import * as path from 'path'
import * as Promise from 'bluebird'
import * as fs from 'fs-extra-promise'

interface Settings {
  id: string,
  name: string,
  tag?: string
}

type SettingsKeys = keyof Settings
type SettingsKeysTypes = Settings[SettingsKeys]

export default class PresentationSettings {
  private settingsPath: string

  constructor(directory: string){
    this.settingsPath = path.resolve(directory, 'app', 'settings', 'app.json')
  }

  get (key: SettingsKeys): Promise<SettingsKeysTypes> {
    return this.readSettings()
      .get(key)
  }

  set (key: SettingsKeys, value: SettingsKeysTypes): Promise<void> {
    return this.readSettings()
      .then(this.setValue(key, value))
      .then(settings => this.outputSettings(settings))
  }

  private readSettings (): Promise<Settings> {
    return fs.readJsonAsync(this.settingsPath)
  }

  private setValue (key: SettingsKeys, value: SettingsKeysTypes): (settings: Settings) => Promise<Settings> {
    return function (settings) {
      return Promise.resolve({
        ...settings,
        [key]: value
      });
    }
  }

  private outputSettings (settings: Settings): Promise<void> {
    return fs.outputJsonAsync(this.settingsPath, settings)
  }
}