#!/usr/bin/env bash
#
# assert_fs_clean - Verify no stray PostgreSQL extension control files exist on
# disk, to prove an extension was deployed purely via pg_tle (not filesystem
# install). Extracted from the pg-tle-test CI job so the SAME check can run at
# every checkpoint that could plausibly write extension files to disk
# (registration, after an update, after a binary pg_upgrade, ...), instead of
# being duplicated inline in ci.yml or trusted to a single check at the end.
#
# A pre-existing filesystem control file silently wins over a pg_tle-registered
# extension of the same name -- PostgreSQL never reports an error, it just
# quietly resolves CREATE EXTENSION from disk instead of pg_tle's catalog. That
# makes "prove pg_tle-only" a real, load-bearing assertion, not a formality: it
# must run AFTER whatever it's guarding, not just before, since the whole point
# is confirming nothing wrote to disk THROUGHOUT the guarded flow, not merely
# that the environment started clean.
#
# USAGE: bin/assert_fs_clean <subcommand> [args]
#
#   snapshot PG_MAJOR BASELINE_FILE
#       Record the current *.control files in PG_MAJOR's extension directory to
#       BASELINE_FILE. Run this BEFORE installing pg_tle (or anything else), so
#       whatever ships on disk by default (e.g. contrib) is excluded
#       automatically -- no hardcoded exclude list to keep in sync.
#
#   verify PG_MAJOR BASELINE_FILE
#       Fail if any *.control file exists now that wasn't in BASELINE_FILE,
#       other than pg_tle.control itself (the one legitimate filesystem install
#       in this flow). Run this after EVERY step that could plausibly have
#       written extension files to disk.
set -euo pipefail

extdir_of() { echo "/usr/share/postgresql/$1/extension"; }

snapshot() {
  local pg_major=$1 baseline=$2
  find "$(extdir_of "$pg_major")" -maxdepth 1 -name '*.control' | sort > "$baseline"
}

verify() {
  local pg_major=$1 baseline=$2 after new
  after=$(mktemp)
  find "$(extdir_of "$pg_major")" -maxdepth 1 -name '*.control' | sort > "$after"
  new=$(comm -13 "$baseline" "$after" | grep -vx '.*/pg_tle\.control' || true)
  rm -f "$after"
  if [ -n "$new" ]; then
    echo "FAIL: unexpected extension control file(s) on disk (everything but pg_tle must be registered via pg_tle, not filesystem-installed):" >&2
    echo "$new" >&2
    exit 1
  fi
  echo "OK: no stray extension control files on disk (PG $pg_major)"
}

usage() {
  echo "usage: bin/assert_fs_clean <subcommand> [args]" >&2
  echo "  snapshot PG_MAJOR BASELINE_FILE" >&2
  echo "  verify PG_MAJOR BASELINE_FILE" >&2
  exit 2
}

main() {
  local cmd=${1:-}
  shift || true
  case "$cmd" in
    snapshot) snapshot "$@" ;;
    verify)   verify "$@" ;;
    *)        usage ;;
  esac
}

main "$@"