/**
 * AdminUI — admin dashboard.
 *
 *   Two display modes:
 *     - modal: centered overlay above the game (opened via admin chip / ?admin URL)
 *     - page : fullscreen primary view (auto-shown when an admin signs in)
 *
 *   Lets the admin view DB stats, every registered user, and:
 *     - reset a user's progress
 *     - toggle the admin flag
 *     - delete a user (except self)
 *     - export / import the user database as JSON
 *     - search by email or name
 *     - switch to the game view (page mode only)
 */

import { Auth } from '../auth/Auth.js';

export class AdminUI {
  constructor({ onSwitchToGame } = {}) {
    this._root = null;
    this._mode = 'modal';
    this._onSwitchToGame = onSwitchToGame;
  }

  /** Centred modal over the game (admin chip / ?admin URL). */
  open() {
    if (!Auth.isAdmin()) {
      alert('Admin access only. Sign in with an admin account first.');
      return false;
    }
    return this._show('modal');
  }

  /** Fullscreen primary view — admin landing page after login. */
  openAsPage() {
    if (!Auth.isAdmin()) return false;
    return this._show('page');
  }

  _show(mode) {
    this._mode = mode;
    if (this._root) { this._root.remove(); this._root = null; }
    this._root = this._build();
    document.body.appendChild(this._root);
    this.render();
    return true;
  }

  close() { if (this._root) { this._root.remove(); this._root = null; } }

  _build() {
    const isPage = this._mode === 'page';
    const r = document.createElement('div');
    r.id = 'adminPanel';
    r.dataset.mode = this._mode;
    const me = Auth.current();
    r.innerHTML = `
      <div class="admin-card${isPage ? ' page' : ''}">
        <header>
          <h2>⚙ Admin Dashboard</h2>
          <div class="admin-current">${me ? `Signed in as <b>${esc(me.email)}</b>` : ''}</div>
          <div class="admin-head-actions">
            ${isPage
              ? `<button class="btn admin-btn ghost" id="admGame" title="Open the game view">🎮 Game</button>
                 <button class="btn admin-btn ghost" id="admSignOut" title="Sign out">⎋ Sign out</button>`
              : `<button class="close" id="admClose" title="Close (Esc)">×</button>`}
          </div>
        </header>
        <section class="admin-stats" id="admStats"></section>
        <section class="admin-actions">
          <button id="admNew"     class="btn admin-btn primary">+ New user</button>
          <button id="admExport"  class="btn admin-btn">⬇ Export DB</button>
          <button id="admImport"  class="btn admin-btn">⬆ Import DB</button>
          <input  id="admImportFile" type="file" accept="application/json" style="display:none">
          <button id="admRefresh" class="btn admin-btn ghost">↻ Refresh</button>
          <span class="admin-spacer"></span>
          <input type="search" id="admSearch" class="admin-search" placeholder="Search email or name…">
        </section>
        <section class="admin-table-wrap">
          <table class="admin-table">
            <thead><tr>
              <th>Email</th><th>Name</th><th>Role</th><th>Grade</th>
              <th>⭐ Stars</th><th>Mastered</th><th>Created</th><th>Age</th><th>Actions</th>
            </tr></thead>
            <tbody id="admBody"></tbody>
          </table>
          <div class="admin-empty" id="admEmpty" style="display:none">No users match.</div>
        </section>
        <footer class="admin-footer">
          <span>ECHO 3D · Admin</span>
          <span>Local-only — stored in this browser's localStorage / IndexedDB</span>
        </footer>
      </div>`;

    r.style.cssText = isPage
      ? `position:fixed;top:0;left:0;width:100vw;height:100vh;z-index:99999;
         display:flex;align-items:stretch;justify-content:center;
         background:radial-gradient(ellipse at 50% 30%,#1a2440 0%,#070912 70%);padding:24px`
      : `position:fixed;top:0;left:0;width:100vw;height:100vh;z-index:99999;
         display:flex;align-items:center;justify-content:center;
         background:rgba(8,10,18,.85);backdrop-filter:blur(6px);padding:20px`;

    if (isPage) {
      r.querySelector('#admGame').onclick     = () => this._switchToGame();
      r.querySelector('#admSignOut').onclick  = () => this._signOut();
    } else {
      r.querySelector('#admClose').onclick    = () => this.close();
    }
    r.querySelector('#admNew').onclick         = () => this._createUserPrompt();
    r.querySelector('#admRefresh').onclick     = () => this.render();
    r.querySelector('#admExport').onclick      = () => this._exportDb();
    r.querySelector('#admImport').onclick      = () => r.querySelector('#admImportFile').click();
    r.querySelector('#admImportFile').onchange = (e) => this._importDb(e.target.files[0]);
    r.querySelector('#admSearch').addEventListener('input', () => this.render());

    document.addEventListener('keydown', (e) => {
      if (e.key === 'Escape' && this._mode === 'modal' && this._root) this.close();
    });
    return r;
  }

  _switchToGame() {
    if (!this._root) return;
    this._root.remove();
    this._root = null;
    if (this._onSwitchToGame) this._onSwitchToGame();
  }

  async _createUserPrompt() {
    const email = prompt('New user email:'); if (!email) return;
    const name  = prompt('Display name (optional):', email.split('@')[0]);
    const pwd   = prompt('Password (6+ chars):');
    if (!pwd) return;
    const isAdmin = confirm('Make this user an admin?');
    try {
      await Auth.adminCreateUser({ email, pwd, name, isAdmin });
      alert(`Created ${email}${isAdmin ? ' (admin)' : ''}`);
      this.render();
    } catch (e) { alert('Could not create user: ' + e.message); }
  }

  async _signOut() {
    if (!confirm('Sign out of the admin dashboard?')) return;
    await Auth.logout().catch(() => {});
    location.reload();
  }

  async render() {
    if (!this._root) return;
    let allUsers;
    try { allUsers = await Auth.adminListUsers(); }
    catch (e) { allUsers = Auth.allUsers(); }
    const me = Auth.current()?.email;

    // Stats — always over the full database, regardless of search filter.
    const totalStars    = allUsers.reduce((s, u) => s + (u.stars    || 0), 0);
    const totalMastered = allUsers.reduce((s, u) => s + (u.mastered || 0), 0);
    const admins        = allUsers.filter(u => u.isAdmin).length;
    const onlineCount = allUsers.filter(u => u.online).length;
    this._root.querySelector('#admStats').innerHTML = `
      ${statCard('Total users', allUsers.length)}
      ${statCard('Online now',  onlineCount, 'online-now')}
      ${statCard('Admins',      admins)}
      ${statCard('⭐ Stars',     totalStars.toLocaleString())}
      ${statCard('Mastered',    totalMastered.toLocaleString())}
    `;

    // Filter + sort.
    const q = (this._root.querySelector('#admSearch').value || '').toLowerCase().trim();
    const users = allUsers
      .filter(u => !q || u.email.toLowerCase().includes(q) || (u.name || '').toLowerCase().includes(q))
      .sort((a, b) => (b.stars || 0) - (a.stars || 0));

    const body  = this._root.querySelector('#admBody');
    const empty = this._root.querySelector('#admEmpty');
    body.innerHTML = '';
    empty.style.display = users.length ? 'none' : 'block';

    const now = Date.now();
    for (const u of users) {
      const tr = document.createElement('tr');
      const isMe = u.email === me;
      const ageDays = u.created ? Math.max(0, Math.floor((now - u.created) / 86400000)) : null;
      tr.innerHTML = `
        <td class="email">
          <span class="${u.online ? 'dot online' : 'dot'}" title="${u.online ? 'online' : 'offline'}"></span>
          ${esc(u.email)}${isMe ? ' <em>(you)</em>' : ''}
        </td>
        <td>${esc(u.name || '—')}</td>
        <td><span class="role ${u.isAdmin ? 'role-admin' : 'role-user'}">${u.isAdmin ? 'admin' : 'user'}</span></td>
        <td>${u.grade || 1}</td>
        <td>${(u.stars || 0).toLocaleString()}</td>
        <td>${(u.mastered || 0).toLocaleString()}</td>
        <td>${u.created ? new Date(u.created).toLocaleDateString() : '—'}</td>
        <td>${ageDays === null ? '—' : (ageDays === 0 ? 'today' : `${ageDays}d`)}</td>
        <td class="acts">
          <button data-act="reset"  data-email="${esc(u.email)}" title="Reset progress">↺</button>
          <button data-act="admin"  data-email="${esc(u.email)}" title="${u.isAdmin ? 'Revoke admin' : 'Make admin'}">${u.isAdmin ? '◐' : '◑'}</button>
          <button data-act="delete" data-email="${esc(u.email)}" title="Delete user" ${isMe ? 'disabled' : ''}>🗑</button>
        </td>`;
      body.appendChild(tr);
    }

    body.onclick = async (e) => {
      const b = e.target.closest('button[data-act]');
      if (!b) return;
      const { act, email } = b.dataset;
      try {
        if (act === 'reset')  { if (confirm(`Reset ${email}'s progress to zero?`)) await Auth.adminResetProgress(email); }
        if (act === 'admin')  {
          const cur = allUsers.find(u => u.email === email)?.isAdmin;
          await Auth.adminSetAdmin(email, !cur);
        }
        if (act === 'delete') { if (confirm(`Delete user ${email}? This cannot be undone.`)) await Auth.adminDeleteUser(email); }
        this.render();
      } catch (err) { alert(err.message); }
    };
  }

  async _exportDb() {
    try {
      const json = await Auth.adminExport();
      const blob = new Blob([json], { type: 'application/json' });
      const a = document.createElement('a');
      a.href = URL.createObjectURL(blob);
      a.download = `echo-users-${new Date().toISOString().slice(0,10)}.json`;
      a.click();
      URL.revokeObjectURL(a.href);
    } catch (e) { alert('Export failed: ' + e.message); }
  }

  _importDb(file) {
    if (!file) return;
    if (!confirm('Overwrite the user database with the contents of this file?')) return;
    const reader = new FileReader();
    reader.onload = async () => {
      try {
        const n = await Auth.adminImport(reader.result);
        alert(`Imported ${n} users.`);
        this.render();
      } catch (e) { alert('Import failed: ' + e.message); }
    };
    reader.readAsText(file);
  }
}

function statCard(label, value, extraCls = '') {
  return `<div class="admin-stat ${extraCls}"><div class="n">${value}</div><div class="l">${label}</div></div>`;
}
function esc(s) {
  return String(s).replace(/[&<>"']/g, c => ({ '&':'&amp;','<':'&lt;','>':'&gt;','"':'&quot;',"'":'&#39;' }[c]));
}