// CONST
const filename = 'db.json';
const tableName = 'events';
const countfield = 'eventCount';

// data
const low = require('lowdb');
const FileSync = require('lowdb/adapters/FileSync');
const adapter = new FileSync('db.json');
const db = low(adapter);

db.defaults({ events: [] }).write();

// utils
const { nanoid } = require('nanoid');
const eventDefs = require('../data/eventsDefinition.js');

// incrementFrom
function incrementFrom(start, incr = 1) {
  try {
    let entries = db.get('events').sortBy('order').value();

    entries.map((e) => {
      if (e.order < start) return;
      db.get('events')
        .find({ id: e.id })
        .assign({ order: e.order + incr })
        .write();
    });
  } catch (error) {
    console.log('error on increment function', error);
  }
}

function _getEventsCount() {
  return db.get('events').size().value();
}

function _pushNew(entry) {
  return db.get('events').push(entry).write();
}

function _removeById(eventId) {
  return db.get('events').remove({ id: eventId }).write();
}

// Create controller for GET request to '/events'
// Returns -
exports.eventsGetAll = async (req, res) => {
  const results = db.get('events').sortBy('order').value();
  res.json(results);
};

// Create controller for GET request to '/events/:eventId'
// Returns -
exports.eventsGetById = async (req, res) => {
  const e = db.get('events').find({ id: req.params.eventId }).value();
  res.json(e);
};

// Create controller for POST request to '/events/'
// Returns -
exports.eventsPost = async (req, res) => {
  // TODO: Validate event
  if (!req.body) {
    res.status(400).send(`No object found in request`);
    return;
  }

  // ensure structure
  let newEvent = {};
  req.body.id = nanoid(6);

  switch (req.body.type) {
    case 'event':
      newEvent = { ...eventDefs.event, ...req.body };
      break;
    case 'delay':
      newEvent = { ...eventDefs.delay, ...req.body };
      break;
    case 'block':
      newEvent = { ...eventDefs.block, ...req.body };
      break;

    default:
      res
        .status(400)
        .send(`Object type missing or unrecognised: ${req.body.type}`);
      break;
  }

  try {
    // increment count if necessary
    const c = _getEventsCount();

    if (c > 0 && newEvent.order < c) incrementFrom(newEvent.order);

    // add new event
    _pushNew(newEvent);

    res.sendStatus(201);
  } catch (error) {
    res.status(400).send(error);
  }
};

// Create controller for PUT request to '/events/'
// Returns -
exports.eventsPut = async (req, res) => {
  // no valid params
  if (!req.body) {
    res.status(400).send(`No object found`);
    return;
  }

  let eventId = req.body.id;
  if (!eventId) {
    res.status(400).send(`No id found`);
    return;
  }

  try {
    db.get('events')
      .find({ id: req.body.id })
      .assign({ ...req.body })
      .write()
      .then(res.sendStatus(200));
  } catch (error) {
    res.status(400).send(error);
  }
};

// Create controller for PATCH request to '/events/'
// Returns -
exports.eventsPatch = async (req, res) => {
  // no valid params
  if (!req.body) {
    res.status(400).send(`No object found`);
    return;
  }

  let eventId = req.body.id;
  if (!eventId) {
    res.status(400).send(`No id found`);
    return;
  }

  try {
    db.get('events')
      .find({ id: req.body.id })
      .assign({ ...req.body })
      .write();

    res.sendStatus(200);
  } catch (error) {
    res.status(400).send(error);
  }
};

// Create controller for DELETE request to '/events/:eventId'
// Returns -
// TODO: should reorder al events down
exports.eventsDelete = async (req, res) => {
  // no valid params
  if (!req.params.eventId) {
    res.status(400).send(`No id found in request`);
    return;
  }

  try {
    // increment count if necessary
    const c = _getEventsCount();
    const e = db.get('events').find({ id: req.params.eventId }).value();

    if (c > 0 && e.order < c) incrementFrom(e.order, -1);

    // add new event
    _removeById(req.params.eventId);

    res.sendStatus(201);
  } catch (error) {
    res.status(400).send(error);
  }
};