/*global I18n:true */

// Instantiate the object
var I18n = I18n || {};

// Set default locale to english
I18n.defaultLocale = "en";

// Set default pluralization rule
I18n.pluralizationRules = {
  en: function(n) {
    return n === 0 ? ["zero", "none", "other"] : n === 1 ? "one" : "other";
  }
};

// Set current locale to null
I18n.locale = null;

// Set the placeholder format. Accepts `{{placeholder}}` and `%{placeholder}`.
I18n.PLACEHOLDER = /(?:\{\{|%\{)(.*?)(?:\}\}?)/gm;

I18n.SEPARATOR = ".";

I18n.noFallbacks = false;

I18n.isValidNode = function(obj, node, undefined) {
  return obj[node] !== null && obj[node] !== undefined;
};

function checkExtras(origScope, sep, extras) {
  if (!extras || extras.length === 0) { return; }

  for (var i = 0; i < extras.length; i++) {
    var messages = extras[i];
    scope = origScope.split(sep);

    if (scope[0] === 'js') { scope.shift(); }

    while (messages && scope.length > 0) {
      currentScope = scope.shift();
      messages = messages[currentScope];
    }

    if (messages !== undefined) { return messages; }
  }
}

I18n.lookup = function(scope, options) {
  options = options || {};

  var translations = this.prepareOptions(I18n.translations),
      locale = options.locale || I18n.currentLocale(),
      messages = translations[locale] || {},
      currentScope;

  options = this.prepareOptions(options);

  if (typeof scope === "object") {
    scope = scope.join(this.SEPARATOR);
  }

  if (options.scope) {
    scope = options.scope.toString() + this.SEPARATOR + scope;
  }

  var origScope = "" + scope;

  scope = origScope.split(this.SEPARATOR);

  while (messages && scope.length > 0) {
    currentScope = scope.shift();
    messages = messages[currentScope];
  }

  if (messages === undefined) {
    messages = checkExtras(origScope, this.SEPARATOR, this.extras);
  }

  if (messages === undefined) {
    messages = options.defaultValue;
  }

  return messages;
};

// Merge serveral hash options, checking if value is set before
// overwriting any value. The precedence is from left to right.
//
//   I18n.prepareOptions({name: "John Doe"}, {name: "Mary Doe", role: "user"});
//   #=> {name: "John Doe", role: "user"}
//
I18n.prepareOptions = function() {
  var options = {},
      opts,
      count = arguments.length;

  for (var i = 0; i < count; i++) {
    opts = arguments[i];

    if (!opts) {
      continue;
    }

    for (var key in opts) {
      if (!this.isValidNode(options, key)) {
        options[key] = opts[key];
      }
    }
  }

  return options;
};

I18n.interpolate = function(message, options) {
  options = this.prepareOptions(options);

  var matches = message.match(this.PLACEHOLDER),
      placeholder,
      value,
      name;

  if (!matches) { return message; }

  for (var i = 0; placeholder = matches[i]; i++) {
    name = placeholder.replace(this.PLACEHOLDER, "$1");

    value = options[name];

    if (!this.isValidNode(options, name)) {
      value = "[missing " + placeholder + " value]";
    }

    var regex = new RegExp(placeholder.replace(/\{/gm, "\\{").replace(/\}/gm, "\\}"));
    message = message.replace(regex, value);
  }

  return message;
};

I18n.translate = function(scope, options) {
  options = this.prepareOptions(options);

  var translation = this.lookup(scope, options);

  if (!this.noFallbacks) {
    if (!translation && this.currentLocale() !== this.defaultLocale) {
      options.locale = this.defaultLocale;
      translation = this.lookup(scope, options);
    }
    if (!translation && this.currentLocale() !== 'en') {
      options.locale = 'en';
      translation = this.lookup(scope, options);
    }
  }

  try {
    if (typeof translation === "object") {
      if (typeof options.count === "number") {
        return this.pluralize(translation, scope, options);
      } else {
        return translation;
      }
    } else {
      return this.interpolate(translation, options);
    }
  } catch (error) {
    return this.missingTranslation(scope);
  }
};

I18n.toNumber = function(number, options) {
  options = this.prepareOptions(
    options,
    this.lookup("number.format"),
    {precision: 3, separator: this.SEPARATOR, delimiter: ",", strip_insignificant_zeros: false}
  );

  var negative = number < 0,
      string = Math.abs(number).toFixed(options.precision).toString(),
      parts = string.split(this.SEPARATOR),
      precision,
      buffer = [],
      formattedNumber;

  number = parts[0];
  precision = parts[1];

  while (number.length > 0) {
    buffer.unshift(number.substr(Math.max(0, number.length - 3), 3));
    number = number.substr(0, number.length -3);
  }

  formattedNumber = buffer.join(options.delimiter);

  if (options.precision > 0) {
    formattedNumber += options.separator + parts[1];
  }

  if (negative) {
    formattedNumber = "-" + formattedNumber;
  }

  if (options.strip_insignificant_zeros) {
    var regex = {
        separator: new RegExp(options.separator.replace(/\./, "\\.") + "$"),
        zeros: /0+$/
    };

    formattedNumber = formattedNumber
      .replace(regex.zeros, "")
      .replace(regex.separator, "")
    ;
  }

  return formattedNumber;
};

I18n.toHumanSize = function(number, options) {
  var kb = 1024,
      size = number,
      iterations = 0,
      unit,
      precision;

  while (size >= kb && iterations < 4) {
    size = size / kb;
    iterations += 1;
  }

  if (iterations === 0) {
    unit = this.t("number.human.storage_units.units.byte", {count: size});
    precision = 0;
  } else {
    unit = this.t("number.human.storage_units.units." + [null, "kb", "mb", "gb", "tb"][iterations]);
    precision = (size - Math.floor(size) === 0) ? 0 : 1;
  }

  options = this.prepareOptions(
    options,
    {precision: precision, format: "%n%u", delimiter: ""}
  );

  number = this.toNumber(size, options);
  number = options.format
    .replace("%u", unit)
    .replace("%n", number)
  ;

  return number;
};

I18n.pluralizer = function(locale) {
  var pluralizer = this.pluralizationRules[locale];
  if (pluralizer !== undefined) return pluralizer;
  return this.pluralizationRules["en"];
};

I18n.findAndTranslateValidNode = function(keys, translation) {
  for (var i = 0; i < keys.length; i++) {
    var key = keys[i];
    if (this.isValidNode(translation, key)) return translation[key];
  }
  return null;
};

I18n.pluralize = function(translation, scope, options) {
  options = this.prepareOptions(options);
  var count = options.count.toString();

  var pluralizer = this.pluralizer(options.locale || this.currentLocale());
  var key = pluralizer(Math.abs(count));
  var keys = ((typeof key === "object") && (key instanceof Array)) ? key : [key];

  var message = this.findAndTranslateValidNode(keys, translation);
  if (message == null) message = this.missingTranslation(scope, keys[0]);

  return this.interpolate(message, options);
};

I18n.missingTranslation = function(scope, key) {
  var message = '[' + this.currentLocale() + this.SEPARATOR + scope;
  if (key) { message += this.SEPARATOR + key; }
  return message + ']';
};

I18n.currentLocale = function() {
  return I18n.locale || I18n.defaultLocale;
};

// shortcuts
I18n.t = I18n.translate;