#!/usr/bin/env bash
# Drive the dockerized Guix build environment (see docker/) to build the
# operating-system definitions in this repo as `guix system docker-image`
# tarballs, loadable straight into Docker Desktop.
set -euo pipefail

cd "$(dirname "$0")/.."

compose() {
  docker compose run --rm guix "$@"
}

usage() {
  cat <<EOF
usage: $0 <command> [args]

commands:
  build                  build/rebuild the guix builder image
  pull                   guix pull -C channels.scm (do this first, and
                          again whenever channels.scm/channels.d/*.scm
                          change)
  shell                  interactive shell inside the builder container
  image FILE.scm [NAME]  build FILE.scm (e.g. metznet/machines/ldap.scm)
                          as a docker image, writing build/NAME.tar.gz
                          (NAME defaults to FILE's basename). -L points
                          at /workspace (this checkout), so uncommitted
                          local edits are picked up directly -- no
                          commit/pull round-trip needed. Load with:
                            docker load < build/NAME.tar.gz
  load-run FILE.scm      build FILE.scm, docker load it into the host
                          Docker, and drop into a shell in a container
                          started from it
EOF
}

cmd="${1:-}"
[ -n "$cmd" ] && shift || true

case "$cmd" in
  build)
    docker compose build
    ;;
  pull)
    compose guix pull -C channels.scm
    ;;
  shell)
    compose bash
    ;;
  image)
    scm="${1:?usage: $0 image FILE.scm [NAME]}"
    name="${2:-$(basename "$scm" .scm)}"
    compose bash -c "
      set -e
      # --no-grafts: with --disable-chroot (see docker/entrypoint.sh),
      # guix-daemon's store-path grafting (security-patch rewriting) hits
      # a permission error creating output files -- skipping grafts
      # avoids it entirely and just uses the un-grafted originals.
      out=\$(guix system docker-image -N --no-grafts -L /workspace '$scm')
      mkdir -p /workspace/build
      cp \"\$out\" '/workspace/build/$name.tar.gz'
      echo \"wrote build/$name.tar.gz\"
    "
    ;;
  load-run)
    scm="${1:?usage: $0 load-run FILE.scm}"
    name="$(basename "$scm" .scm)"
    "$0" image "$scm" "$name"
    image_id="$(docker load -q -i "build/$name.tar.gz" | sed 's/^Loaded image: //')"
    echo "loaded $image_id, starting container..."
    docker run --rm -it "$image_id" /run/current-system/profile/bin/bash --login
    ;;
  *)
    usage
    exit 1
    ;;
esac