#!/usr/bin/env bash
# Resolves — and cross-checks — the cache root a job's directories live under.
#
#   cache-root.sh resolve <cache-root> [lineage]
#   cache-root.sh verify  <cache-root> <lineage> <exported-root>
#
# `resolve` prints the effective root: the cache root unchanged when no lineage
# is given, or `<cache-root>/<lineage>` when one is. Invalid lineage names are
# rejected here rather than downstream — see validate_cache_lineage() in
# cache-lib.sh, where every rejection names the reader that imposes it.
#
# `verify` is the publish side's guard. cargo-cache-publish resolves the same
# two inputs the consume action was given and compares the result against the
# CARGO_CACHE_ROOT the consume step exported into the job environment. The two
# actions have always had to agree — `cache-root`'s description in the publish
# action says "must match the consume action" — and until a lineage existed
# they always did, because nobody overrode the default. A disagreement is not
# a harmless no-op: publish-snapshot.sh takes the root as an argument and
# derives BOTH ends of the swap from it, so a publish step that kept the
# default while its consume step nested would read `<root>/target-<key>` — the
# OTHER lineage's live target dir — and republish it over `<root>/snapshot-<key>`,
# which is that lineage's snapshot. Two jobs would then be publishing one
# snapshot from one tree on every push, and nothing in either action would say
# so. Hence: fail the job, loudly, rather than resolve the ambiguity in
# either direction.
#
# A thin CLI over cache-lib.sh, kept as its own entry point for the same
# reason branch-cache-key.sh is: an out-of-band job that needs to find a
# lineage's directories should resolve the path the way the action does
# instead of reimplementing the rule.
set -euo pipefail
. "$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)/cache-lib.sh"

MODE="${1:-}"
case "$MODE" in
  resolve)
    [ $# -ge 2 ] && [ $# -le 3 ] || {
      echo "::error::cache-root.sh resolve: expected <cache-root> [lineage]" >&2
      exit 1
    }
    [ -n "$2" ] || { echo "::error::cache-root.sh: cache-root must not be empty" >&2; exit 1; }
    cache_root_for "$2" "${3:-}"
    ;;
  verify)
    [ $# -eq 4 ] || {
      echo "::error::cache-root.sh verify: expected <cache-root> <lineage> <exported-root>" >&2
      exit 1
    }
    [ -n "$2" ] || { echo "::error::cache-root.sh: cache-root must not be empty" >&2; exit 1; }
    expected=$(cache_root_for "$2" "$3")
    if [ "$expected" != "$4" ]; then
      echo "::error::cache-root.sh: this step resolves its cache root to '${expected}' (cache-root '$2', cache-lineage '$3') but the cargo-cache step in this job exported '$4'. Pass the SAME cache-root and cache-lineage to both actions." >&2
      exit 1
    fi
    echo "cache root: ${expected} (agrees with the cargo-cache step in this job)"
    ;;
  *)
    echo "::error::cache-root.sh: unknown mode '${MODE}' (expected resolve or verify)" >&2
    exit 1
    ;;
esac