P(&myTimezone, &mtimezone[timezoneNum], sizeof(myTimezone));

	// Store the UTC offset in seconds
	utcOffsetSecs = abs(myTimezone.gmtoffhr) * 3600 + myTimezone.gmtoffmin;
	if (myTimezone.gmtoffhr < 0) utcOffsetSecs = -utcOffsetSecs;

  // Store the timezone human readable string
  strlcpy(timezoneStr, myTimezone.formatstr, sizeof(timezoneStr));

  dstYear = 0; // Force it to fix on the 1st call
	if (myTimezone.rule == RULE_NONE) {
		useDSTRule = false;
	} else {
		// Calculate what UTC time we have to change and store it away
		useDSTRule = true;
  }
  return ret;
}

time_t LocalTime(time_t whenUTC)
{
  struct tm t;
  gmtime_r(&whenUTC, &t);
  
  if ((dstYear != t.tm_year + 1900) && useDSTRule) UpdateDSTInfo(whenUTC);
  if (!useDSTRule) {
    // Just UTC offset needed 
    return whenUTC + utcOffsetSecs;
  } else if ((whenUTC >= dstChangeAtUTC[0]) && (whenUTC < dstChangeAtUTC[1])) {
    // At 1st DST change
    return whenUTC + utcOffsetSecs + dstOffsetSecs[0];
  } else {
    // After 2nd change or before 1st
    return whenUTC + utcOffsetSecs + dstOffsetSecs[1];
  }
}

static char *Weekday(int wd, char *dest, int len)
{
  switch (wd) {
    case 1: strncpy_P(dest, PSTR("Sunday"), len); break;
    case 2: strncpy_P(dest, PSTR("Monday"), len); break;
    case 3: strncpy_P(dest, PSTR("Tuesday"), len); break;
    case 4: strncpy_P(dest, PSTR("Wednesday"), len); break;
    case 5: strncpy_P(dest, PSTR("Thursday"), len); break;
    case 6: strncpy_P(dest, PSTR("Friday"), len); break;
    case 7: strncpy_P(dest, PSTR("Saturday"), len); break;
  }
  return dest;
}

char *AscTime(time_t whenUTC, bool use12Hr, bool useDMY, char *buff, int buffLen)
{
  time_t t = LocalTime(whenUTC);

  char tzID[16];
  if (!useDSTRule) {
    // Just replace any string with "S" for standard
    snprintf(tzID, sizeof(tzID), timezoneStr, "S");
  } else if ((whenUTC >= dstChangeAtUTC[0]) && (whenUTC < dstChangeAtUTC[1])) {
    // At 1st DST change
    snprintf(tzID, sizeof(tzID), timezoneStr, dstString[0]);
  } else {
    // After 2nd change or before 1st
    snprintf(tzID, sizeof(tzID), timezoneStr, dstString[1]);
  }

#ifdef TEST_TIMEZONE
  struct tm q;
  gmtime_r(&t, &q);
  int h = q.tm_hour;
  int m = q.tm_min;
  int s = q.tm_sec;
  int wd = q.tm_wday+1;
  int mn = q.tm_mon+1;
  int dy = q.tm_mday;
  int yr = q.tm_year;
#else
  int h = hour(t);
  int m = minute(t);
  int s = second(t);
  int wd = weekday(t);
  int mn = month(t);
  int dy = day(t);
  int yr = year(t);
#endif

  const char *ampm = "";
  if (use12Hr) {
    if (h==0) { h = 12; ampm = "AM"; }
    else if (h==12) { ampm = "PM"; }
    else if (h<12) { ampm = "AM"; }
    else { h -= 12; ampm = "PM"; }
  }
  char wdName[16];
  snprintf_P(buff, buffLen, PSTR("%2d:%02d:%02d%s %s, %s %d/%d/%d"), h, m, s, ampm, tzID, Weekday(wd, wdName, sizeof(wdName)), useDMY?dy:mn, useDMY?mn:dy, yr);

  return buff;
}


#ifdef TEST_TIMEZONE
int main(int argc, const char *argv[])
{
	setenv("TZ", "", 1);
	if (argc<2) { printf("Please enter a timezone parameter\n"); exit(1); }
	SetTZ(argv[1]);

	time_t now;
	time(&now);
  now -= SECS_PER_DAY;
	for (int i =0; i<365; i++) {
		for (int j=0; j<24; j++) {
			for (int k=0; k<60; k++) {
				time_t local = LocalTime(now);
				struct tm t;
				memcpy(&t, gmtime(&local), sizeof(t));
//				printf("%d/%02d/%d @ %d:%02d\n", t.tm_mon+1, t.tm_mday, t.tm_year+1900, t.tm_hour, t.tm_min);
        char b[128];
        printf("%s\n", AscTime(local, true, false, b, 128));
				now += SECS_PER_MIN;
			}
		}
	}
 return 0;
}
#endif