From d3cb45ffd6ca21aa537e71efdec21f9d78eac155 Mon Sep 17 00:00:00 2001
From: plainheart <yhen@all-my-life.cn>
Date: Fri, 12 Feb 2021 13:48:17 +0800
Subject: [PATCH] fix: always determine if the issue is in English according to
 the detected language by Google Translate.

---
 index.js          | 23 ++++++++++++++++++-----
 src/translator.js | 18 +++++++++++++++++-
 2 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/index.js b/index.js
index d0196a4..e8b98c7 100644
--- a/index.js
+++ b/index.js
@@ -211,22 +211,35 @@ async function commentIssue(context, commentText, needTranslate) {
         const filteredTitle = removeCodeAndComment(title);
         const filteredBody = removeCodeAndComment(body);
 
-        const isEnTitle = translator.detectEnglish(filteredTitle);
-        const isEnBody = translator.detectEnglish(filteredBody);
+        let isEnTitle = translator.detectEnglish(filteredTitle);
+        let isEnBody = translator.detectEnglish(filteredBody);
 
         let translatedTitle;
         let translatedBody;
 
+        // if the franc has detected it's English, so no need to translate it.
         if (!isEnTitle) {
             const res = await translator.translate(title);
-            translatedTitle = res && res.translated;
+            if (res) {
+                // determine if it's English according to the detected language by Google Translate
+                isEnTitle = res.lang === 'en';
+                translatedTitle = !isEnTitle && res.translated;
+            }
         }
         if (!isEnBody) {
             const res = await translator.translate(body);
-            translatedBody = res && res.translated;
+            if (res) {
+                isEnBody = res.lang === 'en';
+                translatedBody = !isEnBody && res.translated;
+            }
         }
 
-        if ((!isEnTitle || !isEnBody) && (translatedTitle || translatedBody)) {
+        if ((!isEnTitle || !isEnBody)
+            && (
+                (translatedTitle && translatedTitle !== title)
+                || (translatedBody && translatedBody !== body)
+            )
+        ) {
             const translateTip = replaceAll(
                 text.ISSUE_COMMENT_TRANSLATE_TIP,
                 'AT_ISSUE_AUTHOR',
diff --git a/src/translator.js b/src/translator.js
index 75f89fa..422d8ef 100644
--- a/src/translator.js
+++ b/src/translator.js
@@ -41,14 +41,30 @@ function detectLanguage(text, detectAll) {
     return detectAll ? franc.all(text) : franc(text);
 }
 
+/**
+ * To detect English by franc
+ *
+ * FIXME: Not accurate enough
+ */
 function detectEnglish(text) {
     const lang = detectLanguage(text, true);
     return lang[0][0] === 'eng'
         && (!lang[1] || (lang[1][0] === 'sco' && lang[1][1] > 0.9) || lang[1][1] < 0.9);
 }
 
+/**
+ * To detect English by Google Translate
+ *
+ * FIXME: Accurate enough but it requires network requests.
+ */
+async function detectEnglishByGoogle(text) {
+    const res = await translate(text);
+    return res && res.lang === 'en';
+}
+
 module.exports = {
     translate,
     detectLanguage,
-    detectEnglish
+    detectEnglish,
+    detectEnglishByGoogle
 }