const {Emitter} = require('event-kit')
const _ = require('underscore-plus')

// Public: A notification to the user containing a message and type.
module.exports =
class Notification {
  constructor (type, message, options = {}) {
    this.type = type
    this.message = message
    this.options = options
    this.emitter = new Emitter()
    this.timestamp = new Date()
    this.dismissed = true
    if (this.isDismissable()) this.dismissed = false
    this.displayed = false
    this.validate()
  }

  validate () {
    if (typeof this.message !== 'string') {
      throw new Error(`Notification must be created with string message: ${this.message}`)
    }

    if (!_.isObject(this.options) || Array.isArray(this.options)) {
      throw new Error(`Notification must be created with an options object: ${this.options}`)
    }
  }

  /*
  Section: Event Subscription
  */

  // Public: Invoke the given callback when the notification is dismissed.
  //
  // * `callback` {Function} to be called when the notification is dismissed.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidDismiss (callback) {
    return this.emitter.on('did-dismiss', callback)
  }

  // Public: Invoke the given callback when the notification is displayed.
  //
  // * `callback` {Function} to be called when the notification is displayed.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidDisplay (callback) {
    return this.emitter.on('did-display', callback)
  }

  getOptions () {
    return this.options
  }

  /*
  Section: Methods
  */

  // Public: Returns the {String} type.
  getType () {
    return this.type
  }

  // Public: Returns the {String} message.
  getMessage () {
    return this.message
  }

  getTimestamp () {
    return this.timestamp
  }

  getDetail () {
    return this.options.detail
  }

  isEqual (other) {
    return (this.getMessage() === other.getMessage()) &&
      (this.getType() === other.getType()) &&
      (this.getDetail() === other.getDetail())
  }

  // Extended: Dismisses the notification, removing it from the UI. Calling this
  // programmatically will call all callbacks added via `onDidDismiss`.
  dismiss () {
    if (!this.isDismissable() || this.isDismissed()) return
    this.dismissed = true
    this.emitter.emit('did-dismiss', this)
  }

  isDismissed () {
    return this.dismissed
  }

  isDismissable () {
    return !!this.options.dismissable
  }

  wasDisplayed () {
    return this.displayed
  }

  setDisplayed (displayed) {
    this.displayed = displayed
    this.emitter.emit('did-display', this)
  }

  getIcon () {
    if (this.options.icon != null) return this.options.icon
    switch (this.type) {
      case 'fatal': return 'bug'
      case 'error': return 'flame'
      case 'warning': return 'alert'
      case 'info': return 'info'
      case 'success': return 'check'
    }
  }
}