import { defineStore } from 'pinia'
import { ref } from 'vue'
import { ApiError, useApi, type MeAuthor } from '@/composables/useApi'
import type { Access } from '@/lib/permissions'

const REFUSAL_REFRESH_GAP_MS = 5000
const STALE_AFTER_MS = 30000

export type SessionStatus = 'idle' | 'checking' | 'ready' | 'error'

export interface Session {
	id?: number
	verified: boolean
	username?: string
	email?: string
	displayName: string
	access?: Access
	author?: MeAuthor
}

export const useSessionStore = defineStore('session', () => {
	const status = ref<SessionStatus>('idle')
	const session = ref<Session | null>(null)
	let pending: Promise<void> | null = null

	let lastAnswerAt: number | null = null
	let lastAttemptAt: number | null = null

	function check() {
		if (pending) {
			return pending
		}

		status.value = 'checking'
		const { getMe } = useApi()

		pending = getMe()
			.then((result) => {
				session.value = result
				status.value = 'ready'
				lastAnswerAt = Date.now()
			})
			.catch((error) => {
				if (error instanceof ApiError && error.status === 401) {
					session.value = null
					status.value = 'ready'
					return
				}
				status.value = 'error'
			})
			.finally(() => {
				pending = null
			})

		return pending
	}

	function retry() {
		status.value = 'idle'
		return check()
	}

	async function refresh() {
		const { getMe } = useApi()
		lastAttemptAt = Date.now()
		try {
			session.value = await getMe()
			lastAnswerAt = Date.now()
		} catch {
			return
		}
	}

	async function refreshAfterRefusal() {
		if (lastAttemptAt !== null && Date.now() - lastAttemptAt < REFUSAL_REFRESH_GAP_MS) {
			return
		}
		await refresh()
	}

	async function refreshIfStale() {
		if (!session.value || lastAnswerAt === null) {
			return
		}
		if (Date.now() - lastAnswerAt > STALE_AFTER_MS) {
			await refresh()
		}
	}

	function setAuthor(author: MeAuthor | undefined) {
		if (!session.value) {
			return
		}
		session.value = { ...session.value, author }
	}

	function clear() {
		session.value = null
		status.value = 'ready'
	}

	function setDisplayName(displayName: string | null | undefined) {
		if (session.value) {
			session.value = { ...session.value, displayName: displayName ?? '' }
		}
	}

	return {
		status,
		session,
		check,
		retry,
		refresh,
		refreshAfterRefusal,
		refreshIfStale,
		clear,
		setAuthor,
		setDisplayName,
	}
})

export function refreshSessionWhenVisible() {
	document.addEventListener('visibilitychange', () => {
		if (document.visibilityState === 'visible') {
			void useSessionStore().refreshIfStale()
		}
	})
}