#!/usr/bin/env bash
# Build a multi-arch (linux/amd64, linux/arm64) image and push it to a registry.
#
# Required:
#   LORABOT_IMAGE   Full image reference, e.g. registry.example.com/team/lorabot
#
# Optional:
#   PLATFORMS       Comma-separated arch list (default: linux/amd64,linux/arm64)
#   EXTRA_TAGS      Space-separated additional tags to push (e.g. "stable v0.1.0")
#   PUSH            "1" (default) to push, "0" to build and load locally only
#                   (note: --load only works with a single platform)
#   BUILDER         buildx builder name (default: lorabot-builder, auto-created)

set -euo pipefail

if [[ -z "${LORABOT_IMAGE:-}" ]]; then
  echo "error: LORABOT_IMAGE is required (e.g. registry.example.com/team/lorabot)" >&2
  exit 1
fi

# Preflight: buildx must be installed (it's a separate package on Arch / some
# minimal distros). If it's missing, `docker buildx ...` is parsed by docker as
# `docker ...` with unknown flags, producing a confusing "unknown flag" error.
if ! docker buildx version >/dev/null 2>&1; then
  echo "error: docker buildx is not available." >&2
  echo "  Arch:        sudo pacman -S docker-buildx" >&2
  echo "  Debian/Ubu:  sudo apt install docker-buildx-plugin" >&2
  echo "  Other:       https://github.com/docker/buildx#installing" >&2
  exit 1
fi

# Preflight: daemon reachable.
if ! docker info >/dev/null 2>&1; then
  echo "error: cannot reach the docker daemon (is it running? are you in the 'docker' group?)" >&2
  echo "  Arch: sudo systemctl start docker" >&2
  exit 1
fi

PLATFORMS="${PLATFORMS:-linux/amd64,linux/arm64}"
PUSH="${PUSH:-1}"
BUILDER="${BUILDER:-lorabot-builder}"

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

# Compute git-derived tags. Fall back to "dev" if not in a git tree.
if git rev-parse --is-inside-work-tree >/dev/null 2>&1; then
  GIT_SHA="$(git rev-parse --short=12 HEAD)"
  if [[ -n "$(git status --porcelain)" ]]; then
    GIT_SHA="${GIT_SHA}-dirty"
  fi
else
  GIT_SHA="dev"
fi

TAGS=(--tag "${LORABOT_IMAGE}:latest" --tag "${LORABOT_IMAGE}:${GIT_SHA}")
for t in ${EXTRA_TAGS:-}; do
  TAGS+=(--tag "${LORABOT_IMAGE}:${t}")
done

# Make sure a buildx builder exists. Reuse if it's already there.
if ! docker buildx inspect "${BUILDER}" >/dev/null 2>&1; then
  echo ">>> creating buildx builder '${BUILDER}'"
  docker buildx create --name "${BUILDER}" --driver docker-container --use >/dev/null
else
  docker buildx use "${BUILDER}" >/dev/null
fi
docker buildx inspect --bootstrap >/dev/null

OUTPUT_FLAG=()
if [[ "${PUSH}" == "1" ]]; then
  OUTPUT_FLAG=(--push)
  echo ">>> building & pushing ${LORABOT_IMAGE} (${PLATFORMS}) tags: latest, ${GIT_SHA}${EXTRA_TAGS:+, $EXTRA_TAGS}"
else
  # --load only works with a single platform; warn if user requested multi.
  if [[ "${PLATFORMS}" == *,* ]]; then
    echo "error: PUSH=0 (local --load) only works with a single platform; got '${PLATFORMS}'" >&2
    exit 1
  fi
  OUTPUT_FLAG=(--load)
  echo ">>> building ${LORABOT_IMAGE} for ${PLATFORMS} (local load, no push)"
fi

docker buildx build \
  --platform "${PLATFORMS}" \
  "${TAGS[@]}" \
  "${OUTPUT_FLAG[@]}" \
  --file Dockerfile \
  .

echo ">>> done"