fix: use deepl jsonrpc for free plan translation (#608)

apps/readest-app/src/pages/api/deepl/translate.ts

@@ -2,6 +2,7 @@ import { NextApiRequest, NextApiResponse } from 'next';
 import { corsAllMethods, runMiddleware } from '@/utils/cors';
 import { supabase } from '@/utils/supabase';
 import { getUserPlan } from '@/utils/access';
+import { query as deeplQuery } from '@/utils/deepl';
 
 const DEEPL_FREE_API = 'https://api-free.deepl.com/v2/translate';
 const DEEPL_PRO_API = 'https://api.deepl.com/v2/translate';
@@ -27,8 +28,9 @@ const getDeepLAPIKey = (keys: string | undefined) => {
 const handler = async (req: NextApiRequest, res: NextApiResponse) => {
   const { user, token } = await getUserAndToken(req.headers['authorization']);
   let deeplApiUrl = DEEPL_FREE_API;
+  let userPlan = 'free';
   if (user && token) {
-    const userPlan = getUserPlan(token);
+    userPlan = getUserPlan(token);
     if (userPlan !== 'free') deeplApiUrl = DEEPL_PRO_API;
   }
   const deeplAuthKey =
@@ -38,7 +40,16 @@ const handler = async (req: NextApiRequest, res: NextApiResponse) => {
 
   await runMiddleware(req, res, corsAllMethods);
 
+  const { text, source_lang = 'auto', target_lang = 'en' } = req.body;
   try {
+    if (userPlan !== 'pro') {
+      const result = await deeplQuery({
+        text: text[0],
+        sourceLang: source_lang,
+        targetLang: target_lang,
+      });
+      return res.status(200).json(result);
+    }
     const response = await fetch(deeplApiUrl, {
       method: 'POST',
       headers: {

apps/readest-app/src/utils/deepl.ts

@@ -0,0 +1,83 @@
+const API_URL = 'https://www2.deepl.com/jsonrpc';
+const HEADERS = {
+  'Content-Type': 'application/json',
+};
+
+export type RequestParams = {
+  text: string;
+  sourceLang: string;
+  targetLang: string;
+};
+
+export type RawResponseParams = {
+  jsonrpc: string;
+  id: number;
+  result: {
+    texts: {
+      alternatives: {
+        text: string;
+      }[];
+      text: string;
+    }[];
+    lang: string;
+    lang_is_confident: boolean;
+    detectedLanguages: { unsupported: number } & Record<string, number>;
+  };
+};
+
+const buildRequestData = (params: RequestParams) => {
+  const getTimeStamp = () => {
+    const ts = Date.now();
+    const iCount = params.text.split('i').length;
+    return iCount > 1 ? ts - (ts % iCount) + iCount : ts;
+  };
+
+  const postData = {
+    jsonrpc: '2.0',
+    method: 'LMT_handle_texts',
+    id: Math.floor(Math.random() * 90000000) + 10000000,
+    params: {
+      texts: [{ text: params.text, requestAlternatives: 3 }],
+      timestamp: getTimeStamp(),
+      splitting: 'newlines',
+      lang: {
+        source_lang_user_selected: params.sourceLang.toUpperCase(),
+        target_lang: params.targetLang.toUpperCase(),
+      },
+    },
+  };
+
+  let postStr = JSON.stringify(postData);
+
+  if ((postData.id + 5) % 29 === 0 || (postData.id + 3) % 13 === 0) {
+    postStr = postStr.replace('"method":"', '"method" : "');
+  } else {
+    postStr = postStr.replace('"method":"', '"method": "');
+  }
+
+  return postStr;
+};
+
+export const query = async (params: RequestParams) => {
+  const response = await fetch(API_URL, {
+    headers: HEADERS,
+    method: 'POST',
+    body: buildRequestData(params),
+  });
+
+  if (!response.ok) {
+    throw new Error(
+      response.status === 429 ? 'Too many requests, please try again later.' : 'Unknown error.',
+    );
+  }
+
+  const { result } = (await response.json()) as RawResponseParams;
+  return {
+    translations: [
+      {
+        detected_source_language: result?.lang || params?.sourceLang || 'auto',
+        text: result?.texts?.[0]?.text || '',
+      },
+    ],
+  };
+};