import { EventEmitter } from 'eventemitter3';
import * as riot from 'riot';
import signout from './scripts/signout';
import Progress from './scripts/loading';
import HomeStreamManager from './scripts/streaming/home-stream-manager';
import api from './scripts/api';

declare const _VERSION_: string;
declare const _LANG_: string;
declare const _API_URL_: string;
declare const _SW_PUBLICKEY_: string;

/**
 * Misskey Operating System
 */
export default class MiOS extends EventEmitter {
	/**
	 * Misskeyの /meta で取得できるメタ情報
	 */
	private meta: {
		data: { [x: string]: any };
		chachedAt: Date;
	};

	private isMetaFetching = false;

	/**
	 * A signing user
	 */
	public i: { [x: string]: any };

	/**
	 * Whether signed in
	 */
	public get isSignedin() {
		return this.i != null;
	}

	/**
	 * Whether is debug mode
	 */
	public get debug() {
		return localStorage.getItem('debug') == 'true';
	}

	/**
	 * A connection manager of home stream
	 */
	public stream: HomeStreamManager;

	/**
	 * A registration of service worker
	 */
	private swRegistration: ServiceWorkerRegistration = null;

	/**
	 * Whether should register ServiceWorker
	 */
	private shouldRegisterSw: boolean;

	/**
	 * MiOSインスタンスを作成します
	 * @param shouldRegisterSw ServiceWorkerを登録するかどうか
	 */
	constructor(shouldRegisterSw = false) {
		super();

		this.shouldRegisterSw = shouldRegisterSw;

		//#region BIND
		this.log = this.log.bind(this);
		this.logInfo = this.logInfo.bind(this);
		this.logWarn = this.logWarn.bind(this);
		this.logError = this.logError.bind(this);
		this.init = this.init.bind(this);
		this.api = this.api.bind(this);
		this.getMeta = this.getMeta.bind(this);
		this.registerSw = this.registerSw.bind(this);
		//#endregion
	}

	public log(...args) {
		if (!this.debug) return;
		console.log.apply(null, args);
	}

	public logInfo(...args) {
		if (!this.debug) return;
		console.info.apply(null, args);
	}

	public logWarn(...args) {
		if (!this.debug) return;
		console.warn.apply(null, args);
	}

	public logError(...args) {
		if (!this.debug) return;
		console.error.apply(null, args);
	}

	/**
	 * Initialize MiOS (boot)
	 * @param callback A function that call when initialized
	 */
	public async init(callback) {
		// ユーザーをフェッチしてコールバックする
		const fetchme = (token, cb) => {
			let me = null;

			// Return when not signed in
			if (token == null) {
				return done();
			}

			// Fetch user
			fetch(`${_API_URL_}/i`, {
				method: 'POST',
				body: JSON.stringify({
					i: token
				})
			})
			// When success
			.then(res => {
				// When failed to authenticate user
				if (res.status !== 200) {
					return signout();
				}

				// Parse response
				res.json().then(i => {
					me = i;
					me.token = token;
					done();
				});
			})
			// When failure
			.catch(() => {
				// Render the error screen
				document.body.innerHTML = '<mk-error />';
				riot.mount('*');

				Progress.done();
			});

			function done() {
				if (cb) cb(me);
			}
		};

		// フェッチが完了したとき
		const fetched = me => {
			if (me) {
				riot.observable(me);

				// この me オブジェクトを更新するメソッド
				me.update = data => {
					if (data) Object.assign(me, data);
					me.trigger('updated');
				};

				// ローカルストレージにキャッシュ
				localStorage.setItem('me', JSON.stringify(me));

				// 自分の情報が更新されたとき
				me.on('updated', () => {
					// キャッシュ更新
					localStorage.setItem('me', JSON.stringify(me));
				});
			}

			this.i = me;

			// Init home stream manager
			this.stream = this.isSignedin
				? new HomeStreamManager(this.i)
				: null;

			// Finish init
			callback();

			//#region Post

			// Init service worker
			if (this.shouldRegisterSw) this.registerSw();

			//#endregion
		};

		// Get cached account data
		const cachedMe = JSON.parse(localStorage.getItem('me'));

		// キャッシュがあったとき
		if (cachedMe) {
			// とりあえずキャッシュされたデータでお茶を濁して(?)おいて、
			fetched(cachedMe);

			// 後から新鮮なデータをフェッチ
			fetchme(cachedMe.token, freshData => {
				Object.assign(cachedMe, freshData);
				cachedMe.trigger('updated');
				cachedMe.trigger('refreshed');
			});
		} else {
			// Get token from cookie
			const i = (document.cookie.match(/i=(!\w+)/) || [null, null])[1];

			fetchme(i, fetched);
		}
	}

	/**
	 * Register service worker
	 */
	private registerSw() {
		// Check whether service worker and push manager supported
		const isSwSupported =
			('serviceWorker' in navigator) && ('PushManager' in window);

		// Reject when browser not service worker supported
		if (!isSwSupported) return;

		// Reject when not signed in to Misskey
		if (!this.isSignedin) return;

		// When service worker activated
		navigator.serviceWorker.ready.then(registration => {
			this.log('[sw] ready: ', registration);

			this.swRegistration = registration;

			// Options of pushManager.subscribe
			// SEE: https://developer.mozilla.org/en-US/docs/Web/API/PushManager/subscribe#Parameters
			const opts = {
				// A boolean indicating that the returned push subscription
				// will only be used for messages whose effect is made visible to the user.
				userVisibleOnly: true,

				// A public key your push server will use to send
				// messages to client apps via a push server.
				applicationServerKey: urlBase64ToUint8Array(_SW_PUBLICKEY_)
			};

			// Subscribe push notification
			this.swRegistration.pushManager.subscribe(opts).then(subscription => {
				this.log('[sw] Subscribe OK:', subscription);

				function encode(buffer: ArrayBuffer) {
					return btoa(String.fromCharCode.apply(null, new Uint8Array(buffer)));
				}

				// Register
				this.api('sw/register', {
					endpoint: subscription.endpoint,
					auth: encode(subscription.getKey('auth')),
					publickey: encode(subscription.getKey('p256dh'))
				});
			}).then(() => {
				this.logInfo('[sw] Server Stored Subscription.');
			}).catch(err => {
				this.logError('[sw] Subscribe Error:', err);
			});
		});

		// The path of service worker script
		const sw = `/sw.${_VERSION_}.${_LANG_}.js`;

		// Register service worker
		navigator.serviceWorker.register(sw).then(registration => {
			// 登録成功
			this.logInfo('[sw] Registration successful with scope: ', registration.scope);
		}).catch(err => {
			// 登録失敗 :(
			this.logError('[sw] Registration failed: ', err);
		});
	}

	/**
	 * Misskey APIにリクエストします
	 * @param endpoint エンドポイント名
	 * @param data パラメータ
	 */
	public api(endpoint: string, data?: { [x: string]: any }) {
		return api(this.i, endpoint, data);
	}

	/**
	 * Misskeyのメタ情報を取得します
	 * @param force キャッシュを無視するか否か
	 */
	public getMeta(force = false) {
		return new Promise<{ [x: string]: any }>(async (res, rej) => {
			if (this.isMetaFetching) {
				this.once('_meta_fetched_', () => {
					res(this.meta.data);
				});
				return;
			}

			const expire = 1000 * 60; // 1min

			// forceが有効, meta情報を保持していない or 期限切れ
			if (force || this.meta == null || Date.now() - this.meta.chachedAt.getTime() > expire) {
				this.isMetaFetching = true;
				const meta = await this.api('meta');
				this.meta = {
					data: meta,
					chachedAt: new Date()
				};
				this.isMetaFetching = false;
				this.emit('_meta_fetched_');
				res(meta);
			} else {
				res(this.meta.data);
			}
		});
	}
}

/**
 * Convert the URL safe base64 string to a Uint8Array
 * @param base64String base64 string
 */
function urlBase64ToUint8Array(base64String: string): Uint8Array {
	const padding = '='.repeat((4 - base64String.length % 4) % 4);
	const base64 = (base64String + padding)
		.replace(/\-/g, '+')
		.replace(/_/g, '/');

	const rawData = window.atob(base64);
	const outputArray = new Uint8Array(rawData.length);

	for (let i = 0; i < rawData.length; ++i) {
		outputArray[i] = rawData.charCodeAt(i);
	}
	return outputArray;
}
