import {
	startOfWeek,
	startOfMonth,
	endOfWeek,
	endOfMonth,
	isBefore,
	addDays,
	isSameDay,
	isWithinInterval,
	toDate,
	parseISO,
	isValid
} from "date-fns";
import { DateRange } from "./types";

export const identity = <T>(x: T) => x;

export const chunks = <T>(array: ReadonlyArray<T>, size: number): T[][] => {
	return Array.from({ length: Math.ceil(array.length / size) }, (v, i) =>
		array.slice(i * size, i * size + size)
	);
};

export const combine = (...args: any[]): string => args.filter(identity).join(" ");

// Date
export const getDaysInMonth = (date: Date) => {
	const startWeek = startOfWeek(startOfMonth(date));
	const endWeek = endOfWeek(endOfMonth(date));
	const days = [];
	for (let curr = startWeek; isBefore(curr, endWeek); ) {
		days.push(curr);
		curr = addDays(curr, 1);
	}
	return days;
};

export const isStartOfRange = ({ startDate }: DateRange, day: Date) =>
	(startDate && isSameDay(day, startDate)) as boolean;

export const isEndOfRange = ({ endDate }: DateRange, day: Date) =>
	(endDate && isSameDay(day, endDate)) as boolean;

export const inDateRange = ({ startDate, endDate }: DateRange, day: Date) =>
	(startDate &&
		endDate &&
		(isWithinInterval(day, {
			start: startDate,
			end: endDate
		}) ||
			isSameDay(day, startDate) ||
			isSameDay(day, endDate))) as boolean;

export const isRangeSameDay = ({ startDate, endDate }: DateRange) => {
	if (startDate && endDate) {
		return isSameDay(startDate, endDate);
	}
	return false;
};

type Falsy = false | null | undefined | 0 | "";

export const parseOptionalDate = (date: Date | string | Falsy, defaultValue: Date) => {
	if (date instanceof Date) {
		const parsed = toDate(date);
		if (isValid(parsed)) return parsed;
	}

	if (date instanceof String) {
		const parsed = parseISO(date as string);
		if (isValid(parsed)) return parsed;
	}

	return defaultValue;
};