(function () {
  "use strict"
  var root = this,
      $ = root.jQuery;

  if (typeof GOVUK === 'undefined') { root.GOVUK = {}; }

  var SelectionButtons = function (elmsOrSelector, opts) {
    var $elms;

    this.selectedClass = 'selected';
    this.focusedClass = 'focused';
    if (opts !== undefined) {
      $.each(opts, function (optionName, optionObj) {
        this[optionName] = optionObj;
      }.bind(this));
    }
    if (typeof elmsOrSelector === 'string') {
      $elms = $(elmsOrSelector);
      this.selector = elmsOrSelector;
      this.setInitialState($(this.selector));
    } else {
      this.$elms = elmsOrSelector;
      this.setInitialState(this.$elms);
    }
    this.addEvents();
  };
  SelectionButtons.prototype.addEvents = function () {
    if (typeof this.$elms !== 'undefined') {
      this.addElementLevelEvents();
    } else {
      this.addDocumentLevelEvents();
    }
  };
  SelectionButtons.prototype.setInitialState = function ($elms) {
    $elms.each(function (idx, elm) {
      var $elm = $(elm);

      if ($elm.is(':checked')) {
        this.markSelected($elm);
      }
    }.bind(this));
  };
  SelectionButtons.prototype.markFocused = function ($elm, state) {
    if (state === 'focused') {
      $elm.parent('label').addClass(this.focusedClass);
    } else {
      $elm.parent('label').removeClass(this.focusedClass);
    }
  };
  SelectionButtons.prototype.markSelected = function ($elm) {
    var radioName;

    if ($elm.attr('type') === 'radio') {
      radioName = $elm.attr('name'),
      $($elm[0].form).find('input[name="' + radioName + '"]')
        .parent('label')
        .removeClass(this.selectedClass);
      $elm.parent('label').addClass(this.selectedClass);
    } else { // checkbox
      if ($elm.is(':checked')) {
        $elm.parent('label').addClass(this.selectedClass);
      } else {
        $elm.parent('label').removeClass(this.selectedClass);
      }
    }
  };
  SelectionButtons.prototype.addElementLevelEvents = function () {
    this.clickHandler = this.getClickHandler();
    this.focusHandler = this.getFocusHandler({ 'level' : 'element' });

    this.$elms
      .on('click', this.clickHandler)
      .on('focus blur', this.focusHandler);
  };
  SelectionButtons.prototype.addDocumentLevelEvents = function () {
    this.clickHandler = this.getClickHandler();
    this.focusHandler = this.getFocusHandler({ 'level' : 'document' });

    $(document)
      .on('click', this.selector, this.clickHandler)
      .on('focus blur', this.selector, this.focusHandler);
  };
  SelectionButtons.prototype.getClickHandler = function () {
    return function (e) {
      this.markSelected($(e.target));
    }.bind(this);
  };
  SelectionButtons.prototype.getFocusHandler = function (opts) {
    var focusEvent = (opts.level === 'document') ? 'focusin' : 'focus'

    return function (e) {
      var state = (e.type === focusEvent) ? 'focused' : 'blurred';

      this.markFocused($(e.target), state);
    }.bind(this);
  };
  SelectionButtons.prototype.destroy = function () {
    if (typeof this.selector !== 'undefined') {
      $(document)
        .off('click', this.selector, this.clickHandler)
        .off('focus blur', this.selector, this.focusHandler);
    } else {
      this.$elms
        .off('click', this.clickHandler)
        .off('focus blur', this.focusHandler);
    }
  };

  root.GOVUK.SelectionButtons = SelectionButtons;
}).call(this);