rates.service.js

import {CustomStorage} from '../../storage/custom-storage';
import * as _ from 'lodash';

export class RatesService {
  constructor() {
    this.storage = new CustomStorage();
    this.createRatesTableIfItDoesNotExist();
  }

  all() {
    return this.storage.query('select * from rates order by id asc').then(result => {
      return _.map(result.rows, row => {
        return this.create({
          id: row.id,
          createdDate: new Date(row.createdDate),
          direction: row.direction,
          description: row.description,
          amount: row.amount,
          days: row.days
        });
      });
    }).catch(error => {
      console.log(error);
    });
  }

  calculateDailyRate() {
    return this.all().then(all => {
      let totalIn = _.chain(all).filter({direction: 'In'}).map('dailyRate').sum().value();
      let totalOut = _.chain(all).filter({direction: 'Out'}).map('dailyRate').sum().value();
      return totalIn - totalOut;
    });
  }

  create(options = {}) {
    let Rate = {
      id: null,
      createdDate: new Date(),
      direction: 'In',
      description: '',
      amount: 0,
      days: 30,
      get dailyRate() {
        return parseFloat(this.amount) / parseInt(this.days);
      }
    };
    let rate = Object.create(Rate);
    return Object.assign(rate, options);
  }

  save(rate) {
    if (rate.id) {
      return this.update(rate);
    } else {
      return this.insert(rate);
    }
  }

  insert(rate) {
    return this.storage.query(`insert into rates(
      createdDate,
      direction,
      description,
      amount,
      days,
      dailyRate
      ) values (?, ?, ?, ?, ?, ?)`,
      [
        rate.createdDate.getTime(),
        rate.direction,
        rate.description,
        parseFloat(rate.amount),
        parseInt(rate.days),
        rate.dailyRate
      ]).then(result => {
        rate.id = result.insertId;
        return rate;
      }).catch(error => {
        console.error('Error inserting rate', error);
      });
  }

  update(rate) {
    return this.storage.query(`update rates set
      createdDate=?,
      direction=?,
      description=?,
      amount=?,
      days=?,
      dailyRate=?
      where id=?`,
      [
        rate.createdDate.getTime(),
        rate.direction,
        rate.description,
        parseFloat(rate.amount),
        parseInt(rate.days),
        rate.dailyRate,
        rate.id
      ]).then(result => {
        return rate;
      }).catch(error => {
        console.error('Error updating rate', error);
      });
  }

  delete(rate) {
    return this.storage.query('delete from rates where id=?', [rate.id]).then(result => {
      return rate;
    }).catch(error => {
      console.error('Error deleting rate', error);
    });
  }

  createRatesTableIfItDoesNotExist() {
    const createSql = `create table if not exists rates(
      id integer primary key autoincrement,
      createdDate long,
      direction text,
      description text,
      amount real,
      days integer,
      dailyRate real
    )`;
    this.storage.query(createSql).catch(error => {
      console.error('Error creating rates table', error);
    });
  }
}