polymer-unit-convert-complex.html

<link rel="import" href="../polymer/polymer.html">
<link rel="import" href="polymer-unit-convert.html">

<dom-module id="unit-convert-complex">
  <template>
    <content></content>
  </template>
</dom-module>
<script>

(function() {

  var abbreviations = {
    'mph': 'mile/hour',
    'knots': 'nautical_mile/hour'
  };

  Polymer({

    is: 'unit-convert-complex',

    properties: {
      from: {
        type: String,
        notify: true
      },
      to: {
        type: String,
        notify: true
      },
      value: {
        type: Number,
        notify: true
      },
      result: {
        type: Number,
        readOnly: true,
        notify: true
      },
      decimals: {
        type: Number,
        notify: true,
        value: null
      }
    },

    calculate: function(fromComplexUnit, toComplexUnit, value) {

      fromComplexUnit = this.resolveAbbreviation(fromComplexUnit || this.from);
      toComplexUnit = this.resolveAbbreviation(toComplexUnit || this.to);
      value = value || this.value;

      var from = this.parseComplexUnit(fromComplexUnit),
          to = this.parseComplexUnit(toComplexUnit);

      var el = document.createElement('unit-convert');
      var tmp = value;

      tmp = el.calculate(from[0], to[0], tmp, true);
      tmp = el.calculate(to[1], from[1], tmp, true);
      return tmp;

    },

    ready: function() {

      var self = this;

      var onUpdate = {
        value: function() {
          self.update();
        }
      };

      this.addEventListener('from-changed', this.update);
      this.addEventListener('to-changed', this.update);
      this.addEventListener('decimals-changed', this.update);
      this.addEventListener('value-changed', onUpdate.value);

      this.update();

    },

    update: function() {
      
      if(!isDefined(this.from) || !isDefined(this.to) || !isDefined(this.value)) {
        this._setResult(null);
        return;
      }

      var result = this.calculate();

      if(isDefined(this.decimals)) {
        result = parseFloat(result).toFixed(this.decimals);
      }

      this._setResult(parseFloat(result));

    },

    parseComplexUnit: function(complexUnit) {

      if(!isDefined(complexUnit)) {
        return undefined;
      }

      return complexUnit.split('/')

    },

    resolveAbbreviation: function(complexUnit) {

      if(abbreviations.hasOwnProperty(complexUnit)) {

        return abbreviations[complexUnit];

      } else {

        var unitConvert = document.createElement('unit-convert');
        return this.parseComplexUnit(complexUnit).map(function(unit) {
          return unitConvert.resolveAbbreviation(unit);
        }).join('/');

      }

    }

  });

  function isDefined(value) {
    return (value !== undefined) && (value !== null);
  }

})();
</script>