export class API extends EventTarget {

	constructor() {
		super();

		this.#socketOpen();
	}

	/** @type {WebSocket} */
	#socket;

	/**
	 * Opens a new websocket connection, and adds all necessary listeners.
	 */
	#socketOpen() {
		this.#socket = new WebSocket("ws://" + location.host + "/ws");

		this.#socket.onopen = event => {
			console.log(`Websocket connection opened.`)
		}

		this.#socket.onmessage = event => {
			/** @type {{type: string, payload: any}} */
			const data = JSON.parse(event.data);

			switch (data.type) {
				case "QueueDeleteAt": {
					/** @type {CustomEventInit<import("./model").APIPacketQueueDeleteAt>} */
					const eventData = { detail: data.payload };
					this.dispatchEvent(new CustomEvent("queuedeleteat", eventData));
					break;
				}
				case "QueueInsertAt": {
					/** @type {CustomEventInit<import("./model").APIPacketQueueInsertAt>} */
					const eventData = { detail: data.payload };
					this.dispatchEvent(new CustomEvent("queueinsertat", eventData));
					break;
				}
				case "QueueReplace": {
					/** @type {CustomEventInit<import("./model").APIPacketQueueReplace>} */
					const eventData = { detail: data.payload };
					this.dispatchEvent(new CustomEvent("queuereplace", eventData));
					break;
				}
				case "QueueShiftAt": {
					/** @type {CustomEventInit<import("./model").APIPacketQueueShift>} */
					const eventData = { detail: data.payload };
					this.dispatchEvent(new CustomEvent("queueshiftat", eventData));
					break;
				}
				default:
					console.error(`Unknown websocket data type "${data.type}"`);
					break;
			}
		}

		this.#socket.onclose = event => {
			console.log(`Socket is closed. Reconnect will be attempted in 1 second. Code: ${event.code} Reason: ${event.reason} WasClean: ${event.wasClean}.`);
			setTimeout(() => {
				this.#socketOpen();
			}, 1000);
		};

		this.#socket.onerror = event => {
			console.error(`Socket encountered error: ${event}. Closing socket.`);
			this.#socket.close();
		};
	}

	/**
	 * Sends a document queue delete request to the server.
	 * @param {...number} ids Document ids.
	 */
	queueDelete(...ids) {
		if (this.#socket.readyState !== WebSocket.OPEN) {
			return
		}

		/** @type {{type: string, payload: import("./model").APIPacketQueueDelete}} */
		const message = { type: "QueueDelete", payload: { ids: ids } };
		this.#socket.send(JSON.stringify(message));
	}

	/**
	 * Sends a document queue shift request to the server.
	 * @param {number} offset
	 * @param {...number} ids Document ids.
	 */
	queueShift(offset, ...ids) {
		if (this.#socket.readyState !== WebSocket.OPEN) {
			return
		}

		/** @type {{type: string, payload: import("./model").APIPacketQueueShift}} */
		const message = { type: "QueueShift", payload: { offset: offset, ids: ids } };
		this.#socket.send(JSON.stringify(message));
	}

	/**
	 * 
	 * @param {"GET"|"POST"|"DELETE"|"UPDATE"} method 
	 * @param {string} url 
	 */
	#ajaxRequest(method, url) {
		return new Promise(function (resolve, reject) {
			const xhr = new XMLHttpRequest();
			xhr.open(method, url);
			xhr.onload = function () {
				if (this.status >= 200 && this.status < 300) {
					resolve(this.response);
				} else {
					reject({
						status: this.status,
						statusText: this.statusText,
					});
				}
			};
			xhr.onerror = function () {
				reject({
					status: this.status,
					statusText: this.statusText,
				});
			};
			xhr.send();
		});
	}

}