Figuring out how long too wait to avoid the limit of maximum 7 CRAN releases last 180 days

cran_submission_limits.R

cran_days_since_release <- function(pkg, now = Sys.time()) {
  db <- rbind(tools:::CRAN_archive_db()[[pkg]], tools:::CRAN_current_db()[pkg,])
  now - sort(db$mtime, decreasing = TRUE)
}

# The CRAN rule is maximum 7 existing releases within the last 180 days
# https://github.com/wch/r-source/blob/tags/R-4-1-2/src/library/tools/R/QC.R#L7990-L8007
cran_wait_needed <- function(pkg, max = 7L, limit = 180, now = Sys.time()) {
  since <- cran_days_since_release(pkg, now = now)
  too_new <- since[since <= limit]
  n <- length(too_new)
  if (n < max) (now-now) else limit - too_new[n]
}

ex-usage.R

## On December 14, 2021
now <- Sys.time()
now
#> [1] "2021-12-14 18:22:59 PST"

## vroom needs to wait another 5 days to avoid
## the 'R CMD check --as-cran' NOTE on:
## Number of updates in past 6 months: 7
cran_wait_needed("vroom")
#> Time difference of 4.706 days

## parallelly can be submitted now
cran_wait_needed("parallelly")
#> Time difference of 0 secs