// Copyright 2019 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import {LitElement, html} from 'lit-element';

import {store, connectStore} from 'reducers/base.js';
import * as issueV0 from 'reducers/issueV0.js';
import * as ui from 'reducers/ui.js';
import 'elements/framework/mr-comment-content/mr-description.js';
import '../mr-comment-list/mr-comment-list.js';
import '../metadata/mr-edit-metadata/mr-edit-issue.js';
import {commentListToDescriptionList} from 'shared/convertersV0.js';

/**
 * `<mr-issue-details>`
 *
 * This is the main details section for a given issue.
 *
 */
export class MrIssueDetails extends connectStore(LitElement) {
  /** @override */
  render() {
    let comments = [];
    let descriptions = [];

    if (this.commentsByApproval && this.commentsByApproval.has('')) {
      // Comments without an approval go into the main view.
      const mainComments = this.commentsByApproval.get('');
      comments = mainComments.slice(1);
      descriptions = commentListToDescriptionList(mainComments);
    }

    return html`
      <style>
        mr-issue-details {
          font-size: var(--chops-main-font-size);
          background-color: var(--chops-white);
          padding-bottom: 1em;
          display: flex;
          align-items: stretch;
          justify-content: flex-start;
          flex-direction: column;
          margin: 0;
          box-sizing: border-box;
        }
        h3 {
          margin-top: 1em;
        }
        mr-description {
          margin-bottom: 1em;
        }
        mr-edit-issue {
          margin-top: 40px;
        }
      </style>
      <mr-description .descriptionList=${descriptions}></mr-description>
      <mr-comment-list
        headingLevel="2"
        .comments=${comments}
        .commentsShownCount=${this.commentsShownCount}
      ></mr-comment-list>
      ${this.issuePermissions.includes('addissuecomment') ?
        html`<mr-edit-issue></mr-edit-issue>` : ''}
    `;
  }

  /** @override */
  static get properties() {
    return {
      commentsByApproval: {type: Object},
      commentsShownCount: {type: Number},
      issuePermissions: {type: Array},
    };
  }

  /** @override */
  constructor() {
    super();
    this.commentsByApproval = new Map();
    this.issuePermissions = [];
  }

  /** @override */
  createRenderRoot() {
    return this;
  }

  /** @override */
  stateChanged(state) {
    this.commentsByApproval = issueV0.commentsByApprovalName(state);
    this.issuePermissions = issueV0.permissions(state);
  }

  /** @override */
  updated(changedProperties) {
    super.updated(changedProperties);
    this._measureCommentLoadTime(changedProperties);
  }

  async _measureCommentLoadTime(changedProperties) {
    if (!changedProperties.has('commentsByApproval')) {
      return;
    }
    if (!this.commentsByApproval || this.commentsByApproval.size === 0) {
      // For cold loads, if the GetIssue call returns before ListComments,
      // commentsByApproval is initially set to an empty Map. Filter that out.
      return;
    }
    const fullAppLoad = ui.navigationCount(store.getState()) === 1;
    if (!(fullAppLoad || changedProperties.get('commentsByApproval'))) {
      // For hot loads, the previous issue data is still in the Redux store, so
      // the first update sets the comments to the previous issue's comments.
      // We need to wait for the following update.
      return;
    }
    const startMark = fullAppLoad ? undefined : 'start load issue detail page';
    if (startMark && !performance.getEntriesByName(startMark).length) {
      // Modifying the issue template, description, comments, or attachments
      // triggers a comment update. We only want to include full issue loads.
      return;
    }

    await Promise.all(_subtreeUpdateComplete(this));

    const endMark = 'finish load issue detail comments';
    performance.mark(endMark);

    const measurementType = fullAppLoad ? 'from outside app' : 'within app';
    const measurementName = `load issue detail page (${measurementType})`;
    performance.measure(measurementName, startMark, endMark);

    const measurement =
      performance.getEntriesByName(measurementName)[0].duration;
    window.getTSMonClient().recordIssueCommentsLoadTiming(
        measurement, fullAppLoad);

    // Be sure to clear this mark even on full page navigations.
    performance.clearMarks('start load issue detail page');
    performance.clearMarks(endMark);
    performance.clearMeasures(measurementName);
  }
}

/**
 * Recursively traverses all shadow DOMs in an element subtree and returns an
 * Array containing the updateComplete Promises for all lit-element nodes.
 * @param {!LitElement} element
 * @return {!Array<Promise<Boolean>>}
 */
function _subtreeUpdateComplete(element) {
  if (!element.updateComplete) {
    return [];
  }

  const context = element.shadowRoot ? element.shadowRoot : element;
  const children = context.querySelectorAll('*');
  const childPromises = Array.from(children, (e) => _subtreeUpdateComplete(e));
  return [element.updateComplete].concat(...childPromises);
}

customElements.define('mr-issue-details', MrIssueDetails);