import add from "date-fns/add"
import { DateResolvable, GuildScheduledEvent } from "discord.js"
import { findInScheduleTypes } from "../../helper/typeFind"
import { RepetitonInfo, supportedSchedule } from "../../types/scheduledEventTypes"

export function getRepetitonInfo(description: string): RepetitonInfo {

	const lines = description.split(`\n`)
	const repetitionString = lines.find(x => x.startsWith('$rep:'))
	if (!repetitionString)
		throw new Error('Cant find repetition string')
	const schedule: supportedSchedule = determineSchedule(repetitionString)
	const { totalAmount, alreadyOccured } = determineRepetitionCount(repetitionString)
	return {
		totalAmount,
		alreadyOccured,
		schedule
	}
}

export function determineSchedule(repetitionLine: string): supportedSchedule {
	const segments = repetitionLine.split(':')
	const scheduleSegment = segments[1]
	const easilyKnownScheduleName = findInScheduleTypes(scheduleSegment)
	if (easilyKnownScheduleName)
		return easilyKnownScheduleName
	else
		throw new Error('Inferring schedule names is not yet supported')
}

export function determineRepetitionCount(description: string): { totalAmount: number; alreadyOccured: number } {
	const segments = description.split(':')
	const amountSegment = segments[2]
	const amounts = amountSegment.split('/')
	return { totalAmount: Number(amounts[1]) ?? 0, alreadyOccured: Number(amounts[0]) ?? 0 }
}

export function buildNewRepetitionString(repetitionInfo: RepetitonInfo) {
	return `$rep:${repetitionInfo.schedule}:${repetitionInfo.alreadyOccured + 1}/${repetitionInfo.totalAmount}`
}

export function addRepetitonStringToEventDescription(oldguildScheduledEvent: string, newRepetitonString: string): string | undefined {
	const lines = oldguildScheduledEvent.split(`\n`)
	const repLineIndex = lines.findIndex(x => x.startsWith('$rep:'))
	const newLines = lines.filter((_, index) => repLineIndex !== index)
	newLines.push(newRepetitonString)
	return newLines.join('\n')
}

export function getNewScheduledStart(oldguildScheduledEvent: GuildScheduledEvent<"SCHEDULED" | "ACTIVE" | "COMPLETED" | "CANCELED">, rInfo: RepetitonInfo): DateResolvable {
	const oldDate = oldguildScheduledEvent.scheduledStartAt
	let daysToAdd = 0
	switch (rInfo.schedule) {
		case 'daily':
			daysToAdd = 1
			break
		case 'weekly':
			daysToAdd = 7
			break
		default:
			throw new Error('No schedule found, cant add days')
	}
	const duration: Duration = {
		days: daysToAdd
	}
	const newDate = add(oldDate, duration)
	return newDate
}