ice-db/db.js

In-memory DB

const {
  Collection
} = require('./collection'),
  fs = require('fs')

class Ice {
  /**
   *Creates an instance of Ice.
   * @memberof Ice
   */
  constructor() {
    // initialize an empty list of collections
    this._collections = {}
    // initialize default storage params
    this.storage = {
      set: false,
      path: ''
    }
  }

  /**
   * Sets a storage in a given folder
   * @param {*} {
   * path
   * }
   * @memberof Ice
   */
  setStorage({
    path
  }) {
    this.storage = {
      set: true,
      path
    }
  }

  /**
   *Saves all collections in files
   *
   * @param {boolean} [sync=false] defines if this operation should be sync or unsync (by default)
   * @memberof Ice
   */
  save(sync = false) {
    if (sync) {
      this._saveSync()
    } else {
      this._save()
    }
  }

  /**
   *Saves all collection sycronously
   *
   * @memberof Ice
   */
  _saveSync() {
    // if folder is not created
    try {
      fs.readdirSync(`${this.storage.path}`)
    } catch (error) {
      // create it
      fs.mkdirSync(`${this.storage.path}`)
    }
    for (let collection in this._collections) {
      fs.writeFileSync(`${this.storage.path}/${collection}.json`, JSON.stringify(this._collections[collection].data))
    }
  }

  /**
   * Saves all collection asyncronously
   * @returns {Promise<undefined>}
   *
   * @memberof Ice
   */
  async _save() {
    // if folder is not created
    try {
      await fs.readdir(`${this.storage.path}`)
    } catch (error) {
      // create it
      fs.mkdirSync(`${this.storage.path}`)
    }
    for (let collection of this._collections) {
      await fs.writeFile(`${this.storage.path}/${collection}.json`, JSON.stringify(this._collections[collection].data))
    }
  }

  /**
   *Create a new collection
   *
   * @param {*} {
   *     name
   *   }
   * @returns {Collection} created collection
   * @throws error if a collection cannot be created
   * @memberof Ice
   */
  createCollection({
    name
  }) {
    if (this._checkCollectionNameVacant(name)) {
      this[name] = new Collection({
        name
      })
      this._collections[name] = this[name]
      return this[name]
    } else {
      throw `Collection "${name}" already exists or it is a reserved identificator`
    }
  }

  /**
   *Retreives a list of collections in this db
   *
   * @returns {[Collection]} all collections
   * @memberof Ice
   */
  listCollections() {
    let collections = {}
    for (let collection in this._collections) {
      collection = this._collections[collection]
      collections[collection.name] = collection
    }
    return collections
  }

  /**
   *Deletes a collection
   *
   * @param {*} collection collection to drop
   * @memberof Ice
   */
  dropCollection(collection) {
    let name = (typeof collection) === 'string' ? collection : collection.name
    this._collections[name].drop();
    delete this._collections[name];
    delete this[name]
  }


  /**
   *Checks if the given collection name does not already exist
   *
   * @param {*} name a name of the collection to check
   * @returns {Boolean} vacant
   * @memberof Ice
   */
  _checkCollectionNameVacant(name) {
    return this[name] ? false : true
  }
}

module.exports = {
  Ice
}