function solve() {
  let openSection = document.getElementsByTagName("section")[1];
  let progressSection = document.getElementsByTagName("section")[2];
  let completedSection = document.getElementsByTagName("section")[3];

  let addBtn = document.getElementById("add");
  addBtn.addEventListener("click", (event) => {
    event.preventDefault();
    let task = document.getElementById("task");
    let description = document.getElementById("description");
    let date = document.getElementById("date");

    if (task.value === "" || description.value === "" || date.value === "") {
      return;
    }

    let article = document.createElement("article");
    let h3 = document.createElement("h3");
    h3.innerText = task.value;
    let pDescription = document.createElement("p");
    pDescription.innerText = `Description: ${description.value}`;
    let pDate = document.createElement("p");
    pDate.innerText = `Due Date: ${date.value}`;

    let div = document.createElement("div");
    div.className = "flex";
    let btnStart = document.createElement("button");
    btnStart.className = "green";
    btnStart.innerText = "Start";
    let btnDelete = document.createElement("button");
    btnDelete.className = "red";
    btnDelete.innerText = "Delete";

    btnDelete.addEventListener("click", deleteArticle);

    btnStart.addEventListener("click", (event) => {
      let btnFinish = document.createElement("button");
      btnFinish.className = "orange";
      btnFinish.innerText = "Finish";

      btnFinish.addEventListener("click", () => {
        article.lastElementChild.remove();
        completedSection.lastElementChild.appendChild(article);
      });

      article.lastElementChild.children[0].remove();
      article.lastElementChild.appendChild(btnFinish);
      progressSection.lastElementChild.appendChild(article);
    });

    div.appendChild(btnStart);
    div.appendChild(btnDelete);

    article.appendChild(h3);
    article.appendChild(pDescription);
    article.appendChild(pDate);
    article.appendChild(div);

    openSection.lastElementChild.appendChild(article);

    task.value = "";
    description.value = "";
    date.value = "";
  });

  function deleteArticle(event) {
    event.target.parentElement.parentElement.remove();
  }
}