// ==UserScript==
// @name     Cocoa Primer
// @version  1
// @grant    none
// ==/UserScript==

const reg = /^https:\/\/boards\.4chan(nel)?\.org\/\w+\/thread\/\d+/;

if (reg.test(document.URL)) {
    const cockoas = ["https://files.catbox.moe/mm50dl.png",
                   "https://files.catbox.moe/bvuuat.png",
                   "https://files.catbox.moe/xw9iob.png",
                   "https://files.catbox.moe/rooom7.png",
                   "https://files.catbox.moe/9pxahb.png",
                   "https://files.catbox.moe/nliigw.png",
                   "https://files.catbox.moe/mm50dl.png",
                   "https://files.catbox.moe/n1qwor.png",
                   "https://files.catbox.moe/cxawh2.png",
                   "https://files.catbox.moe/r5h6dm.png"];
  const chino = document.querySelector(".thread");
  const byme = new MutationObserver(records => {
    records.forEach(record => {
      let newposts = [...record.addedNodes].filter(post => post.classList.contains("postContainer"));

      newposts.forEach(post => {
        check_it(post);
      });
    });
  });
  const posts = chino.querySelectorAll(".postContainer");

  byme.observe(chino, { childList : true });

  posts.forEach(post => {
    check_it(post);
  });

  function check_it(post) {
    const postNumber = Number(post.id.match(/\d+/)[0]);

    if (is_prime(postNumber)) {
      console.log("checked");
      add_cockoa(post);
    }
  }

  function is_prime(number) {
    let sqrt = Math.sqrt(number);

    for (let i = 2; i <= sqrt; i++)
        if (!(number % i)) {
        return false;
      }
    return true;
  }

  function add_cockoa(post) {
    const img = new Image();

    img.src = cockoas[~~(Math.random() * cockoas.length)];
    img.style.width = "40px";
    img.addEventListener("load", () => {
        const postInfo = post.querySelector(".postInfo");
      const menuButton = post.querySelector(".menu-button");

      if (menuButton) {
        menuButton.replaceWith(img);
        postInfo.append(menuButton);
      }
      else
        postInfo.append(img);
    });
  }
}