import Helpers from './Helpers'
import { DAY_MODE, DAY_TIME_POINT } from './typings'

export type calendarWeekType = Date[]
export type calendarMonthType = calendarWeekType[]
export type calendarYearMonths = Date[]

export enum WEEK_START_DAY {
	SUNDAY = 'sunday',
	MONDAY = 'monday'
}

export default class Time {
	FIRST_DAY_OF_WEEK: WEEK_START_DAY
	CALENDAR_LOCALE: string
	ALL_HOURS: DAY_TIME_POINT[] = [
		0,
		100,
		200,
		300,
		400,
		500,
		600,
		700,
		800,
		900,
		1000,
		1100,
		1200,
		1300,
		1400,
		1500,
		1600,
		1700,
		1800,
		1900,
		2000,
		2100,
		2200,
		2300
	]
	DAY_START: DAY_TIME_POINT
	DAY_END: DAY_TIME_POINT
	HOURS_PER_DAY = 24
	MS_PER_DAY: number

	constructor(
		firstDayOfWeek: WEEK_START_DAY = WEEK_START_DAY.MONDAY,
		locale: string | null = null,
		dayBoundaries: { start: DAY_TIME_POINT, end: DAY_TIME_POINT } = { start: 0, end: 2400 }
	) {
		this.FIRST_DAY_OF_WEEK = firstDayOfWeek
		this.CALENDAR_LOCALE = locale || Helpers.getBrowserNavigatorLocale()
		this.DAY_START = dayBoundaries.start
		this.DAY_END = dayBoundaries.end
		this.HOURS_PER_DAY = (() => {
			const dayEnd = Time.getHourFromTimePoints(this.DAY_END)
			const dayStart = Time.getHourFromTimePoints(this.DAY_START)

			if (dayEnd > dayStart) { return dayEnd - dayStart }

			return this.HOURS_PER_DAY - dayStart + dayEnd
		})()
		this.MS_PER_DAY = 86400000
	}

	get dayMode() {
		if (this.DAY_START === 0 && this.DAY_END === 2400) { return DAY_MODE.REGULAR }

		if (this.DAY_START >= this.DAY_END) { return DAY_MODE.FLEXIBLE }

		return DAY_MODE.SHORTENED
	}

	getDatesBetweenTwoDates(start: Date, end: Date): Date[] {
		const arr = []
		const dt = new Date(start)
		// eslint-disable-next-line no-unmodified-loop-condition
		while (dt <= end) {
			arr.push(new Date(dt.getFullYear(), dt.getMonth(), dt.getDate()))
			dt.setDate(dt.getDate() + 1)
		}
		return arr
	}

	getCalendarWeekDateObjects(date: Date): calendarWeekType {
		// If week starts on Sunday, we can get the first date of the week, by simply counting selectedDate.getDate() - selectedDate.getDay()
		let subtractedDaysToGetFirstDate
		if (this.FIRST_DAY_OF_WEEK === 'sunday') {
			subtractedDaysToGetFirstDate = date.getDay()
		}
		// However, if week starts on Monday, we need to make sure Mondays are represented as 0, instead of Sundays
		else {
			subtractedDaysToGetFirstDate
        = date.getDay() === 0 ? 6 : date.getDay() - 1
		}

		const dateOfFirstDayOfWeek = date.getDate() - subtractedDaysToGetFirstDate // First date of week is the date of the month - the day of the week
		const firstDay = new Date(
			date.getFullYear(),
			date.getMonth(),
			dateOfFirstDayOfWeek
		)

		return this.getDatesBetweenTwoDates(
			firstDay,
			new Date(
				firstDay.getFullYear(),
				firstDay.getMonth(),
				firstDay.getDate() + 6
			)
		)
	}

	/**
	 * Returns an array of the weeks that comprise a month
	 *
	 * @param {number} yyyy
	 * @param {number} mm - zero indexed (January === 0)
	 */
	getCalendarMonthSplitInWeeks(yyyy: number, mm: number): calendarMonthType {
		const month: calendarMonthType = []
		const selectedDate = new Date(yyyy, mm, 1)

		// 1. Get the first date of the month, and push the full week of this date into the month list
		const firstDateOfMonth = new Date(
			selectedDate.getFullYear(),
			selectedDate.getMonth(),
			1
		)
		const firstWeekOfMonth = this.getCalendarWeekDateObjects(firstDateOfMonth)
		month.push(firstWeekOfMonth)

		// 2. Then enter a while-loop, which pushes weeks onto the month,
		// until the first Monday is reached, that is not in the specified month
		let isInMonth = true
		let mondayOfWeekToPush = firstWeekOfMonth[0]
		const specifiedMonth = selectedDate.getMonth()

		while (isInMonth) {
			const newMonday = new Date(
				mondayOfWeekToPush.getFullYear(),
				mondayOfWeekToPush.getMonth(),
				mondayOfWeekToPush.getDate() + 7
			)

			if (newMonday.getMonth() === specifiedMonth) {
				month.push(this.getCalendarWeekDateObjects(newMonday))
				mondayOfWeekToPush = newMonday
			} else {
				isInMonth = false
			}
		}

		return month
	}

	/**
	 * Returns an array with the length of 12 dates,
	 * one date for the first day of each month of the year
	 */
	getCalendarYearMonths(year: number): calendarYearMonths {
		const yearList: calendarYearMonths = []
		let month = 0

		while (month <= 11) {
			yearList.push(new Date(year, month, 1))
			month++
		}

		return yearList
	}

	getHourAndMinutesFromTimePoints(timePoints: number) {
		const time = timePoints.toString()
		let hour = '0'
		let minutes = '0'

		if (time.length === 4) {
			hour = time[0] + time[1]
			minutes = time[2] + time[3]
		} else if (time.length === 3) {
			hour = time[0]
			minutes = time[1] + time[2]
		}

		return {
			hour: +hour,
			minutes: +minutes,
		}
	}

	/**
	 * Given timePoints (0, 100, 200 etc.), this function returns
	 * a localized string with the respective hour
	 * (in en-US for example: 0 => 12 AM, 1600 => 4 PM )
	 */
	getHourLocaleStringFromHourDigits(timePoints: number) {
		const { hour, minutes } = this.getHourAndMinutesFromTimePoints(timePoints)

		const hourLocaleString = new Date(
			2100,
			0,
			1,
			+hour,
			+minutes,
			0
		).toLocaleTimeString(this.CALENDAR_LOCALE, {
			hour: '2-digit',
		})

		if (hourLocaleString[0] === '0') { return hourLocaleString.substring(1) }

		return hourLocaleString
	}

	getLocalizedNameOfWeekday(
		date: Date,
		weekdayNameLength: 'long' | 'short' = 'short'
	): string {
		return date.toLocaleDateString(this.CALENDAR_LOCALE, {
			weekday: weekdayNameLength,
		})
	}

	getLocalizedNameOfMonth(
		date: Date,
		monthNameLength: 'long' | 'short' = 'short'
	): string {
		return date.toLocaleDateString(this.CALENDAR_LOCALE, {
			month: monthNameLength,
		})
	}

	getLocalizedDateString(date: Date): string {
		return date.toLocaleDateString(this.CALENDAR_LOCALE)
	}

	/**
	 * Takes a date object, and creates a time string from it, in the format of
	 * YYYY-MM-DD hh:mm
	 */
	getDateTimeStringFromDate(
		date: Date,
		timeIsStartOrEndOfDay?: 'start' | 'end'
	): string {
		const y = date.getFullYear()
		const m = date.getMonth() + 1
		const d = date.getDate()
		const fullDate = `${y}-${m >= 10 ? m : `0${m}`}-${d >= 10 ? d : `0${d}`}`

		if (!timeIsStartOrEndOfDay) {
			const hour = date.getHours()
			const minutes = date.getMinutes()

			return `${fullDate} ${hour >= 10 ? hour : `0${hour}`}:${
				minutes >= 10 ? minutes : `0${minutes}`
			}`
		}

		const fullTime = timeIsStartOrEndOfDay === 'start' ? '00:00' : '23:59'

		return `${fullDate} ${fullTime}`
	}

	getLocalizedTime(dateTimeString: string) {
		// Though only displaying time, the exact date is needed, because otherwise time will be displayed
		// incorrectly on days when daylight saving time changes
		const {
			year,
			month,
			date,
			hour,
			minutes,
		} = this.getAllVariablesFromDateTimeString(dateTimeString)
		const d = new Date(year, month, date, hour, minutes)

		return d.toLocaleTimeString(this.CALENDAR_LOCALE, {
			hour: 'numeric',
			minute: 'numeric',
		})
	}

	getLocalizedHour(date: Date) {
		return date.toLocaleTimeString(this.CALENDAR_LOCALE, { hour: '2-digit' })
	}

	getLocalizedTimeRange(start: string, end: string) {
		return `${this.getLocalizedTime(start)} - ${this.getLocalizedTime(end)}`
	}

	/**
	 * Returns numeric values for year, month, date, hour and minutes, given a dateTimeString
	 * All variables are Date-Object compatible, meaning "month" is zero-indexed
	 */
	getAllVariablesFromDateTimeString(dateTimeString: string) {
		return {
			year: +dateTimeString.substring(0, 4),
			month: +dateTimeString.substring(5, 7) - 1,
			date: +dateTimeString.substring(8, 10),
			hour: this.hourFrom(dateTimeString),
			minutes: this.minutesFrom(dateTimeString),
		}
	}

	dateIsToday(date: Date) {
		const today = new Date()
		const yearToday = today.getFullYear()
		const monthToday = today.getMonth()
		const dateToday = today.getDate()

		const dateYear = date.getFullYear()
		const dateMonth = date.getMonth()
		const dateDate = date.getDate()

		return (
			yearToday === dateYear
			&& monthToday === dateMonth
			&& dateToday === dateDate
		)
	}

	dateIsInWeek(dateToCheck: Date, week: Date[]) {
		const d = new Date(dateToCheck)
		const date = d.getDate()
		const month = d.getMonth()
		const fullYear = d.getFullYear()

		for (const weekDay of week) {
			const dateIsSame = date === weekDay.getDate()
			const monthIsSame = month === weekDay.getMonth()
			const yearIsSame = fullYear === weekDay.getFullYear()

			if (dateIsSame && monthIsSame && yearIsSame) { return true }
		}

		return false
	}

	getDateStringFromDate(date: Date) {
		const yyyy = date.getFullYear()
		const mm = (date.getMonth() + 1)
		const dd = date.getDate()

		return `${yyyy}-${mm >= 10 ? mm : `0${mm}`}-${dd >= 10 ? dd : `0${dd}`}`
	}

	addMinutesToDateTimeString(minutes: number, dateTimeString: string) {
		const {
			year: oldYear,
			month: oldMonth,
			date: oldDate,
			hour: oldHour,
			minutes: oldMinutes
		} = this.getAllVariablesFromDateTimeString(dateTimeString)

		const oldDateObject = new Date(oldYear, oldMonth, oldDate, oldHour, oldMinutes)
		const newDateObject = new Date(oldDateObject.getTime() + (minutes * 60000))

		return this.getDateTimeStringFromDate(newDateObject)
	}

	addDaysToDateTimeString(days: number, dateTimeString: string) {
		return this.addMinutesToDateTimeString((days * 1440), dateTimeString)
	}

	dateStringsHaveEqualDates(dateTimeString1: string, dateTimeString2: string) {
		const { year: year1, month: month1, date: date1 } = this.getAllVariablesFromDateTimeString(dateTimeString1)
		const { year: year2, month: month2, date: date2 } = this.getAllVariablesFromDateTimeString(dateTimeString2)

		return (year1 === year2) && (month1 === month2) && (date1 === date2)
	}

	setDateToEndOfDay(date: Date) {
		return new Date(
			date.getFullYear(),
			date.getMonth(),
			date.getDate(),
			23,
			59,
			59,
			999
		)
	}

	protected turnMinutesIntoPercentageOfHour(minutes: number): string {
		const oneMinutePercentage = 100 / 60
		const minutePoints = oneMinutePercentage * minutes

		if (minutePoints < 10) { return `0${minutePoints}` }

		return minutePoints.toString()
	}

	/**
	 * Every hour between 'dayStart' and 'dayEnd' is 100, in this function referred to as 100 points
	 * If an event starts 30 minutes after 'dayStart', it should have 50 pointsIntoDay
	 * If a day consists of 4 hours (400 points), we then have to count
	 * (50 / 400) * 100 = 12.5 => event starts after 12.5 percent of the day
	 *
	 * Result is supposed to be a number between 0 and 100, and is used for setting the CSS- top- and height-attributes for events
	 */
	getPercentageOfDayFromDateTimeString(
		dateTimeString: string,
		dayStart: number,
		dayEnd: number,
	) {
		const hour = this.hourFrom(dateTimeString)
		const hourPoints = hour * 100
		const minutes = +dateTimeString.substring(14, 16)
		const minutesPoints = +this.turnMinutesIntoPercentageOfHour(+minutes)

		if (dayEnd > dayStart) {
			const pointsInDay = dayEnd - dayStart
			const eventPoints = hourPoints + minutesPoints
			const eventPointsIntoDay = eventPoints - dayStart

			return (eventPointsIntoDay / pointsInDay) * 100
		}

		const hourPointsInOriginalDay = DAY_TIME_POINT.TWELVE_AM - dayStart
		const pointsInDay = hourPointsInOriginalDay + dayEnd
		const eventPoints = hourPoints + minutesPoints
		const pointsIntoDay = eventPoints >= dayStart ? eventPoints - dayStart : hourPointsInOriginalDay + eventPoints

		return (pointsIntoDay / pointsInDay) * 100
	}

	getTimeFromClick(
		clickOffsetY: number,
		weekHeight: number,
	): string {
		if (weekHeight <= 0) { throw new Error('weekHeight cannot be a negative number') }
		if (clickOffsetY < 0) { throw new Error('clickOffsetY cannot be a negative number') }

		const dayStartHour = this.DAY_START / 100
		const hourHeight = weekHeight / this.HOURS_PER_DAY
		const minutes = Math.floor((clickOffsetY % hourHeight) / (hourHeight / 60))

		if (this.DAY_END <= this.DAY_START) {
			const dayEndHour = this.DAY_END / 100
			const nightHeight = (dayEndHour) * hourHeight
			const nightOffset = weekHeight - nightHeight

			if (clickOffsetY > nightOffset) {
				const hour = Math.floor((clickOffsetY - nightOffset) / hourHeight)
				return `${this.doubleDigit(hour)}:${this.doubleDigit(minutes)}`
			}
		}

		const hour = Math.floor(clickOffsetY / hourHeight) + dayStartHour

		return `${this.doubleDigit(hour)}:${this.doubleDigit(minutes)}`
	}

	setSegmentOfDateTimeString(dateTimeString: string, segments: { hour: number }) {
		if (segments.hour < 0 || segments.hour > 23) { throw new Error('Invalid hour') }
		const newHour = this.doubleDigit(segments.hour)
		dateTimeString = dateTimeString.replace(/\d{2}:/, `${newHour}:`)

		return dateTimeString
	}

	isTrailingOrLeadingDate(date: Date, month: number) {
		const d = new Date(date)
		const dateMonth = d.getMonth()

		return month !== dateMonth
	}

	static getTimePointsFromHour(boundary: number) {
		if (boundary < 0 || boundary > 24 || boundary % 1 !== 0) {
			throw new Error('Invalid day boundary')
		}

		if (boundary === 0) { return boundary }

		return boundary * 100
	}

	static getHourFromTimePoints(timePoints: number) {
		if (timePoints < 0 || timePoints > 2400 || timePoints % 100 !== 0) {
			throw new Error('Invalid time points')
		}

		if (timePoints === 0) { return timePoints }

		return timePoints / 100
	}

	getTimelineHours(): DAY_TIME_POINT[] {
		if (this.dayMode !== DAY_MODE.FLEXIBLE) {
			return this.ALL_HOURS.filter((hour) => {
				return hour >= this.DAY_START && hour < this.DAY_END
			})
		}

		return [
			...this.ALL_HOURS.filter(hour => hour >= this.DAY_START),
			...this.ALL_HOURS.filter(hour => hour < this.DAY_END)
		]
	}

	dateStringFrom(dateTimeString: string) {
		return dateTimeString.substring(0, 10)
	}

	timeStringFrom(dateTimeString: string) {
		return dateTimeString.substring(11, 16)
	}

	hourFrom(dateTimeString: string) {
		return +dateTimeString.substring(11, 13)
	}

	minutesFrom(dateTimeString: string) {
		return +dateTimeString.substring(14, 16)
	}

	areDaysConsecutive(dayOne: string, dayTwo: string) {
		const dayOnePlusOneDay = this.dateStringFrom(this.addDaysToDateTimeString(1, dayOne))

		return dayOnePlusOneDay === this.dateStringFrom(dayTwo)
	}

	setHourInDateTimeString(dateTimeString: string, hour: number) {
		const hourString = this.doubleDigit(hour)
		dateTimeString = dateTimeString.replace(/\d{2}:/, `${hourString}:`)

		return dateTimeString
	}

	setMinutesInDateTimeString(dateTimeString: string, minutes: number) {
		const minutesString = this.doubleDigit(minutes)
		dateTimeString = dateTimeString.replace(/:\d{2}/, `:${minutesString}`)

		return dateTimeString
	}

	getDateTimeStringDayBoundariesFrom(dateString: string): { start: string, end: string } {
		if (this.DAY_END <= this.DAY_START) {
			const nextDay = this.addDaysToDateTimeString(1, dateString)
			const endOfDay = this.setHourInDateTimeString(nextDay, this.getHourAndMinutesFromTimePoints(this.DAY_END).hour)
			const startOfDay = this.setHourInDateTimeString(dateString, this.getHourAndMinutesFromTimePoints(this.DAY_START).hour)

			return { start: startOfDay, end: endOfDay }
		}

		const startOfDay = this.setHourInDateTimeString(dateString, this.getHourAndMinutesFromTimePoints(this.DAY_START).hour)
		let endOfDay
		if (this.DAY_END === DAY_TIME_POINT.TWELVE_AM) {
			endOfDay = this.setHourInDateTimeString(dateString, 23)
			endOfDay = this.setMinutesInDateTimeString(endOfDay, 59)
		} else {
			endOfDay = this.setHourInDateTimeString(dateString, this.getHourAndMinutesFromTimePoints(this.DAY_END).hour)
		}

		return { start: startOfDay, end: endOfDay }
	}

	doubleDigit(number: number) {
		if (number < 0 || number > 60) { throw new Error('Invalid number. This is not a valid hour or minute') }

		return number < 10 ? `0${number}` : String(number)
	}
}

export class TimeBuilder {
	private weekStartsOn: WEEK_START_DAY = WEEK_START_DAY.MONDAY
	private locale: string | null = null
	private dayBoundaries: { start: DAY_TIME_POINT, end: DAY_TIME_POINT } = { start: 0, end: 2400 }

	build() {
		return new Time(this.weekStartsOn, this.locale, this.dayBoundaries)
	}

	withDayBoundaries(dayBoundaries: { start: DAY_TIME_POINT, end: DAY_TIME_POINT }) {
		this.dayBoundaries = dayBoundaries

		return this
	}

	withLocale(locale: string) {
		this.locale = locale

		return this
	}
}