#!/bin/sh
# Flags Co-Authored-By trailers with Claude/Anthropic attribution in PR commits.
# The hive convention in /knowledge/hive-rules.md forbids these trailers.
#
# Pattern is loose (case-insensitive, matches `claude`, `anthropic`, or
# `noreply@anthropic.com` anywhere after `co-authored-by`) to cover variants
# like `Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>`.
#
# Scope is the PR's commits (BASE..HEAD), not entire history — old commits
# must not fail the build.
set -eu

if [ -n "${GITHUB_BASE_REF:-}" ]; then
  base="origin/${GITHUB_BASE_REF}"
else
  base="origin/main"
fi

# actions/checkout@v3 fetches the PR head but may not fetch the base branch
if ! git rev-parse --verify "$base" >/dev/null 2>&1; then
  branch="${base#origin/}"
  git fetch origin "$branch" 2>/dev/null || true
  if ! git rev-parse --verify "$base" >/dev/null 2>&1; then
    base="origin/main"
    git fetch origin main 2>/dev/null || base="HEAD~10"
  fi
fi

commits="$(git log --reverse --format='%H' "${base}..HEAD" 2>/dev/null || true)"

if [ -z "$commits" ]; then
  exit 0
fi

hits=""
for sha in $commits; do
  msg="$(git log -1 --format='%B' "$sha")"
  if printf '%s\n' "$msg" | grep -qiE 'co-authored-by.*claude|co-authored-by.*anthropic|co-authored-by.*noreply@anthropic\.com'; then
    subject="$(git log -1 --format='%s' "$sha")"
    hits="${hits}${sha}|${subject}
"
  fi
done

if [ -n "$hits" ]; then
  printf '%s' "$hits" | while IFS='|' read -r sha subject; do
    [ -z "$sha" ] && continue
    short_sha="$(printf '%s' "$sha" | cut -c1-8)"
    printf '::error title=Attribution trailer found in %s::%s — commit carries a Co-Authored-By trailer with Claude/Anthropic attribution, forbidden by /knowledge/hive-rules.md\n' \
      "$short_sha" "$subject"
  done
  count="$(printf '%s' "$hits" | grep -c '|' || true)"
  printf 'check-attribution-trailers: %s commit(s) with prohibited trailers found\n' "$count" >&2
  exit 1
fi

exit 0