message.js

import EventEmitter from "events";
import HookEvent from "./hook.js";

/**
 * @typedef {import('./index').default} Ultraviolet
 */

class MessageApi extends EventEmitter {
	/**
	 *
	 * @param {Ultraviolet} ctx
	 */
	constructor(ctx) {
		super();
		this.ctx = ctx;
		this.window = this.ctx.window;
		this.postMessage = this.window.postMessage;
		this.MessageEvent = this.window.MessageEvent || {};
		this.MessagePort = this.window.MessagePort || {};
		this.mpProto = this.MessagePort.prototype || {};
		this.mpPostMessage = this.mpProto.postMessage;
		this.messageProto = this.MessageEvent.prototype || {};
		this.messageData = ctx.nativeMethods.getOwnPropertyDescriptor(
			this.messageProto,
			"data"
		);
		this.messageOrigin = ctx.nativeMethods.getOwnPropertyDescriptor(
			this.messageProto,
			"origin"
		);
	}
	overridePostMessage() {
		this.ctx.override(this.window, "postMessage", (target, that, args) => {
			if (!args.length) return target.apply(that, args);

			let message;
			let origin;
			let transfer;

			if (!this.ctx.worker) {
				[message, origin, transfer = []] = args;
			} else {
				[message, transfer = []] = args;
			}

			const event = new HookEvent(
				{ message, origin, transfer, worker: this.ctx.worker },
				target,
				that
			);
			this.emit("postMessage", event);

			if (event.intercepted) return event.returnValue;
			return this.ctx.worker
				? event.target.call(event.that, event.data.message, event.data.transfer)
				: event.target.call(
						event.that,
						event.data.message,
						event.data.origin,
						event.data.transfer
					);
		});
	}
	wrapPostMessage(obj, prop, noOrigin = false) {
		return this.ctx.wrap(obj, prop, (target, that, args) => {
			if (this.ctx.worker ? !args.length : 2 > args)
				return target.apply(that, args);
			let message;
			let origin;
			let transfer;

			if (!noOrigin) {
				[message, origin, transfer = []] = args;
			} else {
				[message, transfer = []] = args;
				origin = null;
			}

			const event = new HookEvent(
				{ message, origin, transfer, worker: this.ctx.worker },
				target,
				obj
			);
			this.emit("postMessage", event);

			if (event.intercepted) return event.returnValue;
			return noOrigin
				? event.target.call(event.that, event.data.message, event.data.transfer)
				: event.target.call(
						event.that,
						event.data.message,
						event.data.origin,
						event.data.transfer
					);
		});
	}
	overrideMessageOrigin() {
		this.ctx.overrideDescriptor(this.messageProto, "origin", {
			get: (target, that) => {
				const event = new HookEvent({ value: target.call(that) }, target, that);
				this.emit("origin", event);

				if (event.intercepted) return event.returnValue;
				return event.data.value;
			},
		});
	}
	overrideMessageData() {
		this.ctx.overrideDescriptor(this.messageProto, "data", {
			get: (target, that) => {
				const event = new HookEvent({ value: target.call(that) }, target, that);
				this.emit("data", event);

				if (event.intercepted) return event.returnValue;
				return event.data.value;
			},
		});
	}
}

export default MessageApi;