import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

browser/components/translation/YandexTranslator.jsm

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+/* 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";
+
+const {classes: Cc, interfaces: Ci, utils: Cu} = Components;
+
+this.EXPORTED_SYMBOLS = [ "YandexTranslator" ];
+
+Cu.import("resource://gre/modules/Services.jsm");
+Cu.import("resource://gre/modules/Log.jsm");
+Cu.import("resource://gre/modules/Promise.jsm");
+Cu.import("resource://gre/modules/Task.jsm");
+Cu.import("resource://services-common/utils.js");
+Cu.import("resource://gre/modules/Http.jsm");
+
+// The maximum amount of net data allowed per request on Bing's API.
+const MAX_REQUEST_DATA = 5000; // Documentation says 10000 but anywhere
+                               // close to that is refused by the service.
+
+// The maximum number of chunks allowed to be translated in a single
+// request.
+const MAX_REQUEST_CHUNKS = 1000; // Documentation says 2000.
+
+// Self-imposed limit of 15 requests. This means that a page that would need
+// to be broken in more than 15 requests won't be fully translated.
+// The maximum amount of data that we will translate for a single page
+// is MAX_REQUESTS * MAX_REQUEST_DATA.
+const MAX_REQUESTS = 15;
+
+const YANDEX_RETURN_CODE_OK = 200;
+
+const YANDEX_ERR_KEY_INVALID               = 401; // Invalid API key
+const YANDEX_ERR_KEY_BLOCKED               = 402; // This API key has been blocked
+const YANDEX_ERR_DAILY_REQ_LIMIT_EXCEEDED  = 403; // Daily limit for requests reached
+const YANDEX_ERR_DAILY_CHAR_LIMIT_EXCEEDED = 404; // Daily limit of chars reached
+const YANDEX_ERR_TEXT_TOO_LONG             = 413; // The text size exceeds the maximum
+const YANDEX_ERR_UNPROCESSABLE_TEXT        = 422; // The text could not be translated
+const YANDEX_ERR_LANG_NOT_SUPPORTED        = 501; // The specified translation direction is not supported
+
+// Errors that should activate the service unavailable handling
+const YANDEX_PERMANENT_ERRORS = [
+  YANDEX_ERR_KEY_INVALID,
+  YANDEX_ERR_KEY_BLOCKED,
+  YANDEX_ERR_DAILY_REQ_LIMIT_EXCEEDED,
+  YANDEX_ERR_DAILY_CHAR_LIMIT_EXCEEDED,
+];
+
+/**
+ * Translates a webpage using Yandex's Translation API.
+ *
+ * @param translationDocument  The TranslationDocument object that represents
+ *                             the webpage to be translated
+ * @param sourceLanguage       The source language of the document
+ * @param targetLanguage       The target language for the translation
+ *
+ * @returns {Promise}          A promise that will resolve when the translation
+ *                             task is finished.
+ */
+this.YandexTranslator = function(translationDocument, sourceLanguage, targetLanguage) {
+  this.translationDocument = translationDocument;
+  this.sourceLanguage = sourceLanguage;
+  this.targetLanguage = targetLanguage;
+  this._pendingRequests = 0;
+  this._partialSuccess = false;
+  this._serviceUnavailable = false;
+  this._translatedCharacterCount = 0;
+};
+
+this.YandexTranslator.prototype = {
+  /**
+   * Performs the translation, splitting the document into several chunks
+   * respecting the data limits of the API.
+   *
+   * @returns {Promise}          A promise that will resolve when the translation
+   *                             task is finished.
+   */
+  translate: function() {
+    return Task.spawn(function *() {
+      let currentIndex = 0;
+      this._onFinishedDeferred = Promise.defer();
+
+      // Let's split the document into various requests to be sent to
+      // Yandex's Translation API.
+      for (let requestCount = 0; requestCount < MAX_REQUESTS; requestCount++) {
+        // Generating the text for each request can be expensive, so
+        // let's take the opportunity of the chunkification process to
+        // allow for the event loop to attend other pending events
+        // before we continue.
+        yield CommonUtils.laterTickResolvingPromise();
+
+        // Determine the data for the next request.
+        let request = this._generateNextTranslationRequest(currentIndex);
+
+        // Create a real request to the server, and put it on the
+        // pending requests list.
+        let yandexRequest = new YandexRequest(request.data,
+                                          this.sourceLanguage,
+                                          this.targetLanguage);
+        this._pendingRequests++;
+        yandexRequest.fireRequest().then(this._chunkCompleted.bind(this),
+                                       this._chunkFailed.bind(this));
+
+        currentIndex = request.lastIndex;
+        if (request.finished) {
+          break;
+        }
+      }
+
+      return this._onFinishedDeferred.promise;
+    }.bind(this));
+  },
+
+  /**
+   * Function called when a request sent to the server completed successfully.
+   * This function handles calling the function to parse the result and the
+   * function to resolve the promise returned by the public `translate()`
+   * method when there are no pending requests left.
+   *
+   * @param   request   The YandexRequest sent to the server
+   */
+  _chunkCompleted: function(yandexRequest) {
+    if (this._parseChunkResult(yandexRequest)) {
+      this._partialSuccess = true;
+      // Count the number of characters successfully translated.
+      this._translatedCharacterCount += yandexRequest.characterCount;
+    }
+
+    this._checkIfFinished();
+  },
+
+  /**
+   * Function called when a request sent to the server has failed.
+   * This function handles deciding if the error is transient or means the
+   * service is unavailable (zero balance on the key or request credentials are
+   * not in an active state) and calling the function to resolve the promise
+   * returned by the public `translate()` method when there are no pending
+   * requests left.
+   *
+   * @param   aError   [optional] The XHR object of the request that failed.
+   */
+  _chunkFailed: function(aError) {
+    if (aError instanceof Ci.nsIXMLHttpRequest) {
+      let body = aError.responseText;
+      let json = { code: 0 };
+      try {
+        json = JSON.parse(body);
+      } catch (e) {}
+
+      if (json.code && YANDEX_PERMANENT_ERRORS.indexOf(json.code) != -1)
+        this._serviceUnavailable = true;
+    }
+
+    this._checkIfFinished();
+  },
+
+  /**
+   * Function called when a request sent to the server has completed.
+   * This function handles resolving the promise
+   * returned by the public `translate()` method when all chunks are completed.
+   */
+  _checkIfFinished: function() {
+    // Check if all pending requests have been
+    // completed and then resolves the promise.
+    // If at least one chunk was successful, the
+    // promise will be resolved positively which will
+    // display the "Success" state for the infobar. Otherwise,
+    // the "Error" state will appear.
+    if (--this._pendingRequests == 0) {
+      if (this._partialSuccess) {
+        this._onFinishedDeferred.resolve({
+          characterCount: this._translatedCharacterCount
+        });
+      } else {
+        let error = this._serviceUnavailable ? "unavailable" : "failure";
+        this._onFinishedDeferred.reject(error);
+      }
+    }
+  },
+
+  /**
+   * This function parses the result returned by Yandex's Translation API,
+   * which returns a JSON result that contains a number of elements. The
+   * API is documented here:
+   * http://api.yandex.com/translate/doc/dg/reference/translate.xml
+   *
+   * @param   request      The request sent to the server.
+   * @returns boolean      True if parsing of this chunk was successful.
+   */
+  _parseChunkResult: function(yandexRequest) {
+    let results;
+    try {
+      let result = JSON.parse(yandexRequest.networkRequest.responseText);
+      if (result.code != 200) {
+        Services.console.logStringMessage("YandexTranslator: Result is " + result.code);
+        return false;
+      }
+      results = result.text
+    } catch (e) {
+      return false;
+    }
+
+    let len = results.length;
+    if (len != yandexRequest.translationData.length) {
+      // This should never happen, but if the service returns a different number
+      // of items (from the number of items submitted), we can't use this chunk
+      // because all items would be paired incorrectly.
+      return false;
+    }
+
+    let error = false;
+    for (let i = 0; i < len; i++) {
+      try {
+        let result = results[i];
+        let root = yandexRequest.translationData[i][0];
+        root.parseResult(result);
+      } catch (e) { error = true; }
+    }
+
+    return !error;
+  },
+
+  /**
+   * This function will determine what is the data to be used for
+   * the Nth request we are generating, based on the input params.
+   *
+   * @param startIndex What is the index, in the roots list, that the
+   *                   chunk should start.
+   */
+  _generateNextTranslationRequest: function(startIndex) {
+    let currentDataSize = 0;
+    let currentChunks = 0;
+    let output = [];
+    let rootsList = this.translationDocument.roots;
+
+    for (let i = startIndex; i < rootsList.length; i++) {
+      let root = rootsList[i];
+      let text = this.translationDocument.generateTextForItem(root);
+      if (!text) {
+        continue;
+      }
+
+      let newCurSize = currentDataSize + text.length;
+      let newChunks = currentChunks + 1;
+
+      if (newCurSize > MAX_REQUEST_DATA ||
+          newChunks > MAX_REQUEST_CHUNKS) {
+
+        // If we've reached the API limits, let's stop accumulating data
+        // for this request and return. We return information useful for
+        // the caller to pass back on the next call, so that the function
+        // can keep working from where it stopped.
+        return {
+          data: output,
+          finished: false,
+          lastIndex: i
+        };
+      }
+
+      currentDataSize = newCurSize;
+      currentChunks = newChunks;
+      output.push([root, text]);
+    }
+
+    return {
+      data: output,
+      finished: true,
+      lastIndex: 0
+    };
+  }
+};
+
+/**
+ * Represents a request (for 1 chunk) sent off to Yandex's service.
+ *
+ * @params translationData  The data to be used for this translation,
+ *                          generated by the generateNextTranslationRequest...
+ *                          function.
+ * @param sourceLanguage    The source language of the document.
+ * @param targetLanguage    The target language for the translation.
+ *
+ */
+function YandexRequest(translationData, sourceLanguage, targetLanguage) {
+  this.translationData = translationData;
+  this.sourceLanguage = sourceLanguage;
+  this.targetLanguage = targetLanguage;
+  this.characterCount = 0;
+}
+
+YandexRequest.prototype = {
+  /**
+   * Initiates the request
+   */
+  fireRequest: function() {
+    return Task.spawn(function *() {
+      // Prepare URL.
+      let url = getUrlParam("https://translate.yandex.net/api/v1.5/tr.json/translate",
+                            "browser.translation.yandex.translateURLOverride");
+
+      // Prepare the request body.
+      let apiKey = getUrlParam("%YANDEX_API_KEY%", "browser.translation.yandex.apiKeyOverride");
+      let params = [
+        ["key", apiKey],
+        ["format", "html"],
+        ["lang", this.sourceLanguage + "-" + this.targetLanguage],
+      ];
+
+      for (let [, text] of this.translationData) {
+        params.push(["text", text]);
+        this.characterCount += text.length;
+      }
+
+      // Set up request options.
+      let deferred = Promise.defer();
+      let options = {
+        onLoad: (function(responseText, xhr) {
+          deferred.resolve(this);
+        }).bind(this),
+        onError: function(e, responseText, xhr) {
+          deferred.reject(xhr);
+        },
+        postData: params
+      };
+
+      // Fire the request.
+      this.networkRequest = httpRequest(url, options);
+
+      return deferred.promise;
+    }.bind(this));
+  }
+};
+
+/**
+ * Fetch an auth token (clientID or client secret), which may be overridden by
+ * a pref if it's set.
+ */
+function getUrlParam(paramValue, prefName) {
+  if (Services.prefs.getPrefType(prefName))
+    paramValue = Services.prefs.getCharPref(prefName);
+  paramValue = Services.urlFormatter.formatURL(paramValue);
+  return paramValue;
+}