const DEFAULT_REMINDER_KEY = 'defaultReminder'

export const AMOUNTS_IN_SECONDS: {
	[type in SavedReminderSettings['type']]: number
} = {
	minutes: 60,
	hours: 60 * 60,
	days: 60 * 60 * 24,
	months: 60 * 60 * 24 * 30,
} as const

interface DefaultReminderSettings {
	enabled: boolean,
	amount: number,
}

interface SavedReminderSettings {
	enabled: boolean,
	amount: number,
	type: 'minutes' | 'hours' | 'days' | 'months',
}

function calculateDefaultReminderSeconds(type: SavedReminderSettings['type'], amount: number): number {
	return amount * (AMOUNTS_IN_SECONDS[type] || 0)
}

export function saveDefaultReminder(enabled: boolean, type: SavedReminderSettings['type'], amount: number) {
	const defaultReminderSeconds = calculateDefaultReminderSeconds(type, amount)
	localStorage.setItem(DEFAULT_REMINDER_KEY, JSON.stringify(<DefaultReminderSettings>{
		enabled,
		amount: defaultReminderSeconds,
	}))
}

export function getDefaultReminderAmount(): number | null {
	const settings = getDefaultReminderSettings()

	return settings?.enabled
		? settings.amount
		: null
}

export function getDefaultReminderSettings(): DefaultReminderSettings | null {
	const s: string | null = window.localStorage.getItem(DEFAULT_REMINDER_KEY)
	if (s === null) {
		return null
	}

	return JSON.parse(s)
}

export function parseSavedReminderAmount(amountSeconds: number): SavedReminderSettings {
	const amountMinutes = amountSeconds / 60
	const settings: SavedReminderSettings = {
		enabled: true, // We're assuming the caller to have checked this properly
		amount: amountMinutes,
		type: 'minutes',
	}

	if ((amountMinutes / 60 / 24) % 30 === 0) {
		settings.amount = amountMinutes / 60 / 24 / 30
		settings.type = 'months'
	} else if ((amountMinutes / 60) % 24 === 0) {
		settings.amount = amountMinutes / 60 / 24
		settings.type = 'days'
	} else if (amountMinutes % 60 === 0) {
		settings.amount = amountMinutes / 60
		settings.type = 'hours'
	}

	return settings
}

export function getSavedReminderSettings(): SavedReminderSettings | null {
	const s = getDefaultReminderSettings()
	if (s === null) {
		return null
	}

	if (!s.enabled) {
		return {
			enabled: false,
			type: 'minutes',
			amount: 0,
		}
	}

	return parseSavedReminderAmount(s.amount)
}