#!/bin/sh
# hooks/commit-msg -- keep commit trailers in this project's attribution form.
#
# card-games is published (MELPA, and bound for GNU ELPA), so every commit
# message is a permanent public record.  This hook refuses two trailers the
# project has not agreed to and checks the one form it has:
#
#   refused  a session-link trailer (Claude-Session and the like)
#   refused  Co-Authored-By naming Claude or anthropic.com
#   checked  Assisted-by: NAME (for PERSON; MODEL)
#            e.g.  Assisted-by: Mentat (for Corwin; claude-opus-5-5)
#            A comma in place of the semicolon is accepted too.
#
# Attribution is the author's call: a message with no Assisted-by line
# passes.  Comment lines, and everything after the scissors line that
# `git commit -v' adds, are not checked.
#
# Install:  make hooks  (also installs applypatch-msg, so `git am' is checked)
# Bypass:   git commit --no-verify  -- a hook is a check, not a lock.
# Tests:    make test-hooks
#
# Usage: commit-msg MESSAGE-FILE    Exit 0 accepts, 1 refuses.

set -u

msg=${1:?usage: commit-msg MESSAGE-FILE}
cr=$(printf '\r')
status=0

refuse () {
    printf 'commit-msg: %s\n    %s\n' "$1" "$2" >&2
    status=1
}

while IFS= read -r line || [ -n "$line" ]; do
    line=${line%"$cr"}
    case $line in
        '# ------------------------ >8 ------------------------'*) break ;;
        '#'*) continue ;;
    esac
    lower=$(printf '%s' "$line" | tr '[:upper:]' '[:lower:]')
    case $lower in
        claude-session:*)
            refuse 'session links are not used in this project:' "$line" ;;
        co-authored-by:*claude*|co-authored-by:*anthropic.com*)
            refuse 'credit AI help as Assisted-by: NAME (for PERSON; MODEL), not:' "$line" ;;
        assisted-by:*)
            if ! printf '%s\n' "$line" |
                 grep -Eq '^[Aa]ssisted-[Bb]y: [^ (][^(]* \(for [^;,()]+[;,] [^ ;,()]+\)$'
            then
                refuse 'expected Assisted-by: NAME (for PERSON; MODEL), got:' "$line"
            fi ;;
    esac
done < "$msg"

if [ "$status" -ne 0 ]; then
    echo 'commit-msg: refused; fix the message and try again.' >&2
fi
exit "$status"