Add firebase backend

[skamansam]

We need to start using the firebase store. From now on, we will have to think about how to store the data constructs used. We should be using the realtime database. We will need to implement our own offline solution.

We need to organize data for queries, not for storage. As with any NoSQL database, denormalization is key. Please read completely through the firebase documentation before continuing.

Here is the scheme I have in mind:

NOTE: The top-level items are Collections. The *ref* items are the document references.

{
  states: {
    stateRef1: {
      name: 'CheckBoxes with an Intermediate State',
      description: 'Standard checkboxes with an intermediate state.',
      stateOrder: ['notDone', 'inProgress', 'done'],
      states: {
        notDone: {
          text: 'Not Done',
          value: 0,
          icon: 'mdi-checkbox-blank-outline',
          color: '#ff0000',
        },
        done: {
          text: 'Done',
          value: 1,
          icon: 'mdi-checkbox-marked-outline',
          color: '#00ff00',
        },
        inProgress: {
          text: 'In Progress',
          value: 0.5,
          icon: 'mdi-checkbox-intermediate',
          color: '#00ffff',
        },
      },
    },
  },
  userStatuses: {
    user1Ref: {
      listRef: {
        _status: 'inProgress', // cached status so we don't have to actually get the list items to calculate its status. useful for sublists
        listItemRef: 'done',
        listItem2Ref: 'inProgress',
      },
    },
  },
  lists: { // we want to store the list options here, so we don't have to retrieve the entire list with items when we just want a sublist
    list1Ref: { // firebase assigns new docs these IDs, when using push() we should take full advantage of this.
      title: 'Test One',
      color: '#ff00ff', // the color of the tile and background color of the page view
      states: 'stateref1', // we are deduplicating states by
      prerequisite: 'list3Ref.complete && list5Ref.listItem1Ref1 >= 5', // prerequisites for enabling this list. NO EVAL()!
    },
    list2Ref: {
      title: 'Test Two',
      color: '#ff0000',
    },
    list3Ref: {
      title: 'Test Three',
      color: '#ffff00',
    },
    list4Ref: {
      title: 'Test Four',
      color: '#465362',
    },
  },
  listItems: {
    list1Ref: {
      list1Item1Ref: {
        text: 'Item 1', // the  dispalyed text of the list item
        state: 'done', // state can be any arbitrary value, i.e. "5", "ten",
        prerequisite: '(list item 2 title).done', // one of several ways to specify objects in our
        order: 0,
      },
      list1Item2Ref: {
        text: 'Item 2',
        state: 'inProgress',
        order: 1,
      },
      list1Item3Ref: {
        ref: 'someOtherListID',
        order: 2,
      },
    },
    list2ref: {
      list2Item1Ref: {
        text: 'Item 2',
        state: 'inProgress',
        order: 0,
      },
      list2Item2Ref: {
        text: 'Item 2',
        state: 'inProgress',
        order: 1,
      },
    },
  },
}

NOTE: list.bgColor is now just color.
You should use the firebase emulator for testing this feature. https://firebase.google.com/docs/emulator-suite

[skamansam]

Note: this comment isn't complete yet.

After much information consumption, I have devised a new DB schema. Since firecloud charged based on document reads, and can't return partial documents, I have optimized for views and documents/size.

Note: there is a 1Mb document limit, so some objects may require multiple documents. We will implement that when we get there.

Collections:
  globalPreferences. // Defaults and global configuration options
  lists  // the list objects
  lists/{list.id}/listItems. //the listItems for the list. One document is an array of all the items.
  stateGroups // a group of states
  users. // User information
  users/{user.id}/listItemStates // one document for all the states.