import { defineStore } from 'pinia'
import { computed, ref } from 'vue'
import { ApiError } from '@/composables/useApi'
import { useUpdate, type RestartKind, type UpdateStatus } from '@/composables/useUpdate'
import { displayVersion } from '@/lib/updateFormat'
import { reloadPage } from '@/lib/reloadPage'
import {
	clearRestartMemory,
	isLaterThan,
	readRestartMemory,
	writeRestartMemory,
} from '@/lib/restartMemory'
import { useSessionStore } from '@/stores/session'

export type UpdateLoadState = 'idle' | 'loading' | 'ready' | 'error'
export type UpdateCheckPhase = 'idle' | 'checking' | 'failed' | 'limited'
export type UpdateCheckResult = 'updated' | 'failed' | 'limited' | 'forbidden' | 'busy'
export type UpdateApplyPhase = 'idle' | 'starting' | 'failed' | 'untrusted' | 'limited'
export type UpdateStartResult =
	| 'started'
	| 'failed'
	| 'untrusted'
	| 'limited'
	| 'forbidden'
	| 'nothing'
	| 'conflict'
	| 'busy'

export type RestartRequestResult = 'started' | 'failed' | 'forbidden' | 'conflict' | 'unauthorized'

export interface RestartRun {
	kind: RestartKind | null
	startedAt: string
	version: string
}

export type RestartOutcome = 'updated' | 'rolled-back' | 'restarted'

export const DISMISSED_VERSION_KEY = 'renewcms:update-dismissed'
const DEFAULT_RETRY_SECONDS = 60
const RESTART_POLL_INTERVAL_MS = 1000
const RESTART_SLOW_AFTER_SECONDS = 60

function readDismissedVersion() {
	try {
		return localStorage.getItem(DISMISSED_VERSION_KEY)
	} catch {
		return null
	}
}

function writeDismissedVersion(version: string) {
	try {
		localStorage.setItem(DISMISSED_VERSION_KEY, version)
	} catch {
		return
	}
}

export const useUpdateStore = defineStore('update', () => {
	const session = useSessionStore()
	const status = ref<UpdateStatus | null>(null)
	const loadState = ref<UpdateLoadState>('idle')
	const phase = ref<UpdateCheckPhase>('idle')
	const applyPhase = ref<UpdateApplyPhase>('idle')
	const retryAfter = ref(0)
	const dismissedVersion = ref<string | null>(readDismissedVersion())
	let pendingLoad: Promise<void> | null = null

	const isOwner = computed(() => session.session?.role === 'owner')
	const available = computed(() => status.value?.available === true)
	const showCue = computed(() => isOwner.value && available.value)
	const restarting = computed(() => status.value?.state === 'restarting')
	const bannerVisible = computed(
		() => showCue.value && !restarting.value && status.value?.latest !== dismissedVersion.value,
	)
	const jobRunning = computed(
		() =>
			isOwner.value &&
			status.value?.can_apply === true &&
			(status.value.state === 'downloading' || status.value.state === 'verifying'),
	)
	const readyToInstall = computed(() => isOwner.value && status.value?.state === 'ready')
	const restartRun = ref<RestartRun | null>(null)
	const restartSlow = ref(false)
	const restartNow = ref(Date.now())
	let restartTimer: ReturnType<typeof setInterval> | null = null
	let restartInFlight = false
	let restartSilentSeconds = 0
	let restartReloaded = false

	function load() {
		if (pendingLoad) {
			return pendingLoad
		}
		const { getUpdateStatus } = useUpdate()
		loadState.value = 'loading'
		if (applyPhase.value !== 'starting') {
			applyPhase.value = 'idle'
		}
		pendingLoad = Promise.resolve()
			.then(getUpdateStatus)
			.then((result) => {
				status.value = result
				loadState.value = 'ready'
			})
			.catch(() => {
				loadState.value = status.value === null ? 'error' : 'ready'
			})
			.finally(() => {
				pendingLoad = null
			})
		return pendingLoad
	}

	let pendingPoll = false

	async function poll() {
		if (pendingPoll) {
			return
		}
		const { getUpdateStatus } = useUpdate()
		pendingPoll = true
		try {
			status.value = await getUpdateStatus()
		} catch {
			return
		} finally {
			pendingPoll = false
		}
	}

	async function startDownload(): Promise<UpdateStartResult> {
		if (applyPhase.value === 'starting') {
			return 'busy'
		}
		const { startUpdateDownload } = useUpdate()
		applyPhase.value = 'starting'
		try {
			status.value = await startUpdateDownload()
			loadState.value = 'ready'
			applyPhase.value = 'idle'
			return 'started'
		} catch (error) {
			return settleStartFailure(error)
		}
	}

	function settleStartFailure(error: unknown): UpdateStartResult {
		const outcomes: Record<number, UpdateStartResult> = {
			400: 'nothing',
			403: 'forbidden',
			409: 'conflict',
			422: 'untrusted',
			429: 'limited',
		}
		const outcome = error instanceof ApiError ? outcomes[error.status] : undefined
		if (outcome === 'limited' && error instanceof ApiError) {
			retryAfter.value = error.retryAfter ?? DEFAULT_RETRY_SECONDS
		}
		const phases: Partial<Record<UpdateStartResult, UpdateApplyPhase>> = {
			limited: 'limited',
			untrusted: 'untrusted',
		}
		const result = outcome ?? 'failed'
		applyPhase.value = phases[result] ?? (result === 'failed' ? 'failed' : 'idle')
		return result
	}

	async function check(): Promise<UpdateCheckResult> {
		if (phase.value === 'checking') {
			return 'busy'
		}
		const { checkForUpdate } = useUpdate()
		phase.value = 'checking'
		try {
			status.value = await checkForUpdate()
			loadState.value = 'ready'
			phase.value = 'idle'
			return 'updated'
		} catch (error) {
			if (error instanceof ApiError && error.status === 429) {
				retryAfter.value = error.retryAfter ?? DEFAULT_RETRY_SECONDS
				phase.value = 'limited'
				return 'limited'
			}
			if (error instanceof ApiError && error.status === 403) {
				phase.value = 'idle'
				return 'forbidden'
			}
			phase.value = 'failed'
			return 'failed'
		}
	}

	async function requestRestart(kind: RestartKind): Promise<RestartRequestResult> {
		const { requestRestart: sendRestart } = useUpdate()
		try {
			const next = await sendRestart(kind)
			status.value = next
			const startedAt = next.started_at ?? new Date().toISOString()
			writeRestartMemory({ kind, started_at: startedAt })
			beginRestart({ kind, startedAt, version: displayVersion(next.latest) })
			return 'started'
		} catch (error) {
			return restartFailure(error)
		}
	}

	function restartFailure(error: unknown): RestartRequestResult {
		const outcomes: Record<number, RestartRequestResult> = {
			401: 'unauthorized',
			403: 'forbidden',
			409: 'conflict',
		}
		return (error instanceof ApiError ? outcomes[error.status] : undefined) ?? 'failed'
	}

	function resumeRestart() {
		if (!isOwner.value || restartRun.value || status.value?.state !== 'restarting') {
			return
		}
		const remembered = readRestartMemory()
		beginRestart({
			kind: remembered?.kind ?? null,
			startedAt: status.value.started_at ?? new Date().toISOString(),
			version: displayVersion(status.value.latest),
		})
	}

	function beginRestart(run: RestartRun) {
		stopRestart()
		restartRun.value = run
		restartSlow.value = false
		restartSilentSeconds = 0
		restartReloaded = false
		restartTimer = setInterval(watchRestart, RESTART_POLL_INTERVAL_MS)
	}

	function stopRestart() {
		if (restartTimer !== null) {
			clearInterval(restartTimer)
			restartTimer = null
		}
		restartRun.value = null
		restartSlow.value = false
	}

	async function watchRestart() {
		if (restartInFlight || !restartRun.value) {
			return
		}
		restartInFlight = true
		const run = restartRun.value
		const { isSiteUp, pollUpdateStatus } = useUpdate()
		try {
			const [siteUp, answer] = await Promise.all([
				isSiteUp(),
				pollUpdateStatus().catch(() => null),
			])
			settleRestartPoll(run, siteUp, answer)
		} finally {
			restartInFlight = false
		}
	}

	function settleRestartPoll(run: RestartRun, siteUp: boolean, answer: UpdateStatus | null) {
		restartNow.value = Date.now()
		restartSilentSeconds = siteUp || answer ? 0 : restartSilentSeconds + 1
		restartSlow.value = restartSilentSeconds >= RESTART_SLOW_AFTER_SECONDS
		if (!siteUp || !answer || answer.state === 'restarting') {
			return
		}
		if (isLaterThan(answer.finished_at, run.startedAt) && !restartReloaded) {
			restartReloaded = true
			reloadPage()
		}
	}

	function settleRememberedRestart(): RestartOutcome | null {
		const remembered = readRestartMemory()
		const current = status.value
		if (!remembered || !current || current.state === 'restarting') {
			return null
		}
		if (!isLaterThan(current.finished_at, remembered.started_at)) {
			return null
		}
		clearRestartMemory()
		if (current.state === 'succeeded') {
			return 'updated'
		}
		if (current.state === 'failed') {
			return 'rolled-back'
		}
		return remembered.kind === 'restart' ? 'restarted' : null
	}

	function dismissBanner() {
		if (status.value) {
			dismissedVersion.value = status.value.latest
			writeDismissedVersion(status.value.latest)
		}
	}

	return {
		status,
		loadState,
		phase,
		applyPhase,
		retryAfter,
		isOwner,
		available,
		showCue,
		bannerVisible,
		jobRunning,
		readyToInstall,
		restarting,
		restartRun,
		restartSlow,
		restartNow,
		requestRestart,
		resumeRestart,
		stopRestart,
		settleRememberedRestart,
		load,
		poll,
		startDownload,
		check,
		dismissBanner,
	}
})