/**
 * AdminMandatesPage
 * 
 * Admin page for managing Mandates (tenants) using FormGeneratorTable.
 */

import React, { useState } from 'react';
import { useNavigate } from 'react-router-dom';
import { useAdminMandates, useMandateFormAttributes, type Mandate } from '../../hooks/useMandates';
import { useApiRequest } from '../../hooks/useApi';
import { fetchSettingsAdmin, updateSettingsAdmin } from '../../api/billingApi';
import {
  mergeBillingIntoMandateFormData,
  splitMandateAndBillingFromForm,
} from '../../utils/mandateBillingFormMerge';
import { useToast } from '../../contexts/ToastContext';
import { FormGeneratorTable } from '../../components/FormGenerator/FormGeneratorTable';
import { FormGeneratorForm } from '../../components/FormGenerator/FormGeneratorForm';
import { FaPlus, FaSync, FaBuilding, FaUsers, FaLock } from 'react-icons/fa';
import styles from './Admin.module.css';

export const AdminMandatesPage: React.FC = () => {
  const navigate = useNavigate();
  const { request } = useApiRequest();
  const { showWarning, showSuccess } = useToast();
  const {
    mandates,
    columns,
    permissions,
    pagination,
    loading,
    error,
    refetch,
    fetchMandateById,
    handleCreate,
    handleUpdate,
    handleDelete,
    handleInlineUpdate,
    updateOptimistically,
  } = useAdminMandates();

  const {
    formAttributes,
    createFormAttributes,
    formAttributesWithBilling,
    createFormAttributesWithBilling,
    loading: mandateAttrsLoading,
  } = useMandateFormAttributes();

  const [showCreateModal, setShowCreateModal] = useState(false);
  /** Mandate row merged with billing fields for FormGenerator */
  const [editingFormData, setEditingFormData] = useState<Record<string, unknown> | null>(null);
  const [editingBillingWarning, setEditingBillingWarning] = useState<string | null>(null);

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

  // Handle edit click — load mandate + billing settings (separate persistence)
  const handleEditClick = async (mandate: Mandate) => {
    setEditingBillingWarning(null);
    const fullMandate = await fetchMandateById(mandate.id);
    if (!fullMandate) return;
    try {
      const settings = await fetchSettingsAdmin(request, fullMandate.id);
      setEditingFormData(
        mergeBillingIntoMandateFormData(fullMandate as Record<string, unknown>, settings)
      );
    } catch {
      setEditingFormData(mergeBillingIntoMandateFormData(fullMandate as Record<string, unknown>, null));
      setEditingBillingWarning(
        'Abrechnungseinstellungen konnten nicht geladen werden. Nur Mandantendaten sind sicher bearbeitbar.'
      );
    }
  };

  // Handle create submit — POST mandate, then billing settings
  const handleCreateSubmit = async (data: Record<string, unknown>) => {
    const { mandatePayload, billingUpdate } = splitMandateAndBillingFromForm(data);
    const created = await handleCreate(mandatePayload as Partial<Mandate>);
    if (!created?.id) return;
    try {
      await updateSettingsAdmin(request, created.id, billingUpdate);
      showSuccess('Erstellt', 'Mandant inkl. Abrechnungseinstellungen gespeichert.');
    } catch (e: unknown) {
      console.error(e);
      showWarning(
        'Mandant erstellt',
        'Abrechnungseinstellungen konnten nicht gespeichert werden. Bitte unter Administration → Abrechnung nachpflegen.'
      );
    }
    setShowCreateModal(false);
  };

  // Handle edit submit — PUT mandate + POST billing settings
  const handleEditSubmit = async (data: Record<string, unknown>) => {
    if (!editingFormData?.id) return;
    const mandateId = String(editingFormData.id);
    const { mandatePayload, billingUpdate } = splitMandateAndBillingFromForm(data);
    const mandateOk = await handleUpdate(mandateId, mandatePayload as Partial<Mandate>);
    if (!mandateOk) return;
    try {
      await updateSettingsAdmin(request, mandateId, billingUpdate);
      showSuccess('Gespeichert', 'Mandant und Abrechnung aktualisiert.');
    } catch (e: unknown) {
      console.error(e);
      showWarning('Teilweise gespeichert', 'Mandant gespeichert, Abrechnung konnte nicht aktualisiert werden.');
    }
    setEditingFormData(null);
    setEditingBillingWarning(null);
  };

  // Handle delete (confirmation handled by DeleteActionButton)
  // System mandates (isSystem=true) are protected from deletion
  const handleDeleteMandate = async (mandate: Mandate) => {
    if (mandate.isSystem) {
      return; // Safety guard - should not be reachable due to disabled button
    }
    await handleDelete(mandate.id);
  };

  if (error) {
    return (
      <div className={`${styles.adminPage} ${styles.adminPageFill}`}>
        <div className={styles.errorContainer}>
          <span className={styles.errorIcon}>⚠️</span>
          <p className={styles.errorMessage}>Fehler beim Laden der Mandanten: {error}</p>
          <button className={styles.secondaryButton} onClick={() => refetch()}>
            <FaSync /> Erneut versuchen
          </button>
        </div>
      </div>
    );
  }

  return (
    <div className={`${styles.adminPage} ${styles.adminPageFill}`}>
      <div className={styles.pageHeader}>
        <div>
          <h1 className={styles.pageTitle}>Mandanten</h1>
          <p className={styles.pageSubtitle}>Verwalten Sie alle Mandanten im System</p>
        </div>
        <div className={styles.headerActions}>
          <button
            type="button"
            className={styles.secondaryButton}
            onClick={() => navigate('/admin/user-mandates')}
          >
            <FaUsers /> Benutzer-Zuweisungen
          </button>
          <button 
            className={styles.secondaryButton} 
            onClick={() => refetch()}
            disabled={loading}
          >
            <FaSync className={loading ? 'spinning' : ''} /> Aktualisieren
          </button>
          {canCreate && (
            <button 
              className={styles.primaryButton}
              onClick={() => setShowCreateModal(true)}
            >
              <FaPlus /> Neuer Mandant
            </button>
          )}
        </div>
      </div>

      <div className={styles.tableContainer}>
        {loading && mandates.length === 0 ? (
          <div className={styles.loadingContainer}>
            <div className={styles.spinner} />
            <span>Lade Mandanten...</span>
          </div>
        ) : mandates.length === 0 ? (
          <div className={styles.emptyState}>
            <FaBuilding className={styles.emptyIcon} />
            <h3 className={styles.emptyTitle}>Keine Mandanten vorhanden</h3>
            <p className={styles.emptyDescription}>
              Erstellen Sie einen neuen Mandanten, um loszulegen.
            </p>
            {canCreate && (
              <button 
                className={styles.primaryButton}
                onClick={() => setShowCreateModal(true)}
              >
                <FaPlus /> Ersten Mandanten erstellen
              </button>
            )}
          </div>
        ) : (
          <FormGeneratorTable
            data={mandates}
            columns={columns}
            apiEndpoint="/api/mandates/"
            loading={loading}
            pagination={true}
            pageSize={25}
            searchable={true}
            filterable={true}
            sortable={true}
            selectable={false}
            actionButtons={[
              ...(canUpdate ? [{
                type: 'edit' as const,
                onAction: handleEditClick,
                title: 'Bearbeiten',
              }] : []),
              ...(canDelete ? [{
                type: 'delete' as const,
                title: 'Löschen',
                disabled: (row: Mandate) => row.isSystem 
                  ? { disabled: true, message: 'System-Mandanten können nicht gelöscht werden' } 
                  : false
              }] : []),
            ]}
            onDelete={handleDeleteMandate}
            hookData={{
              refetch,
              permissions,
              pagination,
              handleDelete,
              handleInlineUpdate,
              updateOptimistically,
            }}
            emptyMessage="Keine Mandanten gefunden"
          />
        )}
      </div>

      {/* Create Modal */}
      {showCreateModal && (
        <div className={styles.modalOverlay} onClick={() => setShowCreateModal(false)}>
          <div className={styles.modal} onClick={e => e.stopPropagation()}>
            <div className={styles.modalHeader}>
              <h2 className={styles.modalTitle}>Neuer Mandant</h2>
              <button 
                className={styles.modalClose}
                onClick={() => setShowCreateModal(false)}
              >
                ✕
              </button>
            </div>
            <div className={styles.modalContent}>
              <p style={{ fontSize: '13px', color: 'var(--text-secondary)', marginTop: 0, marginBottom: '12px' }}>
                Stammdaten kommen aus dem Modell <code>Mandate</code> (API). Abrechnung wird in{' '}
                <code>BillingSettings</code> pro Mandant gespeichert.
              </p>
              {mandateAttrsLoading || createFormAttributes.length === 0 ? (
                <div className={styles.loadingContainer}>
                  <div className={styles.spinner} />
                  <span>Lade Formular...</span>
                </div>
              ) : (
                <FormGeneratorForm
                  attributes={createFormAttributesWithBilling}
                  mode="create"
                  onSubmit={handleCreateSubmit}
                  onCancel={() => setShowCreateModal(false)}
                  submitButtonText="Erstellen"
                  cancelButtonText="Abbrechen"
                />
              )}
            </div>
          </div>
        </div>
      )}

      {/* Edit Modal */}
      {editingFormData && (
        <div
          className={styles.modalOverlay}
          onClick={() => {
            setEditingFormData(null);
            setEditingBillingWarning(null);
          }}
        >
          <div className={styles.modal} onClick={e => e.stopPropagation()}>
            <div className={styles.modalHeader}>
              <h2 className={styles.modalTitle}>Mandant bearbeiten</h2>
              <button
                className={styles.modalClose}
                onClick={() => {
                  setEditingFormData(null);
                  setEditingBillingWarning(null);
                }}
              >
                ✕
              </button>
            </div>
            <div className={styles.modalContent}>
              {Boolean(editingFormData.isSystem) && (
                <div className={styles.infoBox} style={{ marginBottom: '1rem', background: 'var(--warning-bg, #fffbeb)', borderColor: 'var(--warning-color, #d69e2e)' }}>
                  <FaLock style={{ marginRight: 8, color: 'var(--warning-color, #d69e2e)' }} />
                  <span>
                    Dies ist ein <strong>System-Mandant</strong>. Er kann nicht gelöscht werden und der Name sollte nicht geändert werden.
                  </span>
                </div>
              )}
              {editingBillingWarning && (
                <div
                  className={styles.infoBox}
                  style={{ marginBottom: '1rem', background: 'var(--warning-bg, #fffbeb)', borderColor: 'var(--warning-color, #d69e2e)' }}
                >
                  {editingBillingWarning}
                </div>
              )}
              {formAttributes.length === 0 ? (
                <div className={styles.loadingContainer}>
                  <div className={styles.spinner} />
                  <span>Lade Formular...</span>
                </div>
              ) : (
                <FormGeneratorForm
                  attributes={formAttributesWithBilling}
                  data={editingFormData}
                  mode="edit"
                  onSubmit={handleEditSubmit}
                  onCancel={() => {
                    setEditingFormData(null);
                    setEditingBillingWarning(null);
                  }}
                  submitButtonText="Speichern"
                  cancelButtonText="Abbrechen"
                />
              )}
            </div>
          </div>
        </div>
      )}
    </div>
  );
};

export default AdminMandatesPage;