/**
 * Short-TTL in-process cache for the plugin-settings singleton.
 *
 * Settings are read on virtually every payment operation (create-order reads
 * them several times) but change only on an explicit admin save. A short TTL
 * removes the per-request DB round-trips while keeping multi-instance
 * deployments acceptably fresh: another instance picks a change up within the
 * TTL, and the instance that wrote it invalidates immediately.
 *
 * `PAYPAL_SETTINGS_CACHE_MS` overrides the TTL; `0` disables caching.
 */

export const SETTINGS_CACHE_TTL_MS = (() => {
  const v = Number(process.env.PAYPAL_SETTINGS_CACHE_MS)
  return Number.isFinite(v) && v >= 0 ? v : 15_000
})()

type Slot = { value: unknown; at: number }

const slots = new Map<string, Slot>()

export function getCachedSettings<T>(key: string): T | null {
  if (SETTINGS_CACHE_TTL_MS <= 0) return null
  const slot = slots.get(key)
  if (!slot) return null
  if (Date.now() - slot.at >= SETTINGS_CACHE_TTL_MS) {
    slots.delete(key)
    return null
  }
  return slot.value as T
}

export function setCachedSettings(key: string, value: unknown): void {
  if (SETTINGS_CACHE_TTL_MS <= 0) return
  slots.set(key, { value, at: Date.now() })
}

/**
 * Drop every cached settings view (module service AND credential resolver —
 * they cache different shapes of the same row). Called after a settings write
 * so reads in this process are immediately fresh.
 */
export function invalidateSettingsCache(): void {
  slots.clear()
}