/** Pure toast state — testable without a DOM. */

export interface Toast { id: number; tone: 'ok' | 'err'; message: string }
export interface ToastState { nextId: number; toasts: Toast[] }

export const TOAST_LIMIT = 3
export const initialToasts: ToastState = { nextId: 1, toasts: [] }

export function pushToast(s: ToastState, tone: Toast['tone'], message: string): ToastState {
  const toast: Toast = { id: s.nextId, tone, message }
  const toasts = [...s.toasts, toast].slice(-TOAST_LIMIT)
  return { nextId: s.nextId + 1, toasts }
}

export function dismissToast(s: ToastState, id: number): ToastState {
  return { ...s, toasts: s.toasts.filter((t) => t.id !== id) }
}