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

script_dir="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
repo_root="$(cd "${script_dir}/.." && pwd)"

env_file="${repo_root}/.env.devprod"
template_file="${repo_root}/.env.example"
dry_run="0"
backup_mode="1"

usage() {
  cat <<USAGE
Usage: ./scripts/ensure-env-keys.sh [options]

Append missing KEY=VALUE entries from a template env file into a target env file.
Existing keys are never modified.

Options:
  --env-file <path>         Target env file (default: .env.devprod)
  --template-file <path>    Source template file (default: .env.example)
  --dry-run                 Print missing keys without modifying files
  --no-backup               Do not create a timestamped backup before writing
  -h, --help                Show this help
USAGE
}

while [[ $# -gt 0 ]]; do
  case "$1" in
    --env-file)
      env_file="${2:-}"
      shift 2
      ;;
    --env-file=*)
      env_file="${1#*=}"
      shift
      ;;
    --template-file)
      template_file="${2:-}"
      shift 2
      ;;
    --template-file=*)
      template_file="${1#*=}"
      shift
      ;;
    --dry-run)
      dry_run="1"
      shift
      ;;
    --no-backup)
      backup_mode="0"
      shift
      ;;
    -h|--help)
      usage
      exit 0
      ;;
    *)
      echo "Unknown option: $1"
      usage
      exit 1
      ;;
  esac
done

if [[ "${env_file}" != /* ]]; then
  env_file="${repo_root}/${env_file}"
fi
if [[ "${template_file}" != /* ]]; then
  template_file="${repo_root}/${template_file}"
fi

if [[ ! -f "${template_file}" ]]; then
  echo "Missing template file: ${template_file}"
  exit 1
fi

if [[ ! -f "${env_file}" ]]; then
  echo "Missing env file: ${env_file}"
  exit 1
fi

key_exists() {
  local key="$1"
  grep -qE "^${key}=" "${env_file}"
}

missing_keys=()
missing_lines=()

while IFS= read -r line || [[ -n "${line}" ]]; do
  [[ -z "${line}" ]] && continue
  [[ "${line}" == \#* ]] && continue
  [[ "${line}" =~ ^[[:space:]]*# ]] && continue
  [[ "${line}" =~ ^[A-Za-z_][A-Za-z0-9_]*= ]] || continue

  key="${line%%=*}"
  if ! key_exists "${key}"; then
    missing_keys+=("${key}")
    missing_lines+=("${line}")
  fi
done < "${template_file}"

if [[ "${#missing_keys[@]}" -eq 0 ]]; then
  echo "No missing env keys found in ${env_file} (template: ${template_file})."
  exit 0
fi

if [[ "${dry_run}" == "1" ]]; then
  echo "Missing keys in ${env_file}:"
  printf '  %s\n' "${missing_keys[@]}"
  echo "Dry run only; no file changes made."
  exit 0
fi

if [[ "${backup_mode}" == "1" ]]; then
  backup_path="${env_file}.bak.$(date +%Y%m%d%H%M%S)"
  cp "${env_file}" "${backup_path}"
  echo "Backup created: ${backup_path}"
fi

{
  echo
  echo "# Added automatically from ${template_file##*/} on $(date -u +%Y-%m-%dT%H:%M:%SZ)"
  for line in "${missing_lines[@]}"; do
    echo "${line}"
  done
} >> "${env_file}"

echo "Added ${#missing_keys[@]} missing env key(s) to ${env_file}:"
printf '  %s\n' "${missing_keys[@]}"