// The order of the pages in the rail is the account's: kept here for instant use and saved
// with the UI prefs, so it follows the login. Pages the saved order doesn't name (added since)
// go after the ones it does, in their built-in order.
import { useEffect, useState } from 'react'

const KEY = 'hamlab.rail'

export function getRailOrder(): string[] {
  try { const v = JSON.parse(localStorage.getItem(KEY) ?? '[]'); return Array.isArray(v) ? v.filter((x) => typeof x === 'string') : [] } catch { return [] }
}

export function setRailOrder(ids: string[], save = true) {
  localStorage.setItem(KEY, JSON.stringify(ids))
  window.dispatchEvent(new Event('hamlab:rail'))
  if (save) import('./accents').then((m) => m.savePrefs())
}

export function resetRailOrder() { localStorage.removeItem(KEY); window.dispatchEvent(new Event('hamlab:rail')); import('./accents').then((m) => m.savePrefs()) }

export function useRailOrder(): string[] {
  const [order, setOrder] = useState(getRailOrder)
  useEffect(() => {
    const h = () => setOrder(getRailOrder())
    window.addEventListener('hamlab:rail', h)
    return () => window.removeEventListener('hamlab:rail', h)
  }, [])
  return order
}

export function orderBy<T extends { id: string }>(items: T[], order: string[]): T[] {
  const by = new Map(items.map((g) => [g.id, g]))
  const named = order.map((id) => by.get(id)).filter((g): g is T => !!g)
  const seen = new Set(named.map((g) => g.id))
  return [...named, ...items.filter((g) => !seen.has(g.id))]
}