hummingbird-me/hummingbird

import Ember from 'ember';
import PreloadStore from '../utils/preload-store';

export default Ember.Mixin.create({
  // Return an empty array or preloaded content immediately from the model hook.
  model: function() {
    if (this.get('preloadKey')) {
      this.set('cursor', 2);

      var store = this.store,
          key = this.get('preloadKey'),
          path = this.get('preloadPath'),
          object = this.get('preloadObject');

      return PreloadStore.popEmberData(key, path, object, store,
                                       function() { return []; });
    } else {
      this.set('cursor', null);
      return [];
    }
  },

  // Wrapper around fetchPage which needs to be implemented by the route.
  // Keeps track of whether we are currently fetching a page, and saves the
  // cursor returned by the server.
  fetchPageProxy: function(cursor) {
    var self = this;
    this.set('currentlyFetchingPage', true);

    if (!cursor) { cursor = 1; }
    return this.fetchPage(cursor).then(function(objects) {
      self.set('cursor', objects.get('meta.cursor'));

      Ember.run.next(function() { self.set('currentlyFetchingPage', false); });

      if (objects.get('length') === 0) { self.setCanLoadMore(false); }
      else { self.setCanLoadMore(true); }

      return objects;
    });
  },

  // Set canLoadMore on the controller while setting it up.
  setupController: function(controller, model) {
    this.setCanLoadMore(true);
    controller.set('canLoadMore', this.get('canLoadMore'));
    if (model.length === 0) {
      this.set('cursor', null);
    }
    controller.set('model', model);
  },

  // Set `canLoadMore` on the route and, if possible, on the controller.
  setCanLoadMore: function(canLoadMore) {
    this.set('canLoadMore', canLoadMore);
    if (this.controller) { this.controller.set('canLoadMore', canLoadMore); }
  },

  loadNextPage: function() {
    var that = this;
    if (this.get('canLoadMore') && !this.get('currentlyFetchingPage')) {
      this.fetchPageProxy(this.get('cursor')).then(function(objects) {
        that.controller.get('content').addObjects(objects);
      });
    }
  },

  actions: {
    loadNextPage: function() {
      this.loadNextPage();
    }
  }
});