let {
  BaseComponent,
  DefaultButton,
  IDetailsList,
  DetailsList,
  IColumn,
  IGroup,
  Toggle,
  IToggleStyles,
  mergeStyles,
  Fabric
} = window.Fabric;

const margin = '0 20px 20px 0';
const controlWrapperClass = mergeStyles({
  display: 'flex',
  flexWrap: 'wrap'
});
const toggleStyles: Partial<IToggleStyles> = {
  root: { margin: margin },
  label: { marginLeft: 10 }
};

interface IDetailsListGroupedExampleItem {
  key: string;
  name: string;
  color: string;
}

interface IDetailsListGroupedExampleState {
  items: IDetailsListGroupedExampleItem[];
  groups: IGroup[];
  showItemIndexInView: boolean;
  isCompactMode: boolean;
}

const _blueGroupIndex = 2;

class DetailsListGroupedExample extends BaseComponent<{}, IDetailsListGroupedExampleState> {
  private _root = React.createRef<IDetailsList>();
  private _columns: IColumn[];

  constructor(props: {}) {
    super(props);

    this.state = {
      items: [
        { key: 'a', name: 'a', color: 'red' },
        { key: 'b', name: 'b', color: 'red' },
        { key: 'c', name: 'c', color: 'blue' },
        { key: 'd', name: 'd', color: 'blue' },
        { key: 'e', name: 'e', color: 'blue' }
      ],
      // This is based on the definition of items
      groups: [
        { key: 'groupred0', name: 'Color: "red"', startIndex: 0, count: 2 },
        { key: 'groupgreen2', name: 'Color: "green"', startIndex: 2, count: 0 },
        { key: 'groupblue2', name: 'Color: "blue"', startIndex: 2, count: 3 }
      ],
      showItemIndexInView: false,
      isCompactMode: false
    };

    this._columns = [
      { key: 'name', name: 'Name', fieldName: 'name', minWidth: 100, maxWidth: 200, isResizable: true },
      { key: 'color', name: 'Color', fieldName: 'color', minWidth: 100, maxWidth: 200 }
    ];
  }

  public componentWillUnmount() {
    if (this.state.showItemIndexInView) {
      const itemIndexInView = this._root.current!.getStartItemIndexInView();
      alert('first item index that was in view: ' + itemIndexInView);
    }
  }

  public render() {
    const { items, groups, isCompactMode } = this.state;

    return (
      <div>
        <div className={controlWrapperClass}>
          <DefaultButton onClick={this._addItem} text="Add an item" styles={{ root: { margin: margin } }} />
          <Toggle
            label="Compact mode"
            inlineLabel
            checked={isCompactMode}
            onChange={this._onChangeCompactMode}
            styles={toggleStyles}
          />
          <Toggle
            label="Show index of first item in view when unmounting"
            inlineLabel
            checked={this.state.showItemIndexInView}
            onChange={this._onShowItemIndexInViewChanged}
            styles={toggleStyles}
          />
        </div>
        <DetailsList
          componentRef={this._root}
          items={items}
          groups={groups}
          columns={this._columns}
          ariaLabelForSelectAllCheckbox="Toggle selection for all items"
          ariaLabelForSelectionColumn="Toggle selection"
          groupProps={{
            showEmptyGroups: true
          }}
          onRenderItemColumn={this._onRenderColumn}
          compact={isCompactMode}
        />
      </div>
    );
  }

  private _addItem = (): void => {
    const items = this.state.items;
    const groups = [...this.state.groups];
    groups[_blueGroupIndex].count++;

    this.setState(
      {
        items: items.concat([
          {
            key: 'item-' + items.length,
            name: 'New item ' + items.length,
            color: 'blue'
          }
        ]),
        groups
      },
      () => {
        if (this._root.current) {
          this._root.current.focusIndex(items.length, true);
        }
      }
    );
  };

  private _onRenderColumn(item: IDetailsListGroupedExampleItem, index: number, column: IColumn) {
    const value =
      item && column && column.fieldName ? item[column.fieldName as keyof IDetailsListGroupedExampleItem] || '' : '';

    return <div data-is-focusable={true}>{value}</div>;
  }

  private _onShowItemIndexInViewChanged = (event: React.MouseEvent<HTMLInputElement>, checked: boolean): void => {
    this.setState({ showItemIndexInView: checked });
  };

  private _onChangeCompactMode = (ev: React.MouseEvent<HTMLElement>, checked: boolean): void => {
    this.setState({ isCompactMode: checked });
  };
}

ReactDOM.render(<DetailsListGroupedExample />, document.getElementById('content'));
