BlackDice/b3-chief

import { init } from 'stampit'
import invariant from 'invariant'
import { oneLine } from 'common-tags'

const FirebaseAdapter = init(initializeFirebaseAdapter).methods({ sync })

function initializeFirebaseAdapter({ chief, firebaseRef }) {
    invariant(firebaseRef, oneLine`
        'The Firebase adapter is expecting firebaseRef specified in options object.'
    `)

    this.chief = chief
    this.firebaseRef = firebaseRef
}

const syncedInstances = new WeakSet()

function sync(watchRemote = false) {
    invariant(syncedInstances.has(this.chief) === false, oneLine`
        The Chief %s is already synced with firebase %s
    `, this.chief.id, this.firebaseRef.toString())

    syncedInstances.add(this.chief)

    const { selectors, observe } = this.chief.store

    const updateState = (snapshot) => {
        const state = snapshot.val()
        if (state !== null) {
            this.chief.replaceState(state)
        }
    }

    const syncPromise = this.firebaseRef.once('value').then(updateState)

    const behaviorsRef = this.firebaseRef.child('behaviors')
    const treesRef = this.firebaseRef.child('trees')
    const subjectsRef = this.firebaseRef.child('subjects')

    if (watchRemote === true) {
        behaviorsRef.on('value', (snapshot) => this.chief.store.actions.replaceBehaviors(snapshot.val()))
        treesRef.on('value', (snapshot) => this.chief.store.actions.replaceTrees(snapshot.val()))
        // subjects are synchronized to the firebase, not from it
        observe(selectors.subjects, (subjects) => subjectsRef.set(subjects))
        return syncPromise.then(() => this.chief)
    }

    return syncPromise.then(() => {
        observe(selectors.behaviors, (behaviors) => {
            behaviorsRef.set(behaviors)
        })

        observe(selectors.trees, (trees) => {
            treesRef.set(trees)
        })

        observe(selectors.subjects, (subjects) => {
            subjectsRef.set(subjects)
        })

        return this.chief
    })
}

export default FirebaseAdapter