#!/usr/bin/env sh
#MISE description="Restore or save the Rust build cache (cargo home + target) in R2, keyed on OS + rustc + Cargo.lock"

set -e

shared="${POD_RUST_CACHE_SHARED_KEY:-}"
[ -n "${shared}" ] || shared="default"

os="$(printf '%s' "${RUNNER_OS:-$(uname -s)}" | tr '[:upper:]' '[:lower:]')"
rustc_id="$(rustc -V | git hash-object --stdin | cut -c1-12)"
lock_id="$(git hash-object Cargo.lock | cut -c1-16)"

dir="rust-cache/${shared}"
name_prefix="${os}-${rustc_id}-"
key_base="${name_prefix}${lock_id}"

cargo_home="${CARGO_HOME:-${HOME}/.cargo}"
# git-bash on the Windows runner hands back a Windows-form path (C:\Users\...\.cargo)
# that tar's -C and mkdir -p cannot open; normalize it to POSIX. cygpath is absent on
# Linux/macOS, where the path is already POSIX, so this is a no-op there.
if command -v cygpath >/dev/null 2>&1; then
  cargo_home="$(cygpath -u "${cargo_home}")"
fi

work="$(mktemp -d)"
trap 'rm -rf "${work}"' EXIT

# The cargo home (registry + git) and target/ have different roots, so each is a
# separate object tarred relative to its own base — no absolute paths, portable
# across the Linux, macOS, and Windows (git-bash) runners.
pick_newest() {
  part="$1"
  mise run ci:r2 list "${dir}/" 2>/dev/null |
    awk -F';' -v pfx="${name_prefix}" -v sfx=".${part}.tar.gz" \
      'index($2, pfx) == 1 && substr($2, length($2) - length(sfx) + 1) == sfx' |
    sort -r | head -1 | cut -d';' -f2
}

restore_part() {
  part="$1"
  base="$2"
  exact="${dir}/${key_base}.${part}.tar.gz"
  tarball="${work}/${part}.tar.gz"

  if mise run ci:r2 get "${exact}" "${tarball}"; then
    echo "rust-cache: restored ${part} (exact Cargo.lock ${lock_id})"
  else
    name="$(pick_newest "${part}")"
    if [ -z "${name}" ]; then
      echo "rust-cache: no ${part} cache — cold"
      return 0
    fi
    if ! mise run ci:r2 get "${dir}/${name}" "${tarball}"; then
      echo "rust-cache: ${part} fallback fetch failed — cold"
      return 0
    fi
    echo "rust-cache: restored ${part} via fallback ${name}"
  fi

  mkdir -p "${base}"
  tar -xzf "${tarball}" -C "${base}" || echo "rust-cache: ${part} extract failed — continuing cold"
  rm -f "${tarball}"
}

save_part() {
  part="$1"
  base="$2"
  shift 2
  members=""
  for m in "$@"; do
    if [ -d "${base}/${m}" ]; then
      members="${members} ${m}"
    fi
  done
  if [ -z "${members}" ]; then
    echo "rust-cache: nothing to save for ${part}"
    return 0
  fi

  excludes=""
  if [ "${part}" = "target" ]; then
    for pat in '*.dmg' '*.app' '*.app.tar.gz' '*.app.tar.gz.sig' '*-setup.exe' \
      '*.msi' '*.exe.sig' '*.AppImage' '*.AppImage.sig' '*.deb' '*.pkg.tar.zst' \
      '*.tar.gz' '*.dSYM'; do
      excludes="${excludes} --exclude=${pat}"
    done
  fi

  tarball="${work}/${part}.tar.gz"
  # shellcheck disable=SC2086
  tar -czf "${tarball}" ${excludes} -C "${base}" ${members}
  mise run ci:r2 put "${tarball}" "${dir}/${key_base}.${part}.tar.gz"
  echo "rust-cache: saved ${part} (${members# })"
  rm -f "${tarball}"
}

case "${1:-}" in
restore)
  echo "rust-cache: key ${dir}/${key_base}"
  restore_part cargo "${cargo_home}"
  restore_part target "$(pwd)"
  ;;
save)
  echo "rust-cache: key ${dir}/${key_base}"
  save_part cargo "${cargo_home}" registry git
  save_part target "$(pwd)" target
  ;;
*)
  echo "usage: rust-cache <restore|save>" >&2
  exit 2
  ;;
esac