/**
 * AdminUsersPage
 * 
 * Admin page for managing Users using FormGeneratorTable.
 */

import React, { useState, useMemo } from 'react';
import { useNavigate } from 'react-router-dom';
import { useOrgUsers, useUserOperations } from '../../hooks/useUsers';
import { FormGeneratorTable } from '../../components/FormGenerator/FormGeneratorTable';
import { FormGeneratorForm } from '../../components/FormGenerator/FormGeneratorForm';
import { FaPlus, FaSync, FaKey, FaEnvelopeOpenText, FaUserShield } from 'react-icons/fa';
import styles from './Admin.module.css';
import { getUserDataCache } from '../../utils/userCache';

import { useLanguage } from '../../providers/language/LanguageContext';

const _PRIVILEGED_FLAGS = ['isSysAdmin', 'isPlatformAdmin'] as const;

interface User {
  id: string;
  username: string;
  email: string;
  fullName: string;
  enabled: boolean;
  isSysAdmin?: boolean;
  isPlatformAdmin?: boolean;
  [key: string]: any;
}

export const AdminUsersPage: React.FC = () => {
    const { t } = useLanguage();

  const navigate = useNavigate();
  // Use two hooks: one for data, one for operations
  const {
    data: users,
    attributes,
    permissions,
    pagination,
    loading,
    error,
    refetch,
    fetchUserById,
    updateOptimistically,
  } = useOrgUsers();
  
  const {
    handleUserCreate: createUser,
    handleUserUpdate: updateUser,
    handleUserDelete: deleteUser,
    handleSendPasswordLink,
    handleInlineUpdate,
    sendingPasswordLink: sendingPasswordLinkState,
  } = useUserOperations();

  const [showCreateModal, setShowCreateModal] = useState(false);
  const [editingUser, setEditingUser] = useState<User | null>(null);

  // Generate columns from attributes
  const columns = useMemo(() => {
    return (attributes || []).map(attr => ({
      key: attr.name,
      label: attr.label || attr.name,
      type: attr.type as any,
      sortable: attr.sortable !== false,
      filterable: attr.filterable !== false,
      searchable: attr.searchable !== false,
      width: attr.width || 150,
      minWidth: attr.minWidth || 100,
      maxWidth: attr.maxWidth || 400,
      fkSource: (attr as any).fkSource,
      fkDisplayField: (attr as any).fkDisplayField,
    }));
  }, [attributes]);

  // Check permissions
  const canCreate = permissions?.create !== 'n';
  const canUpdate = permissions?.update !== 'n';
  const canDelete = permissions?.delete !== 'n';

  // Handle edit click
  const handleEditClick = async (user: User) => {
    const fullUser = await fetchUserById(user.id);
    if (fullUser) {
      setEditingUser(fullUser as User);
    }
  };

  // Handle create submit
  const handleCreateSubmit = async (data: Partial<User>) => {
    const result = await createUser(data as Omit<User, 'id'>);
    if (result.success) {
      setShowCreateModal(false);
      refetch(); // Refresh the list
    }
  };

  // Handle edit submit
  const handleEditSubmit = async (data: Partial<User>) => {
    if (!editingUser) return;
    const result = await updateUser(editingUser.id, data);
    if (result.success) {
      setEditingUser(null);
      refetch(); // Refresh the list
    }
  };

  // Handle delete (confirmation handled by DeleteActionButton)
  const handleDeleteUser = async (user: User) => {
    const success = await deleteUser(user.id);
    if (success) {
      refetch(); // Refresh the list
    }
  };

  // Handle send password link
  const handleSendPassword = async (user: User) => {
    await handleSendPasswordLink(user.id);
  };

  // Privileged-flag gating mirrors the backend rules in routeDataUsers.update_user
  // and create_user: only a Platform-Admin may set isSysAdmin / isPlatformAdmin,
  // and even then never on themselves (Self-Protection).
  const currentUserCache = getUserDataCache();
  const callerIsPlatformAdmin = currentUserCache?.isPlatformAdmin === true;
  const callerId = currentUserCache?.id;

  const _buildFormAttributes = (mode: 'create' | 'edit', targetUserId?: string) => {
    const excludedFields = ['id', 'hashedPassword', 'authenticationAuthority'];
    const isSelfEdit = mode === 'edit' && targetUserId !== undefined && targetUserId === callerId;
    // Caller may flip flags only when PlatformAdmin AND not editing themselves.
    const flagsEditable = callerIsPlatformAdmin && !isSelfEdit;

    return (attributes || [])
      .filter(attr => !excludedFields.includes(attr.name))
      .map(attr => {
        if (_PRIVILEGED_FLAGS.includes(attr.name as any) && !flagsEditable) {
          return { ...attr, editable: false };
        }
        if (attr.name === 'username') {
          return { ...attr, editable: false };
        }
        return attr;
      });
  };

  const formAttributesCreate = useMemo(
    () => _buildFormAttributes('create'),
    [attributes, callerIsPlatformAdmin],
  );

  const formAttributesEdit = useMemo(
    () => _buildFormAttributes('edit', editingUser?.id),
    [attributes, callerIsPlatformAdmin, callerId, editingUser?.id],
  );

  if (error) {
    return (
      <div className={`${styles.adminPage} ${styles.adminPageFill}`}>
        <div className={styles.errorContainer}>
          <span className={styles.errorIcon}>⚠️</span>
          <p className={styles.errorMessage}>
            {t('Fehler beim Laden der Benutzer')}: {error}
          </p>
          <button className={styles.secondaryButton} onClick={() => refetch()}>
            <FaSync /> {t('Erneut versuchen')}
          </button>
        </div>
      </div>
    );
  }

  return (
    <div className={`${styles.adminPage} ${styles.adminPageFill}`}>
      <div className={styles.pageHeader}>
        <div>
          <h1 className={styles.pageTitle}>{t('Benutzer')}</h1>
          <p className={styles.pageSubtitle}>{t('Verwalten Sie alle Benutzer im')}</p>
        </div>
        <div className={styles.headerActions}>
          <button
            type="button"
            className={styles.secondaryButton}
            onClick={() => navigate('/admin/user-access-overview')}
          >
            <FaUserShield /> {t('Zugriffsübersicht')}
          </button>
          <button
            type="button"
            className={styles.secondaryButton}
            onClick={() => navigate('/admin/invitations')}
          >
            <FaEnvelopeOpenText /> {t('Einladungen')}
          </button>
          <button 
            className={styles.secondaryButton} 
            onClick={() => refetch()}
            disabled={loading}
          >
            <FaSync className={loading ? 'spinning' : ''} /> {t('Aktualisieren')}
          </button>
          {canCreate && (
            <button 
              className={styles.primaryButton}
              onClick={() => setShowCreateModal(true)}
            >
              <FaPlus /> {t('Neuer Benutzer')}
            </button>
          )}
        </div>
      </div>

      <div className={styles.tableContainer}>
        <FormGeneratorTable
            data={users}
            columns={columns}
            apiEndpoint="/api/users/"
            loading={loading}
            pagination={true}
            pageSize={25}
            searchable={true}
            filterable={true}
            sortable={true}
            selectable={true}
            actionButtons={[
              ...(canUpdate ? [{
                type: 'edit' as const,
                onAction: handleEditClick,
                title: t('Bearbeiten'),
              }] : []),
              ...(canDelete ? [{
                type: 'delete' as const,
                title: t('Löschen'),
              }] : []),
            ]}
            customActions={canUpdate ? [
              {
                id: 'sendPasswordLink',
                icon: <FaKey />,
                onClick: handleSendPassword,
                title: t('Passwort-Link senden'),
                loading: (row: User) => sendingPasswordLinkState.has(row.id),
              }
            ] : []}
            onDelete={handleDeleteUser}
            hookData={{
              refetch,
              permissions,
              pagination,
              handleDelete: deleteUser,
              handleInlineUpdate,
              updateOptimistically,
            }}
            emptyMessage={t('Keine Benutzer gefunden')}
          />
      </div>

      {/* Create Modal */}
      {showCreateModal && (
        <div className={styles.modalOverlay}>
          <div className={styles.modal}>
            <div className={styles.modalHeader}>
              <h2 className={styles.modalTitle}>{t('Neuer Benutzer')}</h2>
              <button 
                className={styles.modalClose}
                onClick={() => setShowCreateModal(false)}
              >
                ✕
              </button>
            </div>
            <div className={styles.modalContent}>
              {formAttributesCreate.length === 0 ? (
                <div className={styles.loadingContainer}>
                  <div className={styles.spinner} />
                  <span>{t('Lade Formular')}</span>
                </div>
              ) : (
                <FormGeneratorForm
                  attributes={formAttributesCreate}
                  mode="create"
                  onSubmit={handleCreateSubmit}
                  onCancel={() => setShowCreateModal(false)}
                  submitButtonText={t('Erstellen')}
                  cancelButtonText={t('Abbrechen')}
                />
              )}
            </div>
          </div>
        </div>
      )}

      {/* Edit Modal */}
      {editingUser && (
        <div className={styles.modalOverlay}>
          <div className={styles.modal}>
            <div className={styles.modalHeader}>
              <h2 className={styles.modalTitle}>{t('Benutzer bearbeiten')}</h2>
              <button 
                className={styles.modalClose}
                onClick={() => setEditingUser(null)}
              >
                ✕
              </button>
            </div>
            <div className={styles.modalContent}>
              {formAttributesEdit.length === 0 ? (
                <div className={styles.loadingContainer}>
                  <div className={styles.spinner} />
                  <span>{t('Lade Formular')}</span>
                </div>
              ) : (
                <FormGeneratorForm
                  attributes={formAttributesEdit}
                  data={editingUser}
                  mode="edit"
                  onSubmit={handleEditSubmit}
                  onCancel={() => setEditingUser(null)}
                  submitButtonText={t('Speichern')}
                  cancelButtonText={t('Abbrechen')}
                />
              )}
            </div>
          </div>
        </div>
      )}
    </div>
  );
};

export default AdminUsersPage;