### Record, per flat-slot object, whether it loads under every supported R minor.
#
# Usage: Rscript local/backfill-flat-safety.R <arch> <codename> [limit]
#
# `union_index_records()` keeps a carried flat record when that object is
# recorded safe, and drops it otherwise. Objects uploaded before that record
# existed have no verdict, so they are dropped: a full re-index removed ~2000
# records per per-minor index, all resolving to CRAN source for clients the
# routing serves correctly.
#
# This inspects the objects already in the bucket and writes the verdict, which
# is what restores that coverage. The question is decided by symbols, not
# heuristics: a binary fails at dyn.load() under minor M exactly when it
# references a symbol M does not export, and the volatile set is derived by
# diffing the R builds installed in this image.
#
# Only compiled packages are inspected. A package with no shared object cannot
# fail this way and is never dropped, so proving it would be wasted downloads.
#
# Resumable: objects already recorded are skipped, so a re-run costs one query.

options(error = function() {
  cat("ERROR:", geterrmessage(), "\n", file = stdout())
  traceback(2)
  q(status = 1)
})

library(bincraft, quietly = TRUE)

args <- commandArgs(trailingOnly = TRUE)
if (length(args) < 2L) {
  stop("usage: backfill-flat-safety.R <arch> <codename> [limit]", call. = FALSE)
}
arch <- args[[1L]]
codename <- args[[2L]]
limit <- if (length(args) >= 3L) as.integer(args[[3L]]) else NA_integer_

sets <- bincraft:::installed_r_symbol_sets()
if (is.null(sets)) {
  stop(
    "Fewer than two R minors are installed here, so nothing can be compared. Refusing to record verdicts that would all read 'safe'.", # nolint
    call. = FALSE
  )
}
cat(sprintf(
  "Comparing R minors: %s (%d symbols vary across them)\n",
  paste(names(sets), collapse = ", "),
  length(bincraft:::cross_minor_volatile_symbols(sets))
))

read_index <- function(index_url) {
  con <- gzcon(url(index_url, open = "rb"))
  on.exit(close(con), add = TRUE)
  read.dcf(con, fields = c("Package", "Version", "Built", "NeedsCompilation"))
}

flat <- read_index(sprintf(
  "https://cran.rpkgs.com/%s/%s/latest/src/contrib/PACKAGES.gz",
  arch,
  codename
))
# Source fallbacks carry no binary, so there is nothing to inspect.
flat <- flat[!is.na(flat[, "Built"]), , drop = FALSE]
compiled <- flat[
  !is.na(flat[, "NeedsCompilation"]) & flat[, "NeedsCompilation"] == "yes",
  ,
  drop = FALSE
]
cat(sprintf(
  "%s/%s: %d flat binaries, %d compiled and worth inspecting\n",
  arch,
  codename,
  nrow(flat),
  nrow(compiled)
))
if (!is.na(limit) && limit > 0L && limit < nrow(compiled)) {
  compiled <- compiled[seq_len(limit), , drop = FALSE]
  cat(sprintf("Limited to the first %d\n", limit))
}

base <- sprintf(
  "https://cran.rpkgs.com/%s/%s/latest/src/contrib",
  arch,
  codename
)
safe <- 0L
unsafe <- 0L
skipped <- 0L
for (i in seq_len(nrow(compiled))) {
  pkg <- compiled[i, "Package"]
  ver <- compiled[i, "Version"]
  tarball <- file.path(tempdir(), sprintf("%s_%s.tar.gz", pkg, ver))
  ok <- tryCatch(
    {
      utils::download.file(
        sprintf("%s/%s_%s.tar.gz", base, pkg, ver),
        tarball,
        quiet = TRUE,
        mode = "wb"
      )
      TRUE
    },
    error = function(e) FALSE,
    warning = function(w) FALSE
  )
  if (!ok) {
    skipped <- skipped + 1L
    next
  }
  verdict <- bincraft:::tarball_abi_verdict(tarball, sets)
  unlink(tarball)
  if (!isTRUE(verdict$inspected)) {
    skipped <- skipped + 1L
    next
  }
  bincraft:::flat_safety_store(
    pkg,
    ver,
    codename,
    arch,
    safe = !isTRUE(verdict$sensitive),
    unsupported = verdict$unsupported
  )
  if (isTRUE(verdict$sensitive)) {
    unsafe <- unsafe + 1L
  } else {
    safe <- safe + 1L
  }
  if (i %% 250L == 0L) {
    cat(sprintf(
      "  inspected %d/%d (%d safe, %d unsafe, %d skipped)\n",
      i,
      nrow(compiled),
      safe,
      unsafe,
      skipped
    ))
    utils::flush.console()
  }
}

cat(sprintf(
  "Done: %d inspected, %d safe for every minor, %d unsafe, %d skipped\n",
  nrow(compiled),
  safe,
  unsafe,
  skipped
))