import Screen from 'Player/web/Screen/Screen';
import type { SelectionChange } from '../../messages';
import type { VElement } from './VirtualDOM';
import ListWalker from '../../../common/ListWalker';

export default class SelectionManager extends ListWalker<SelectionChange> {
  constructor(
    private readonly vElements: Map<number, VElement>,
    private readonly screen: Screen,
  ) {
    super();
  }

  private selected: [
    { id: number; node: Element } | null,
    { id: number; node: Element } | null,
  ] = [null, null];

  public clearSelection = () => {
    if (this.selected[0] === null && this.selected[1] === null) return;

    this.screen.clearSelection();
    this.selected = [null, null];
  };

  move(t: number) {
    const msg = this.moveGetLast(t);
    if (!msg) {
      return;
    }

    // in theory: empty selection or selection removed
    if (msg.selectionStart <= 0) {
      this.clearSelection();
      return;
    }
    // preventing clones
    if (
      this.selected[0] &&
      this.selected[0].id === msg.selectionStart &&
      this.selected[1] &&
      this.selected[1].id === msg.selectionEnd
    )
      return;

    const startVNode = this.vElements.get(msg.selectionStart - 1);
    const endVNode = this.vElements.get(msg.selectionEnd - 1);

    // only one selection present on page at the same time
    if (this.selected[0] && this.selected[0]?.id !== msg.selectionStart)
      this.clearSelection();

    if (startVNode && endVNode) {
      const startCoords = startVNode.node.getBoundingClientRect();
      const endCoords = endVNode.node.getBoundingClientRect();

      const startPointer = document.createElement('div');
      const endPointer = document.createElement('div');

      Object.assign(endPointer.style, {
        top: `${endCoords.top}px`,
        left: `${endCoords.left}px`,
        width: `${endCoords.width}px`,
        height: `${endCoords.height}px`,
        position: 'absolute',
        boxShadow: '1px 4px 1px -2px blue',
      });
      Object.assign(startPointer.style, {
        top: `${startCoords.top}px`,
        left: `${startCoords.left}px`,
        width: `${startCoords.width}px`,
        height: `${startCoords.height}px`,
        position: 'absolute',
        boxShadow: '1px 4px 1px -2px blue',
      });

      this.screen.createSelection(startPointer, endPointer);

      this.selected = [
        { id: msg.selectionStart, node: startPointer },
        { id: msg.selectionEnd, node: endPointer },
      ];
    }
  }
}