#!/usr/bin/env bash
###############################################################################
# infra/agent/build-image.sh — build the pinned `agent-runner` image and prove it works.
#
#   ./build-image.sh                 # build the verify target, then the image
#   ./build-image.sh --print-build-args   # print KEY=VALUE build args (what CI consumes)
#   ./build-image.sh --no-verify     # build only (skip the in-image proof)
#   ENGINE=docker ./build-image.sh   # build with docker instead of podman
#   AGENT_BASE_IMAGE=home-k3s-dev:local ./build-image.sh
#                                    # build on a LOCAL toolbox instead of the pinned one
#                                    #   (`infra/devcontainer/dev.sh build` makes that tag)
#   IMAGE_TAG=foo ./build-image.sh   # override the local tag (CI uses this)
#
# THIS SCRIPT NEVER PUSHES — and nobody pushes this image from a workstation either.
# Publishing is done by CI: .gitea/workflows/images.yaml builds the SAME Containerfile on
# rootless BuildKit (platform/buildkit/), taking its build args from `--print-build-args`, and
# on a push to `main` pushes it to the Gitea registry and records the registry-returned digest
# in the job summary. Renovate then opens the pull request that moves platform/pm-agent/ onto
# that digest. This script is the LOCAL path (podman by default); its proof — the
# Containerfile's `verify` stage — is the same one CI runs.
#
# VERSIONS ARE NOT DEFINED HERE. infra/agent/versions.env holds the pins this image adds
# (base image, node, Claude Code CLI, model) and infra/devcontainer/versions.env holds the
# platform toolchain the base already carries. Nothing in this file invents a version.
#
# THE BASE. AGENT_BASE_IMAGE in versions.env is the PUBLISHED toolbox, pinned by digest and
# kept current by Renovate. An AGENT_BASE_IMAGE in the environment overrides it — CI passes
# the toolbox it built in the same run, and a developer can pass `home-k3s-dev:local`.
#
# NO `run` STEP. Verification used to `run` the image as uid 65532 with a read-only rootfs.
# CI has no container runtime (rootless BuildKit only), so the assertions moved into the
# Containerfile's `verify` stage and this script builds that target. `--print-build-args`
# prints the pins as KEY=VALUE for the CI pipeline; AGENT_BASE_IMAGE is the caller's choice.
###############################################################################
set -euo pipefail

HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO_ROOT="$(cd "${HERE}/../.." && pwd)"
ENGINE="${ENGINE:-podman}"

VERIFY=1
PRINT_ARGS=0
for arg in "$@"; do
  case "$arg" in
    --no-verify) VERIFY=0 ;;
    --print-build-args) PRINT_ARGS=1 ;;
    -h|--help) sed -n '2,/^####/p' "${BASH_SOURCE[0]}" | sed '$d' | sed 's/^# \{0,1\}//'; exit 0 ;;
    *) echo "unknown argument: $arg" >&2; exit 2 ;;
  esac
done

log()  { printf '\n\033[1m==> %s\033[0m\n' "$*"; }
info() { printf '    %s\n' "$*"; }
die()  { printf '\033[31mERROR: %s\033[0m\n' "$*" >&2; exit 1; }

# --- pins: sourced, never invented -------------------------------------------
AGENT_ENV="${HERE}/versions.env"
[ -f "${AGENT_ENV}" ] || die "missing ${AGENT_ENV} — the pins live there, not here"
BASE_OVERRIDE="${AGENT_BASE_IMAGE:-}"
TAG_OVERRIDE="${IMAGE_TAG:-}"
# shellcheck disable=SC1090
source "${AGENT_ENV}"
[ -z "${BASE_OVERRIDE}" ] || AGENT_BASE_IMAGE="${BASE_OVERRIDE}"
: "${AGENT_BASE_IMAGE:?AGENT_BASE_IMAGE not set in ${AGENT_ENV}}"
: "${NODEJS_MAJOR:?NODEJS_MAJOR not set in ${AGENT_ENV}}"
: "${CLAUDE_CODE_VERSION:?CLAUDE_CODE_VERSION not set in ${AGENT_ENV}}"
: "${CLAUDE_CODE_MIN_VERSION:?CLAUDE_CODE_MIN_VERSION not set in ${AGENT_ENV}}"
: "${AGENT_MODEL:?AGENT_MODEL not set in ${AGENT_ENV}}"
: "${AGENT_IMAGE_REPO:?AGENT_IMAGE_REPO not set in ${AGENT_ENV}}"

# THE build args, in ONE place; `--print-build-args` hands them to CI (which builds on rootless
# BuildKit and supplies its own base reference). AGENT_BASE_IMAGE is deliberately NOT in this
# list: the caller decides the base.
BUILD_ARGS=(
  "NODEJS_MAJOR=${NODEJS_MAJOR}" "CLAUDE_CODE_VERSION=${CLAUDE_CODE_VERSION}"
  "CLAUDE_CODE_MIN_VERSION=${CLAUDE_CODE_MIN_VERSION}" "AGENT_MODEL=${AGENT_MODEL}"
)
if [ "${PRINT_ARGS}" -eq 1 ]; then printf '%s\n' "${BUILD_ARGS[@]}"; exit 0; fi

command -v "${ENGINE}" >/dev/null 2>&1 || die "'${ENGINE}' not on PATH (set ENGINE=docker to use docker)"

# --- the base must exist, locally or in the registry ---------------------------
# Deliberately NOT built on demand. The toolbox is its own reviewed artefact with its own
# pins, and silently building it here would mean this script could change the toolchain a
# worker gates with as a side effect of rebuilding the agent image.
case "${AGENT_BASE_IMAGE}" in
  *@sha256:0000000000000000000000000000000000000000000000000000000000000000)
    die "AGENT_BASE_IMAGE is still the all-zero placeholder in ${AGENT_ENV}: the toolbox has
       not been published yet. Either let CI publish it (.gitea/workflows/images.yaml) and
       merge Renovate's digest bump, or build on a local toolbox:
         ${REPO_ROOT}/infra/devcontainer/dev.sh build
         AGENT_BASE_IMAGE=home-k3s-dev:local $0" ;;
esac
if ! "${ENGINE}" image inspect "${AGENT_BASE_IMAGE}" >/dev/null 2>&1; then
  info "base ${AGENT_BASE_IMAGE} is not local; pulling it"
  "${ENGINE}" pull "${AGENT_BASE_IMAGE}" >/dev/null \
    || die "base image '${AGENT_BASE_IMAGE}' is neither local nor pullable (registry login?).
       To build on a local toolbox instead:
         ${REPO_ROOT}/infra/devcontainer/dev.sh build
         AGENT_BASE_IMAGE=home-k3s-dev:local $0"
fi

IMAGE_TAG="${TAG_OVERRIDE:-claude${CLAUDE_CODE_VERSION}-node${NODEJS_MAJOR}}"
IMAGE_REF="${AGENT_IMAGE_REPO}:${IMAGE_TAG}"

log "Building ${IMAGE_REF}"
info "engine        ${ENGINE} ($(${ENGINE} --version 2>/dev/null | head -1))"
info "pins from     ${AGENT_ENV}"
info "  base        ${AGENT_BASE_IMAGE}"
info "  node        ${NODEJS_MAJOR}"
info "  claude      ${CLAUDE_CODE_VERSION} (floor ${CLAUDE_CODE_MIN_VERSION})"
info "  model       ${AGENT_MODEL}"

# Provenance: CI passes the commit it is building, so a pulled image names its source tree.
LABEL_ARGS=()
[ -z "${BUILD_REVISION:-}" ] || LABEL_ARGS+=(--label "org.opencontainers.image.revision=${BUILD_REVISION}")
ARG_FLAGS=(--build-arg "AGENT_BASE_IMAGE=${AGENT_BASE_IMAGE}")
for a in "${BUILD_ARGS[@]}"; do ARG_FLAGS+=(--build-arg "$a"); done

# --- verify: the point of the whole exercise ---------------------------------
# A build that merely succeeded is not evidence this image is usable. The proof is the
# Containerfile's `verify` stage: as the NON-ROOT uid, with no network, the toolchain executes,
# both entrypoints refuse arguments, the dispatcher selftest passes, the entrypoints are not
# writable, nothing outside /workspace and /tmp is writable, and pm-worker's input guards
# (probe-validation.sh) refuse every hostile input. It is a build target rather than a
# `run` so the SAME proof runs here and in CI, where no container runtime exists — see the
# stage's header for what a build step can and cannot reproduce of the pod's shape.
if [ "${VERIFY}" -eq 1 ]; then
  log "Verifying (Containerfile target: verify)"
  "${ENGINE}" build "${ARG_FLAGS[@]}" --target verify --file "${HERE}/Containerfile" "${HERE}"
  log "Image verified"
fi

"${ENGINE}" build "${LABEL_ARGS[@]}" "${ARG_FLAGS[@]}" --target agent-runner \
  --file "${HERE}/Containerfile" --tag "${IMAGE_REF}" "${HERE}"

# --- result ------------------------------------------------------------------
# No digest is printed: a manifest digest does not exist until a registry has the manifest,
# and the only digest anything may pin is the one the REGISTRY returns. CI captures that at
# push time and prints it in the job summary (.gitea/workflows/scripts/images.sh).
SIZE="$("${ENGINE}" image inspect --format '{{.Size}}' "${IMAGE_REF}")"
log "Built ${IMAGE_REF}"
info "image id  $("${ENGINE}" image inspect --format '{{.Id}}' "${IMAGE_REF}")"
info "size      $(( SIZE / 1024 / 1024 )) MiB"
info "Not pushed. CI publishes this image from main (.gitea/workflows/images.yaml); see"
info "platform/pm-agent/README.md for how a new digest reaches the cluster."