1 files changed, 163 insertions, 0 deletions
diff --git a/browser/components/translation/TranslationChild.jsm b/browser/components/translation/TranslationChild.jsm
new file mode 100644
index 0000000000..80a4c48661
--- /dev/null
+++ b/browser/components/translation/TranslationChild.jsm
@@ -0,0 +1,163 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+var EXPORTED_SYMBOLS = ["TranslationChild"];
+
+const lazy = {};
+ChromeUtils.defineESModuleGetters(lazy, {
+  LanguageDetector:
+    "resource://gre/modules/translation/LanguageDetector.sys.mjs",
+});
+
+const STATE_OFFER = 0;
+const STATE_TRANSLATED = 2;
+const STATE_ERROR = 3;
+
+class TranslationChild extends JSWindowActorChild {
+  handleEvent(aEvent) {
+    switch (aEvent.type) {
+      case "pageshow":
+        // We are only listening to pageshow events.
+        let content = this.contentWindow;
+        if (!content.detectedLanguage) {
+          return;
+        }
+
+        let data = {};
+        let trDoc = content.translationDocument;
+        if (trDoc) {
+          data.state = trDoc.translationError ? STATE_ERROR : STATE_TRANSLATED;
+          data.translatedFrom = trDoc.translatedFrom;
+          data.translatedTo = trDoc.translatedTo;
+          data.originalShown = trDoc.originalShown;
+        } else {
+          data.state = STATE_OFFER;
+          data.originalShown = true;
+        }
+        data.detectedLanguage = content.detectedLanguage;
+
+        this.sendAsyncMessage("Translation:DocumentState", data);
+        break;
+
+      case "load":
+        this.checkForTranslation();
+        break;
+    }
+  }
+
+  checkForTranslation() {
+    let url = String(this.document.location);
+    if (!url.startsWith("http://") && !url.startsWith("https://")) {
+      return;
+    }
+
+    let content = this.contentWindow;
+    if (content.detectedLanguage) {
+      return;
+    }
+
+    // Grab a 60k sample of text from the page.
+    let encoder = Cu.createDocumentEncoder("text/plain");
+    encoder.init(this.document, "text/plain", encoder.SkipInvisibleContent);
+    let string = encoder.encodeToStringWithMaxLength(60 * 1024);
+
+    // Language detection isn't reliable on very short strings.
+    if (string.length < 100) {
+      return;
+    }
+
+    lazy.LanguageDetector.detectLanguage(string).then(result => {
+      // Bail if we're not confident.
+      if (!result.confident) {
+        return;
+      }
+
+      // The window might be gone by now.
+      if (Cu.isDeadWrapper(content)) {
+        return;
+      }
+
+      content.detectedLanguage = result.language;
+
+      let data = {
+        state: STATE_OFFER,
+        originalShown: true,
+        detectedLanguage: result.language,
+      };
+      this.sendAsyncMessage("Translation:DocumentState", data);
+    });
+  }
+
+  async doTranslation(aFrom, aTo) {
+    var { TranslationDocument } = ChromeUtils.import(
+      "resource:///modules/translation/TranslationDocument.jsm"
+    );
+
+    // If a TranslationDocument already exists for this document, it should
+    // be used instead of creating a new one so that we can use the original
+    // content of the page for the new translation instead of the newly
+    // translated text.
+    let translationDocument =
+      this.contentWindow.translationDocument ||
+      new TranslationDocument(this.document);
+
+    let engine = Services.prefs.getCharPref("browser.translation.engine");
+    let importScope = ChromeUtils.import(
+      `resource:///modules/translation/${engine}Translator.jsm`
+    );
+    let translator = new importScope[engine + "Translator"](
+      translationDocument,
+      aFrom,
+      aTo
+    );
+
+    this.contentWindow.translationDocument = translationDocument;
+    translationDocument.translatedFrom = aFrom;
+    translationDocument.translatedTo = aTo;
+    translationDocument.translationError = false;
+
+    let result;
+    try {
+      let translateResult = await translator.translate();
+
+      result = {
+        characterCount: translateResult.characterCount,
+        from: aFrom,
+        to: aTo,
+        success: true,
+      };
+
+      translationDocument.showTranslation();
+      return result;
+    } catch (ex) {
+      translationDocument.translationError = true;
+      result = { success: false };
+      if (ex == "unavailable") {
+        result.unavailable = true;
+      }
+    }
+
+    return result;
+  }
+
+  receiveMessage(aMessage) {
+    switch (aMessage.name) {
+      case "Translation:TranslateDocument": {
+        return this.doTranslation(aMessage.data.from, aMessage.data.to);
+      }
+
+      case "Translation:ShowOriginal":
+        this.contentWindow.translationDocument.showOriginal();
+        break;
+
+      case "Translation:ShowTranslation":
+        this.contentWindow.translationDocument.showTranslation();
+        break;
+    }
+
+    return undefined;
+  }
+}