/**********************************
 * This is a convenience utility to
 * abstract a bit of the Firestore
 * boilerplate and complexity dealing
 * with docs vs collections.
 *********************************/

import conf from './conf';

const TRANSACTION_LIMIT = 500;

import * as admin from "firebase-admin";
import {DocumentReference, FirebaseFirestore} from "@firebase/firestore-types";
if( admin.apps.length === 0 ) {
  admin.initializeApp();
}

// this is not a privileged ref
const db = admin.firestore();

function buildPath(url: string|Array<string>) {
  let ref: any = db;
  splitUrl(conf.basePath, url).forEach(p => {
    if( typeof ref.collection === 'function' ) {
      ref = ref.collection(p);
    }
    else {
      ref = ref.doc(p);
    }
  });
  return ref;
}

function getData(url: string|Array<string>) {
  return buildPath(url).get().then(snap => {
    if( snap instanceof admin.firestore.DocumentSnapshot ) {
      if( snap.exists ) {
        return snap.data();
      }
      else {
        return null;
      }
    }
    else {
      const data = {};
      snap.forEach(doc => data[doc.id] = doc.data());
      return data;
    }
  });
}

function splitUrl(...url: Array<string|Array<string>>): Array<string> {
  let parts = [];
  url.forEach(u => {
    if( typeof u === 'string' ) {
      u.replace(/^\//, '').replace(/\/$/, '').split('/').forEach(uu =>{
        if( uu !== '' ) { parts.push(uu); }
      });
    }
    else {
      u.forEach(ubit => parts = [...parts, ...splitUrl(ubit)]);
    }
  });
  return parts;
}

export default {
  path: buildPath,

  get: getData,

  relativePath(ref: DocumentReference) {
    const re = new RegExp(`^${conf.basePath}/?`);
    return ref.path.replace(re, '');
  },

  newId: function() {
    return buildPath('foo/bar').id;
  },

  addToArray: function(url: string|Array<string>, field: string, val) {
    const data = {};
    data[field] = admin.firestore.FieldValue.arrayUnion(val);
    return buildPath(url).update(data);
  },

  removeFromArray: function(url: string|Array<string>, field: string, val) {
    const data = {};
    data[field] = admin.firestore.FieldValue.arrayRemove(val);
    return buildPath(url).update(data);
  },

  batch: function() { return db.batch(); },

  root: function(): FirebaseFirestore.DocumentReference { return db.doc(conf.basePath); },

  transaction: db.runTransaction.bind(db),

  FieldValue: admin.firestore.FieldValue,

  TRANSACTION_LIMIT: TRANSACTION_LIMIT
};