#!/usr/bin/env bash
# Refuse to commit working memory, and refuse format-only dirt nobody staged.
#
# `context/` is local: artifacts, externals, agent clones and the RE tooling and
# its bases live there and `.gitignore` keeps them out. This is the second wall
# — `git add -f` walks through the first. Nothing under `context/` is an
# exception: the shipped repo is the runtime, and the RE side of the work is not
# published.
#
# Installed from xtask/githooks/pre-commit by `cargo xtask mr new|fmt|ship`.
set -euo pipefail

ROOT="$(git rev-parse --show-toplevel)"

# Deletions (untracking something that should never have been in) are fine.
staged=()
while IFS= read -r rel; do
  [[ -n "$rel" ]] || continue
  staged+=("$rel")
done < <(git diff --cached --name-only --diff-filter=ACMR -- context/ || true)

if ((${#staged[@]} > 0)); then
  printf '%s\n' \
    'pre-commit: context/ is working memory, not the product. Do not git add it (not even -f).' \
    'The files stay on disk. Unstage with:' \
    '  git restore --staged -- context/' \
    'Nothing under context/ belongs in git.' \
    'Staged paths:' >&2
  printf '  %s\n' "${staged[@]}" >&2
  exit 1
fi

# Unstaged .rs whose working tree equals rustfmt(index) is the cargo-fmt-all
# leftover: files the agent did not stage, rewritten in place. Real WIP does
# not compare equal. Do not guess "my files" — refuse the leftover.
if command -v rustfmt >/dev/null; then
  dirt=()
  tmpdir="$(mktemp -d)"
  cleanup() { rm -rf "$tmpdir"; }
  trap cleanup EXIT
  while IFS= read -r rel; do
    [[ -n "$rel" && "$rel" == *.rs ]] || continue
    wt="$ROOT/$rel"
    [[ -f "$wt" ]] || continue
    idx="$tmpdir/idx.rs"
    if ! git show ":$rel" >"$idx" 2>/dev/null; then
      continue
    fi
    if ! rustfmt --edition 2024 "$idx" >/dev/null 2>&1; then
      continue
    fi
    if cmp -s "$idx" "$wt"; then
      dirt+=("$rel")
    fi
  done < <(git diff --name-only --diff-filter=ACMR || true)
  if ((${#dirt[@]} > 0)); then
    printf '%s\n' \
      'pre-commit: unstaged .rs files match rustfmt(index) — likely cargo fmt --all / -p.' \
      'Restore them; format only the files you own:' \
      "  git restore -- ${dirt[*]}" \
      '  cargo xtask mr fmt <your .rs paths>' \
      'Unstaged format-only paths:' >&2
    printf '  %s\n' "${dirt[@]}" >&2
    exit 1
  fi
fi

exit 0