// 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 './mr-grid-tile.js';

import {css, html, LitElement} from 'lit-element';
import qs from 'qs';
import {connectStore} from 'reducers/base.js';
import * as projectV0 from 'reducers/projectV0.js';
import {issueRefToUrl} from 'shared/convertersV0.js';
import {setHasAny} from 'shared/helpers.js';
import {EMPTY_FIELD_VALUE} from 'shared/issue-fields.js';
import {SHARED_STYLES} from 'shared/shared-styles.js';

import {extractGridData, makeGridCellKey} from './extract-grid-data.js';

const PROPERTIES_TRIGGERING_GROUPING = Object.freeze([
  'xField',
  'yField',
  'issues',
  '_extractFieldValuesFromIssue',
  '_extractTypeForFieldName',
  '_statusDefs',
]);

/**
 * <mr-grid>
 *
 * A grid of issues grouped optionally horizontally and vertically.
 *
 * Throughout the file 'x' corresponds to column headers and 'y' corresponds to
 * row headers.
 *
 * @extends {LitElement}
 */
export class MrGrid extends connectStore(LitElement) {
  /** @override */
  render() {
    return html`
      <table>
        <tr>
          <th>&nbsp</th>
          ${this._xHeadings.map((heading) => html`
              <th>${heading}</th>`)}
        </tr>
        ${this._yHeadings.map((yHeading) => html`
          <tr>
            <th>${yHeading}</th>
            ${this._xHeadings.map((xHeading) => html`
                ${this._renderCell(xHeading, yHeading)}`)}
          </tr>
        `)}
      </table>
    `;
  }
  /**
   *
   * @param {string} xHeading
   * @param {string} yHeading
   * @return {TemplateResult}
   */
  _renderCell(xHeading, yHeading) {
    const cell = this._groupedIssues.get(makeGridCellKey(xHeading, yHeading));
    if (!cell) {
      return html`<td></td>`;
    }

    const cellMode = this.cellMode.toLowerCase();
    let content;
    if (cellMode === 'ids') {
      content = html`
        ${cell.map((issue) => html`
          <mr-issue-link
            .projectName=${this.projectName}
            .issue=${issue}
            .text=${issue.localId}
            .queryParams=${this.queryParams}
          ></mr-issue-link>
        `)}
      `;
    } else if (cellMode === 'counts') {
      const itemCount = cell.length;
      if (itemCount === 1) {
        const issue = cell[0];
        content = html`
          <a href=${issueRefToUrl(issue, this.queryParams)} class="counts">
            1 item
          </a>
        `;
      } else {
        content = html`
          <a href=${this._formatListUrl(xHeading, yHeading)} class="counts">
            ${itemCount} items
          </a>
        `;
      }
    } else {
      // Default to tiles.
      content = html`
        ${cell.map((issue) => html`
          <mr-grid-tile
            .issue=${issue}
            .queryParams=${this.queryParams}
          ></mr-grid-tile>
          `)}
        `;
    }
    return html`<td>${content}</td>`;
  }

  /**
   * Creates a URL to the list view for the group of issues corresponding to
   * the given headings.
   *
   * @param {string} xHeading
   * @param {string} yHeading
   * @return {string}
   */
  _formatListUrl(xHeading, yHeading) {
    let url = 'list?';
    const params = Object.assign({}, this.queryParams);
    params.mode = '';

    params.q = this._addHeadingToQuery(params.q, xHeading, this.xField);
    params.q = this._addHeadingToQuery(params.q, yHeading, this.yField);

    url += qs.stringify(params);

    return url;
  }

  /**
   * @param {string} query
   * @param {string} heading The value of field for the current group.
   * @param {string} field Field on which we're grouping the issue.
   * @return {string} The query with an additional clause if needed.
   */
  _addHeadingToQuery(query, heading, field) {
    if (field && field !== 'None') {
      if (heading === EMPTY_FIELD_VALUE) {
        query += ' -has:' + field;
      // The following two cases are to handle grouping issues by Blocked
      } else if (heading === 'No') {
        query += ' -is:' + field;
      } else if (heading === 'Yes') {
        query += ' is:' + field;
      } else {
        query += ' ' + field + '=' + heading;
      }
    }
    return query;
  }

  /** @override */
  static get properties() {
    return {
      xField: {type: String},
      yField: {type: String},
      issues: {type: Array},
      cellMode: {type: String},
      queryParams: {type: Object},
      projectName: {type: String},
      _extractFieldValuesFromIssue: {type: Object},
      _extractTypeForFieldName: {type: Object},
      _statusDefs: {type: Array},
      _labelPrefixValueMap: {type: Map},
    };
  }

  /** @override */
  static get styles() {
    return [
      SHARED_STYLES,
      css`
        table {
          table-layout: auto;
          border-collapse: collapse;
          width: 98%;
          margin: 0.5em 1%;
          text-align: left;
        }
        th {
          border: 1px solid white;
          padding: 5px;
          background-color: var(--chops-table-header-bg);
          white-space: nowrap;
        }
        td {
          border: var(--chops-table-divider);
          padding-left: 0.3em;
          background-color: var(--chops-white);
          vertical-align: top;
        }
        mr-issue-link {
          display: inline-block;
          margin-right: 8px;
        }
      `,
    ];
  }

  /** @override */
  constructor() {
    super();
    /** @type {string} */
    this.cellMode = 'tiles';
    /** @type {Array<Issue>} */
    this.issues = [];
    /** @type {string} */
    this.projectName;
    this.queryParams = {};

    /** @type {string} The issue field on which to group columns. */
    this.xField;

    /** @type {string} The issue field on which to group rows. */
    this.yField;

    /**
     * Grid cell key mapped to issues associated with that cell.
     * @type {Map.<string, Array<Issue>>}
     */
    this._groupedIssues = new Map();

    /** @type {Array<string>} */
    this._xHeadings = [];

    /** @type {Array<string>} */
    this._yHeadings = [];

    /**
     * Method for extracting values from an issue for a given
     * project config.
     * @type {function(Issue, string): Array<string>}
     */
    this._extractFieldValuesFromIssue = undefined;

    /**
     * Method for finding the types of fields based on their names.
     * @type {function(string): string}
     */
    this._extractTypeForFieldName = undefined;

    /**
     * Note: no default assigned here: it can be undefined in stateChanged.
     * @type {Array<StatusDef>}
     */
    this._statusDefs;

    /**
     * Mapping predefined label prefix to set of values
     * @type {Map}
     */
    this._labelPrefixValueMap = new Map();
  }

  /** @override */
  stateChanged(state) {
    this._extractFieldValuesFromIssue =
      projectV0.extractFieldValuesFromIssue(state);
    this._extractTypeForFieldName = projectV0.extractTypeForFieldName(state);
    this._statusDefs = projectV0.viewedConfig(state).statusDefs;
    this._labelPrefixValueMap = projectV0.labelPrefixValueMap(state);
  }

  /** @override */
  update(changedProperties) {
    if (setHasAny(changedProperties, PROPERTIES_TRIGGERING_GROUPING)) {
      if (this._extractFieldValuesFromIssue) {
        const gridData = extractGridData({
          issues: this.issues,
          extractFieldValuesFromIssue: this._extractFieldValuesFromIssue,
        }, {
          xFieldName: this.xField,
          yFieldName: this.yField,
          extractTypeForFieldName: this._extractTypeForFieldName,
          statusDefs: this._statusDefs,
          labelPrefixValueMap: this._labelPrefixValueMap,
        });

        this._xHeadings = gridData.xHeadings;
        this._yHeadings = gridData.yHeadings;
        this._groupedIssues = gridData.groupedIssues;
      }
    }

    super.update(changedProperties);
  }
};
customElements.define('mr-grid', MrGrid);