app/stores/forums.js


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import { readable } from 'svelte/store';
import { onMessage } from '../socket_coordinator';

const internals = {

  // Constants

  kChangeFeedEventName: 'changefeed:forums',

  // The exported data structure

  forums: [],

  // Handles messages from the event

  handleChangeFeed(data) {

    // No old value == add
    if (!data.old_val) {
      return internals.forums.push(data.new_val);
    }

    // We have an old value, let's find it.
    const index = internals.forums.findIndex((element) => element.id === data.old_val.id);

    if (index > -1) {
      if (data.new_val) {
        return internals.forums.splice(index, 1, data.new_val || undefined);
      }

      return internals.forums.splice(index, 1);
    }
  }
};

export const forums = readable(internals.forums, (set) => {

  onMessage((message) => {

    if (message.name === internals.kChangeFeedEventName) {
      internals.handleChangeFeed(message.data);
      set(internals.forums);
    }
  });
});