BIP39 Mnemonic words advice directive

twMnemonicAdvice.directive.js

'use strict';

angular.module('copayAddon.twinWallet').directive('twMnemonicAdvice', function () {
  return {
    restrict: 'AE',
    transclude: true,
    scope: {
      prefix: '=',
      language: '=',
      words: '='
    },
    //controllerAs: 'advice',
    controller: ['$scope', 'lodash', 'bitcoreMnemonic', function ($scope, lodash, bitcoreMnemonic) {
      //TODO automatic language selection
      var lang = 'ENGLISH'
      if ($scope.language) $scope.language = lang;
      var words = bitcoreMnemonic.Words[lang];
      //TODO optimize! this code scans the word list 3 times
      var index = lodash(words)
        .groupBy(function(w) { return w.charAt(0); })
        .mapValues(function(e) { return lodash(e)
            .groupBy(function(w) { return w.charAt(1); })
            .mapValues(function(e) { return lodash(e)
              .groupBy(function(w) { return w.charAt(2); })
              .value();
            }).value();
        }).value();
      $scope.$watch('prefix', function (newVal) {
        var sl = newVal && newVal.length;
        if (!sl) {
          $scope.words = '';
          return;
        }
        var found =  index;
        var i=0;
        for (; i < 3 && i<sl; i++){
          if (found)
            found = found[newVal.charAt(i)];
        }
        //TODO limit array elements on long list of matching words
        for (; i<3; i++) {
          found = lodash.reduce(found, function(total, v) { return total.concat(lodash.values(v)) }, []);
        }
        if (sl > 3) {
          found = lodash.filter(found, function(v) { return v.lastIndexOf(newVal, 0) === 0 });
        }
        $scope.words = found;
      });
    }],
    template: '<div ng-transclude></div>'
  };
});