refactor (backend): separate translate function into another file, use post language info for translations, use deepl-node package

packages/backend/package.json

@@ -53,6 +53,7 @@
 		"date-fns": "3.3.1",
 		"decompress": "^4.2.1",
 		"deep-email-validator": "0.1.21",
+		"deepl-node": "1.12.0",
 		"escape-regexp": "0.0.1",
 		"feed": "4.2.2",
 		"file-type": "19.0.0",

packages/backend/src/misc/langmap.ts

@@ -380,3 +380,4 @@ export const iso639Regional = {
 };
 
 export const langmap = Object.assign({}, langmapNoRegion, iso639Regional);
+export type PostLanguage = keyof typeof langmap;

packages/backend/src/misc/translate.ts

@@ -0,0 +1,88 @@
+import fetch from "node-fetch";
+import { Converter } from "opencc-js";
+import { getAgentByUrl } from "@/misc/fetch.js";
+import { fetchMeta } from "@/misc/fetch-meta.js";
+import type { PostLanguage } from "@/misc/langmap";
+import * as deepl from "deepl-node";
+
+function convertChinese(convert: boolean, src: string) {
+	if (!convert) return src;
+	const converter = Converter({ from: "cn", to: "twp" });
+	return converter(src);
+}
+
+function stem(lang: PostLanguage): string {
+	let toReturn = lang as string;
+	if (toReturn.includes("-")) toReturn = toReturn.split("-")[0];
+	if (toReturn.includes("_")) toReturn = toReturn.split("_")[0];
+	return toReturn;
+}
+
+export async function translate(
+	text: string,
+	from: PostLanguage | null,
+	to: PostLanguage,
+) {
+	const instance = await fetchMeta();
+
+	if (instance.deeplAuthKey == null && instance.libreTranslateApiUrl == null) {
+		throw Error("No translator is set up on this server.");
+	}
+
+	const source = from == null ? null : stem(from);
+	const target = stem(to);
+
+	if (instance.libreTranslateApiUrl != null) {
+		const jsonBody = {
+			q: text,
+			source: source ?? "auto",
+			target,
+			format: "text",
+			api_key: instance.libreTranslateApiKey ?? "",
+		};
+
+		const url = new URL(instance.libreTranslateApiUrl);
+		if (url.pathname.endsWith("/")) {
+			url.pathname = url.pathname.slice(0, -1);
+		}
+		if (!url.pathname.endsWith("/translate")) {
+			url.pathname += "/translate";
+		}
+		const res = await fetch(url.toString(), {
+			method: "POST",
+			headers: {
+				"Content-Type": "application/json",
+			},
+			body: JSON.stringify(jsonBody),
+			agent: getAgentByUrl,
+		});
+
+		const json = (await res.json()) as {
+			detectedLanguage?: {
+				confidence: number;
+				language: string;
+			};
+			translatedText: string;
+		};
+
+		return {
+			sourceLang: source ?? json.detectedLanguage?.language,
+			text: convertChinese(
+				["zh-hant", "zh-TW"].includes(to),
+				json.translatedText,
+			),
+		};
+	}
+
+	const deeplTranslator = new deepl.Translator(instance.deeplAuthKey ?? "");
+	const result = await deeplTranslator.translateText(
+		text,
+		source as deepl.SourceLanguageCode | null,
+		(target === "en" ? to : target) as deepl.TargetLanguageCode,
+	);
+
+	return {
+		sourceLang: source ?? result.detectedSourceLang,
+		text: convertChinese(["zh-hant", "zh-TW"].includes(to), result.text),
+	};
+}

packages/backend/src/server/api/endpoints/notes/translate.ts

@@ -1,11 +1,7 @@
-import { URLSearchParams } from "node:url";
-import fetch from "node-fetch";
-import config from "@/config/index.js";
-import { Converter } from "opencc-js";
-import { getAgentByUrl } from "@/misc/fetch.js";
-import { fetchMeta } from "@/misc/fetch-meta.js";
 import { ApiError } from "@/server/api/error.js";
 import { getNote } from "@/server/api/common/getters.js";
+import { translate } from "@/misc/translate.js";
+import type { PostLanguage } from "@/misc/langmap.js";
 import define from "@/server/api/define.js";
 
 export const meta = {
@@ -38,13 +34,6 @@ export const paramDef = {
 	required: ["noteId", "targetLang"],
 } as const;
 
-function convertChinese(convert: boolean, src: string) {
-	if (!convert) return src;
-
-	const converter = Converter({ from: "cn", to: "twp" });
-	return converter(src);
-}
-
 export default define(meta, paramDef, async (ps, user) => {
 	const note = await getNote(ps.noteId, user).catch((err) => {
 		if (err.id === "9725d0ce-ba28-4dde-95a7-2cbb2c15de24")
@@ -56,86 +45,9 @@ export default define(meta, paramDef, async (ps, user) => {
 		return 204;
 	}
 
-	const instance = await fetchMeta();
-
-	if (instance.deeplAuthKey == null && instance.libreTranslateApiUrl == null) {
-		return 204; // TODO: 良い感じのエラー返す
-	}
-
-	let targetLang = ps.targetLang;
-	if (targetLang.includes("-")) targetLang = targetLang.split("-")[0];
-	if (targetLang.includes("_")) targetLang = targetLang.split("_")[0];
-
-	if (instance.libreTranslateApiUrl != null) {
-		const jsonBody = {
-			q: note.text,
-			source: "auto",
-			target: targetLang,
-			format: "text",
-			api_key: instance.libreTranslateApiKey ?? "",
-		};
-
-		const url = new URL(instance.libreTranslateApiUrl);
-		if (url.pathname.endsWith("/")) {
-			url.pathname = url.pathname.slice(0, -1);
-		}
-		if (!url.pathname.endsWith("/translate")) {
-			url.pathname += "/translate";
-		}
-		const res = await fetch(url.toString(), {
-			method: "POST",
-			headers: {
-				"Content-Type": "application/json",
-			},
-			body: JSON.stringify(jsonBody),
-			agent: getAgentByUrl,
-		});
-
-		const json = (await res.json()) as {
-			detectedLanguage?: {
-				confidence: number;
-				language: string;
-			};
-			translatedText: string;
-		};
-
-		return {
-			sourceLang: json.detectedLanguage?.language,
-			text: convertChinese(ps.targetLang === "zh-TW", json.translatedText),
-		};
-	}
-
-	const params = new URLSearchParams();
-	params.append("auth_key", instance.deeplAuthKey ?? "");
-	params.append("text", note.text);
-	params.append("target_lang", targetLang);
-
-	const endpoint = instance.deeplIsPro
-		? "https://api.deepl.com/v2/translate"
-		: "https://api-free.deepl.com/v2/translate";
-
-	const res = await fetch(endpoint, {
-		method: "POST",
-		headers: {
-			"Content-Type": "application/x-www-form-urlencoded",
-			"User-Agent": config.userAgent,
-			Accept: "application/json, */*",
-		},
-		body: params,
-		// TODO
-		//timeout: 10000,
-		agent: getAgentByUrl,
-	});
-
-	const json = (await res.json()) as {
-		translations: {
-			detected_source_language: string;
-			text: string;
-		}[];
-	};
-
-	return {
-		sourceLang: json.translations[0].detected_source_language,
-		text: convertChinese(ps.targetLang === "zh-TW", json.translations[0].text),
-	};
+	return translate(
+		note.text,
+		note.lang as PostLanguage | null,
+		ps.targetLang as PostLanguage,
+	);
 });

pnpm-lock.yaml

@@ -150,6 +150,9 @@ importers:
       deep-email-validator:
         specifier: 0.1.21
         version: 0.1.21
+      deepl-node:
+        specifier: 1.12.0
+        version: 1.12.0
       escape-regexp:
         specifier: 0.0.1
         version: 0.0.1
@@ -7430,6 +7433,18 @@ packages:
     resolution: {integrity: sha512-oIPzksmTg4/MriiaYGO+okXDT7ztn/w3Eptv/+gSIdMdKsJo0u4CfYNFJPy+4SKMuCqGw2wxnA+URMg3t8a/bQ==}
     dev: true
 
+  /deepl-node@1.12.0:
+    resolution: {integrity: sha512-c/8x1R0dXPL7NSDdQ94lYPou/A+I6cbo6b7gFb/28HbjcHnKB4RtWXWLgdv7n51GEXL7OE2eoRZQcAu4ZI+vGg==}
+    engines: {node: '>=12.0'}
+    dependencies:
+      '@types/node': 20.11.21
+      axios: 1.6.7
+      form-data: 3.0.1
+      loglevel: 1.9.1
+    transitivePeerDependencies:
+      - debug
+    dev: false
+
   /deepmerge@4.3.1:
     resolution: {integrity: sha512-3sUqbMEc77XqpdNO7FRyRog+eW3ph+GYCbj+rK+uYyRMuwsVy0rMiVtPn+QJlKFvWP/1PYpapqYn0Me2knFn+A==}
     engines: {node: '>=0.10.0'}
@@ -9416,6 +9431,15 @@ packages:
     engines: {node: '>= 18'}
     dev: false
 
+  /form-data@3.0.1:
+    resolution: {integrity: sha512-RHkBKtLWUVwd7SqRIvCZMEvAMoGUp0XU+seQiZejj0COz3RI3hWP4sCv3gZWWLjJTd7rGwcsF5eKZGii0r/hbg==}
+    engines: {node: '>= 6'}
+    dependencies:
+      asynckit: 0.4.0
+      combined-stream: 1.0.8
+      mime-types: 2.1.35
+    dev: false
+
   /form-data@4.0.0:
     resolution: {integrity: sha512-ETEklSGi5t0QMZuiXoA/Q6vcnxcLQP5vdugSpuAyi6SVGi2clPPp+xgEhuMaHC+zGgn31Kd235W35f7Hykkaww==}
     engines: {node: '>= 6'}
@@ -12254,6 +12278,11 @@ packages:
       is-unicode-supported: 0.1.0
     dev: true
 
+  /loglevel@1.9.1:
+    resolution: {integrity: sha512-hP3I3kCrDIMuRwAwHltphhDM1r8i55H33GgqjXbrisuJhF4kRhW1dNuxsRklp4bXl8DSdLaNLuiL4A/LWRfxvg==}
+    engines: {node: '>= 0.6.0'}
+    dev: false
+
   /lowercase-keys@2.0.0:
     resolution: {integrity: sha512-tqNXrS78oMOE73NMxK4EMLQsQowWf8jKooH9g7xPavRT706R6bkQJ6DY2Te7QukaZsulxa30wQ7bk0pm4XiHmA==}
     engines: {node: '>=8'}