(function() {
  var exports = {};

  window.module = {
    export: function(data) {
      var _ = this;

      var exportUrl = document.currentScript.getAttributeNode('src');
      var moduleHash = _.hash(exportUrl.value);

      exports[moduleHash] = data;
    },
    import: function(url) {
      var _ = this

      var moduleHash = _.hash(url)
      if (result = exports[moduleHash]) {
        console.log('cache hit!')
        return Promise.resolve(result)
      }

      return new Promise(function(resolve, reject) {
        var script = document.createElement('script');
        var src = document.createAttribute('src');

        src.value = url
        script.setAttributeNode(src)

        script.addEventListener('load',function() {
          resolve(exports[moduleHash])
        })
        script.addEventListener('error', function(err) {
          reject(err)
        })

        document.body.appendChild(script)
      })
    },
    hash: function(str){
      var hash = 0;
      if (str.length == 0) return hash;
      for (i = 0; i < str.length; i++) {
          char = str.charCodeAt(i);
          hash = ((hash<<5)-hash)+char;
          hash = hash & hash; // Convert to 32bit integer
      }
      return hash;
    }
  }
})()