/**
 * @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.
 */
import '../../plugins/gr-endpoint-decorator/gr-endpoint-decorator.js';
import '../../plugins/gr-endpoint-param/gr-endpoint-param.js';
import '../../shared/gr-button/gr-button.js';
import '../../shared/gr-editable-label/gr-editable-label.js';
import '../../shared/gr-rest-api-interface/gr-rest-api-interface.js';
import '../../shared/gr-storage/gr-storage.js';
import '../gr-default-editor/gr-default-editor.js';
import '../../../styles/shared-styles.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-editor-view_html.js';
import {KeyboardShortcutMixin} from '../../../mixins/keyboard-shortcut-mixin/keyboard-shortcut-mixin.js';
import {GerritNav} from '../../core/gr-navigation/gr-navigation.js';
import {SPECIAL_PATCH_SET_NUM} from '../../../utils/patch-set-util.js';
import {computeTruncatedPath} from '../../../utils/path-list-util.js';

const RESTORED_MESSAGE = 'Content restored from a previous edit.';
const SAVING_MESSAGE = 'Saving changes...';
const SAVED_MESSAGE = 'All changes saved';
const SAVE_FAILED_MSG = 'Failed to save changes';

const STORAGE_DEBOUNCE_INTERVAL_MS = 100;

/**
 * @extends PolymerElement
 */
class GrEditorView extends KeyboardShortcutMixin(GestureEventListeners(
    LegacyElementMixin(
        PolymerElement))) {
  static get template() { return htmlTemplate; }

  static get is() { return 'gr-editor-view'; }
  /**
   * Fired when the title of the page should change.
   *
   * @event title-change
   */

  /**
   * Fired to notify the user of
   *
   * @event show-alert
   */

  static get properties() {
    return {
    /**
     * URL params passed from the router.
     */
      params: {
        type: Object,
        observer: '_paramsChanged',
      },

      _change: Object,
      _changeEditDetail: Object,
      _changeNum: String,
      _patchNum: String,
      _path: String,
      _type: String,
      _content: String,
      _newContent: String,
      _saving: {
        type: Boolean,
        value: false,
      },
      _successfulSave: {
        type: Boolean,
        value: false,
      },
      _saveDisabled: {
        type: Boolean,
        value: true,
        computed: '_computeSaveDisabled(_content, _newContent, _saving)',
      },
      _prefs: Object,
      _lineNum: Number,
    };
  }

  get keyBindings() {
    return {
      'ctrl+s meta+s': '_handleSaveShortcut',
    };
  }

  /** @override */
  created() {
    super.created();
    this.addEventListener('content-change',
        e => this._handleContentChange(e));
  }

  /** @override */
  attached() {
    super.attached();
    this._getEditPrefs().then(prefs => { this._prefs = prefs; });
  }

  get storageKey() {
    return `c${this._changeNum}_ps${this._patchNum}_${this._path}`;
  }

  _getLoggedIn() {
    return this.$.restAPI.getLoggedIn();
  }

  _getEditPrefs() {
    return this.$.restAPI.getEditPreferences();
  }

  _paramsChanged(value) {
    if (value.view !== GerritNav.View.EDIT) {
      return;
    }

    this._changeNum = value.changeNum;
    this._path = value.path;
    this._patchNum = value.patchNum || SPECIAL_PATCH_SET_NUM.EDIT;
    this._lineNum = value.lineNum;

    // NOTE: This may be called before attachment (e.g. while parentElement is
    // null). Fire title-change in an async so that, if attachment to the DOM
    // has been queued, the event can bubble up to the handler in gr-app.
    this.async(() => {
      const title = `Editing ${computeTruncatedPath(this._path)}`;
      this.dispatchEvent(new CustomEvent('title-change', {
        detail: {title},
        composed: true, bubbles: true,
      }));
    });

    const promises = [];

    promises.push(this._getChangeDetail(this._changeNum));
    promises.push(
        this._getFileData(this._changeNum, this._path, this._patchNum));
    return Promise.all(promises);
  }

  _getChangeDetail(changeNum) {
    return this.$.restAPI.getDiffChangeDetail(changeNum).then(change => {
      this._change = change;
    });
  }

  _handlePathChanged(e) {
    const path = e.detail;
    if (path === this._path) {
      return Promise.resolve();
    }
    return this.$.restAPI.renameFileInChangeEdit(this._changeNum,
        this._path, path).then(res => {
      if (!res.ok) { return; }

      this._successfulSave = true;
      this._viewEditInChangeView();
    });
  }

  _viewEditInChangeView() {
    const patch = this._successfulSave ? SPECIAL_PATCH_SET_NUM.EDIT
      : this._patchNum;
    GerritNav.navigateToChange(this._change, patch, null,
        patch !== SPECIAL_PATCH_SET_NUM.EDIT);
  }

  _getFileData(changeNum, path, patchNum) {
    const storedContent =
          this.$.storage.getEditableContentItem(this.storageKey);

    return this.$.restAPI.getFileContent(changeNum, path, patchNum)
        .then(res => {
          const content = (res && res.content) || '';
          if (storedContent && storedContent.message &&
              storedContent.message !== content) {
            this.dispatchEvent(new CustomEvent('show-alert', {
              detail: {message: RESTORED_MESSAGE},
              bubbles: true,
              composed: true,
            }));

            this._newContent = storedContent.message;
          } else {
            this._newContent = content;
          }
          this._content = content;

          // A non-ok response may result if the file does not yet exist.
          // The `type` field of the response is only valid when the file
          // already exists.
          if (res && res.ok && res.type) {
            this._type = res.type;
          } else {
            this._type = '';
          }
        });
  }

  _saveEdit() {
    this._saving = true;
    this._showAlert(SAVING_MESSAGE);
    this.$.storage.eraseEditableContentItem(this.storageKey);
    return this.$.restAPI.saveChangeEdit(this._changeNum, this._path,
        this._newContent).then(res => {
      this._saving = false;
      this._showAlert(res.ok ? SAVED_MESSAGE : SAVE_FAILED_MSG);
      if (!res.ok) { return; }

      this._content = this._newContent;
      this._successfulSave = true;
    });
  }

  _showAlert(message) {
    this.dispatchEvent(new CustomEvent('show-alert', {
      detail: {message},
      bubbles: true,
      composed: true,
    }));
  }

  _computeSaveDisabled(content, newContent, saving) {
    // Polymer 2: check for undefined
    if ([
      content,
      newContent,
      saving,
    ].includes(undefined)) {
      return true;
    }

    if (saving) {
      return true;
    }
    return content === newContent;
  }

  _handleCloseTap() {
    // TODO(kaspern): Add a confirm dialog if there are unsaved changes.
    this._viewEditInChangeView();
  }

  _handleContentChange(e) {
    this.debounce('store', () => {
      const content = e.detail.value;
      if (content) {
        this.set('_newContent', e.detail.value);
        this.$.storage.setEditableContentItem(this.storageKey, content);
      } else {
        this.$.storage.eraseEditableContentItem(this.storageKey);
      }
    }, STORAGE_DEBOUNCE_INTERVAL_MS);
  }

  _handleSaveShortcut(e) {
    e.preventDefault();
    if (!this._saveDisabled) {
      this._saveEdit();
    }
  }
}

customElements.define(GrEditorView.is, GrEditorView);