#!/usr/bin/env bash
# Run a command inside the DarkRoom Windows cross-build container.
#
#   ./docker/windows/build.sh cargo build --release --target x86_64-pc-windows-gnu -p darkroom-desktop
#   ./docker/windows/build.sh cargo clippy --target x86_64-pc-windows-gnu -p darkroom-desktop
#   ./docker/windows/build.sh                    # interactive shell
#
# Builds the image on first use. Rebuild after editing the Dockerfile with:
#   ./docker/windows/build.sh --rebuild
set -euo pipefail

IMAGE="darkroom-windows:latest"
HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
REPO="$(cd "${HERE}/../.." && pwd)"

# Prefer podman (rootless by default); fall back to docker.
if command -v podman >/dev/null 2>&1; then
    ENGINE=podman
elif command -v docker >/dev/null 2>&1; then
    ENGINE=docker
else
    echo "error: neither podman nor docker found" >&2
    exit 1
fi

if [[ "${1:-}" == "--rebuild" ]]; then
    shift
    "${ENGINE}" build -t "${IMAGE}" "${HERE}"
elif ! "${ENGINE}" image exists "${IMAGE}" 2>/dev/null && \
     ! "${ENGINE}" image inspect "${IMAGE}" >/dev/null 2>&1; then
    echo "==> building ${IMAGE} (first run; several minutes)"
    "${ENGINE}" build -t "${IMAGE}" "${HERE}"
fi

# Persist the cargo registry and target dir across runs, or every build
# re-downloads the crate index.
CACHE="${XDG_CACHE_HOME:-${HOME}/.cache}/darkroom-windows"
# `home` is the container's $HOME: Wine keeps its prefix there for the smoke
# tests, and refuses one it does not own — which rules out anything the image
# could have created, since the container runs as the host user.
mkdir -p "${CACHE}/registry" "${CACHE}/target" "${CACHE}/home"

ARGS=(
    --rm
    -v "${REPO}:/work:z"
    -v "${CACHE}/registry:/opt/cargo/registry:z"
    -v "${CACHE}/target:/work/target-windows:z"
    -v "${CACHE}/home:/tmp/home:z"
    -e CARGO_TARGET_DIR=/work/target-windows
    -w /work
)

# Build parallelism. A full cross-compile will otherwise take every thread on
# the host and make the machine unusable for the length of the build, which is
# a poor trade when it is running in the background.
#
# Both halves are needed: CARGO_BUILD_JOBS caps how many rustc processes cargo
# starts, while --cpus caps what the container gets no matter what any nested
# build script decides to spawn (cc, cmake, and ring's asm build all parallelise
# on their own account and do not consult cargo).
JOBS="${DARKROOM_BUILD_JOBS:-8}"
if [[ "${JOBS}" != "0" ]]; then
    ARGS+=(--cpus "${JOBS}" -e "CARGO_BUILD_JOBS=${JOBS}")
fi

# Rootless podman already maps the host user; docker needs it stated.
if [[ "${ENGINE}" == "docker" ]]; then
    ARGS+=(--user "$(id -u):$(id -g)")
fi

if [[ $# -eq 0 ]]; then
    ARGS+=(-it)
    set -- /bin/bash
fi

exec "${ENGINE}" run "${ARGS[@]}" "${IMAGE}" "$@"