/**
 * @license
 * Copyright (C) 2018 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';

  /** @extends Polymer.Element */
  class GrDiffModeSelector extends Polymer.GestureEventListeners(
      Polymer.LegacyElementMixin(
          Polymer.Element)) {
    static get is() { return 'gr-diff-mode-selector'; }

    static get properties() {
      return {
        mode: {
          type: String,
          notify: true,
        },

        /**
         * If set to true, the user's preference will be updated every time a
         * button is tapped. Don't set to true if there is no user.
         */
        saveOnChange: {
          type: Boolean,
          value: false,
        },

        /** @type {?} */
        _VIEW_MODES: {
          type: Object,
          readOnly: true,
          value: {
            SIDE_BY_SIDE: 'SIDE_BY_SIDE',
            UNIFIED: 'UNIFIED_DIFF',
          },
        },
      };
    }

    /**
     * Set the mode. If save on change is enabled also update the preference.
     */
    setMode(newMode) {
      if (this.saveOnChange && this.mode && this.mode !== newMode) {
        this.$.restAPI.savePreferences({diff_view: newMode});
      }
      this.mode = newMode;
    }

    _computeSelectedClass(diffViewMode, buttonViewMode) {
      return buttonViewMode === diffViewMode ? 'selected' : '';
    }

    _handleSideBySideTap() {
      this.setMode(this._VIEW_MODES.SIDE_BY_SIDE);
    }

    _handleUnifiedTap() {
      this.setMode(this._VIEW_MODES.UNIFIED);
    }
  }

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