export type WeekRange = [number, number | null];
export interface CalendarWeek {
  n: number;
  start: string;
  end: string;
  color: "white" | "green";
  semester?: string;
}
export interface Semester {
  id: string;
  kind: "autumn" | "spring";
  year: number;
  label: string;
  start: string;
  end: string;
}
export interface Bell {
  pair: number;
  start: string;
  end: string;
  halves: [string, string][];
}
export interface AcademicCalendar {
  weeks: CalendarWeek[];
  semesters?: Semester[];
  bells: Bell[];
  source: {
    weeks?: string | null;
    bells?: string | null;
    weeksFiles?: string[];
    bellsFile?: string | null;
  };
  updatedAt: string | null;
  stale?: boolean;
  error?: string;
}
/** A calendar narrowed to the semester a schedule belongs to. */
export interface SemesterCalendar extends AcademicCalendar {
  semester: Semester;
}
interface ScheduleLike {
  lessons: { date: string | null }[];
  period?: string;
  academicYear?: string | number | null;
}
interface WeekLesson {
  day: number;
  date: string | null;
  dates?: string[];
  condition: string;
  variant: "all" | "upper" | "lower";
  weekRanges?: WeekRange[] | null;
}
export function parseWeekRanges(condition: string): WeekRange[] | null;
export function parseTextDates(raw: string, year: string | number): string[];
export const DATE_LIST: RegExp;
export function isoDate(time: number): string;
export function addDays(iso: string, days: number): string;
export function weekday(iso: string): number;
export function todayIso(now?: Date): string;
export function weekIndexOf(
  calendar: AcademicCalendar | null | undefined,
  iso: string,
): number;
export function dateInWeek(week: CalendarWeek, day: number): string | null;
export function lessonWeeks(lesson: WeekLesson, lastWeek: number): number[] | null;
export function lessonDates(
  lesson: WeekLesson,
  calendar: AcademicCalendar | null | undefined,
): string[] | null;
export function academicStartYear(iso: string): number;
export function assignSemesters(weeks: CalendarWeek[]): {
  weeks: CalendarWeek[];
  semesters: Semester[];
};
export function semesterFor(
  calendar: AcademicCalendar | null | undefined,
  schedule: ScheduleLike | null | undefined,
  today: string,
): Semester | null;
export function semesterView(
  calendar: AcademicCalendar | null | undefined,
  schedule: ScheduleLike | null | undefined,
  today: string,
): SemesterCalendar | null;