#!/usr/bin/env bash
# Run a game-binary command under a freshly created isolated HOME so it can
# never touch the real save, then prove the real save directory is untouched.
#
# Motivation (2026-07-11): `HOME=x printf ... | ./binary` scopes the override
# to printf, not the binary — a mis-scoped observed run truncated a real
# playthrough save in place. This wrapper exports the isolated HOME for the
# child process itself and fails loudly if the real
# `dirs::data_dir()/misaligned/` changed in any way.
#
# Usage:
#   tools/observed-run.sh <command> [args...]
# Example:
#   printf 'wait 1\nquit\n' | tools/observed-run.sh ./target/debug/misaligned --agent --seed 1
#
# The sandbox HOME is retained after the run (its path is printed) so the
# sandboxed save can be inspected as evidence.
set -euo pipefail

if [ "$#" -lt 1 ]; then
  echo "usage: tools/observed-run.sh <command> [args...]" >&2
  exit 2
fi

real_home="$HOME"
case "$(uname -s)" in
  Darwin) real_data_dir="$real_home/Library/Application Support/misaligned" ;;
  *) real_data_dir="${XDG_DATA_HOME:-$real_home/.local/share}/misaligned" ;;
esac

# One line per entry under the real save directory: path, size/mtime, and a
# content hash for files. Directory mtimes are included so a file created and
# deleted during the run still trips the comparison. Empty if the directory
# does not exist.
snapshot() {
  [ -e "$real_data_dir" ] || return 0
  find "$real_data_dir" -print | LC_ALL=C sort | while IFS= read -r entry; do
    meta=$(stat -f '%z %m' "$entry" 2>/dev/null || stat -c '%s %Y' "$entry")
    if [ -f "$entry" ]; then
      hash=$(shasum -a 256 "$entry" | awk '{print $1}')
    else
      hash=dir
    fi
    printf '%s|%s|%s\n' "$entry" "$meta" "$hash"
  done
}

before=$(snapshot)
sandbox=$(mktemp -d "${TMPDIR:-/tmp}/misaligned-observed-run.XXXXXX")
echo "observed-run: sandbox HOME: $sandbox" >&2

status=0
HOME="$sandbox" XDG_DATA_HOME="$sandbox/.local/share" "$@" || status=$?

after=$(snapshot)
if [ "$before" != "$after" ]; then
  echo "observed-run: FAIL — the real save directory changed: $real_data_dir" >&2
  diff <(printf '%s\n' "$before") <(printf '%s\n' "$after") >&2 || true
  echo "observed-run: sandbox retained at $sandbox" >&2
  exit 1
fi
echo "observed-run: real save directory untouched: $real_data_dir" >&2
echo "observed-run: sandbox retained at $sandbox" >&2
exit "$status"