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### Tests of often platform-dependent features of the POSIX[cl]t implementation.

### Expect differences, historically with 32-bit time_t and platforms

### without tm_zone/tm_gmtoff.

### Also with musl (wrongly using current not historic "zone" abbreviations).

### Please use the R-internal version for .Rout.save.

## IGNORE_RDIFF_BEGIN

(tzCtype <- sessionInfo()[["tzcode_type"]])

## IGNORE_RDIFF_END

z <- ISOdate(1890:1912, 1, 10, tz="UTC")

## Rome changed to CET for 1894

as.POSIXlt(z, tz="Europe/Rome")

## Paris changed to PMT for 1892, WET for 1912

(zz <- as.POSIXlt(z, tz="Europe/Paris"))

strftime(zz, "%Y-%m-%d %H:%M:%S %Z")

## The offset was really +00:09:21 until 1911, then +00:00

## Many platforms will give the current offset, +0100

strftime(zz, "%Y-%m-%d %H:%M:%S %z")

## Some platforms give details of the latest conversion.

z <- ISOdate(c(seq(1890, 1940, 5), 1941:1946, 1950), 1, 10, tz="UTC")

as.POSIXlt(z, tz="Europe/Paris")

for(i in seq_along(z)) print(as.POSIXlt(z[i], tz="Europe/Paris"))

## use pf %z needs tm_gmtoff

for(i in seq_along(z))

    print(strftime(as.POSIXlt(z[i], tz="Europe/Paris"), "%Y-%m-%d %H:%M:%S %z"))

strptime("1920-12-27 08:18:23", "%Y-%m-%d %H:%M:%S", tz="Europe/Paris")

## check %V etc

d <- expand.grid(day = 1:7, year = 2000:2010)

z1 <- with(d, ISOdate(year, 1, day))

d <- expand.grid(day = 25:31, year = 2000:2010)

z2 <- with(d, ISOdate(year, 12, day))

z <- sort(c(z1, z2))

strftime(z, "%G %g %W %U %u %V %W %w", tz="Europe/Paris")

## tests of earlier years.  Default format is OS-dependent, so don't test it.

## ISOdate only accepts positive years.

z <- as.Date(ISOdate(c(0, 8, 9, 10, 11, 20, 110, 1010), 1, 10)) - 3630

strftime(z, "%04Y-%m-%d") # with leading zero(s), where supported

strftime(z, "%_4Y-%m-%d") # with leading space(s), where supported

strftime(z, "%0Y-%m-%d") # without

## more test of strftime

x <- ISOdate(2014, 3, 10, c(7, 13))

fmts <- c("%Y-%m-%d %H:%M:%S", "%F", "%A %a %b %h %e %I %j",

          ## locale-dependent ones

          "%X", # but the same in all English locales

          "%c", "%x", "%p", "%r")

for (f in fmts) print(format(x, f))

## Moved from reg-tests-1d.R

## as.POSIXlt(<very large Date>) gave integer overflow

## and needed C-level change for 32-bit time_t.

.Machine$sizeof.time_t

(z <- .Date(2^31 + 10))

as.POSIXlt(z)$year == 5879680L

## year was negative in R <= 4.2.1, even for 64-bit time_t

## ------------- Tests of far-distant dates -----------

Sys.setenv(TZ = "Europe/London")

## the pre-1902 POSIXct values will be 75s out on platforms that do not

## know about UK changes prior to 1902 (in fact in 1847-12-01: see below).

as.POSIXct("4000-07-01")

as.Date("4000-07-01")

zz <- z <- as.POSIXlt("2000-07-01")

unclass(z)

years <- c(-1e6, -1e5, -1e4, seq(-1000, 4000, by = 100), 1e4, 1e5, 1e6)

y <- character(length(years))

for(i in seq_along(years)) {

    zz$year = years[i] - 1900

    y[i] <- strftime(zz)

}

## IGNORE_RDIFF_BEGIN

y

## IGNORE_RDIFF_END

y <- double(length(years))

for(i in seq_along(years)) {

    zz$year = years[i] - 1900

    zz$isdst <- -1 # some are DST, some not so let the code decide

    y[i] <- as.POSIXct(zz)

}

print(y, digits=14)

y <- .POSIXct(y)

## IGNORE_RDIFF_BEGIN

(y1 <- strftime(y)) # leading zeros or spaces is platform-dependant

## IGNORE_RDIFF_END

y2 <- strftime(y, "%_4Y-%m-%d") # not all platforms interpret this

if(y2[1] != "4Y-07-01") print(y2) else message('format "%_4Y" unsupported')

y <- double(length(years))

for(i in seq_along(years)) {

    zz$year = years[i] - 1900

    zz$isdst <- -1

    y[i] <- as.Date(zz)

}

y

class(y) <- "Date"

## IGNORE_RDIFF_BEGIN

(y3 <- strftime(y))

## IGNORE_RDIFF_END

y4 <- strftime(y, "%_4Y-%m-%d")

stopifnot(identical(y3, y1))

zz <- as.POSIXlt("1900-07-01")

years <- c(1800, 1847:1848, 1899:1902)

y <- double(length(years))

for(i in seq_along(years)) {

    zz$year = years[i] - 1900

    zz$isdst <- -1 # some are DST, some not so let the code decide

    y[i] <- as.POSIXct(zz)

}

print(y, digits=14)

.POSIXct(y)

## change of 75s in 1847

seq(as.POSIXlt("1847-11-24"), as.POSIXlt("1847-12-07"), by ="day")

## end of ------------- Tests of far-distant dates -----------

## Tests of %z and %Z for output.

## Use pf %z needs tm_gmtoff so offsets will otherwise be +0000

x1 <- strptime("2022-07-01", "%Y-%m-%d", tz = "UTC")

x2 <- strptime("2022-07-01", "%Y-%m-%d", tz = "Europe/Rome")

x1

x2

# RFC5322 format

format(x1, "%a, %d %b %Y %H:%M:%S %z")

# offset may not not determined: +0200 is correct

format(x2, "%a, %d %b %Y %H:%M:%S %z")

format(as.POSIXct(x2), "%a, %d %b %Y %H:%M:%S %z") # usually correct

format(x1, "%a, %d %b %Y %H:%M:%S %Z")

format(x2, "%a, %d %b %Y %H:%M:%S %Z")

## offsets not in whole hours:

x3 <- strptime("2022-01-01", "%Y-%m-%d", tz = "Australia/Adelaide")

format(as.POSIXct(x3), "%a, %d %b %Y %H:%M:%S %z") # +10h30m

# Liberia does/did not have DST and, before 1972-01-07, used MMT (-44m30s)

x4 <- strptime("1971-01-01", "%Y-%m-%d", tz = "Africa/Monrovia")

y4 <- as.POSIXct(x4)

lt4 <- unclass(as.POSIXlt(y4))

## IGNORE_RDIFF_BEGIN

attr(lt4, "tzone")

## glibc prints an abbreviation for DST. internal and musl leave it blank.

## IGNORE_RDIFF_END

stopifnot(identical(

    attr(lt4, "tzone") |> trimws(), # ignore "   " (internal) vs. "" (musl)

    c("Africa/Monrovia", "GMT", if(grepl("glibc", tzCtype)) "GMT" else "")

))

str(`attr<-`(lt4, "tzone", NULL))

## musl wrongly gives zone="GMT" (the current, not that at the time).

## macOS' strftime printed gmtoff wrong as -44m.

format(y4, "%a, %d %b %Y %H:%M:%S %z")

## timezones in 1900 might not be supported

x5 <- strptime("1900-03-01", "%Y-%m-%d", tz = "Europe/Paris")

y5 <- as.POSIXct(x5)

str(unclass(as.POSIXlt(y5))) # ditto

format(y5, "%a, %d %b %Y %H:%M:%S %z")

cat('Time elapsed: ', proc.time(),'\n')