declare const _API_URL_: string;

import { EventEmitter } from 'eventemitter3';
import * as ReconnectingWebsocket from 'reconnecting-websocket';

/**
 * Misskey stream connection
 */
export default class Connection extends EventEmitter {
	private state: string;
	private buffer: any[];
	private socket: ReconnectingWebsocket;

	constructor(endpoint, params?) {
		super();

		//#region BIND
		this.onOpen =    this.onOpen.bind(this);
		this.onClose =   this.onClose.bind(this);
		this.onMessage = this.onMessage.bind(this);
		this.send =      this.send.bind(this);
		this.close =     this.close.bind(this);
		//#endregion

		this.state = 'initializing';
		this.buffer = [];

		const host = _API_URL_.replace('http', 'ws');
		const query = params
			? Object.keys(params)
				.map(k => encodeURIComponent(k) + '=' + encodeURIComponent(params[k]))
				.join('&')
			: null;

		this.socket = new ReconnectingWebsocket(`${host}/${endpoint}${query ? '?' + query : ''}`);
		this.socket.addEventListener('open', this.onOpen);
		this.socket.addEventListener('close', this.onClose);
		this.socket.addEventListener('message', this.onMessage);
	}

	/**
	 * Callback of when open connection
	 */
	private onOpen() {
		this.state = 'connected';
		this.emit('_connected_');

		// バッファーを処理
		const _buffer = [].concat(this.buffer); // Shallow copy
		this.buffer = []; // Clear buffer
		_buffer.forEach(message => {
			this.send(message); // Resend each buffered messages
		});
	}

	/**
	 * Callback of when close connection
	 */
	private onClose() {
		this.state = 'reconnecting';
		this.emit('_closed_');
	}

	/**
	 * Callback of when received a message from connection
	 */
	private onMessage(message) {
		try {
			const msg = JSON.parse(message.data);
			if (msg.type) this.emit(msg.type, msg.body);
		} catch (e) {
			// noop
		}
	}

	/**
	 * Send a message to connection
	 */
	public send(message) {
		// まだ接続が確立されていなかったらバッファリングして次に接続した時に送信する
		if (this.state != 'connected') {
			this.buffer.push(message);
			return;
		}

		this.socket.send(JSON.stringify(message));
	}

	/**
	 * Close this connection
	 */
	public close() {
		this.socket.removeEventListener('open', this.onOpen);
		this.socket.removeEventListener('message', this.onMessage);
	}
}
