interface OrderColumnPreferences {
  visibleColumnKeys: string[]
  orderedColumnKeys: string[]
}

function storageKey(ownerId: string) {
  return `cc:client:first-leg:order-columns:${ownerId}`
}

export function readOrderColumnPreferences(ownerId: string, selectableKeys: string[], defaultVisibleKeys: string[]): OrderColumnPreferences {
  const defaults = { visibleColumnKeys: [...defaultVisibleKeys], orderedColumnKeys: [...selectableKeys] }
  if (!ownerId) return defaults
  try {
    const saved: unknown = JSON.parse(localStorage.getItem(storageKey(ownerId)) ?? 'null')
    if (!saved || typeof saved !== 'object') return defaults
    const preferences = saved as Partial<OrderColumnPreferences>
    if (!Array.isArray(preferences.visibleColumnKeys) || !Array.isArray(preferences.orderedColumnKeys)) return defaults
    const validKeys = (keys: unknown[]) => [...new Set(keys.filter((key): key is string => typeof key === 'string' && selectableKeys.includes(key)))]
    return {
      visibleColumnKeys: validKeys(preferences.visibleColumnKeys),
      orderedColumnKeys: [...new Set([...validKeys(preferences.orderedColumnKeys), ...selectableKeys])],
    }
  } catch {
    return defaults
  }
}

export function saveOrderColumnPreferences(ownerId: string, preferences: OrderColumnPreferences) {
  if (!ownerId) return
  try {
    localStorage.setItem(storageKey(ownerId), JSON.stringify(preferences))
  } catch {
    // Column selection remains usable when browser storage is unavailable.
  }
}