#!/usr/bin/env bash
# SPDX-License-Identifier: GPL-2.0-or-later
# Copyright (C) 2026 Bryan Joshua Pedini

# tests/docker/snapshot.sh - record the host's Docker image set BEFORE tests run,
# so tests/docker/cleanup.sh can restore it afterwards.
#
# Writes, next to this script:
#   images-before.tsv     repo:tag<TAB>image-id     (docker images --no-trunc, sorted)
#   image-ids-before.txt  every image id, incl. untagged (docker images -a -q --no-trunc, sort -u)
#
# An existing snapshot is NEVER overwritten without --force: running `make test`
# twice must not "launder" images pulled by the first run into the baseline.
# Without --force an existing snapshot is kept and the script exits 0, so
# `make docker-snapshot` / `make test` can call it every time.
#
# usage: snapshot.sh [--force]
set -euo pipefail

prog=${0##*/}
here=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)
tags_file=$here/images-before.tsv
ids_file=$here/image-ids-before.txt

usage() {
	cat <<USAGE
usage: $prog [--force]

Record the current Docker image set to
  $tags_file
  $ids_file

An existing snapshot is kept unless --force is given. Only use --force when
the images currently on the host are exactly the ones you want to keep: every
image present at snapshot time is treated as pre-existing by cleanup.sh.
USAGE
}

die() {
	printf '%s: error: %s\n' "$prog" "$*" >&2
	exit 1
}

force=0
for arg in "$@"; do
	case $arg in
	--force) force=1 ;;
	-h | --help) usage; exit 0 ;;
	*) printf '%s: unknown argument: %s\n' "$prog" "$arg" >&2; usage >&2; exit 1 ;;
	esac
done

if [[ -e $tags_file && -e $ids_file ]]; then
	if ((!force)); then
		printf '%s: snapshot already exists (taken %s), NOT overwriting it.\n' \
			"$prog" "$(date -r "$tags_file" '+%Y-%m-%d %H:%M:%S %Z')" >&2
		printf '%s: to re-baseline on purpose: %s --force\n' "$prog" "$0" >&2
		exit 0
	fi
elif [[ -e $tags_file || -e $ids_file ]]; then
	((force)) || die "incomplete snapshot (only one of ${tags_file##*/}, ${ids_file##*/} exists); inspect it, then re-run with --force"
fi

docker info >/dev/null 2>&1 || die "cannot talk to the Docker daemon (is it running, are you in the docker group?)"

tmp_tags=$(mktemp "$tags_file.XXXXXX.tmp")
tmp_ids=$(mktemp "$ids_file.XXXXXX.tmp")
trap 'rm -f -- "$tmp_tags" "$tmp_ids"' EXIT

# Exactly the commands of the original manual snapshot (plain `sort`, so the
# order follows the caller's locale, byte-identical to running them by hand).
# Consumers must not depend on the order: cleanup.sh reads both files into maps.
docker images --no-trunc --format '{{.Repository}}:{{.Tag}}\t{{.ID}}' | sort >"$tmp_tags"
docker images -a -q --no-trunc | sort -u >"$tmp_ids"

if [[ -e $tags_file && -e $ids_file ]]; then
	# --force over an existing snapshot: show what the baseline gains, so an
	# accidental re-baseline after a test run is at least visible.
	gained_tags=$(LC_ALL=C comm -13 <(LC_ALL=C sort "$tags_file") <(LC_ALL=C sort "$tmp_tags"))
	gained_ids=$(LC_ALL=C comm -13 <(LC_ALL=C sort -u "$ids_file") <(LC_ALL=C sort -u "$tmp_ids"))
	if [[ -n $gained_tags || -n $gained_ids ]]; then
		printf '%s: WARNING: the new baseline adopts images that were not in the old one:\n' "$prog" >&2
		if [[ -n $gained_tags ]]; then mapfile -t lines <<<"$gained_tags"; printf '  tag  %s\n' "${lines[@]}" >&2; fi
		if [[ -n $gained_ids ]]; then mapfile -t lines <<<"$gained_ids"; printf '  id   %s\n' "${lines[@]}" >&2; fi
	fi
fi

chmod 0644 "$tmp_tags" "$tmp_ids"
mv -f -- "$tmp_tags" "$tags_file"
mv -f -- "$tmp_ids" "$ids_file"
trap - EXIT

printf '%s: snapshot written: %d tags -> %s, %d ids -> %s\n' "$prog" \
	"$(wc -l <"$tags_file")" "${tags_file#"$PWD"/}" "$(wc -l <"$ids_file")" "${ids_file#"$PWD"/}"