Modernize gtranslate scraper

src/background/background.ts

@@ -8,7 +8,7 @@ let con = new BackgroundMessenger();
 
 const scraper = new GTranslateScraper();
 con.addMessageListener("translate", async (toTranslate, sender) =>
-	scraper.translate(toTranslate, await getCurrentLanguages(), sender.tab?.id)
+	scraper.translate(toTranslate, await getCurrentLanguages(), sender!.tab?.id)
 );
 
 con.addMessageListener("getLanguages", () => scraper.languages);
@@ -62,8 +62,8 @@ const injectScript = async (tabID: number, enabled?: boolean) => {
 
 con.addMessageListener(
 	"setEnabled",
-	async (v: boolean, s: Runtime.MessageSender) => {
-		const tab = await getTabID(s);
+	async (v: boolean, s?: Runtime.MessageSender) => {
+		const tab = await getTabID(s!);
 		if ((await isEnabledSession(tab)) == v) return;
 
 		injectScript(tab);

src/background/gtranslate_content_script.ts

@@ -1,4 +1,4 @@
-import { browser } from "webextension-polyfill-ts";
+import { ContentScriptMessenger } from "./gtranslate_commands";
 
 export enum MessageKinds {
 	translationFinished = "translation",
@@ -18,11 +18,7 @@ export type Message = TranslationMessage | LanguageListMessage;
 	if (window.location.host != "translate.google.com" || window.hasRun) return;
 	window.hasRun = true;
 
-	const conn = browser.runtime.connect(<any>{
-		name: "gtranslate_scraper_conn",
-	});
-
-	const sendMessage = (m: Message) => conn.postMessage(m);
+	const conn = new ContentScriptMessenger();
 
 	const src = <HTMLTextAreaElement>document.querySelector("textarea#source");
 	const result = <HTMLDivElement>(
@@ -39,7 +35,6 @@ export type Message = TranslationMessage | LanguageListMessage;
 	const isTranslating = () => result.classList.contains("translating");
 
 	const observer = new MutationObserver((mutations) => {
-		console.log(mutations);
 		const wasTranslating = mutations.some((m) =>
 			m.oldValue!.split(" ").some((c) => c == "translating")
 		);
@@ -54,22 +49,19 @@ export type Message = TranslationMessage | LanguageListMessage;
 	});
 
 	const sendTranslation = () => {
-		sendMessage({
-			messageKind: MessageKinds.translationFinished,
-			translation: {
-				src: src.value,
-				result: result.innerText.trim(),
-				languages: {
-					srcLang: srcLang,
-					dstLang: dstLang,
-				},
+		conn.runCommand("translationFinished", {
+			src: src.value,
+			result: result.innerText.trim(),
+			languages: {
+				srcLang: srcLang,
+				dstLang: dstLang,
 			},
 		});
 	};
 
-	conn.onMessage.addListener((to_translate: string) => {
-		if (src.value == to_translate && !isTranslating()) sendTranslation();
-		else src.value = to_translate;
+	conn.addMessageListener("translate", (toTranslate) => {
+		if (src.value == toTranslate && !isTranslating()) sendTranslation();
+		else src.value = toTranslate;
 	});
 
 	const getLanguages = () => {
@@ -83,8 +75,5 @@ export type Message = TranslationMessage | LanguageListMessage;
 			return { code: code!, name: name! };
 		});
 	};
-	sendMessage({
-		messageKind: MessageKinds.languageList,
-		languages: getLanguages(),
-	});
+	conn.runCommand("languageList", getLanguages());
 })();

src/background/gtranslate_scraper.ts

@@ -1,6 +1,6 @@
 import { browser, WebRequest, Runtime } from "webextension-polyfill-ts";
 import content_script from "./gtranslate_content_script.ts?file";
-import { Message, MessageKinds } from "./gtranslate_content_script";
+import { BackgroundMessenger } from "./gtranslate_commands";
 import { newPromise } from "../utils";
 
 interface TranslationRequest {
@@ -12,42 +12,50 @@ interface TranslationRequest {
 }
 
 export class GTranslateScraper {
-	private conn?: Runtime.Port;
 	private queue: Array<TranslationRequest> = [];
+	private current?: TranslationRequest;
 	private iframe = <HTMLIFrameElement>document.createElement("iframe");
+	private current_lang: LanguagePair | undefined;
+
 	languages: Promise<Array<Language>>;
-	lang: LanguagePair | undefined;
+	msg: BackgroundMessenger;
 
 	constructor() {
 		let languagesResolve: (value: Array<Language>) => void;
 		[this.languages, languagesResolve] = newPromise<Array<Language>>();
 
-		browser.runtime.onConnect.addListener((p) => {
-			if (p.name != "gtranslate_scraper_conn") return;
-			this.conn = p;
-			this.processFromQueue(p);
-			p.onMessage.addListener((m: Message) => {
-				switch (m.messageKind) {
-					case MessageKinds.languageList:
-						languagesResolve(m.languages);
-						return;
-					case MessageKinds.translationFinished:
-						this.onTranslationRecieved(m.translation);
-				}
-			});
-		});
-		this.loadIframe("de", "en"); //Sample languages so we can get the language list
+		this.msg = new BackgroundMessenger();
+		this.msg.addMessageListener("languageList", languagesResolve);
+		this.msg.addMessageListener("translationFinished", (trans) =>
+			this.onTranslationRecieved(trans)
+		);
+
+		//This allows us to create the google translate iframe by removing the x-frame-options header
+		browser.webRequest.onHeadersReceived.addListener(
+			allowIFrameAccess,
+			{
+				urls: ["https://translate.google.com/?*"],
+				types: ["sub_frame"],
+			},
+			["blocking", "responseHeaders"]
+		);
+
+		this.ChangeLanguage("de", "en"); //Sample languages so we can get the language list
 	}
 
-	private loadIframe(srcLangCode: string, dstLangCode: string) {
+	private async ChangeLanguage(
+		srcLangCode: string,
+		dstLangCode: string
+	): Promise<void> {
 		if (!document.body.contains(this.iframe))
 			document.body.appendChild(this.iframe);
-		this.conn = undefined;
+
+		const [connectedPromise, onConnected] = newPromise<void>();
 
 		//Registers a temp content script, because we cannot inject scripts into iframes created on the background html page, because they have no tabId
 		browser.contentScripts
 			.register({
-				matches: ["<all_urls>"],
+				matches: ["https://translate.google.com/?*"],
 				allFrames: true,
 				js: [
 					{
@@ -57,39 +65,60 @@ export class GTranslateScraper {
 				runAt: "document_end",
 			})
 			.then((r) => {
-				this.iframe.addEventListener("load", r.unregister, { once: true });
+				this.iframe.addEventListener(
+					"load",
+					() => {
+						r.unregister;
+						this.msg.conn.then(() => onConnected());
+					},
+					{ once: true }
+				);
 				this.iframe.src = `https://translate.google.com/?op=translate&sl=${srcLangCode}&tl=${dstLangCode}`;
 			});
 
-		//This allows us to create the google translate iframe by removing the x-frame-options header
-		browser.webRequest.onHeadersReceived.addListener(
-			allowIFrameAccess,
-			{
-				urls: ["<all_urls>"],
-				types: ["sub_frame"],
-			},
-			["blocking", "responseHeaders"]
-		);
+		return connectedPromise;
 	}
 
 	private onTranslationRecieved(trans: Translation) {
-		const current = this.queue.pop();
-		if (current) current.resolveFn(trans);
-		this.processFromQueue(this.conn!);
+		if (this.current?.toTranslate !== trans.src)
+			//I don't know how to code well so I gotta put in sanity checks like this to make debugging easier
+			console.error(
+				"Current request changed before OnTranslationRecieved was called. This should never happen"
+			);
+		if (this.current) this.current.resolveFn(trans);
+		this.current = undefined;
+		this.processFromQueue();
 	}
 
-	private processFromQueue(conn: Runtime.Port) {
-		const request = this.queue.slice(-1).pop();
-		if (!request) return;
+	private async processFromQueue() {
+		if (this.current) return;
+		this.current = this.queue.pop();
+		if (!this.current) return;
 
-		if (this.lang != request.lang) {
-			this.lang = request.lang;
-
-			this.loadIframe(this.lang.srcLang.code, this.lang.dstLang.code);
-		} else conn.postMessage(request.toTranslate);
+		this.processCurrent();
 	}
 
-	translate(
+	private async processCurrent() {
+		if (!this.current)
+			throw "ProcessCurrent called while current translation request is undefined";
+		const cur = this.current;
+
+		let promise = Promise.resolve();
+		if (this.current_lang != this.current.lang) {
+			this.current_lang = cur.lang;
+
+			promise = this.ChangeLanguage(
+				this.current_lang.srcLang.code,
+				this.current_lang.dstLang.code
+			);
+		}
+		await promise;
+		if (cur == this.current) this.msg.runCommand("translate", cur.toTranslate);
+		else
+			throw "The current request changed while processCurrent was running. This should never happen";
+	}
+
+	async translate(
 		toTranslate: string,
 		langs: LanguagePair,
 		tabID?: number
@@ -119,9 +148,14 @@ export class GTranslateScraper {
 					return true;
 				}
 			});
-		this.queue.push(req);
-		if (this.queue.length == 1 && this.conn) this.processFromQueue(this.conn);
 
+		this.queue.push(req);
+
+		if (this.queue.length == 1 && !this.current) {
+			this.current = this.queue.pop();
+			await this.msg.conn;
+			this.processCurrent();
+		}
 		return promise;
 	}
 }

src/background_frontend_commands.ts

@@ -1,7 +1,7 @@
 import { Communicator, commandFunction, commandList } from "./communicator";
 import { browser } from "webextension-polyfill-ts";
 
-export interface commands extends commandList {
+interface BackgroundCommands extends commandList {
 	setEnabled: setEnabled;
 	getEnabled: getEnabled;
 	translate: translate;
@@ -12,6 +12,10 @@ export interface commands extends commandList {
 	setCurrentLanguages: setCurrentLanguages;
 }
 
+interface FrontendCommands extends commandList {
+	setEnabled: setEnabled;
+}
+
 interface setEnabled extends commandFunction {
 	args: boolean;
 }
@@ -46,14 +50,17 @@ interface setCurrentLanguages extends commandFunction {
 	args: Partial<LanguagePair>;
 }
 
-export class BackgroundMessenger extends Communicator<commands> {
+export class BackgroundMessenger extends Communicator<
+	BackgroundCommands,
+	FrontendCommands
+> {
 	constructor() {
 		super();
 		browser.runtime.onMessage.addListener((m, s) => this.onMessage(m, s));
 	}
-	runCommand<K extends keyof commands>(
+	runCommand<K extends keyof BackgroundCommands>(
 		command: K,
-		args: commands[K]["args"],
+		args: BackgroundCommands[K]["args"],
 		tabID: number
 	) {
 		const msg = this.getCommandMessage(command, args);
@@ -61,16 +68,19 @@ export class BackgroundMessenger extends Communicator<commands> {
 	}
 }
 
-export class FrontendMessenger extends Communicator<commands> {
+export class FrontendMessenger extends Communicator<
+	FrontendCommands,
+	BackgroundCommands
+> {
 	constructor() {
 		super();
 		browser.runtime.onMessage.addListener((m, s) => this.onMessage(m, s));
 	}
 
-	runCommand<K extends keyof commands>(
+	runCommand<K extends keyof BackgroundCommands>(
 		command: K,
-		args: commands[K]["args"]
-	): commands[K]["return"] {
+		args: BackgroundCommands[K]["args"]
+	): BackgroundCommands[K]["return"] {
 		const message = this.getCommandMessage(command, args);
 		return browser.runtime.sendMessage(message);
 	}

src/communicator.ts

@@ -16,35 +16,47 @@ interface commandMessage<T extends commandList, K extends keyof T> {
 
 declare type listener<T extends commandList, K extends keyof T> = (
 	args: T[K]["args"],
-	s: Runtime.MessageSender
-) => Promise<T[K]["return"]>;
+	s?: Runtime.MessageSender
+) => Promise<T[K]["return"]> | T[K]["return"];
 
-export abstract class Communicator<T extends commandList> {
-	private listeners = new Map<keyof T, listener<T, keyof T>>();
+export abstract class Communicator<
+	RecvCommands extends commandList,
+	SendCommands extends commandList
+> {
+	private listeners = new Map<
+		keyof RecvCommands,
+		listener<RecvCommands, keyof RecvCommands>
+	>();
 
-	abstract runCommand<K extends keyof T>(
+	abstract async runCommand<K extends keyof SendCommands>(
 		command: K,
-		args: T[K]["args"],
+		args: SendCommands[K]["args"],
 		...rest: any[]
-	): Promise<T[K]["return"]>;
+	): Promise<SendCommands[K]["return"]>;
 
-	addMessageListener<K extends keyof T>(command: K, callback: listener<T, K>) {
+	addMessageListener<K extends keyof RecvCommands>(
+		command: K,
+		callback: listener<RecvCommands, K>
+	) {
 		this.listeners.set(command, <any>callback);
 	}
 
-	getCommandMessage<K extends keyof T>(
+	protected getCommandMessage<K extends keyof RecvCommands>(
 		command: K,
-		...args: T[K]["args"]
-	): commandMessage<T, K> {
+		...args: RecvCommands[K]["args"]
+	): commandMessage<RecvCommands, K> {
 		return { name: command, args: args };
 	}
 
-	onMessage<K extends keyof T>(
-		m: commandMessage<T, K>,
-		s: Runtime.MessageSender
+	protected onMessage<K extends keyof RecvCommands>(
+		m: commandMessage<RecvCommands, K>,
+		s?: Runtime.MessageSender
 	) {
 		let listener = this.listeners.get(m.name);
-		let args: [T[keyof T]["args"], Runtime.MessageSender] = m.args;
+		let args: [
+			RecvCommands[keyof RecvCommands]["args"],
+			Runtime.MessageSender
+		] = m.args;
 		if (args[0] === undefined) args.pop();
 		args.push(s);
 		if (listener) return listener.apply(null, args);