/**
 * A simple helper for creating nested dom tree inspired by snabbdom-jsx syntax
 * @param {string} name
 * @param {{[attr: string]: any}} attrs
 * @param {Array<HTMLElement | string>} children
 * @returns {HTMLElement}
 */
export function createElem(name, attrs, children) {
  const elem = document.createElement(name);

  for (const [attr, val] of Object.entries(attrs || {})) {
    const match = attr.match(/^(prop|class|on|)-([\w-]+)$/);
    if (match) {
      const [_, prefix, name] = match; // eslint-disable-line no-unused-vars
      if (prefix === `prop`) {
        elem[name] = val;
      } else if (prefix === `class` && val) {
        elem.classList.add(name);
      } else if (prefix === `on`) {
        elem.addEventListener(name, val);
      }
    } else {
      elem.setAttribute(attr, val);
    }
  }

  if (!Array.isArray(children)) {
    children = [children];
  }

  for (const child of children) {
    if (typeof child === `string`) {
      elem.appendChild(document.createTextNode(child));
    } else if (child) {
      elem.appendChild(child);
    }
  }

  return elem;
}