/**
 * @license
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
(function() {
  'use strict';

  /**
    * @appliesMixin Gerrit.FireMixin
    * @appliesMixin Gerrit.KeyboardShortcutMixin
    * @appliesMixin Polymer.IronFitMixin
    */
  class GrAutocompleteDropdown extends Polymer.mixinBehaviors( [
    Gerrit.FireBehavior,
    Gerrit.KeyboardShortcutBehavior,
    Polymer.IronFitBehavior,
  ], Polymer.GestureEventListeners(
      Polymer.LegacyElementMixin(
          Polymer.Element))) {
    static get is() { return 'gr-autocomplete-dropdown'; }
    /**
     * Fired when the dropdown is closed.
     *
     * @event dropdown-closed
     */

    /**
     * Fired when item is selected.
     *
     * @event item-selected
     */

    static get properties() {
      return {
        index: Number,
        isHidden: {
          type: Boolean,
          value: true,
          reflectToAttribute: true,
        },
        verticalOffset: {
          type: Number,
          value: null,
        },
        horizontalOffset: {
          type: Number,
          value: null,
        },
        suggestions: {
          type: Array,
          value: () => [],
          observer: '_resetCursorStops',
        },
        _suggestionEls: Array,
      };
    }

    get keyBindings() {
      return {
        up: '_handleUp',
        down: '_handleDown',
        enter: '_handleEnter',
        esc: '_handleEscape',
        tab: '_handleTab',
      };
    }

    close() {
      this.isHidden = true;
    }

    open() {
      this.isHidden = false;
      this._resetCursorStops();
      // Refit should run after we call Polymer.flush inside _resetCursorStops
      this.refit();
    }

    getCurrentText() {
      return this.getCursorTarget().dataset.value;
    }

    _handleUp(e) {
      if (!this.isHidden) {
        e.preventDefault();
        e.stopPropagation();
        this.cursorUp();
      }
    }

    _handleDown(e) {
      if (!this.isHidden) {
        e.preventDefault();
        e.stopPropagation();
        this.cursorDown();
      }
    }

    cursorDown() {
      if (!this.isHidden) {
        this.$.cursor.next();
      }
    }

    cursorUp() {
      if (!this.isHidden) {
        this.$.cursor.previous();
      }
    }

    _handleTab(e) {
      e.preventDefault();
      e.stopPropagation();
      this.fire('item-selected', {
        trigger: 'tab',
        selected: this.$.cursor.target,
      });
    }

    _handleEnter(e) {
      e.preventDefault();
      e.stopPropagation();
      this.fire('item-selected', {
        trigger: 'enter',
        selected: this.$.cursor.target,
      });
    }

    _handleEscape() {
      this._fireClose();
      this.close();
    }

    _handleClickItem(e) {
      e.preventDefault();
      e.stopPropagation();
      let selected = e.target;
      while (!selected.classList.contains('autocompleteOption')) {
        if (!selected || selected === this) { return; }
        selected = selected.parentElement;
      }
      this.fire('item-selected', {
        trigger: 'click',
        selected,
      });
    }

    _fireClose() {
      this.fire('dropdown-closed');
    }

    getCursorTarget() {
      return this.$.cursor.target;
    }

    _resetCursorStops() {
      if (this.suggestions.length > 0) {
        if (!this.isHidden) {
          Polymer.dom.flush();
          this._suggestionEls = Array.from(
              this.$.suggestions.querySelectorAll('li'));
          this._resetCursorIndex();
        }
      } else {
        this._suggestionEls = [];
      }
    }

    _resetCursorIndex() {
      this.$.cursor.setCursorAtIndex(0);
    }

    _computeLabelClass(item) {
      return item.label ? '' : 'hide';
    }
  }

  customElements.define(GrAutocompleteDropdown.is, GrAutocompleteDropdown);
})();