//     (c) 2012-2018 Airbnb, Inc.
//
//     polyglot.js may be freely distributed under the terms of the BSD
//     license. For all licensing information, details, and documentation:
//     http://airbnb.github.com/polyglot.js
//
//
// Polyglot.js is an I18n helper library written in JavaScript, made to
// work both in the browser and in Node. It provides a simple solution for
// interpolation and pluralization, based off of Airbnb's
// experience adding I18n functionality to its Backbone.js and Node apps.
//
// Polylglot is agnostic to your translation backend. It doesn't perform any
// translation; it simply gives you a way to manage translated phrases from
// your client- or server-side JavaScript application.
//

'use strict';

var entries = require('object.entries');
var warning = require('warning');
var has = require('hasown');

var warn = function warn(message) {
  warning(false, message);
};

var defaultReplace = String.prototype.replace;
var split = String.prototype.split;

// #### Pluralization methods
// The string that separates the different phrase possibilities.
var delimiter = '||||';

var russianPluralGroups = function (n) {
  var lastTwo = n % 100;
  var end = lastTwo % 10;
  if (lastTwo !== 11 && end === 1) {
    return 0;
  }
  if (2 <= end && end <= 4 && !(lastTwo >= 12 && lastTwo <= 14)) {
    return 1;
  }
  return 2;
};

var defaultPluralRules = {
  // Mapping from pluralization group plural logic.
  pluralTypes: {
    arabic: function (n) {
      // http://www.arabeyes.org/Plural_Forms
      if (n < 3) { return n; }
      var lastTwo = n % 100;
      if (lastTwo >= 3 && lastTwo <= 10) return 3;
      return lastTwo >= 11 ? 4 : 5;
    },
    bosnian_serbian: russianPluralGroups,
    chinese: function () { return 0; },
    croatian: russianPluralGroups,
    french: function (n) { return n >= 2 ? 1 : 0; },
    german: function (n) { return n !== 1 ? 1 : 0; },
    russian: russianPluralGroups,
    lithuanian: function (n) {
      if (n % 10 === 1 && n % 100 !== 11) { return 0; }
      return n % 10 >= 2 && n % 10 <= 9 && (n % 100 < 11 || n % 100 > 19) ? 1 : 2;
    },
    czech: function (n) {
      if (n === 1) { return 0; }
      return (n >= 2 && n <= 4) ? 1 : 2;
    },
    polish: function (n) {
      if (n === 1) { return 0; }
      var end = n % 10;
      return 2 <= end && end <= 4 && (n % 100 < 10 || n % 100 >= 20) ? 1 : 2;
    },
    icelandic: function (n) { return (n % 10 !== 1 || n % 100 === 11) ? 1 : 0; },
    slovenian: function (n) {
      var lastTwo = n % 100;
      if (lastTwo === 1) {
        return 0;
      }
      if (lastTwo === 2) {
        return 1;
      }
      if (lastTwo === 3 || lastTwo === 4) {
        return 2;
      }
      return 3;
    },
    romanian: function (n) {
      if (n === 1) { return 0; }
      var lastTwo = n % 100;
      if (n === 0 || (lastTwo >= 2 && lastTwo <= 19)) { return 1; }
      return 2;
    },
    ukrainian: russianPluralGroups
  },

  // Mapping from pluralization group to individual language codes/locales.
  // Will look up based on exact match, if not found and it's a locale will parse the locale
  // for language code, and if that does not exist will default to 'en'
  pluralTypeToLanguages: {
    arabic: ['ar'],
    bosnian_serbian: ['bs-Latn-BA', 'bs-Cyrl-BA', 'srl-RS', 'sr-RS'],
    chinese: ['id', 'id-ID', 'ja', 'ko', 'ko-KR', 'lo', 'ms', 'th', 'th-TH', 'zh'],
    croatian: ['hr', 'hr-HR'],
    german: ['fa', 'da', 'de', 'en', 'es', 'fi', 'el', 'he', 'hi-IN', 'hu', 'hu-HU', 'it', 'nl', 'no', 'pt', 'sv', 'tr'],
    french: ['fr', 'tl', 'pt-br'],
    russian: ['ru', 'ru-RU'],
    lithuanian: ['lt'],
    czech: ['cs', 'cs-CZ', 'sk'],
    polish: ['pl'],
    icelandic: ['is', 'mk'],
    slovenian: ['sl-SL'],
    romanian: ['ro'],
    ukrainian: ['uk', 'ua']
  }
};

function langToTypeMap(mapping) {
  var ret = {};
  var mappingEntries = entries(mapping);
  for (var i = 0; i < mappingEntries.length; i += 1) {
    var type = mappingEntries[i][0];
    var langs = mappingEntries[i][1];
    for (var j = 0; j < langs.length; j += 1) {
      ret[langs[j]] = type;
    }
  }
  return ret;
}

function pluralTypeName(pluralRules, locale) {
  var langToPluralType = langToTypeMap(pluralRules.pluralTypeToLanguages);
  return langToPluralType[locale]
    || langToPluralType[split.call(locale, /-/, 1)[0]]
    || langToPluralType.en;
}

function pluralTypeIndex(pluralRules, pluralType, count) {
  return pluralRules.pluralTypes[pluralType](count);
}

function createMemoizedPluralTypeNameSelector() {
  var localePluralTypeStorage = {};

  return function (pluralRules, locale) {
    var pluralType = localePluralTypeStorage[locale];

    if (pluralType && !pluralRules.pluralTypes[pluralType]) {
      pluralType = null;
      localePluralTypeStorage[locale] = pluralType;
    }

    if (!pluralType) {
      pluralType = pluralTypeName(pluralRules, locale);

      if (pluralType) {
        localePluralTypeStorage[locale] = pluralType;
      }
    }

    return pluralType;
  };
}

function escape(token) {
  return token.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
}

function constructTokenRegex(opts) {
  var prefix = (opts && opts.prefix) || '%{';
  var suffix = (opts && opts.suffix) || '}';

  if (prefix === delimiter || suffix === delimiter) {
    throw new RangeError('"' + delimiter + '" token is reserved for pluralization');
  }

  return new RegExp(escape(prefix) + '(.*?)' + escape(suffix), 'g');
}

var memoizedPluralTypeName = createMemoizedPluralTypeNameSelector();

var defaultTokenRegex = /%\{(.*?)\}/g;

// ### transformPhrase(phrase, substitutions, locale)
//
// Takes a phrase string and transforms it by choosing the correct
// plural form and interpolating it.
//
//     transformPhrase('Hello, %{name}!', {name: 'Spike'});
//     // "Hello, Spike!"
//
// The correct plural form is selected if substitutions.smart_count
// is set. You can pass in a number instead of an Object as `substitutions`
// as a shortcut for `smart_count`.
//
//     transformPhrase('%{smart_count} new messages |||| 1 new message', {smart_count: 1}, 'en');
//     // "1 new message"
//
//     transformPhrase('%{smart_count} new messages |||| 1 new message', {smart_count: 2}, 'en');
//     // "2 new messages"
//
//     transformPhrase('%{smart_count} new messages |||| 1 new message', 5, 'en');
//     // "5 new messages"
//
// You should pass in a third argument, the locale, to specify the correct plural type.
// It defaults to `'en'` with 2 plural forms.
function transformPhrase(
  phrase,
  substitutions,
  locale,
  tokenRegex,
  pluralRules,
  replaceImplementation
) {
  if (typeof phrase !== 'string') {
    throw new TypeError('Polyglot.transformPhrase expects argument #1 to be string');
  }

  if (substitutions == null) {
    return phrase;
  }

  var result = phrase;
  var interpolationRegex = tokenRegex || defaultTokenRegex;
  var replace = replaceImplementation || defaultReplace;

  // allow number as a pluralization shortcut
  var options = typeof substitutions === 'number' ? { smart_count: substitutions } : substitutions;

  // Select plural form: based on a phrase text that contains `n`
  // plural forms separated by `delimiter`, a `locale`, and a `substitutions.smart_count`,
  // choose the correct plural form. This is only done if `count` is set.
  if (options.smart_count != null && phrase) {
    var pluralRulesOrDefault = pluralRules || defaultPluralRules;
    var texts = split.call(phrase, delimiter);
    var bestLocale = locale || 'en';
    var pluralType = memoizedPluralTypeName(pluralRulesOrDefault, bestLocale);
    var pluralTypeWithCount = pluralTypeIndex(
      pluralRulesOrDefault,
      pluralType,
      options.smart_count
    );

    result = defaultReplace.call(texts[pluralTypeWithCount] || texts[0], /^[^\S]*|[^\S]*$/g, '');
  }

  // Interpolate: Creates a `RegExp` object for each interpolation placeholder.
  result = replace.call(result, interpolationRegex, function (expression, argument) {
    if (!has(options, argument) || options[argument] == null) { return expression; }
    return options[argument];
  });

  return result;
}

// ### Polyglot class constructor
function Polyglot(options) {
  var opts = options || {};
  this.phrases = {};
  this.extend(opts.phrases || {});
  this.currentLocale = opts.locale || 'en';
  var allowMissing = opts.allowMissing ? transformPhrase : null;
  this.onMissingKey = typeof opts.onMissingKey === 'function' ? opts.onMissingKey : allowMissing;
  this.warn = opts.warn || warn;
  this.replaceImplementation = opts.replace || defaultReplace;
  this.tokenRegex = constructTokenRegex(opts.interpolation);
  this.pluralRules = opts.pluralRules || defaultPluralRules;
}

// ### polyglot.locale([locale])
//
// Get or set locale. Internally, Polyglot only uses locale for pluralization.
Polyglot.prototype.locale = function (newLocale) {
  if (newLocale) this.currentLocale = newLocale;
  return this.currentLocale;
};

// ### polyglot.extend(phrases)
//
// Use `extend` to tell Polyglot how to translate a given key.
//
//     polyglot.extend({
//       "hello": "Hello",
//       "hello_name": "Hello, %{name}"
//     });
//
// The key can be any string.  Feel free to call `extend` multiple times;
// it will override any phrases with the same key, but leave existing phrases
// untouched.
//
// It is also possible to pass nested phrase objects, which get flattened
// into an object with the nested keys concatenated using dot notation.
//
//     polyglot.extend({
//       "nav": {
//         "hello": "Hello",
//         "hello_name": "Hello, %{name}",
//         "sidebar": {
//           "welcome": "Welcome"
//         }
//       }
//     });
//
//     console.log(polyglot.phrases);
//     // {
//     //   'nav.hello': 'Hello',
//     //   'nav.hello_name': 'Hello, %{name}',
//     //   'nav.sidebar.welcome': 'Welcome'
//     // }
//
// `extend` accepts an optional second argument, `prefix`, which can be used
// to prefix every key in the phrases object with some string, using dot
// notation.
//
//     polyglot.extend({
//       "hello": "Hello",
//       "hello_name": "Hello, %{name}"
//     }, "nav");
//
//     console.log(polyglot.phrases);
//     // {
//     //   'nav.hello': 'Hello',
//     //   'nav.hello_name': 'Hello, %{name}'
//     // }
//
// This feature is used internally to support nested phrase objects.
Polyglot.prototype.extend = function (morePhrases, prefix) {
  var phraseEntries = entries(morePhrases || {});
  for (var i = 0; i < phraseEntries.length; i += 1) {
    var key = phraseEntries[i][0];
    var phrase = phraseEntries[i][1];
    var prefixedKey = prefix ? prefix + '.' + key : key;
    if (typeof phrase === 'object') {
      this.extend(phrase, prefixedKey);
    } else {
      this.phrases[prefixedKey] = phrase;
    }
  }
};

// ### polyglot.unset(phrases)
// Use `unset` to selectively remove keys from a polyglot instance.
//
//     polyglot.unset("some_key");
//     polyglot.unset({
//       "hello": "Hello",
//       "hello_name": "Hello, %{name}"
//     });
//
// The unset method can take either a string (for the key), or an object hash with
// the keys that you would like to unset.
Polyglot.prototype.unset = function (morePhrases, prefix) {
  if (typeof morePhrases === 'string') {
    delete this.phrases[morePhrases];
  } else {
    var phraseEntries = entries(morePhrases || {});
    for (var i = 0; i < phraseEntries.length; i += 1) {
      var key = phraseEntries[i][0];
      var phrase = phraseEntries[i][1];
      var prefixedKey = prefix ? prefix + '.' + key : key;
      if (typeof phrase === 'object') {
        this.unset(phrase, prefixedKey);
      } else {
        delete this.phrases[prefixedKey];
      }
    }
  }
};

// ### polyglot.clear()
//
// Clears all phrases. Useful for special cases, such as freeing
// up memory if you have lots of phrases but no longer need to
// perform any translation. Also used internally by `replace`.
Polyglot.prototype.clear = function () {
  this.phrases = {};
};

// ### polyglot.replace(phrases)
//
// Completely replace the existing phrases with a new set of phrases.
// Normally, just use `extend` to add more phrases, but under certain
// circumstances, you may want to make sure no old phrases are lying around.
Polyglot.prototype.replace = function (newPhrases) {
  this.clear();
  this.extend(newPhrases);
};

// ### polyglot.t(key, options)
//
// The most-used method. Provide a key, and `t` will return the
// phrase.
//
//     polyglot.t("hello");
//     => "Hello"
//
// The phrase value is provided first by a call to `polyglot.extend()` or
// `polyglot.replace()`.
//
// Pass in an object as the second argument to perform interpolation.
//
//     polyglot.t("hello_name", {name: "Spike"});
//     => "Hello, Spike"
//
// If you like, you can provide a default value in case the phrase is missing.
// Use the special option key "_" to specify a default.
//
//     polyglot.t("i_like_to_write_in_language", {
//       _: "I like to write in %{language}.",
//       language: "JavaScript"
//     });
//     => "I like to write in JavaScript."
//
Polyglot.prototype.t = function (key, options) {
  var phrase, result;
  var opts = options == null ? {} : options;
  if (typeof this.phrases[key] === 'string') {
    phrase = this.phrases[key];
  } else if (typeof opts._ === 'string') {
    phrase = opts._;
  } else if (this.onMissingKey) {
    var onMissingKey = this.onMissingKey;
    result = onMissingKey(
      key,
      opts,
      this.currentLocale,
      this.tokenRegex,
      this.pluralRules,
      this.replaceImplementation
    );
  } else {
    this.warn('Missing translation for key: "' + key + '"');
    result = key;
  }
  if (typeof phrase === 'string') {
    result = transformPhrase(
      phrase,
      opts,
      this.currentLocale,
      this.tokenRegex,
      this.pluralRules,
      this.replaceImplementation
    );
  }
  return result;
};

// ### polyglot.has(key)
//
// Check if polyglot has a translation for given key
Polyglot.prototype.has = function (key) {
  return has(this.phrases, key);
};

// export transformPhrase
Polyglot.transformPhrase = function transform(phrase, substitutions, locale) {
  return transformPhrase(phrase, substitutions, locale);
};

module.exports = Polyglot;