Initial version of translate extension.

src/extensions/scratch3_translate/index.js

@@ -0,0 +1,206 @@
+const ArgumentType = require('../../extension-support/argument-type');
+const BlockType = require('../../extension-support/block-type');
+const log = require('../../util/log');
+const nets = require('nets');
+
+// TODO: Change these to the correct icons.
+const blockIconURI = 'https://www.gstatic.com/images/icons/material/system/1x/translate_white_24dp.png';
+const menuIconURI = 'https://www.gstatic.com/images/icons/material/system/1x/translate_grey600_24dp.png';
+
+/**
+ * The url of the translate server.
+ * @type {string}
+ */
+const serverURL = 'https://translate-service.scratch.mit.edu/';
+
+/**
+ * How long to wait in ms before timing out requests to translate server.
+ * @type {int}
+ */
+const serverTimeoutMs = 10000; // 10 seconds (chosen arbitrarily).
+
+/**
+ * Class for the translate-related block in Scratch 3.0
+ * @constructor
+ */
+class Scratch3TranslateBlocks {
+    constructor () {
+        /**
+         * List of supported language name and language code pairs.
+         * @type {Array.<object.<string, string>>}
+         * @private
+         */
+        this._supportedLanguages = null;
+
+        /**
+         * The result from the most recent translation.
+         * @type {string}
+         * @private
+         */
+        this._translateResult = '';
+
+        /**
+         * The language of the text most recently translated.
+         * @type {string}
+         * @private
+         */
+        this._lastLangTranslated = '';
+
+        /**
+         * The text most recently translated.
+         * @type {string}
+         * @private
+         */
+        this._lastTextTranslated = '';
+
+
+        // Kick off the request to get supported languages from the server.
+        this._getSupportedLanguagesFromServer();
+    }
+
+    /**
+     * The key to load & store a target's translate state.
+     * @return {string} The key.
+     */
+    static get STATE_KEY () {
+        return 'Scratch.translate';
+    }
+
+    /**
+     * Makes a request to the translate server to fetch a list of langauges
+     * to fill in the block's language menu.
+     * @private
+     */
+    _getSupportedLanguagesFromServer () {
+        // TODO: Pass through project language instead of English.
+        const url = `${serverURL}supported?language=en`;
+        const langPromise = new Promise(resolve => {
+            nets({
+                method: 'GET',
+                url: url,
+                timeout: serverTimeoutMs,
+                json: {}
+            }, (err, res, body) => {
+                // If we fail to fetch languages, just return an empty list.
+                // TODO: Figure out a reasonable time to retry. Otherwise,
+                // the list stays empty until the extension is reloaded.
+                if (err) {
+                    log.warn(`error fetching language list: ${err}`);
+                    resolve(null);
+                    return;
+                }
+                const langs = body.result;
+                if (!langs) {
+                    log.warn('No result in langauge response.');
+                    resolve(null);
+                    return;
+                }
+                resolve(langs);
+            });
+        });
+        langPromise.then(langs => {
+            if (langs) {
+                this._supportedLanguages =
+                      langs.map(entry => {
+                          const obj = [entry.name, entry.code];
+                          return obj;
+                      });
+            }
+        });
+    }
+
+    /**
+     * List of supported language name and language code pairs.
+     * @return {Array.<object.<string, string>>} The list of language name/code pairs.
+     * @private
+     */
+    _buildLanguageMenu () {
+        if (!this._supportedLanguages) {
+            return [{}];
+        }
+        return this._supportedLanguages;
+    }
+
+    /**
+     * @returns {object} metadata for this extension and its blocks.
+     */
+    getInfo () {
+        return {
+            id: 'translate',
+            name: 'Translate',
+            menuIconURI: menuIconURI,
+            blockIconURI: blockIconURI,
+            blocks: [
+                {
+                    opcode: 'getTranslate',
+                    text: 'translate [WORDS] to [LANGUAGE]',
+                    blockType: BlockType.REPORTER,
+                    arguments: {
+                        WORDS: {
+                            type: ArgumentType.STRING,
+                            defaultValue: 'hello'
+                        },
+                        LANGUAGE: {
+                            type: ArgumentType.STRING,
+                            menu: 'languages'
+
+                        }
+                    }
+                }
+            ],
+            menus: {
+                languages: '_buildLanguageMenu'
+            }
+        };
+    }
+     
+    /**
+     * Translates the text in the translate block to the language specified in the menu.
+     * @param {object} args - the block arguments.
+     * @return {Promise} - a promise that resolves after the response from the translate server.
+     */
+    getTranslate (args) {
+        // Don't remake the request if we already have the value.
+        if (this._lastTextTranslated === args.WORDS &&
+            this._lastLangTranslated === args.LANGUAGE) {
+            return this._translateResult;
+        }
+
+        // TODO: Set default to project language instead of english?
+        let urlBase = `${serverURL}translate?language=`;
+        let lang = 'en';
+        if (args.LANGUAGE) {
+            lang = args.LANGUAGE;
+        }
+
+        urlBase += lang;
+        urlBase += '&text=';
+        urlBase += encodeURIComponent(args.WORDS);
+
+        const tempThis = this;
+        const translatePromise = new Promise(resolve => {
+            nets({
+                url: urlBase,
+                timeout: serverTimeoutMs
+            }, (err, res, body) => {
+                if (err) {
+                    log.warn(`error fetching translate result! ${res}`);
+                    resolve('');
+                    return '';
+                }
+                const translated = JSON.parse(body).result;
+                tempThis._translateResult = translated;
+                // Cache what we just translated so we don't keep making the
+                // same call over and over.
+                tempThis._lastTextTranslated = args.WORDS;
+                tempThis._lastLangTranslated = args.LANGUAGE;
+                resolve(translated);
+                return translated;
+            });
+
+        });
+        translatePromise.then(translatedText => translatedText);
+        return translatePromise;
+    }
+}
+module.exports = Scratch3TranslateBlocks;