restful-api-task/services/NotesService.js

import * as path from 'path'
import * as fs from 'fs'

class NotesService {
  dbPath
  db
  limit

  constructor () {

    this.dbPath = path.resolve('./repositories/data.json')

    try {
      const data = fs.readFileSync(this.dbPath, 'utf8')
      this.db = JSON.parse(data || '[]')
    } catch (e) {
      this.db = []
    }

    this.limit = 7

  }

  /**
   * USE AT FINAL STAGE BEFORE RETURN FROM THE METHOD TO AVOID HELTER SKELTER IN THE RESULT
   *
   * @param result
   * @param query
   * @returns {*|{result: null, data: *[], query: null, message: string, type: string, status: string}}
   * @private
   */
  _composeResponse (result, query) {

    const response = {
      code: 200,
      status: 'Accepted',
      message: `The database contains ${this.db.length} notes`,
      result: `Matched ${result.length} note(s)`,
      query: query,
      type: 'Completed',
      data: [],
    }

    if (result.length === 1) {
      response.data = result[0]
    } else if (result.length > 1) {
      response.data = result
    } else {
      response.code = 404
      response.type = 'Warning'
    }

    return response
  }

  /**
   *
   * @param id
   * @returns {*|{result: null, data: *[], query: null, message: string, type: string, status: string}}
   */
  getSingle (id) {
    //, returned LIMIT ${this.limit} ORDER BY id DESC
    const note = this.db.filter(el => el.id === +id)
    return this._composeResponse(note, `id = ${id} LIMIT 1`)
  }

  /**
   *
   * @returns {*|{result: null, data: *[], query: null, message: string, type: string, status: string}}
   */
  get getNotes () {
    const notes = this.db.sort((a, b) => new Date(a.created_at) > new Date(b.created_at) ? -1 : 1)
    return this._composeResponse(notes.slice(0, this.limit), `ORDER BY created_at DESC LIMIT ` + this.limit)
  }

  /**
   *
   * @param id
   * @returns {Promise<*|{result: null, data: *[], query: null, message: string, type: string, status: string}>}
   */
  async deleteNote (id) {
    const deletedNote = this.db.filter(note => note.id === +id)

    if (deletedNote.length === 1) {
      this.db = this.db.filter(note => note.id !== +id)
      await this.saveDatabase()
    }

    return this._composeResponse(deletedNote, `DELETED FROM db WHERE id = ${id}`)
  }

  /**
   *
   * @param data
   * @returns {Promise<*|{result: null, data: *[], query: null, message: string, type: string, status: string}>}
   */
  async insertNote (data) {

    const notes = this.db.sort((a, b) => new Date(a.id) > new Date(b.id) ? -1 : 1)
    data.id = (notes.length >= 1) ? notes[0].id + 1 : 1
    this.db.push(data)
    await this.saveDatabase()

    return this._composeResponse([data], `INSERT INTO database SET id = ${data.id} (AI)`)
  }

  /**
   *
   * @param data
   * @returns {Promise<*|{result: null, data: *[], query: null, message: string, type: string, status: string}>}
   */
  async updateNote (data) {

    const noteExists = this.db.find(note => note.id === +data.id)

    if (noteExists) {
      noteExists.title = data.title
      noteExists.content = data.content
      noteExists.category = data.category
      noteExists.archive = data.archive
      noteExists.updated_at = data.updated_at

      await this.saveDatabase()
      return this._composeResponse([noteExists], `UPDATED WHERE id = ${data.id}`)
    }

    return this._composeResponse([], `UPDATED WHERE id = ${data.id}`)

  }

  /**
   *
   * @returns {Promise<void>}
   */
  async saveDatabase () {
    try {
      await fs.promises.writeFile(this.dbPath, JSON.stringify(this.db, null, 2), { encoding: 'utf-8' })
    } catch (e) {
      console.error(e)
    }
  }

  /**
   *
   * @returns {{result: string, data: {}, query: string, message: string, status: string}}
   */
  get getStats () {

    const stats = {}
    const cats = [...new Set(this.db.map(item => item.category))]

    if (typeof cats[0] !== 'undefined') {
      const isArchive = this.db.map(item => {
        const container = {}
        container[item.category] = item.archive
        return container
      })

      cats.forEach((cat, i) => {
        stats[cat] = {
          total: this.db.filter(el => el.category === cat).length,
          archived: isArchive.filter(el => el[cat] === true).length,
          active: isArchive.filter(el => el[cat] === false).length,
        }
      })
    }

    return {
      code: 200,
      status: 'Accepted',
      message: `The database contains ${this.db.length} notes`,
      result: `Aggregated data statistics`,
      query: `GROUP BY categories, (active|archived)`,
      type: 'Completed',
      data: stats,
    }
  }
}

export default NotesService