# CI job image for the Gitea act_runner: the runner's default job image with
# Node pre-planted where actions/setup-node looks first.
#
# Why this layout: setup-node ignores `node` on PATH; its only fast path is a
# probe of /opt/hostedtoolcache/node/<version>/<arch>. Without an entry there
# it downloads the ~50 MB distribution on EVERY job (the runner's job
# containers are ephemeral, so its tool cache never survives a job). The
# official node images keep exactly the layout setup-node expects under
# /usr/local, so this layer is a pure file overlay — no scripts, no env.
#
# Why not a host bind of /opt/hostedtoolcache: binds never self-prune. Docker
# images are content-addressed: the base layers dedupe against the act image
# the host already has, and `docker image prune` / re-pulls are the cleanup
# story.
#
# NODE_VERSION must match `.node-version` exactly. setup-node resolves a float
# like `26` to the latest known patch at runtime, so a bump silently busts the
# baked entry; `.node-version` is pinned to x.y.z and scripts/runner-image.sh
# guards the coupling. Rebuild + repoint `container.image` in
# .gitea/workflows/ci.yml on every bump.
#
# The extra `nodebase` stage is load-bearing: `COPY --from=` resolves its value
# as a *stage name* at parse time, before build args exist, so
# `COPY --from=node:${NODE_VERSION}` collapses to the invalid `node:` on
# frontends that do not expand args there. ARGs declared before the first FROM
# *are* expanded in FROM, so routing through a named stage works everywhere.

# Global scope: only visible to FROM lines, but that is exactly where we need it.
ARG NODE_VERSION=26.8.2
FROM node:${NODE_VERSION} AS nodebase

FROM catthehacker/ubuntu:act-latest

# ARGs do not cross stage boundaries; redeclare (with the same default, so a
# bare `docker build -f docker/Dockerfile .` still works) for the paths below.
# Keep this default in sync with the global one above.
ARG NODE_VERSION=26.8.2

# node image: bin/ + lib/ under /usr/local → tool cache: bin/ + lib/ under <ver>/x64.
COPY --from=nodebase /usr/local /opt/hostedtoolcache/node/${NODE_VERSION}/x64

# Fail the build (not CI) if the overlay or the version arg were wrong.
# Shell form on purpose: exec form (`RUN [...]`) does not expand ARG values.
RUN "/opt/hostedtoolcache/node/${NODE_VERSION}/x64/bin/node" --version