/**
 * @license
 * Copyright (C) 2016 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.
 */
import {IronOverlayBehaviorImpl} from '@polymer/iron-overlay-behavior/iron-overlay-behavior.js';
import '@polymer/iron-dropdown/iron-dropdown.js';
import '@polymer/paper-input/paper-input.js';
import '../../../styles/shared-styles.js';
import '../gr-button/gr-button.js';
import {dom} from '@polymer/polymer/lib/legacy/polymer.dom.js';
import {mixinBehaviors} from '@polymer/polymer/lib/legacy/class.js';
import {GestureEventListeners} from '@polymer/polymer/lib/mixins/gesture-event-listeners.js';
import {LegacyElementMixin} from '@polymer/polymer/lib/legacy/legacy-element-mixin.js';
import {PolymerElement} from '@polymer/polymer/polymer-element.js';
import {htmlTemplate} from './gr-editable-label_html.js';
import {KeyboardShortcutBehavior} from '../../../behaviors/keyboard-shortcut-behavior/keyboard-shortcut-behavior.js';

const AWAIT_MAX_ITERS = 10;
const AWAIT_STEP = 5;

/**
 * @extends PolymerElement
 */
class GrEditableLabel extends mixinBehaviors( [
  KeyboardShortcutBehavior,
], GestureEventListeners(
    LegacyElementMixin(
        PolymerElement))) {
  static get template() { return htmlTemplate; }

  static get is() { return 'gr-editable-label'; }
  /**
   * Fired when the value is changed.
   *
   * @event changed
   */

  static get properties() {
    return {
      labelText: String,
      editing: {
        type: Boolean,
        value: false,
      },
      value: {
        type: String,
        notify: true,
        value: '',
        observer: '_updateTitle',
      },
      placeholder: {
        type: String,
        value: '',
      },
      readOnly: {
        type: Boolean,
        value: false,
      },
      uppercase: {
        type: Boolean,
        reflectToAttribute: true,
        value: false,
      },
      maxLength: Number,
      _inputText: String,
      // This is used to push the iron-input element up on the page, so
      // the input is placed in approximately the same position as the
      // trigger.
      _verticalOffset: {
        type: Number,
        readOnly: true,
        value: -30,
      },
    };
  }

  /** @override */
  ready() {
    super.ready();
    this._ensureAttribute('tabindex', '0');
  }

  get keyBindings() {
    return {
      enter: '_handleEnter',
      esc: '_handleEsc',
    };
  }

  _usePlaceholder(value, placeholder) {
    return (!value || !value.length) && placeholder;
  }

  _computeLabel(value, placeholder) {
    if (this._usePlaceholder(value, placeholder)) {
      return placeholder;
    }
    return value;
  }

  _showDropdown() {
    if (this.readOnly || this.editing) { return; }
    return this._open().then(() => {
      this._nativeInput.focus();
      if (!this.$.input.value) { return; }
      this._nativeInput.setSelectionRange(0, this.$.input.value.length);
    });
  }

  open() {
    return this._open().then(() => {
      this._nativeInput.focus();
    });
  }

  _open(...args) {
    this.$.dropdown.open();
    this._inputText = this.value;
    this.editing = true;

    return new Promise(resolve => {
      IronOverlayBehaviorImpl.open.apply(this.$.dropdown, args);
      this._awaitOpen(resolve);
    });
  }

  /**
   * NOTE: (wyatta) Slightly hacky way to listen to the overlay actually
   * opening. Eventually replace with a direct way to listen to the overlay.
   */
  _awaitOpen(fn) {
    let iters = 0;
    const step = () => {
      this.async(() => {
        if (this.$.dropdown.style.display !== 'none') {
          fn.call(this);
        } else if (iters++ < AWAIT_MAX_ITERS) {
          step.call(this);
        }
      }, AWAIT_STEP);
    };
    step.call(this);
  }

  _id() {
    return this.getAttribute('id') || 'global';
  }

  _save() {
    if (!this.editing) { return; }
    this.$.dropdown.close();
    this.value = this._inputText;
    this.editing = false;
    this.dispatchEvent(new CustomEvent('changed', {
      detail: this.value,
      composed: true, bubbles: true,
    }));
  }

  _cancel() {
    if (!this.editing) { return; }
    this.$.dropdown.close();
    this.editing = false;
    this._inputText = this.value;
  }

  get _nativeInput() {
    // In Polymer 2, the namespace of nativeInput
    // changed from input to nativeInput
    return this.$.input.$.nativeInput || this.$.input.$.input;
  }

  _handleEnter(e) {
    e = this.getKeyboardEvent(e);
    const target = dom(e).rootTarget;
    if (target === this._nativeInput) {
      e.preventDefault();
      this._save();
    }
  }

  _handleEsc(e) {
    e = this.getKeyboardEvent(e);
    const target = dom(e).rootTarget;
    if (target === this._nativeInput) {
      e.preventDefault();
      this._cancel();
    }
  }

  _computeLabelClass(readOnly, value, placeholder) {
    const classes = [];
    if (!readOnly) { classes.push('editable'); }
    if (this._usePlaceholder(value, placeholder)) {
      classes.push('placeholder');
    }
    return classes.join(' ');
  }

  _updateTitle(value) {
    this.setAttribute('title', this._computeLabel(value, this.placeholder));
  }
}

customElements.define(GrEditableLabel.is, GrEditableLabel);