elliptical-observe-inline/lib-es/store.js

Dynamic sideways Data Loading for Elliptical

import _ from 'lodash';
import Observable from 'zen-observable';

export default function createStore() {
  var items = [];
  var observer = void 0;
  var data = new Observable(function (newObserver) {
    observer = newObserver;
  });

  function fetchAndSubscribe(element, item) {
    var fetched = element.type.fetch(element);

    var subscription = fetched.subscribe({
      next: function next(value) {
        item.value = value;

        if (observer) {
          observer.next({ element: element, value: value });
        }
      }
    });
    if (item.subscription) {
      item.subscription.unsubscribe();
    }
    item.subscription = subscription;
  }

  function register(element) {
    var existing = _.find(items, function (item) {
      return _.isEqual(element, item.element);
    });

    if (existing) {
      var currentValue = existing.value;

      return currentValue;
    } else {
      var newItem = { element: element, dirty: false };
      items.push(newItem);

      fetchAndSubscribe(element, newItem);

      return newItem.value;
    }
  }

  function remove(item) {
    var index = items.indexOf(item);
    var removed = items.splice(index, 1);
    removed[0].subscription.unsubscribe();
  }

  return { data: data, register: register, items: items, remove: remove };
}