#!/bin/bash
# Write the short hash of the commit this build came from to BUILD_STAMP.
#
# bash 3.2-clean and ASCII-only on purpose: the system bash on this Mac is 3.2.
#
# Why a stamp and not the manifest version: Cowork caches an uploaded plugin,
# and plugin.json's version does not change between milestones, so a stale
# build would echo the right number and every answer after it would be about
# some other build (risk H11). The short hash moves on every commit, which is
# exactly the property the check needs.
#
# The stamp is a build artefact and is gitignored. It is regenerated by
# scripts/package_plugin.sh before every archive; a committed stamp would be
# false the instant the next commit moved HEAD.
#
# Usage:
#   bash scripts/build_stamp.sh                 # write <plugin root>/BUILD_STAMP
#   bash scripts/build_stamp.sh --ut <sti>      # write somewhere else

set -eu

SCRIPT_DIR=$(cd "$(dirname "$0")" && pwd)
REPO_ROOT=$(cd "$SCRIPT_DIR/.." && pwd)
OUT="${REPO_ROOT}/BUILD_STAMP"

while [ $# -gt 0 ]; do
  case "$1" in
    --ut)
      if [ $# -lt 2 ]; then
        echo "build_stamp: --ut needs a path" >&2
        exit 2
      fi
      OUT="$2"
      shift 2 ;;
    -h|--help)
      sed -n '2,20p' "$0"
      exit 0 ;;
    *)
      echo "build_stamp: unknown argument: $1" >&2
      exit 2 ;;
  esac
done

if ! git -C "$REPO_ROOT" rev-parse --git-dir >/dev/null 2>&1; then
  echo "build_stamp: $REPO_ROOT is not a git working tree." >&2
  echo "build_stamp: the stamp is the commit this build came from; there is nothing to stamp." >&2
  exit 1
fi

STAMP=$(git -C "$REPO_ROOT" rev-parse --short HEAD)
printf '%s\n' "$STAMP" > "$OUT"
echo "build_stamp: $STAMP -> $OUT"