index.js

var querystring = require('querystring');

var got = require('got');
var safeEval = require('safe-eval');

translate.suffix = 'com';

var languages = {
    'auto': 'Automatic',
    'af': 'Afrikaans',
    'sq': 'Albanian',
    'am': 'Amharic',
    'ar': 'Arabic',
    'hy': 'Armenian',
    'az': 'Azerbaijani',
    'eu': 'Basque',
    'be': 'Belarusian',
    'bn': 'Bengali',
    'bs': 'Bosnian',
    'bg': 'Bulgarian',
    'ca': 'Catalan',
    'ceb': 'Cebuano',
    'ny': 'Chichewa',
    'zh-cn': 'Chinese Simplified',
    'zh-tw': 'Chinese Traditional',
    'co': 'Corsican',
    'hr': 'Croatian',
    'cs': 'Czech',
    'da': 'Danish',
    'nl': 'Dutch',
    'en': 'English',
    'eo': 'Esperanto',
    'et': 'Estonian',
    'tl': 'Filipino',
    'fi': 'Finnish',
    'fr': 'French',
    'fy': 'Frisian',
    'gl': 'Galician',
    'ka': 'Georgian',
    'de': 'German',
    'el': 'Greek',
    'gu': 'Gujarati',
    'ht': 'Haitian Creole',
    'ha': 'Hausa',
    'haw': 'Hawaiian',
    'iw': 'Hebrew',
    'hi': 'Hindi',
    'hmn': 'Hmong',
    'hu': 'Hungarian',
    'is': 'Icelandic',
    'ig': 'Igbo',
    'id': 'Indonesian',
    'ga': 'Irish',
    'it': 'Italian',
    'ja': 'Japanese',
    'jw': 'Javanese',
    'kn': 'Kannada',
    'kk': 'Kazakh',
    'km': 'Khmer',
    'ko': 'Korean',
    'ku': 'Kurdish (Kurmanji)',
    'ky': 'Kyrgyz',
    'lo': 'Lao',
    'la': 'Latin',
    'lv': 'Latvian',
    'lt': 'Lithuanian',
    'lb': 'Luxembourgish',
    'mk': 'Macedonian',
    'mg': 'Malagasy',
    'ms': 'Malay',
    'ml': 'Malayalam',
    'mt': 'Maltese',
    'mi': 'Maori',
    'mr': 'Marathi',
    'mn': 'Mongolian',
    'my': 'Myanmar (Burmese)',
    'ne': 'Nepali',
    'no': 'Norwegian',
    'ps': 'Pashto',
    'fa': 'Persian',
    'pl': 'Polish',
    'pt': 'Portuguese',
    'ma': 'Punjabi',
    'ro': 'Romanian',
    'ru': 'Russian',
    'sm': 'Samoan',
    'gd': 'Scots Gaelic',
    'sr': 'Serbian',
    'st': 'Sesotho',
    'sn': 'Shona',
    'sd': 'Sindhi',
    'si': 'Sinhala',
    'sk': 'Slovak',
    'sl': 'Slovenian',
    'so': 'Somali',
    'es': 'Spanish',
    'su': 'Sundanese',
    'sw': 'Swahili',
    'sv': 'Swedish',
    'tg': 'Tajik',
    'ta': 'Tamil',
    'te': 'Telugu',
    'th': 'Thai',
    'tr': 'Turkish',
    'uk': 'Ukrainian',
    'ur': 'Urdu',
    'uz': 'Uzbek',
    'vi': 'Vietnamese',
    'cy': 'Welsh',
    'xh': 'Xhosa',
    'yi': 'Yiddish',
    'yo': 'Yoruba',
    'zu': 'Zulu'
};

function getCode(desiredLang) {
    if (!desiredLang) {
        return false;
    }
    desiredLang = desiredLang.toLowerCase();

    if (languages[desiredLang]) {
        return desiredLang;
    }

    var keys = Object.keys(languages).filter(function (key) {
        if (typeof languages[key] !== 'string') {
            return false;
        }

        return languages[key].toLowerCase() === desiredLang;
    });

    return keys[0] || false;
}

function isSupported(desiredLang) {
    return Boolean(getCode(desiredLang));
}

function translate(text, opts) {
    opts = opts || {};

    var e;
    [opts.from, opts.to].forEach(function (lang) {
        if (lang && !isSupported(lang)) {
            e = new Error();
            e.code = 400;
            e.message = 'The language \'' + lang + '\' is not supported';
        }
    });
    if (e) {
        return new Promise(function (resolve, reject) {
            reject(e);
        });
    }

    opts.from = opts.from || 'auto';
    opts.to = opts.to || 'en';

    opts.from = getCode(opts.from);
    opts.to = getCode(opts.to);
    var url = 'https://translate.google.' + translate.suffix + '/translate_a/single';
    var data = {
        client: 'gtx',
        sl: opts.from,
        tl: opts.to,
        hl: opts.to,
        dt: ['at', 'bd', 'ex', 'ld', 'md', 'qca', 'rw', 'rm', 'ss', 't'],
        ie: 'UTF-8',
        oe: 'UTF-8',
        otf: 1,
        ssel: 0,
        tsel: 0,
        kc: 7
    };
    url = url + '?' + querystring.stringify(data);

    return got(url, { 
        'method': 'POST', 
        'body': {
            q: text
        }
    }).then(function (res) {
        var result = {
            text: '',
            from: {
                language: {
                    didYouMean: false,
                    iso: ''
                },
                text: {
                    autoCorrected: false,
                    value: '',
                    didYouMean: false
                }
            },
            raw: ''
        };

        if (opts.raw) {
            result.raw = res.body;
        }

        var body = safeEval(res.body);
        body[0].forEach(function (obj) {
            if (obj[0]) {
                result.text += obj[0];
            }
        });

        if (body[2] === body[8][0][0]) {
            result.from.language.iso = body[2];
        } else {
            result.from.language.didYouMean = true;
            result.from.language.iso = body[8][0][0];
        }

        if (body[7] && body[7][0]) {
            var str = body[7][0];

            str = str.replace(/<b><i>/g, '[');
            str = str.replace(/<\/i><\/b>/g, ']');

            result.from.text.value = str;

            if (body[7][5] === true) {
                result.from.text.autoCorrected = true;
            } else {
                result.from.text.didYouMean = true;
            }
        }

        return result;
    }).catch(function (err) {
        throw err;
    });
}

module.exports = translate;
module.exports.languages = languages;