// Leaderboard page: public leaderboard with tabs for Level, Gold, Kills.
// Uses createElement + textContent only — DOM property is never overwritten.

const VALUE_LABELS = { level: 'Level', gold: 'Gold', kills: 'Kills' };

let currentType = 'level';
let currentPage = 1;

// ─── API helper (no auth needed) ──────────────────────────────────────────

async function apiGet(path) {
  const res = await fetch(path);
  return res.json();
}

// ─── Render: leaderboard entries ──────────────────────────────────────────

function renderLeaderboard(entries, pagination) {
  const tbody = document.getElementById('leaderboard-body');
  tbody.replaceChildren();

  if (entries.length === 0) {
    const tr = document.createElement('tr');
    const td = document.createElement('td');
    td.className = 'placeholder';
    td.textContent = 'No heroes yet.';
    td.setAttribute('colspan', '4');
    tr.appendChild(td);
    tbody.appendChild(tr);
    return;
  }

  for (const entry of entries) {
    const tr = document.createElement('tr');

    // Rank
    const rankTd = document.createElement('td');
    rankTd.className = 'rank-cell';
    rankTd.textContent = entry.rank;
    tr.appendChild(rankTd);

    // Name (link to profile)
    const nameTd = document.createElement('td');
    nameTd.className = 'name-cell';
    const nameLink = document.createElement('a');
    nameLink.href = `/profile.html?name=${encodeURIComponent(entry.name)}`;
    nameLink.textContent = entry.name;
    nameTd.appendChild(nameLink);
    tr.appendChild(nameTd);

    // Class
    const classTd = document.createElement('td');
    classTd.className = 'class-cell';
    classTd.textContent = entry.class;
    tr.appendChild(classTd);

    // Value (level / gold / kills)
    const valueTd = document.createElement('td');
    valueTd.className = 'value-cell';
    valueTd.textContent = entry[currentType];
    tr.appendChild(valueTd);

    tbody.appendChild(tr);
  }
}

// ─── Render: pagination ──────────────────────────────────────────────────

function renderPagination(page, totalPages) {
  const container = document.getElementById('pagination');
  container.replaceChildren();

  if (totalPages <= 1) return;

  // Previous button
  const prevBtn = document.createElement('button');
  prevBtn.textContent = '‹';
  prevBtn.disabled = page <= 1;
  prevBtn.addEventListener('click', () => {
    currentPage = page - 1;
    loadLeaderboard();
  });
  container.appendChild(prevBtn);

  // Page number buttons (show up to 5 pages)
  let startPage = Math.max(1, page - 2);
  let endPage = Math.min(totalPages, startPage + 4);
  if (endPage - startPage < 4) startPage = Math.max(1, endPage - 4);

  for (let p = startPage; p <= endPage; p++) {
    const btn = document.createElement('button');
    btn.textContent = p;
    if (p === page) btn.className = 'active';
    btn.addEventListener('click', () => {
      currentPage = p;
      loadLeaderboard();
    });
    container.appendChild(btn);
  }

  // Next button
  const nextBtn = document.createElement('button');
  nextBtn.textContent = '›';
  nextBtn.disabled = page >= totalPages;
  nextBtn.addEventListener('click', () => {
    currentPage = page + 1;
    loadLeaderboard();
  });
  container.appendChild(nextBtn);
}

// ─── Load leaderboard data ───────────────────────────────────────────────

async function loadLeaderboard() {
  const tbody = document.getElementById('leaderboard-body');
  const tr = document.createElement('tr');
  const td = document.createElement('td');
  td.className = 'placeholder';
  td.textContent = 'Loading...';
  td.setAttribute('colspan', '4');
  tr.appendChild(td);
  tbody.replaceChildren(tr);

  try {
    const data = await apiGet(`/api/leaderboard?type=${currentType}&page=${currentPage}`);
    if (!data || !data.ok) {
      throw new Error(data?.error?.message || 'Failed to load leaderboard.');
    }
    renderLeaderboard(data.data.entries, data.data.pagination);
    renderPagination(data.data.pagination.page, data.data.pagination.totalPages);
  } catch (err) {
    const errorTr = document.createElement('tr');
    const errorTd = document.createElement('td');
    errorTd.className = 'placeholder';
    errorTd.textContent = 'Failed to load leaderboard.';
    errorTd.setAttribute('colspan', '4');
    errorTr.appendChild(errorTd);
    tbody.replaceChildren(errorTr);
  }
}

// ─── Tab switching ───────────────────────────────────────────────────────

function switchTab(type) {
  currentType = type;
  currentPage = 1;

  document.querySelectorAll('#leaderboard-tabs .tab').forEach((t) => {
    const isActive = t.dataset.type === type;
    t.classList.toggle('active', isActive);
    t.setAttribute('aria-selected', isActive);
  });

  // Update header
  document.getElementById('value-header').textContent = VALUE_LABELS[type];
  loadLeaderboard();
}

// ─── Init ─────────────────────────────────────────────────────────────────

document.addEventListener('DOMContentLoaded', () => {
  document.querySelectorAll('#leaderboard-tabs .tab').forEach((tab) => {
    tab.addEventListener('click', () => switchTab(tab.dataset.type));
  });

  loadLeaderboard();
});

// Logout handler
document.getElementById('logout-btn')?.addEventListener('click', async (e) => {
  e.preventDefault();
  try {
    await fetch('/api/auth/logout', {
      method: 'POST',
      credentials: 'include',
    });
  } catch (_) {
    // Ignore
  }
  window.location.href = '/login.html';
});