import-node.ts

import { nodeDocument } from './node-document';
import { isElementNode } from './node-types';

/**
 * Imports DOM node from one document to another.
 *
 * @typeParam TNode - DOM node type.
 * @param from - The node to import.
 * @param to - The node to append imported node to.
 * @param importContent - A function that imports nodes nested in parent element. {@link importNodeContent} by default.
 *
 * @returns Imported node.
 */
export function importNode<TNode extends Node>(
  from: TNode,
  to: Node,
  importContent?: (this: void, from: TNode, to: TNode) => void,
): TNode;

/**
 * Imports DOM node from one document to another and inserts it before the given node.
 *
 * @typeParam TNode - DOM node type.
 * @param from - The node to import.
 * @param to - The node to append imported node to.
 * @param before - The node to insert imported node before, or `null` to append it to the end of target one.
 * @param importContent - A function that imports nodes nested in parent element. {@link importNodeContent} by default.
 *
 * @returns Imported node.
 */
export function importNode<TNode extends Node>(
  from: TNode,
  to: Node,
  before?: Node | null,
  importContent?: (this: void, from: TNode, to: TNode) => void,
): TNode;

export function importNode<TNode extends Node>(
  from: TNode,
  to: Node,
  beforeOrImport?: Node | null | ((this: void, from: TNode, to: TNode) => void),
  importContent: (this: void, from: TNode, to: TNode) => void = importNodeContent,
): TNode {
  let before: Node | null;

  if (typeof beforeOrImport === 'function') {
    importContent = beforeOrImport;
    before = null;
  } else {
    before = beforeOrImport || null;
  }

  const doc = nodeDocument(to);

  if (isElementNode(from)) {
    const elementClone = doc.createElement(from.tagName.toLowerCase()) as Node as Element & TNode;

    from
      .getAttributeNames()
      .forEach(attr => elementClone.setAttribute(attr, from.getAttribute(attr)!));
    importContent(from, elementClone);
    to.insertBefore(elementClone, before);

    return elementClone;
  }

  const nodeClone = doc.importNode(from, false);

  to.insertBefore(nodeClone, before);

  return nodeClone;
}

/**
 * Imports DOM node contents from one document to another.
 *
 * @param from - The node which contents to import.
 * @param to - The node to append imported nodes to.
 */
export function importNodeContent(from: Node, to: Node): void {
  // eslint-disable-next-line @typescript-eslint/prefer-for-of
  for (let i = 0; i < from.childNodes.length; ++i) {
    importNode(from.childNodes[i], to);
  }
}