<main>

  <h1>Pagination with Vanilla JavaScript</h1>
  <ul id="paginated-list" data-current-page="1" aria-live="polite">
    <li>Item 1</li>
    <li>Item 2</li>
    <li>Item 3</li>
    <li>Item 4</li>
    <li>Item 5</li>
    <li>Item 6</li>
    <li>Item 7</li>
    <li>Item 8</li>
    <li>Item 9</li>
    <li>Item 10</li>
    <li>Item 11</li>
    <li>Item 12</li>
    <li>Item 13</li>
    <li>Item 14</li>
    <li>Item 15</li>
    <li>Item 16</li>
    <li>Item 17</li>
    <li>Item 18</li>
    <li>Item 19</li>
    <li>Item 20</li>
    <li>Item 21</li>
    <li>Item 22</li>
    <li>Item 23</li>
    <li>Item 24</li>
    <li>Item 25</li>
    <li>Item 26</li>
    <li>Item 27</li>
    <li>Item 28</li>
    <li>Item 29</li>
    <li>Item 30</li>
    <li>Item 31</li>
    <li>Item 32</li>
    <li>Item 33</li>
    <li>Item 34</li>
    <li>Item 35</li>
    <li>Item 36</li>
    <li>Item 37</li>
    <li>Item 38</li>
    <li>Item 39</li>
    <li>Item 40</li>
    <li>Item 41</li>
    <li>Item 42</li>
    <li>Item 43</li>
    <li>Item 44</li>
    <li>Item 45</li>
    <li>Item 46</li>
    <li>Item 47</li>
    <li>Item 48</li>
    <li>Item 49</li>
    <li>Item 50</li>
  </ul>

  <nav class="pagination-container">
    <button class="pagination-button" id="prev-button" aria-label="Previous page" title="Previous page">
      &lt;
    </button>

    <div id="pagination-numbers">

    </div>

    <button class="pagination-button" id="next-button" aria-label="Next page" title="Next page">
      &gt;
    </button>
  </nav>
</main>

<footer>
  Pen by <a href="https://www.jemimaabu.com" target="_blank" rel="noopener">Jemima Abu</a> <span class="heart">&hearts;</span>
</footer>

@import url('https://fonts.googleapis.com/css2?family=Inter&display=swap');

body {
  font-family: 'Inter', sans-serif;
  line-height: 1.7;
  font-size: 1.1rem;
  margin: 0;
  color: #27253d;
  background: #e6f3f8;
}

main {
  position: relative;
  padding: 1rem 1rem 3rem;
  min-height: calc(100vh - 4rem);
}

h1 {
  margin-top: 0;
}

.hidden {
  display: none;
}

.pagination-container {
  width: calc(100% - 2rem);
  display: flex;
  align-items: center;
  position: absolute;
  bottom: 0;
  padding: 1rem 0;
  justify-content: center;
}

.pagination-number,
.pagination-button{
  font-size: 1.1rem;
  background-color: transparent;
  border: none;
  margin: 0.25rem 0.25rem;
  cursor: pointer;
  height: 2.5rem;
  width: 2.5rem;
  border-radius: .2rem;
}

.pagination-number:hover,
.pagination-button:not(.disabled):hover {
  background: #fff;
}

.pagination-number.active {
  color: #fff;
  background: #0085b6;
}

footer {
  padding: 1em;
  text-align: center;
  background-color: #FFDFB9;
}

footer a {
  color: inherit;
  text-decoration: none;
}

footer .heart {
  color: #DC143C;
}

const paginationNumbers = document.getElementById("pagination-numbers");
const paginatedList = document.getElementById("paginated-list");
const listItems = paginatedList.querySelectorAll("li");
const nextButton = document.getElementById("next-button");
const prevButton = document.getElementById("prev-button");

const paginationLimit = 10;
const pageCount = Math.ceil(listItems.length / paginationLimit);
let currentPage = 1;

const disableButton = (button) => {
  button.classList.add("disabled");
  button.setAttribute("disabled", true);
};

const enableButton = (button) => {
  button.classList.remove("disabled");
  button.removeAttribute("disabled");
};

const handlePageButtonsStatus = () => {
  if (currentPage === 1) {
    disableButton(prevButton);
  } else {
    enableButton(prevButton);
  }

  if (pageCount === currentPage) {
    disableButton(nextButton);
  } else {
    enableButton(nextButton);
  }
};

const handleActivePageNumber = () => {
  document.querySelectorAll(".pagination-number").forEach((button) => {
    button.classList.remove("active");
    const pageIndex = Number(button.getAttribute("page-index"));
    if (pageIndex == currentPage) {
      button.classList.add("active");
    }
  });
};

const appendPageNumber = (index) => {
  const pageNumber = document.createElement("button");
  pageNumber.className = "pagination-number";
  pageNumber.innerHTML = index;
  pageNumber.setAttribute("page-index", index);
  pageNumber.setAttribute("aria-label", "Page " + index);

  paginationNumbers.appendChild(pageNumber);
};

const getPaginationNumbers = () => {
  for (let i = 1; i <= pageCount; i++) {
    appendPageNumber(i);
  }
};

const setCurrentPage = (pageNum) => {
  currentPage = pageNum;

  handleActivePageNumber();
  handlePageButtonsStatus();
  
  const prevRange = (pageNum - 1) * paginationLimit;
  const currRange = pageNum * paginationLimit;

  listItems.forEach((item, index) => {
    item.classList.add("hidden");
    if (index >= prevRange && index < currRange) {
      item.classList.remove("hidden");
    }
  });
};

window.addEventListener("load", () => {
  getPaginationNumbers();
  setCurrentPage(1);

  prevButton.addEventListener("click", () => {
    setCurrentPage(currentPage - 1);
  });

  nextButton.addEventListener("click", () => {
    setCurrentPage(currentPage + 1);
  });

  document.querySelectorAll(".pagination-number").forEach((button) => {
    const pageIndex = Number(button.getAttribute("page-index"));

    if (pageIndex) {
      button.addEventListener("click", () => {
        setCurrentPage(pageIndex);
      });
    }
  });
});