#!/bin/sh
# Enforce Conventional Commits with a detailed body and an active vault-context
# token for this repository.
# Git-generated merge, revert, fixup, and squash commits are allowed so common
# history maintenance workflows still work without manual overrides.
set -eu

commit_msg_file=${1:-}

if [ -z "$commit_msg_file" ] || [ ! -f "$commit_msg_file" ]; then
  echo "commit-msg: expected a commit message file path" >&2
  exit 1
fi

first_subject=''
body_line_count=0
body_word_count=0
state=need_separator
subject_skipped=0

is_footer_line() {
  case $1 in
    BREAKING\ CHANGE:*|Signed-off-by:*|Co-authored-by:*|Reviewed-by:*|Acked-by:*|Refs\ *|Fixes\ *|Closes\ *|Resolves\ *)
      return 0
      ;;
  esac

  return 1
}

require_vault_context() {
  local repo_root project_name ready_dir ready_file ready_token

  if [ -z "${AI_MEM_ROOT:-}" ]; then
    echo "commit-msg: AI_MEM_ROOT is not set; run ai-context first" >&2
    return 1
  fi

  repo_root="$(git rev-parse --show-toplevel 2>/dev/null)" || return 1
  project_name="$(basename "$repo_root")"
  ready_dir="$AI_MEM_ROOT/_session_logs/.context-ready"
  ready_file="$ready_dir/$project_name.token"

  if [ ! -f "$ready_file" ]; then
    echo "commit-msg: load the vault context first with ai-context" >&2
    return 1
  fi

  if [ -z "${AI_MEM_CONTEXT_TOKEN:-}" ]; then
    echo "commit-msg: this shell has not loaded the vault context; run ai-context first" >&2
    return 1
  fi

  ready_token="$(sed -n '1p' "$ready_file")"

  if [ "$ready_token" != "$AI_MEM_CONTEXT_TOKEN" ]; then
    echo "commit-msg: this shell's vault context token does not match the active session; rerun ai-context" >&2
    return 1
  fi
}

while IFS= read -r line || [ -n "$line" ]; do
  case $line in
    '')
      continue
      ;;
    '#'*)
      continue
      ;;
  esac
  first_subject=$line
  break
done < "$commit_msg_file"

if [ -z "$first_subject" ]; then
  echo "commit-msg: commit message is empty" >&2
  exit 1
fi

case $first_subject in
  Merge\ *|Revert\ *|fixup!\ *|squash!\ *)
    exit 0
    ;;
esac

if printf '%s\n' "$first_subject" | grep -Eq '^(feat|fix|docs|style|refactor|perf|test|chore|build|ci|revert)(\([^()[:space:]][^()[:space:]]*\))?(!)?: [^[:space:]].*$'; then
  :
else
  cat >&2 <<'EOF'
Commit message rejected.

Use Conventional Commits:
  type(scope): description

Use a structured body after a blank line:
  - short summary paragraph
  - optional Why / Cause paragraph
  - `-` bullet concrete changes or defenses
  - optional notes or follow-up

Examples:
  feat(tmux): add session color sync
  fix(zsh): avoid duplicate prompt initialization
  docs(memory): clarify commit policy

Allowed types:
  feat, fix, docs, style, refactor, perf, test, chore, build, ci, revert

Git-generated Merge, Revert, fixup!, and squash! messages are allowed.
EOF

  exit 1
fi

while IFS= read -r line || [ -n "$line" ]; do
  case $line in
    '#'*)
      continue
      ;;
  esac

  if [ "$subject_skipped" -eq 0 ]; then
    case $line in
      '')
        continue
        ;;
    esac
    subject_skipped=1
    continue
  fi

  if [ "$state" = need_separator ]; then
    if [ -z "$line" ]; then
      state=body
      continue
    fi

    echo "commit-msg: add a blank line after the subject, then a detailed body" >&2
    exit 1
  fi

  if [ "$state" = footer ]; then
    continue
  fi

  if [ -z "$line" ]; then
    continue
  fi

  if is_footer_line "$line"; then
    if [ "$body_line_count" -eq 0 ]; then
      echo "commit-msg: add a detailed body before footers" >&2
      exit 1
    fi
    state=footer
    continue
  fi

  body_line_count=$((body_line_count + 1))
  words=$(printf '%s\n' "$line" | awk '{print NF}')
  body_word_count=$((body_word_count + words))
done < "$commit_msg_file"

if [ "$body_line_count" -eq 0 ]; then
  echo "commit-msg: commit message needs a structured body, not just a title" >&2
  exit 1
fi

if [ "$body_line_count" -lt 2 ] && [ "$body_word_count" -lt 20 ]; then
  echo "commit-msg: body is too short; add a summary and - bullet changes or defenses" >&2
  exit 1
fi

if ! require_vault_context; then
  exit 1
fi

exit 0