From e18797f55b2a0dd1dc154d1ae36d13a4a5634a2b Mon Sep 17 00:00:00 2001
From: Pawel Rucki <12943682+pawelru@users.noreply.github.com>
Date: Thu, 29 Aug 2024 17:57:15 +0200
Subject: [PATCH] better handle very old and latest snapshots

---
 R/get_ref.R | 10 +++++++++-
 R/utils.R   |  3 +++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/R/get_ref.R b/R/get_ref.R
index 7d9f22c..54f1774 100644
--- a/R/get_ref.R
+++ b/R/get_ref.R
@@ -596,6 +596,9 @@ get_avail_date <- function(remote_ref, start = get_release_date(remote_ref)) {
 }
 
 #' @rdname get_avail_date
+#'
+#' @importFrom pkgcache ppm_snapshots
+#'
 #' @export
 #'
 #' @examplesIf Sys.getenv("R_USER_CACHE_DIR", "") != ""
@@ -606,8 +609,13 @@ get_avail_date.remote_ref_cran <- function(remote_ref, start = get_release_date(
   i <- 0
   date <- start
   while (i <= max_iter) {
+    # there are some gaps in the snapshots so it's important to at first find the closest date
     ppm_url <- get_ppm_snapshot_by_date(date)
-    date <- unname(as.Date(sub(".*/", "", ppm_url)))
+    date <- `if`(
+      grepl("/latest$", ppm_url),
+      tail(pkgcache::ppm_snapshots(), 1)$date,
+      unname(as.Date(sub(".*/", "", ppm_url)))
+    )
     data <- available.packages(
       repos = ppm_url,
       filters = list(function(db) db[db[, "Package"] == remote_ref$package, ])
diff --git a/R/utils.R b/R/utils.R
index 874d91d..060272e 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -36,6 +36,9 @@ get_ppm_snapshot_by_date <- function(date = NA) {
   if (date >= tail(pkgcache::ppm_snapshots(), 1)$date) {
     return(pkgcache::repo_resolve("PPM@latest"))
   }
+  if (date <= head(pkgcache::ppm_snapshots(), 1)$date) {
+    return(pkgcache::repo_resolve(sprintf("PPM@%s", head(pkgcache::ppm_snapshots(), 1)$date)))
+  }
   tryCatch(
     pkgcache::repo_resolve(sprintf("PPM@%s", as.character(as.Date(date) + 1))),
     error = function(err) {