request.js

import firebase from 'firebase/app';
import 'firebase/database';
import { firebaseConfig } from '@/common/config';
import { firebaseKeys } from '@/common/constants';

firebase.initializeApp(firebaseConfig);

const database = firebase.database();

const snapshotMapper = snap => {
  const data = snap.val();

  return data ? { ...snap.val(), key: snap.key } : {};
};

const getMethod = endpoint =>
  database
    .ref(endpoint)
    .once(firebaseKeys.VALUE)
    .then(snapshotMapper);

const postMethod = (endpoint, data) =>
  database
    .ref(endpoint)
    .push(data)
    .then(({ key }) => database.ref(`${endpoint}/${key}`))
    .then(ref => ref.once(firebaseKeys.VALUE))
    .then(snapshotMapper);

const patchMethod = (endpoint, data) => {
  const entity = database.ref(endpoint);

  return entity
    .once(firebaseKeys.VALUE)
    .then(snapshotMapper)
    .then(snap => {
      delete snap.key;
      delete data.key;

      if (snap) {
        return entity.update({
          ...snap,
          ...data
        });
      }

      throw new Error('Record not found.');
    })
    .then(() => database.ref(endpoint))
    .then(ref => ref.once(firebaseKeys.VALUE))
    .then(snapshotMapper);
};

const subscribeMethod = (endpoint, callback) => {
  database.ref(endpoint).on(firebaseKeys.ONCHANGE, data => {
    callback(snapshotMapper(data));
  });
};

const unsubscribeMethod = endpoint => database.ref(endpoint).off();

export { firebase };

export default {
  get: getMethod,
  post: postMethod,
  patch: patchMethod,
  subscribe: subscribeMethod,
  unsubscribe: unsubscribeMethod
};