Add initial project files

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/js/auth.js

@@ -0,0 +1,72 @@
+/* Auth state helpers shared across all pages */
+
+const Auth = (() => {
+  const KEY = 'bb_token';
+  const USER_KEY = 'bb_user';
+
+  function getToken() { return localStorage.getItem(KEY); }
+
+  function saveToken(token) { localStorage.setItem(KEY, token); }
+
+  function getUser() {
+    const raw = localStorage.getItem(USER_KEY);
+    return raw ? JSON.parse(raw) : null;
+  }
+
+  function saveUser(user) { localStorage.setItem(USER_KEY, JSON.stringify(user)); }
+
+  function logout() {
+    localStorage.removeItem(KEY);
+    localStorage.removeItem(USER_KEY);
+    window.location.href = '/index.html';
+  }
+
+  function isLoggedIn() { return !!getToken(); }
+
+  /* Redirect to login if not authenticated */
+  function requireAuth() {
+    if (!isLoggedIn()) {
+      window.location.href = '/login.html';
+      return false;
+    }
+    return true;
+  }
+
+  /* Redirect away from auth pages if already logged in */
+  function redirectIfLoggedIn() {
+    if (isLoggedIn()) {
+      window.location.href = '/dashboard.html';
+    }
+  }
+
+  /* Render the nav user area; call after DOM ready */
+  async function renderNav(activePage) {
+    const navLinksEl = document.getElementById('nav-links');
+    const navUserEl  = document.getElementById('nav-user');
+    if (!navLinksEl || !navUserEl) return;
+
+    if (isLoggedIn()) {
+      let user = getUser();
+      if (!user) {
+        try { user = await API.users.me(); saveUser(user); } catch (_) {}
+      }
+      navLinksEl.innerHTML = `
+        <a href="/dashboard.html" class="${activePage === 'dashboard' ? 'active' : ''}">My Bottle</a>
+        <a href="/log.html" class="${activePage === 'log' ? 'active' : ''}">Log Entry</a>
+      `;
+      navUserEl.innerHTML = `
+        <a href="/profile.html" class="nav-user">${user?.display_name || user?.email || 'Account'}</a>
+        <a href="#" class="btn btn-ghost btn-sm" id="logout-btn">Logout</a>
+      `;
+      document.getElementById('logout-btn')?.addEventListener('click', (e) => {
+        e.preventDefault();
+        logout();
+      });
+    } else {
+      navLinksEl.innerHTML = '';
+      navUserEl.innerHTML = `<a href="/login.html" class="btn btn-primary btn-sm">Login</a>`;
+    }
+  }
+
+  return { getToken, saveToken, getUser, saveUser, logout, isLoggedIn, requireAuth, redirectIfLoggedIn, renderNav };
+})();