/**
 * @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';

  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;

  /**
   * @appliesMixin Gerrit.FireMixin
   * @appliesMixin Gerrit.KeyboardShortcutMixin
   * @appliesMixin Gerrit.PatchSetMixin
   * @appliesMixin Gerrit.PathListMixin
   * @extends Polymer.Element
   */
  class GrEditorView extends Polymer.mixinBehaviors( [
    Gerrit.FireBehavior,
    Gerrit.KeyboardShortcutBehavior,
    Gerrit.PatchSetBehavior,
    Gerrit.PathListBehavior,
  ], Polymer.GestureEventListeners(
      Polymer.LegacyElementMixin(
          Polymer.Element))) {
    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,
      };
    }

    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 !== Gerrit.Nav.View.EDIT) {
        return;
      }

      this._changeNum = value.changeNum;
      this._path = value.path;
      this._patchNum = value.patchNum || this.EDIT_NAME;

      // 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 ${this.computeTruncatedPath(this._path)}`;
        this.fire('title-change', {title});
      });

      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 ? this.EDIT_NAME : this._patchNum;
      Gerrit.Nav.navigateToChange(this._change, patch, null,
          patch !== this.EDIT_NAME);
    }

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

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

              this._newContent = storedContent.message;
            } else {
              this._newContent = res.content || '';
            }
            this._content = res.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.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,
      ].some(arg => arg === 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);
})();