#!/usr/bin/env bash
set -euo pipefail

SKILL_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
TEMPLATE="$SKILL_DIR/../assets/templates/instructions.md"

usage() {
  cat <<USAGE
Usage: new-instructions.sh <name> <root>

Scaffold an apm instructions file from the bundled template.

Arguments:
  name  Kebab-case stem. Becomes <name>.instructions.md and, after install,
        the deployed rule's filename.
  root  Existing path at or below the target package. The script walks up for
        the nearest apm.yml with a top-level type: field (instructions, skill,
        hybrid or prompts); an apm.yml without type: is a marketplace-only
        manifest and is skipped. Creates
        <package-root>/.apm/instructions/<name>.instructions.md

Exit codes:
  0  File created, or already existed (no-op)
  1  Invalid arguments, missing root, no package found, or template not found
USAGE
}

if [[ "${1:-}" == "--help" || "${1:-}" == "-h" ]]; then
  usage
  exit 0
fi

if [[ $# -lt 2 ]]; then
  echo "Error: name and root are required." >&2
  echo "" >&2
  usage >&2
  exit 1
fi

NAME="$1"
ROOT="${2/#\~/$HOME}"

if ! grep -qE '^[a-z0-9]+(-[a-z0-9]+)*$' <<< "$NAME"; then
  echo "Error: name must use lowercase letters, numbers, and hyphens only." >&2
  echo "       No leading, trailing, or consecutive hyphens." >&2
  echo "       Received: '$NAME'" >&2
  exit 1
fi

if [[ ! -f "$TEMPLATE" ]]; then
  echo "Error: template not found at '$TEMPLATE'." >&2
  echo "       Run this script from its original location inside the instructions-author skill." >&2
  exit 1
fi

if [[ ! -d "$ROOT" ]]; then
  echo "Error: root directory '$ROOT' does not exist." >&2
  exit 1
fi
ROOT="$(cd "$ROOT" && pwd)"

# Same marker as agent-author's new-agent.sh: a top-level type: naming one of
# the four package types, with matching quotes if quoted.
is_apm_package_manifest() {
  local apm_yml="$1" line
  while IFS= read -r line || [[ -n "$line" ]]; do
    if [[ "$line" =~ ^type:[[:space:]]*(instructions|skill|hybrid|prompts)([[:space:]]|$) ]]; then
      return 0
    fi
    if [[ "$line" =~ ^type:[[:space:]]*([\"\'])(instructions|skill|hybrid|prompts)([\"\'])([[:space:]]|$) ]] \
       && [[ "${BASH_REMATCH[1]}" == "${BASH_REMATCH[3]}" ]]; then
      return 0
    fi
  done < "$apm_yml"
  return 1
}

PACKAGE_ROOT=""
current="$ROOT"
while true; do
  if [[ -f "$current/apm.yml" ]] && is_apm_package_manifest "$current/apm.yml"; then
    PACKAGE_ROOT="$current"
    break
  fi
  if [[ -e "$current/.git" ]]; then
    break
  fi
  parent="$(dirname "$current")"
  [[ "$parent" == "$current" ]] && break
  current="$parent"
done

if [[ -z "$PACKAGE_ROOT" ]]; then
  echo "Error: no apm package found at or above '$ROOT'." >&2
  echo "       Instructions only deploy from a package's .apm/instructions/. Run" >&2
  echo "       /apm-workflow configure (apm plugin init) there first, then retry." >&2
  exit 1
fi

DEST_DIR="$PACKAGE_ROOT/.apm/instructions"
DEST="$DEST_DIR/$NAME.instructions.md"

if [[ -f "$DEST" ]]; then
  echo "Skipping '$DEST' — already exists." >&2
  exit 0
fi

mkdir -p "$DEST_DIR"
cp "$TEMPLATE" "$DEST"
echo "Created: $DEST" >&2
echo "" >&2
echo "Next steps:" >&2
echo "  1. Fill in $DEST — replace every FILL IN: placeholder and delete the comments." >&2
echo "  2. Check '$NAME' does not collide with a hand-authored rule: install overwrites" >&2
echo "     <target>/rules/$NAME.* on most targets without warning." >&2
echo "  3. Verify with a real compile, not --validate: apm compile --dry-run --target <target>" >&2