import { add } from "date-fns"
import { DateResolvable, GuildScheduledEvent, GuildScheduledEventCreateOptions, InternalDiscordGatewayAdapterCreator } from "discord.js"

export const name = 'guildScheduledEventUpdate'
export function execute(oldguildScheduledEvent: GuildScheduledEvent, newguildScheduledEvent: GuildScheduledEvent) {
	console.dir(oldguildScheduledEvent)
	console.dir(newguildScheduledEvent)

	if (oldguildScheduledEvent.description && repetitionMarkerFound(oldguildScheduledEvent.description)) {
		// valid repeating event
		if (newguildScheduledEvent.status === 'COMPLETED') {
			const repetitionInfo = getRepetitonInfo(oldguildScheduledEvent.description)
			if (needsToBeRepeated(repetitionInfo)) {
				try {

					const newRepetitonString = buildNewRepetitionString(repetitionInfo)
					const newEventOptions: GuildScheduledEventCreateOptions = {
						name: oldguildScheduledEvent.name,
						description: addRepetitonStringToEventDescription(oldguildScheduledEvent.description, newRepetitonString),
						scheduledStartTime: getNewScheduledStart(oldguildScheduledEvent, repetitionInfo),
						privacyLevel: oldguildScheduledEvent.privacyLevel,
						entityType: oldguildScheduledEvent.entityType,
						channel: oldguildScheduledEvent.channel?.id,
						reason: 'Repetition'
					}
					newguildScheduledEvent.guild?.scheduledEvents.create(newEventOptions)
				} catch (err) {
					console.error(err)
				}
			}
		}
	}
}
interface RepetitonInfo {
	startDate?: Date, // If defined will take precedence over repetitonAmount
	endDate?: Date,// If defined will take precedence over repetitonAmount
	totalAmount: number,
	alreadyOccured: number,
	schedule: supportedSchedules
	numberOfDays?: number
}
type supportedSchedules = 'daily' | 'weekly' | 'monthly' | 'everyTwoWeeks' | 'everyNDays'
function getRepetitonInfo(description: string): RepetitonInfo {

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

function needsToBeRepeated(rInfo: RepetitonInfo): boolean {
	return rInfo.alreadyOccured < rInfo.totalAmount
}

function determineSchedule(description: string): supportedSchedules {
	return 'daily'
}

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 }
}

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

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')
}

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
}