// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import * as i18n from '../../../../core/i18n/i18n.js';
import type * as Trace from '../../../../models/trace/trace.js';
import * as UI from '../../../../ui/legacy/legacy.js';
import * as Lit from '../../../../ui/lit/lit.js';

import type * as BaseInsightComponent from './BaseInsightComponent.js';
import {EventReferenceClick} from './EventRef.js';
import tableStyles from './table.css.js';

const UIStrings = {
  /**
   * @description Table row value representing the remaining items not shown in the table due to size constraints. This row will always represent at least 2 items.
   * @example {5} PH1
   */
  others: '{PH1} others',
} as const;

const str_ = i18n.i18n.registerUIStrings('panels/timeline/components/insights/Table.ts', UIStrings);
export const i18nString = i18n.i18n.getLocalizedString.bind(undefined, str_);

const {html} = Lit;

type BaseInsightComponent = BaseInsightComponent.BaseInsightComponent<Trace.Insights.Types.InsightModel>;

/**
 * @file An interactive table component.
 *
 * On hover:
 *           desaturates the relevant events (in both the minimap and the flamegraph), and
 *           replaces the current insight's overlays with the overlays attached to that row.
 *           The currently selected trace bounds does not change.
 *
 *           Removing the mouse from the table without clicking on any row restores the original
 *           overlays.
 *
 * On click:
 *           "sticks" the selection, replaces overlays like hover does, and additionally updates
 *           the current trace bounds to fit the bounds of the row's overlays.
 */

export interface TableState {
  selectedRowEl: HTMLElement|null;
  selectionIsSticky: boolean;
}

interface TableData {
  insight: BaseInsightComponent;
  headers: string[];
  rows: TableDataRow[];
}

export interface TableDataRow {
  values: Array<number|string|Lit.LitTemplate>;
  overlays?: Trace.Types.Overlays.Overlay[];
  subRows?: TableDataRow[];
}

interface FlattenedTableDataRow {
  row: TableDataRow;
  depth: number;
}

export function renderOthersLabel(numOthers: number): string {
  return i18nString(UIStrings.others, {PH1: numOthers});
}

export interface RowLimitAggregator<T> {
  mapToRow: (item: T) => TableDataRow;
  createAggregatedTableRow: (remaining: T[]) => TableDataRow;
}

/**
 * Maps `arr` to a list of `TableDataRow`s  using `aggregator.mapToRow`, but limits the number of `TableDataRow`s to `limit`.
 * If the length of `arr` is larger than `limit`, any excess rows will be aggregated into the final `TableDataRow` using `aggregator.createAggregatedTableRow`.
 *
 * Useful for creating a "N others" row in a data table.
 *
 * Example: `arr` is a list of 15 items & `limit` is 10. The first 9 items in `arr` would be mapped to `TableDataRow`s using `aggregator.mapToRow` and
 * the 10th `TableDataRow` would be created by using `aggregator.createAggregatedTableRow` on the 6 items that were not sent through `aggregator.mapToRow`.
 */
export function createLimitedRows<T>(arr: T[], aggregator: RowLimitAggregator<T>, limit = 10): TableDataRow[] {
  if (arr.length === 0 || limit === 0) {
    return [];
  }

  const aggregateStartIndex = limit - 1;
  const items = arr.slice(0, aggregateStartIndex).map(aggregator.mapToRow.bind(aggregator));
  if (arr.length > limit) {
    items.push(aggregator.createAggregatedTableRow(arr.slice(aggregateStartIndex)));
  } else if (arr.length === limit) {
    items.push(aggregator.mapToRow(arr[aggregateStartIndex]));
  }

  return items;
}

interface ViewInput {
  interactive: boolean;
  headers: string[];
  flattenedRows: FlattenedTableDataRow[];

  onHoverRow: (row: TableDataRow, rowEl: HTMLElement) => void;
  onClickRow: (row: TableDataRow, rowEl: HTMLElement) => void;
  onMouseLeave: () => void;
}

type View = (input: ViewInput, output: undefined, target: HTMLElement) => void;

export const DEFAULT_VIEW: View = (input, output, target) => {
  const {
    interactive,
    headers,
    flattenedRows,
    onHoverRow,
    onClickRow,
    onMouseLeave,
  } = input;

  const numColumns = headers.length;

  function renderRow({row, depth}: FlattenedTableDataRow): Lit.TemplateResult {
    const thStyles = Lit.Directives.styleMap({
      paddingLeft: `calc(${depth} * var(--sys-size-5))`,
      backgroundImage: `repeating-linear-gradient(
            to right,
            var(--sys-color-tonal-outline) 0 var(--sys-size-1),
            transparent var(--sys-size-1) var(--sys-size-5)
          )`,
      backgroundPosition: '0 0',
      backgroundRepeat: 'no-repeat',
      backgroundSize: `calc(${depth} * var(--sys-size-5))`,
    });
    const trStyles = Lit.Directives.styleMap({
      color: depth ? 'var(--sys-color-on-surface-subtle)' : '',
    });
    const columnEls = row.values.map(
        (value, i) => i === 0 ? html`<th
              scope="row"
              colspan=${i === row.values.length - 1 ? numColumns - i : 1}
              style=${thStyles}>${value}
            </th>` :
                                html`<td>${value}</td>`);
    return html`<tr style=${trStyles}>${columnEls}</tr>`;
  }

  const findRowAndEl = (el: HTMLElement): {row: TableDataRow, rowEl: HTMLElement} => {
    const rowEl = el.closest('tr') as HTMLTableRowElement;
    const row = flattenedRows[rowEl.sectionRowIndex].row;
    return {row, rowEl};
  };

  // clang-format off
  Lit.render(html`
    <style>${tableStyles}</style>
    <table
        class=${Lit.Directives.classMap({
        interactive,
      })}
        @mouseleave=${interactive ? onMouseLeave : null}>
      <thead>
        <tr>
          ${headers.map(h => html`<th scope="col">${h}</th>`)}
        </tr>
      </thead>
      <tbody
        @mouseover=${interactive ? (e: Event) => {
          const {row, rowEl} = findRowAndEl(e.target as HTMLElement);
          onHoverRow(row, rowEl);
        } : null}
        @click=${interactive ? (e: Event) => {
          const {row, rowEl} = findRowAndEl(e.target as HTMLElement);
          onClickRow(row, rowEl);
        } : null}
      >${flattenedRows.map(renderRow)}</tbody>
    </table>`,
    target);
  // clang-format on
};

export class Table extends UI.Widget.Widget {
  #view: View;
  #insight?: BaseInsightComponent;
  #state?: TableState;
  #headers?: string[];
  /** The rows as given as by the user, which may include recursive rows via subRows. */
  #rows?: TableDataRow[];
  /** All rows/subRows, in the order that they appear visually. This is the result of traversing `#rows` and any subRows found. */
  #flattenedRows?: FlattenedTableDataRow[];
  #rowToParentRow = new Map<TableDataRow, TableDataRow>();
  #interactive = false;
  #currentHoverRow: TableDataRow|null = null;

  constructor(element?: HTMLElement, view: View = DEFAULT_VIEW) {
    super(element, {useShadowDom: true});
    this.#view = view;
  }

  set data(data: TableData) {
    this.#insight = data.insight;
    this.#state = data.insight.sharedTableState;
    this.#headers = data.headers;
    this.#rows = data.rows;
    this.#flattenedRows = this.#createFlattenedRows();
    // If this table isn't interactive, don't attach mouse listeners or use CSS :hover.
    this.#interactive = this.#rows.some(row => row.overlays || row.subRows?.length);
    this.requestUpdate();
  }

  #createFlattenedRows(): FlattenedTableDataRow[] {
    if (!this.#rows) {
      return [];
    }

    const rowToParentRow = this.#rowToParentRow;
    rowToParentRow.clear();

    const flattenedRows: FlattenedTableDataRow[] = [];
    function traverse(parent: TableDataRow|null, row: TableDataRow, depth = 0): void {
      if (parent) {
        rowToParentRow.set(row, parent);
      }

      flattenedRows.push({depth, row});

      for (const subRow of row.subRows ?? []) {
        traverse(row, subRow, depth + 1);
      }
    }

    for (const row of this.#rows) {
      traverse(null, row);
    }

    return flattenedRows;
  }

  #onHoverRow(row: TableDataRow, rowEl: HTMLElement): void {
    if (row === this.#currentHoverRow || !this.element.shadowRoot) {
      return;
    }

    for (const el of this.element.shadowRoot.querySelectorAll('.hover')) {
      el.classList.remove('hover');
    }

    // Add 'hover' class to all parent rows.
    let curRow: TableDataRow|undefined = this.#rowToParentRow.get(row);
    while (curRow) {
      rowEl.classList.add('hover');
      curRow = this.#rowToParentRow.get(curRow);
    }

    this.#currentHoverRow = row;
    // Temporarily selects the row, but only if there is not already a sticky selection.
    this.#onSelectedRowChanged(row, rowEl, {isHover: true});
  }

  #onClickRow(row: TableDataRow, rowEl: HTMLElement): void {
    // If the desired overlays consist of just a single ENTRY_OUTLINE, then
    // it is more intuitive to just select the target event.
    const overlays = row.overlays;
    if (overlays?.length === 1 && overlays[0].type === 'ENTRY_OUTLINE') {
      this.element.dispatchEvent(new EventReferenceClick(overlays[0].entry));
      return;
    }

    // Select the row and make it sticky.
    this.#onSelectedRowChanged(row, rowEl, {sticky: true});
  }

  #onMouseLeave(): void {
    for (const el of this.element.shadowRoot?.querySelectorAll('.hover') ?? []) {
      el.classList.remove('hover');
    }

    this.#currentHoverRow = null;
    // Unselect the row, unless it's sticky.
    this.#onSelectedRowChanged(null, null);
  }

  #onSelectedRowChanged(row: TableDataRow|null, rowEl: HTMLElement|null, opts: {
    sticky?: boolean,
    isHover?: boolean,
  } = {}): void {
    if (!this.#state || !this.#insight) {
      return;
    }

    if (this.#state.selectionIsSticky && !opts.sticky) {
      return;
    }

    // Unselect a sticky-selection when clicking it for a second time.
    if (this.#state.selectionIsSticky && rowEl === this.#state.selectedRowEl) {
      rowEl = null;
      opts.sticky = false;
    }

    if (rowEl && row) {
      const overlays = row.overlays;
      if (overlays) {
        this.#insight.toggleTemporaryOverlays(overlays, {updateTraceWindow: !opts.isHover});
      }
    } else {
      this.#insight.toggleTemporaryOverlays(null, {updateTraceWindow: false});
    }

    this.#state.selectedRowEl?.classList.remove('selected');
    rowEl?.classList.add('selected');
    this.#state.selectedRowEl = rowEl;
    this.#state.selectionIsSticky = opts.sticky ?? false;
  }

  override performUpdate(): void {
    if (!this.#headers || !this.#flattenedRows) {
      return;
    }

    const input: ViewInput = {
      interactive: this.#interactive,
      headers: this.#headers,
      flattenedRows: this.#flattenedRows,
      onHoverRow: this.#onHoverRow.bind(this),
      onClickRow: this.#onClickRow.bind(this),
      onMouseLeave: this.#onMouseLeave.bind(this),
    };
    this.#view(input, undefined, this.contentElement);
  }
}