#!/usr/bin/env bash
set -euo pipefail

usage() {
  printf 'Usage: %s {client|server} [Gradle arguments...]\n' "$0"
}

case "${1:-}" in
  client | server) module=$1; shift ;;
  -h | --help) usage; exit 0 ;;
  *) usage >&2; exit 2 ;;
esac

engine_mode() {
  local state
  case "$1" in
    podman)
      state=$("$1" info --format '{{.Host.Security.Rootless}}') || return
      [[ $state == true ]] && printf rootless || printf rootful
      ;;
    docker | nerdctl)
      state=$("$1" info --format '{{json .SecurityOptions}}') || return
      [[ $state == *'"name=rootless"'* ]] && printf rootless || printf rootful
      ;;
  esac
}

engine=${CONTAINER_ENGINE:-}
if [[ -n $engine ]]; then
  case "$engine" in
    podman | nerdctl | docker) ;;
    *) printf 'Unsupported container engine: %s\n' "$engine" >&2; exit 2 ;;
  esac
  kind=$(engine_mode "$engine")
else
  fallback=
  for candidate in podman nerdctl docker; do
    command -v "$candidate" >/dev/null || continue
    kind=$(engine_mode "$candidate" 2>/dev/null) || continue
    if [[ $kind == rootless ]]; then
      engine=$candidate
      break
    fi
    [[ -n $fallback ]] || fallback=$candidate
  done
  if [[ -z $engine ]]; then
    engine=$fallback
    kind=rootful
  fi
fi
if [[ -z $engine ]]; then
  printf 'No working Podman, nerdctl or Docker engine found.\n' >&2
  exit 1
fi

printf 'Building %s with %s (%s)\n' "$module" "$engine" "$kind" >&2
repo=$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd -P)
cache="${XDG_CACHE_HOME:-$HOME/.cache}/saltatory/gradle"
mkdir -p -- "$cache"
image_file=$(mktemp)
trap 'rm -f -- "$image_file"' EXIT
build=(build --quiet --iidfile "$image_file" --tag localhost/saltatory-build --file "$repo/Containerfile")
[[ $engine != podman ]] || build+=(--layers)
"$engine" "${build[@]}" "$repo" >/dev/null
image=$(<"$image_file")
rm -- "$image_file"
trap - EXIT

user=(--user "$(id -u):$(id -g)")
if [[ $kind == rootless ]]; then
  case "$engine" in
    podman) user=(--userns keep-id "${user[@]}") ;;
    docker | nerdctl) user=(--user 0:0) ;;
  esac
fi
exec "$engine" run --rm --init \
  --label saltatory.build=true \
  "${user[@]}" \
  --cap-drop ALL --security-opt no-new-privileges \
  --mount "type=bind,src=$repo,dst=/workspace" \
  --mount "type=bind,src=$cache,dst=/cache/gradle" \
  "$image" ":$module:build" "$@"