import Component from '@ember/component'
import { computed, observer } from '@ember/object'
import { alias, empty } from '@ember/object/computed'
import { scheduleOnce } from '@ember/runloop'

import layout from 'leaf-semantic-core/templates/components/leaf-keywords-suggest'


KEYS = {
  BACKSPACE: 8
  SPACE: 32
  TAB: 9
  ENTER: 13
  SHIFT: 16
  ESC: 27
  ARROW_LEFT: 37
  ARROW_UP: 38
  ARROW_RIGHT: 39
  ARROW_DOWN: 40
  COMMA: 188
}

LeafKeywordsSuggestions = Component.extend(
  layout: layout


  tagName: 'ul'
  classNames: ['suggestions', 'ui', 'basic', 'pointing', 'prompt', 'fluid', 'label']
  classNameBindings: ['active', 'hidden']

  attributeBindings: [
    'role'
    'ariaMultiselectable:aria-multiselectable'
    'ariaExpanded:aria-expanded'
    'tabindex'
    'value'
  ],


  role: 'listbox'
  ariaMultiselectable: 'false'
  ariaExpanded: alias('active')

  tabindex: 0

  suggestions: []
  current: null

  active: false
  hidden: empty('suggestions')


  onActivation: observer('active', 'suggestions', ( ->
    if @get('active')
      @set('current', @get('suggestions.firstObject'))
      scheduleOnce('afterRender', this, ( -> @.$().focus()))
    else
      @set('current', null)
  ))


  nextSuggestion: computed('current', 'suggestions', ( ->
    { current,
      suggestions } = @getProperties('current', 'suggestions')

    i = suggestions.indexOf(current)
    suggestions[ if ( i == suggestions.length - 1) then 0 else ( i + 1 )]
  ))

  prevSuggestion: computed('current', 'suggestions', ( ->
    { current,
      suggestions } = @getProperties('current', 'suggestions')

    i = suggestions.indexOf(current)
    suggestions[ if ( i == 0) then (suggestions.length - 1) else ( i - 1 )]

  ))


  keyDown: ((ev) ->
    @_super(arguments...)

    handled = false
    switch ev.keyCode
      when KEYS.ARROW_RIGHT, KEYS.ARROW_DOWN
        @set('current', @get('nextSuggestion'))
        handled = true

      when KEYS.ARROW_LEFT, KEYS.ARROW_UP
        @set('current', @get('prevSuggestion'))
        handled = true

      when KEYS.ENTER, KEYS.SPACE
        @sendAction('on-add', @get('current'))
        handled = true

      when KEYS.ESC, KEYS.TAB
        @sendAction('on-escape', @get('current'))
        handled = true

    if handled
      ev.preventDefault()

  )


  focusOut: ((ev) ->
    @_super(arguments...)
    @sendAction('on-blur', @get('current'))
  )


  actions:
    addSuggestion: (tag) ->
      @sendAction('on-add', tag)

)

export default LeafKeywordsSuggestions