/**
 * Payment-icon serving — Phase 5.x icon hosting.
 *
 * Backend wraps the `idn-finlogos` npm package and serves its SVGs at
 * `/assets/payment-icons/<slug>.svg`. The catalog endpoint returns
 * `icon_url: "/assets/payment-icons/<slug>.svg"`; the client app fetches +
 * caches with `flutter_cache_manager`. No bundled icons in the app anymore.
 *
 * License: idn-finlogos ships under CC-BY-NC-4.0 for the assets (per-brand
 * permission still required for production use). Code under MIT. See
 * `backend/node_modules/idn-finlogos/LICENSE-ASSETS` + `NOTICE`.
 *
 * Slug set is loaded ONCE at module init from `dist/icons/*.svg` filenames so
 * the request path stays a single Set.has() lookup. Bump the package version
 * to add/replace icons; restart the backend to refresh the slug set.
 */

import { readdirSync } from 'fs'
import { dirname, join } from 'path'
import { createRequire } from 'module'

const require = createRequire(import.meta.url)

const PACKAGE_DIR = dirname(require.resolve('idn-finlogos/package.json'))
const ICONS_DIR = join(PACKAGE_DIR, 'dist', 'icons')

const SLUGS = new Set(
  readdirSync(ICONS_DIR)
    .filter((f) => f.endsWith('.svg'))
    .map((f) => f.slice(0, -4)),
)

export const hasIconSlug = (slug) => typeof slug === 'string' && SLUGS.has(slug)

export const resolveIconPath = (slug) => {
  if (!hasIconSlug(slug)) return null
  return join(ICONS_DIR, `${slug}.svg`)
}

/** Sorted slug list for the CC dropdown. */
export const listIconSlugs = () => Array.from(SLUGS).sort()