import { format } from 'date-fns';
import { TimeScaleOptions } from '../interfaces/axis-scales';
import { Tools } from '../tools';

// D3 Imports
import { min } from 'd3-array';

export const TIME_INTERVALS = [
	['15seconds', 15 * 1000],
	['minute', 60 * 1000],
	['30minutes', 30 * 60 * 1000],
	['hourly', 60 * 60 * 1000],
	['daily', 24 * 60 * 60 * 1000],
	['monthly', 30 * 24 * 60 * 60 * 1000],
	['quarterly', 3 * 30 * 24 * 60 * 60 * 1000],
	['yearly', 12 * 30 * 24 * 60 * 60 * 1000],
];

// Return true if the tick is a primary tick, false otherwise
export function isTickPrimary(
	tick: number,
	i: number,
	interval: string,
	showDayName: boolean
): boolean {
	const isFirstTick = i === 0;
	const hasANewWeekStarted = Number(format(new Date(tick), 'c')) === 2;
	const isFirstQuarter = Number(format(new Date(tick), 'q')) === 1;

	switch (interval) {
		case '15seconds':
			return (
				isFirstTick ||
				isDayOfMonthChanged(tick) ||
				isMonthChanged(tick) ||
				isYearChanged(tick)
			);
		case 'minute':
			return (
				isFirstTick ||
				isDayOfMonthChanged(tick) ||
				isMonthChanged(tick) ||
				isYearChanged(tick)
			);
		case '30minutes':
			return (
				isFirstTick ||
				isDayOfMonthChanged(tick) ||
				isMonthChanged(tick) ||
				isYearChanged(tick)
			);
		case 'hourly':
			return (
				isFirstTick ||
				isDayOfMonthChanged(tick) ||
				isMonthChanged(tick) ||
				isYearChanged(tick)
			);
		case 'daily':
			if (!showDayName) {
				// daily
				return (
					isFirstTick || isMonthChanged(tick) || isYearChanged(tick)
				);
			} else {
				// weekly
				return isFirstTick || hasANewWeekStarted || isYearChanged(tick);
			}
		case 'monthly':
			return isFirstTick || isYearChanged(tick);
		case 'quarterly':
			return isFirstTick || isFirstQuarter;
		case 'yearly':
			return false;
		default:
			throw new Error(`${interval} is not a valid time interval.`);
	}
}

// Return the formatted current tick
export function formatTick(
	tick: number,
	i: number,
	interval: string,
	timeScaleOptions: TimeScaleOptions
): string {
	const showDayName = timeScaleOptions.showDayName;
	const intervalConsideringAlsoShowDayNameOption =
		interval === 'daily' && showDayName ? 'weekly' : interval;
	const date = new Date(tick);
	const formats = Tools.getProperty(timeScaleOptions, 'timeIntervalFormats')[
		intervalConsideringAlsoShowDayNameOption
	];
	const primary = Tools.getProperty(formats, 'primary');
	const secondary = Tools.getProperty(formats, 'secondary');
	const formatString = isTickPrimary(tick, i, interval, showDayName)
		? primary
		: secondary;
	const locale = timeScaleOptions.localeObject;

	return format(date, formatString, { locale });
}

// Given a timestamp, return an object of useful time formats
// Use Unicode date field symbol (https://www.unicode.org/reports/tr35/tr35-dates.html#Date_Field_Symbol_Table)
export function getTimeformats(timestamp: number) {
	const date = new Date(timestamp);
	return {
		M: date.getMonth() + 1, // month: 1-12
		d: date.getDate(), // day of the month: 1-31
		H: date.getHours(), // 24-hour clock: 0-23
		m: date.getMinutes(), // minute: 0-59
		s: date.getSeconds(), // seconds: 0-59
	};
}

// Find the differences between consecutive numbers in an array
function getConsecutiveDifferences(elements: number[]): number[] {
	if (!elements) {
		return;
	}
	return elements.slice(1).map((elem, i) => elem - elements[i]);
}

// Given a duration in ms, return the closest TIME_INTERVAL name
function closestTimeIntervalName(duration: number): string {
	const index = TIME_INTERVALS.reduce(
		(nearestIndex, [intervalName, delta]: [string, number], i) => {
			const deltaNearest = TIME_INTERVALS[nearestIndex][1] as number;
			const oldNearestSpan = Math.abs(deltaNearest - duration);
			const currentSpan = Math.abs(delta - duration);
			return oldNearestSpan < currentSpan ? nearestIndex : i;
		},
		0
	);
	return TIME_INTERVALS[index][0] as string;
}

// Given an array of timestamps, return the interval name
// between 15seconds, minute, 30minutes, hourly, daily, weekly, monthly, quarterly, yearly
export function computeTimeIntervalName(ticks: number[]): string {
	// special case: if the dataset has only one datum, we show the tick in the most detailed way possible
	if (ticks.length === 1) {
		return '15seconds';
	}
	const differences = getConsecutiveDifferences(ticks);
	const minDifference = min(differences);
	return closestTimeIntervalName(minDifference);
}

// Return true if the day of the month (D = 1-31) is changed, false otherwise
function isDayOfMonthChanged(timestamp: number): boolean {
	const { s, m, H } = getTimeformats(timestamp);
	return H === 0 && m === 0 && s === 0;
}

// Return true if the month (M = 1-12) is changed, false otherwise
function isMonthChanged(timestamp: number): boolean {
	const { d, s, m, H } = getTimeformats(timestamp);
	return d === 1 && H === 0 && m === 0 && s === 0;
}

// Return true if the year (YYYY) is changed, false otherwise
function isYearChanged(timestamp: number): boolean {
	const { M, d, s, m, H } = getTimeformats(timestamp);
	return M === 1 && d === 1 && H === 0 && m === 0 && s === 0;
}