/**
 * Brute-force lockout as a pure reducer so POS and back office share the exact
 * policy and it is testable without a clock. Attempts are audit-logged by the
 * caller (I7: every mutation audit-logged in the same transaction).
 */
export interface LockoutPolicy {
  maxFailures: number
  lockMs: number
}

export const DEFAULT_LOCKOUT: LockoutPolicy = { maxFailures: 5, lockMs: 60_000 }

export interface LockoutState {
  failures: number
  lockedUntilMs?: number
}

export const FRESH_LOCKOUT: LockoutState = { failures: 0 }

export function isLocked(state: LockoutState, nowMs: number): boolean {
  return state.lockedUntilMs !== undefined && nowMs < state.lockedUntilMs
}

export function recordFailure(
  state: LockoutState,
  nowMs: number,
  policy: LockoutPolicy = DEFAULT_LOCKOUT,
): LockoutState {
  const failures = state.failures + 1
  if (failures >= policy.maxFailures) {
    return { failures, lockedUntilMs: nowMs + policy.lockMs }
  }
  return { failures }
}

export function recordSuccess(): LockoutState {
  return FRESH_LOCKOUT
}