// ── Admin Page (User Management) ──

registerPage('admin', {
  async init() {
    if (!currentUser || !currentUser.isAdmin) {
      navigateTo('dashboard');
      return;
    }

    var users = [];
    var editingUserId = null;

    var list = document.getElementById('adminUserList');
    var newUserBtn = document.getElementById('adminNewUserBtn');
    var userForm = document.getElementById('adminUserForm');
    var formTitle = document.getElementById('adminFormTitle');
    var usernameInput = document.getElementById('adminUsername');
    var displayNameInput = document.getElementById('adminDisplayName');
    var passwordInput = document.getElementById('adminPassword');
    var passwordLabel = document.getElementById('adminPasswordLabel');
    var isAdminCheckbox = document.getElementById('adminIsAdmin');
    var saveBtn = document.getElementById('adminFormSaveBtn');
    var formMessage = document.getElementById('adminFormMessage');
    var pageMessage = document.getElementById('adminMessage');

    // ── Hilfsfunktionen ──

    function showFormMessage(text, isError) {
      formMessage.textContent = text;
      formMessage.className = 'profile-message ' + (isError ? 'profile-message-error' : 'profile-message-success');
      formMessage.hidden = false;
      if (!isError) {
        setTimeout(function() { formMessage.hidden = true; }, 3000);
      }
    }

    function showPageMessage(text, isError) {
      pageMessage.textContent = text;
      pageMessage.className = 'profile-message ' + (isError ? 'profile-message-error' : 'profile-message-success');
      pageMessage.hidden = false;
      setTimeout(function() { pageMessage.hidden = true; }, 4000);
    }

    function renderUsers() {
      list.innerHTML = '';

      users.forEach(function(user) {
        var row = document.createElement('div');
        row.className = 'admin-user-row';

        var info = document.createElement('div');
        info.className = 'admin-user-info';

        var nameSpan = document.createElement('span');
        nameSpan.className = 'admin-user-name';
        nameSpan.textContent = user.displayName || user.username;

        var metaSpan = document.createElement('span');
        metaSpan.className = 'admin-user-meta';
        var metaParts = ['@' + user.username];
        if (user.isAdmin) metaParts.push('Administrator');
        metaSpan.textContent = metaParts.join(' ▪ ');

        info.appendChild(nameSpan);
        info.appendChild(metaSpan);

        var actions = document.createElement('div');
        actions.className = 'admin-user-actions';

        var editBtn = document.createElement('button');
        editBtn.className = 'icon-btn';
        editBtn.title = 'Bearbeiten';
        editBtn.innerHTML = '<i class="fa fa-pencil"></i>';
        editBtn.addEventListener('click', function() {
          startEdit(user);
        });
        actions.appendChild(editBtn);

        // Sich selbst kann man nicht löschen
        if (user.userId !== currentUser.userId) {
          var deleteBtn = document.createElement('button');
          deleteBtn.className = 'icon-btn';
          deleteBtn.title = 'Löschen';
          deleteBtn.innerHTML = '<i class="fa fa-trash"></i>';
          deleteBtn.addEventListener('click', function() {
            deleteUser(user);
          });
          actions.appendChild(deleteBtn);
        }

        row.appendChild(info);
        row.appendChild(actions);
        list.appendChild(row);
      });
    }

    async function loadUsers() {
      try {
        users = await apiAdminGetUsers();
        renderUsers();
      } catch (err) {
        showPageMessage(err.message, true);
      }
    }

    function startEdit(user) {
      editingUserId = user.userId;
      formTitle.textContent = 'Benutzer bearbeiten';
      usernameInput.value = user.username;
      usernameInput.disabled = false;
      displayNameInput.value = user.displayName || '';
      passwordInput.value = '';
      passwordLabel.textContent = 'Neues Passwort (leer = unverändert)';
      passwordInput.placeholder = 'Neues Passwort (optional)';
      passwordInput.required = false;
      isAdminCheckbox.checked = user.isAdmin;
      saveBtn.textContent = 'Speichern';
      formMessage.hidden = true;
      userForm.hidden = false;
      usernameInput.focus();
    }

    async function deleteUser(user) {
      if (!confirm('Benutzer "' + (user.displayName || user.username) + '" wirklich löschen?\n\nAlle Tokens werden ebenfalls gelöscht.')) {
        return;
      }

      try {
        await apiAdminDeleteUser(user.userId);
        await loadUsers();
      } catch (err) {
        showPageMessage(err.message, true);
      }
    }

    // ── Event-Listener ──

    // Neuer Benutzer
    newUserBtn.addEventListener('click', function() {
      editingUserId = null;
      formTitle.textContent = 'Neuer Benutzer';
      usernameInput.value = '';
      usernameInput.disabled = false;
      displayNameInput.value = '';
      passwordInput.value = '';
      passwordLabel.textContent = 'Passwort';
      passwordInput.placeholder = 'Passwort';
      passwordInput.required = true;
      isAdminCheckbox.checked = false;
      saveBtn.textContent = 'Erstellen';
      formMessage.hidden = true;
      userForm.hidden = false;
      usernameInput.focus();
    });

    // Speichern
    saveBtn.addEventListener('click', async function() {
      formMessage.hidden = true;
      saveBtn.disabled = true;

      try {
        if (editingUserId) {
          // Update
          var data = {
            username: usernameInput.value.trim(),
            displayName: displayNameInput.value.trim(),
            isAdmin: isAdminCheckbox.checked
          };
          await apiAdminUpdateUser(editingUserId, data);

          // Passwort nur wenn ausgefüllt
          var pw = passwordInput.value;
          if (pw) {
            await apiAdminResetPassword(editingUserId, pw);
          }

          showFormMessage('Benutzer aktualisiert', false);
        } else {
          // Create
          var username = usernameInput.value.trim();
          var password = passwordInput.value;

          if (!username || !password) {
            showFormMessage('Benutzername und Passwort erforderlich', true);
            return;
          }

          await apiAdminCreateUser({
            username: username,
            password: password,
            displayName: displayNameInput.value.trim(),
            isAdmin: isAdminCheckbox.checked
          });

          showFormMessage('Benutzer erstellt', false);
        }

        userForm.hidden = true;
        await loadUsers();
      } catch (err) {
        showFormMessage(err.message, true);
      } finally {
        saveBtn.disabled = false;
      }
    });

    // ── Init: User laden ──
    await loadUsers();
  },

  destroy() {}
});