source(file.path("..", "r-minor-helpers.R"))

# Build a fake _metadata dir under a temp R_PKG_CACHE_DIR. Each entry's mtime is
# set to `age_secs` in the past so we can exercise the age gate deterministically.
make_meta <- function(patched = 0L, pkgs = 0L, keep_repos = TRUE, age_secs = 3600) {
  root <- tempfile("pkgcache-")
  meta <- file.path(root, "R", "pkgcache", "_metadata")
  dir.create(meta, recursive = TRUE)
  old <- Sys.time() - age_secs
  mk_dir <- function(p) { dir.create(p); Sys.setFileTime(p, old); p }
  mk_file <- function(p) { writeLines("x", p); Sys.setFileTime(p, old); p }
  for (i in seq_len(patched)) mk_dir(file.path(meta, sprintf("patched-%03d", i)))
  for (i in seq_len(pkgs)) mk_file(file.path(meta, sprintf("pkgs-%03d.rds", i)))
  if (keep_repos) {
    mk_dir(file.path(meta, "CRAN-075c426938"))
    mk_dir(file.path(meta, "BioCsoft-1ac964ed6c"))
    mk_file(file.path(meta, "bioc-sysreqs.dcf.gz"))
    mk_dir(file.path(root, "R", "pkgcache", "pkg")) # downloads, must survive
  }
  root
}

n_churn <- function(root) {
  meta <- file.path(root, "R", "pkgcache", "_metadata")
  length(Sys.glob(file.path(meta, "patched-*"))) +
    length(Sys.glob(file.path(meta, "pkgs-*.rds")))
}

test_that("empty cache_dir is a no-op", {
  expect_identical(trim_pkgcache_metadata("", keep = 5L, min_age_secs = 0), 0L)
})

test_that("missing _metadata dir is a no-op", {
  expect_identical(
    trim_pkgcache_metadata(tempfile("absent-"), keep = 5L, min_age_secs = 0),
    0L
  )
})

test_that("fewer than keep entries removes nothing", {
  root <- make_meta(patched = 2L, pkgs = 2L)
  expect_identical(trim_pkgcache_metadata(root, keep = 20L, min_age_secs = 0), 0L)
  expect_identical(n_churn(root), 4L)
})

test_that("trims down to keep newest, leaving churn == keep", {
  root <- make_meta(patched = 30L, pkgs = 30L) # 60 churn entries, all old
  removed <- trim_pkgcache_metadata(root, keep = 20L, min_age_secs = 0)
  expect_identical(removed, 40L)
  expect_identical(n_churn(root), 20L)
})

test_that("entries younger than min_age_secs are protected", {
  root <- make_meta(patched = 30L, pkgs = 0L, keep_repos = FALSE, age_secs = 60)
  # keep=5 would drop 25, but all are 60s old < 600s gate -> nothing removed
  expect_identical(trim_pkgcache_metadata(root, keep = 5L, min_age_secs = 600), 0L)
  expect_identical(n_churn(root), 30L)
})

test_that("stable repo dirs and pkg downloads are never touched", {
  root <- make_meta(patched = 30L, pkgs = 30L)
  trim_pkgcache_metadata(root, keep = 0L, min_age_secs = 0)
  meta <- file.path(root, "R", "pkgcache", "_metadata")
  expect_true(dir.exists(file.path(meta, "CRAN-075c426938")))
  expect_true(dir.exists(file.path(meta, "BioCsoft-1ac964ed6c")))
  expect_true(file.exists(file.path(meta, "bioc-sysreqs.dcf.gz")))
  expect_true(dir.exists(file.path(root, "R", "pkgcache", "pkg")))
})