/* Declarations for lib/srs.js — the module itself ships unchanged. */

export const AGAIN: 0;
export const HARD: 1;
export const GOOD: 2;
export const EASY: 3;
export type Grade = 0 | 1 | 2 | 3;

export const NEW: 0;
export const LEARNING: 1;
export const REVIEW: 2;
export type CardState = 0 | 1 | 2;

/** Days at which a card counts as known. */
export const SECURE_INTERVAL: number;

export interface Card {
  state: CardState;
  interval: number;
  ease: number;
  /** Day number, not a timestamp — see dayNumber(). */
  due: number;
  reps: number;
  lapses: number;
}

export function newCard(): Card;
export function grade(card: Card, g: Grade, today: number): Card;
export function markKnown(today: number): Card;

export type CardStatus = "new" | "learning" | "review" | "secure";
export function statusOf(card: Card | null | undefined): CardStatus;

/** Label for the interval a grade would produce — shown on the buttons. */
export function preview(card: Card | null | undefined, g: Grade, today: number): string;

/** Local day number, DST-safe. */
export function dayNumber(d?: Date): number;