storage-folder.js

const path = require('path')
const fs = require('fs-plus')

module.exports =
class StorageFolder {
  constructor (containingPath) {
    if (containingPath) {
      this.path = path.join(containingPath, 'storage')
    }
  }

  store (name, object) {
    return new Promise((resolve, reject) => {
      if (!this.path) return resolve()
      fs.writeFile(this.pathForKey(name), JSON.stringify(object), 'utf8', error =>
        error ? reject(error) : resolve()
      )
    })
  }

  load (name) {
    return new Promise(resolve => {
      if (!this.path) return resolve(null)
      const statePath = this.pathForKey(name)
      fs.readFile(statePath, 'utf8', (error, stateString) => {
        if (error && error.code !== 'ENOENT') {
          console.warn(`Error reading state file: ${statePath}`, error.stack, error)
        }

        if (!stateString) return resolve(null)

        try {
          resolve(JSON.parse(stateString))
        } catch (error) {
          console.warn(`Error parsing state file: ${statePath}`, error.stack, error)
          resolve(null)
        }
      })
    })
  }

  pathForKey (name) {
    return path.join(this.getPath(), name)
  }

  getPath () {
    return this.path
  }
}