import type { IRocketChatRecord } from '@rocket.chat/core-typings';
import type { StreamNames } from '@rocket.chat/ddp-client';
import { isTruthy } from '@rocket.chat/tools';
import localforage from 'localforage';
import { Meteor } from 'meteor/meteor';
import { create, type StoreApi, type UseBoundStore } from 'zustand';

import { baseURI } from '../baseURI';
import { onLoggedIn } from '../loggedIn';
import { CachedStoresManager } from './CachedStoresManager';
import type { IDocumentMapStore } from './DocumentMapStore';
import { withDebouncing } from '../../../lib/utils/highOrderFunctions';
import { sdk } from '../SDKClient';
import { getDdpSdk } from '../sdk/ddpSdk';
import { STORAGE_KEYS, getStoredItem } from '../sdk/storage';
import { getUserId } from '../user';
import { getConfig } from '../utils/getConfig';

type Name = 'rooms' | 'subscriptions' | 'permissions' | 'public-settings' | 'private-settings';

const hasId = <T>(record: T): record is T & { _id: string } => typeof record === 'object' && record !== null && '_id' in record;
const hasUpdatedAt = <T>(record: T): record is T & { _updatedAt: Date } =>
	typeof record === 'object' &&
	record !== null &&
	'_updatedAt' in record &&
	(record as unknown as { _updatedAt: unknown })._updatedAt instanceof Date;
const hasDeletedAt = <T>(record: T): record is T & { _deletedAt: Date } =>
	typeof record === 'object' &&
	record !== null &&
	'_deletedAt' in record &&
	(record as unknown as { _deletedAt: unknown })._deletedAt instanceof Date;
const hasUnserializedUpdatedAt = <T>(record: T): record is T & { _updatedAt: ConstructorParameters<typeof Date>[0] } =>
	typeof record === 'object' &&
	record !== null &&
	'_updatedAt' in record &&
	!((record as unknown as { _updatedAt: unknown })._updatedAt instanceof Date);

localforage.config({ name: baseURI });

export interface IWithManageableCache {
	clearCacheOnLogout(): void;
}

export abstract class CachedStore<T extends IRocketChatRecord, U = T> implements IWithManageableCache {
	private static readonly MAX_CACHE_TIME = 60 * 60 * 24 * 30;

	readonly store: UseBoundStore<StoreApi<IDocumentMapStore<T>>>;

	protected name: Name;

	protected eventType: StreamNames;

	// Bumped from 18 → 19 to invalidate caches populated before the DDPSDK
	// wire encoding was switched from JSON to EJSON. Entries written by the
	// JSON window stored dates as ISO strings instead of Date instances, so
	// fields like subscription.ls would fail `.getTime()` when read back.
	private readonly version = 19;

	private updatedAt = new Date(0);

	protected log: (...args: any[]) => void;

	private timer: ReturnType<typeof setTimeout>;

	readonly useReady = create(() => false);

	constructor({ name, eventType, store }: { name: Name; eventType: StreamNames; store: UseBoundStore<StoreApi<IDocumentMapStore<T>>> }) {
		this.name = name;
		this.eventType = eventType;
		this.store = store;

		this.log = [getConfig(`debugCachedCollection-${this.name}`), getConfig('debugCachedCollection'), getConfig('debug')].includes('true')
			? console.log.bind(console, `%cCachedCollection ${this.name}`, `color: navy; font-weight: bold;`)
			: () => undefined;

		CachedStoresManager.register(this);
	}

	protected get eventName(): `${Name}-changed` | `${string}/${Name}-changed` {
		if (this.eventType === 'notify-user') {
			return `${getUserId()}/${this.name}-changed`;
		}
		return `${this.name}-changed`;
	}

	protected abstract getToken(): unknown;

	private async loadFromCache() {
		const data = await localforage.getItem<{ version: number; token: unknown; records: unknown[]; updatedAt: Date | string }>(this.name);

		if (!data) {
			return false;
		}

		if (data.version < this.version || data.token !== this.getToken()) {
			return false;
		}

		if (data.records.length <= 0) {
			return false;
		}

		// updatedAt may be a Date or a string depending on the used localForage backend
		if (!(data.updatedAt instanceof Date)) {
			data.updatedAt = new Date(data.updatedAt);
		}

		if (Date.now() - data.updatedAt.getTime() >= 1000 * CachedStore.MAX_CACHE_TIME) {
			return false;
		}

		this.log(`${data.records.length} records loaded from cache`);

		const deserializedRecords = data.records.map((record) => this.deserializeFromCache(record)).filter(isTruthy);

		const updatedAt = Math.max(...deserializedRecords.filter(hasUpdatedAt).map((record) => record?._updatedAt.getTime() ?? 0));

		if (updatedAt > this.updatedAt.getTime()) {
			this.updatedAt = new Date(updatedAt);
		}

		this.store.getState().replaceAll(deserializedRecords.filter(hasId));

		this.updatedAt = data.updatedAt || this.updatedAt;

		return true;
	}

	protected deserializeFromCache(record: unknown): T | undefined {
		if (typeof record !== 'object' || record === null) {
			return undefined;
		}

		return {
			...(record as unknown as T),
			...(hasUnserializedUpdatedAt(record) && {
				_updatedAt: new Date(record._updatedAt),
			}),
		};
	}

	private async callLoad() {
		// TODO: workaround for bad function overload
		const data = await sdk.call(`${this.name}/get`);
		return data as unknown as U[];
	}

	private async callSync(updatedSince: Date) {
		// TODO: workaround for bad function overload
		const data = await sdk.call(`${this.name}/get`, updatedSince);
		return data as unknown as { update: U[]; remove: U[] };
	}

	private async loadFromServer() {
		const startTime = new Date();
		const lastTime = this.updatedAt;
		const data = await this.callLoad();
		this.log(`${data.length} records loaded from server`);

		const newRecords = data.map((record) => {
			const mapped = this.mapRecord(record);

			if (hasUpdatedAt(mapped) && mapped._updatedAt > this.updatedAt) {
				this.updatedAt = mapped._updatedAt;
			}

			return mapped;
		});

		this.store.getState().storeMany(newRecords);
		this.handleLoadedFromServer(newRecords);

		this.updatedAt = this.updatedAt === lastTime ? startTime : this.updatedAt;
	}

	protected mapRecord(record: U): T {
		return record as unknown as T;
	}

	protected handleLoadedFromServer(_records: T[]): void {
		// This method can be overridden to handle records after they are loaded from the server
	}

	protected handleSyncEvent(_action: 'removed' | 'changed', _record: T): void {
		// This method can be overridden to handle sync events
	}

	private async loadFromServerAndPopulate() {
		await this.loadFromServer();
		await this.save();
	}

	private save = withDebouncing({ wait: 1000 })(async () => {
		this.log('saving cache');
		await localforage.setItem(this.name, {
			updatedAt: this.updatedAt,
			version: this.version,
			token: this.getToken(),
			records: Array.from(this.store.getState().records.values()),
		});
		this.log('saving cache (done)');
	});

	abstract clearCacheOnLogout(): void;

	protected async clearCache() {
		this.log('clearing cache');
		await localforage.removeItem(this.name);
		this.store.getState().replaceAll([]);
	}

	protected setupListener() {
		return sdk.stream(this.eventType, [this.eventName], (async (action: 'removed' | 'changed', record: U) => {
			this.log('record received', action, record);
			await this.handleRecordEvent(action, record);
		}) as (...args: unknown[]) => void);
	}

	protected async handleRecordEvent(action: 'removed' | 'changed', record: U) {
		const newRecord = this.mapRecord(record);

		if (action === 'removed') {
			this.store.getState().delete(newRecord._id);
		} else {
			this.store.getState().store(newRecord);
		}

		await this.save();
	}

	private trySync(delay = 10) {
		clearTimeout(this.timer);
		// Wait for an empty queue to load data again and sync
		this.timer = setTimeout(async () => {
			if (!(await this.sync())) {
				return this.trySync(delay);
			}
			await this.save();
		}, delay);
	}

	protected async sync() {
		if (!this.updatedAt || this.updatedAt.getTime() === 0 || Meteor.connection._outstandingMethodBlocks.length !== 0) {
			return false;
		}

		const startTime = new Date();
		const lastTime = this.updatedAt;

		this.log(`syncing from ${this.updatedAt}`);

		const data = await this.callSync(this.updatedAt);
		const changes = [];

		if (data.update && data.update.length > 0) {
			this.log(`${data.update.length} records updated in sync`);
			for (const record of data.update) {
				const newRecord = this.mapRecord(record);

				const actionTime = hasUpdatedAt(newRecord) ? newRecord._updatedAt : startTime;
				changes.push({
					action: () => {
						this.store.getState().store(newRecord);
						if (actionTime > this.updatedAt) {
							this.updatedAt = actionTime;
						}
						this.handleSyncEvent('changed', newRecord);
					},
					timestamp: actionTime.getTime(),
				});
			}
		}

		if (data.remove && data.remove.length > 0) {
			this.log(`${data.remove.length} records removed in sync`);
			for (const record of data.remove) {
				const newRecord = this.mapRecord(record);

				if (!hasDeletedAt(newRecord)) {
					continue;
				}

				const actionTime = newRecord._deletedAt;
				changes.push({
					action: () => {
						this.store.getState().delete(newRecord._id);
						if (actionTime > this.updatedAt) {
							this.updatedAt = actionTime;
						}
						this.handleSyncEvent('removed', newRecord);
					},
					timestamp: actionTime.getTime(),
				});
			}
		}

		changes
			.sort((a, b) => a.timestamp - b.timestamp)
			.forEach((c) => {
				c.action();
			});

		this.updatedAt = this.updatedAt === lastTime ? startTime : this.updatedAt;

		return true;
	}

	private listenerUnsubscriber: (() => void) | undefined;

	private async performInitialization() {
		if (await this.loadFromCache()) {
			this.trySync();
		} else {
			await this.loadFromServerAndPopulate();
		}

		this.reconnectionUnsubscribe?.();
		const sdk = getDdpSdk();
		let wentOffline = sdk.connection.status !== 'connected';
		this.reconnectionUnsubscribe = sdk.connection.on('connection', () => {
			if (sdk.connection.status !== 'connected') {
				wentOffline = true;
				return;
			}
			if (wentOffline) {
				wentOffline = false;
				this.trySync();
			}
		});

		const subscription = this.setupListener();
		this.listenerUnsubscriber = () => {
			subscription.stop();
			this.listenerUnsubscriber = undefined;
		};
	}

	private initializationPromise: Promise<void> | undefined;

	init() {
		if (this.initializationPromise) {
			return this.initializationPromise;
		}

		this.initializationPromise = this.performInitialization()
			.catch(console.error)
			.finally(() => {
				this.initializationPromise = undefined;
				this.setReady(true);
			});

		return this.initializationPromise;
	}

	async release() {
		if (this.initializationPromise) {
			await this.initializationPromise;
		}

		this.listenerUnsubscriber?.();
		this.setReady(false);
	}

	private reconnectionUnsubscribe: (() => void) | undefined;

	setReady(ready: boolean) {
		this.useReady.setState(ready);
	}
}

export class PublicCachedStore<T extends IRocketChatRecord, U = T> extends CachedStore<T, U> {
	protected override getToken() {
		return undefined;
	}

	override clearCacheOnLogout() {
		// do nothing
	}
}

export class PrivateCachedStore<T extends IRocketChatRecord, U = T> extends CachedStore<T, U> {
	protected override getToken() {
		return getStoredItem(STORAGE_KEYS.LOGIN_TOKEN);
	}

	override clearCacheOnLogout() {
		void this.clearCache();
	}

	listen() {
		if (process.env.NODE_ENV === 'test') {
			return;
		}

		onLoggedIn(() => {
			void this.init();
		});

		getDdpSdk().account.onLogout(() => {
			this.release();
		});
	}
}