const extractorEl = document.createElement('div');

export function insertHtmlInSelection(html: string) {
  const selection = window.getSelection();

  if (selection?.getRangeAt && selection.rangeCount) {
    const range = selection.getRangeAt(0);
    range.deleteContents();

    const fragment = range.createContextualFragment(html);
    const lastInsertedNode = fragment.lastChild;
    range.insertNode(fragment);
    if (lastInsertedNode) {
      range.setStartAfter(lastInsertedNode);
      range.setEndAfter(lastInsertedNode);
    } else {
      range.collapse(false);
    }
    selection.removeAllRanges();
    selection.addRange(range);
  }
}

export function getHtmlBeforeSelection(container?: HTMLElement, useCommonAncestor?: boolean) {
  if (!container) {
    return '';
  }

  const sel = window.getSelection();
  if (!sel || !sel.rangeCount) {
    return container.innerHTML;
  }

  const range = sel.getRangeAt(0).cloneRange();
  if (!range.intersectsNode(container)) {
    return container.innerHTML;
  }

  if (!useCommonAncestor && !container.contains(range.commonAncestorContainer)) {
    return '';
  }

  range.collapse(true);
  range.setStart(container, 0);

  extractorEl.innerHTML = '';
  extractorEl.appendChild(range.cloneContents());

  return extractorEl.innerHTML;
}

// https://stackoverflow.com/a/3976125
export function getCaretPosition(element: HTMLElement) {
  let caretPosition = 0;
  const selection = window.getSelection();
  if (!selection || selection.rangeCount === 0) {
    return caretPosition;
  }

  const range = selection.getRangeAt(0);
  const caretRange = range.cloneRange();
  caretRange.selectNodeContents(element);
  caretRange.setEnd(range.endContainer, range.endOffset);
  caretPosition = caretRange.toString().length;

  return caretPosition;
}

// https://stackoverflow.com/a/36953852
export function setCaretPosition(element: Node, position: number) {
  for (const node of element.childNodes) {
    if (node.nodeType === Node.TEXT_NODE) {
      if ((node as Text).length >= position) {
        const range = document.createRange();
        const selection = window.getSelection()!;
        range.setStart(node, position);
        range.collapse(true);
        selection.removeAllRanges();
        selection.addRange(range);

        return -1;
      } else {
        position -= 'length' in node ? node.length as number : 0;
      }
    } else {
      position = setCaretPosition(node, position);
      if (position === -1) {
        return -1;
      }
    }
  }

  return position;
}

export function removeAllSelections() {
  const selection = window.getSelection();
  selection?.removeAllRanges();
}