/**
 * TrusteeDocumentsView
 * 
 * Dokument-Verwaltung für eine Trustee-Instanz.
 * Verwendet FormGeneratorTable für konsistentes UI.
 */

import React, { useState, useMemo, useEffect } from 'react';
import { useTrusteeDocuments, useTrusteeDocumentOperations, TrusteeDocument } from '../../../hooks/useTrustee';
import { useInstanceId } from '../../../hooks/useCurrentInstance';
import { FormGeneratorTable } from '../../../components/FormGenerator/FormGeneratorTable';
import { FormGeneratorForm } from '../../../components/FormGenerator/FormGeneratorForm';
import { FaSync, FaFileAlt, FaDownload } from 'react-icons/fa';
import { useToast } from '../../../contexts/ToastContext';
import api from '../../../api';
import styles from '../../admin/Admin.module.css';

export const TrusteeDocumentsView: React.FC = () => {
  const { showError } = useToast();
  const instanceId = useInstanceId();
  
  // Entity hook
  const {
    items: documents,
    attributes,
    permissions,
    pagination,
    loading,
    error,
    refetch,
    fetchById,
    updateOptimistically,
    removeOptimistically,
  } = useTrusteeDocuments();

  // Operations hook
  const {
    handleDelete,
    handleCreate,
    handleUpdate,
    deletingItems,
  } = useTrusteeDocumentOperations();

  // Modal state
  const [editingDocument, setEditingDocument] = useState<TrusteeDocument | null>(null);
  const [isCreateMode, setIsCreateMode] = useState(false);
  const [downloadingId, setDownloadingId] = useState<string | null>(null);

  // Initial fetch
  useEffect(() => {
    if (instanceId) {
      refetch();
    }
  }, [instanceId]);

  // 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,
    }));
  }, [attributes]);

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

  // Handle edit click
  const handleEditClick = async (doc: TrusteeDocument) => {
    const fullDoc = await fetchById(doc.id);
    if (fullDoc) {
      setEditingDocument(fullDoc);
      setIsCreateMode(false);
    }
  };

  // Handle create click
  const handleCreateClick = () => {
    setEditingDocument(null);
    setIsCreateMode(true);
  };

  // Handle form submit
  const handleFormSubmit = async (data: Partial<TrusteeDocument>) => {
    if (isCreateMode) {
      const result = await handleCreate(data);
      if (result.success) {
        setIsCreateMode(false);
        refetch();
      }
    } else if (editingDocument) {
      const result = await handleUpdate(editingDocument.id, data);
      if (result.success) {
        setEditingDocument(null);
        refetch();
      }
    }
  };

  // Handle delete (confirmation handled by DeleteActionButton)
  const handleDeleteDoc = async (doc: TrusteeDocument) => {
    removeOptimistically(doc.id);
    const success = await handleDelete(doc.id);
    if (!success) {
      refetch(); // Revert on error
    }
  };

  // Handle download
  const handleDownload = async (doc: TrusteeDocument) => {
    if (!instanceId) return;
    
    setDownloadingId(doc.id);
    try {
      const response = await api.get(
        `/api/trustee/${instanceId}/documents/${doc.id}/data`,
        { responseType: 'blob' }
      );
      
      const blob = new Blob([response.data], { type: doc.documentMimeType });
      const url = window.URL.createObjectURL(blob);
      const link = document.createElement('a');
      link.href = url;
      link.download = doc.documentName || 'document';
      document.body.appendChild(link);
      link.click();
      document.body.removeChild(link);
      window.URL.revokeObjectURL(url);
    } catch (err) {
      console.error('Download error:', err);
      showError('Fehler', 'Fehler beim Herunterladen des Dokuments.');
    } finally {
      setDownloadingId(null);
    }
  };

  // Close modal
  const handleCloseModal = () => {
    setEditingDocument(null);
    setIsCreateMode(false);
  };

  // Form attributes (exclude system fields)
  const formAttributes = useMemo(() => {
    const excludedFields = ['id', 'mandateId', 'instanceId', '_createdBy', '_createdAt', '_modifiedAt', '_modifiedBy'];
    return (attributes || []).filter(attr => !excludedFields.includes(attr.name));
  }, [attributes]);

  // Handle inline update
  const handleInlineUpdate = async (itemId: string, updateData: Partial<TrusteeDocument>, row: TrusteeDocument) => {
    updateOptimistically(itemId, updateData);
    const result = await handleUpdate(itemId, { ...row, ...updateData });
    if (!result.success) {
      refetch(); // Revert on error
    }
  };

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

  return (
    <div className={styles.adminPage}>
      <div className={styles.pageHeader}>
        <div>
          <p className={styles.pageSubtitle}>Belege und Dokumente verwalten</p>
        </div>
        <div className={styles.headerActions}>
          <button 
            className={styles.secondaryButton} 
            onClick={() => refetch()}
            disabled={loading}
          >
            <FaSync className={loading ? 'spinning' : ''} /> Aktualisieren
          </button>
          {canCreate && (
            <button 
              className={styles.primaryButton}
              onClick={handleCreateClick}
            >
              + Neues Dokument
            </button>
          )}
        </div>
      </div>

      <div className={styles.tableContainer}>
        {loading && (!documents || documents.length === 0) ? (
          <div className={styles.loadingContainer}>
            <div className={styles.spinner} />
            <span>Lade Dokumente...</span>
          </div>
        ) : !documents || documents.length === 0 ? (
          <div className={styles.emptyState}>
            <FaFileAlt className={styles.emptyIcon} />
            <h3 className={styles.emptyTitle}>Keine Dokumente vorhanden</h3>
            <p className={styles.emptyDescription}>
              Erstellen Sie ein neues Dokument, um zu beginnen.
            </p>
            {canCreate && (
              <button 
                className={styles.primaryButton}
                onClick={handleCreateClick}
              >
                + Neues Dokument
              </button>
            )}
          </div>
        ) : (
          <FormGeneratorTable
            data={documents}
            columns={columns}
            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',
                loading: (row: TrusteeDocument) => deletingItems.has(row.id),
              }] : []),
            ]}
            customActions={[
              {
                id: 'download',
                icon: <FaDownload />,
                onClick: handleDownload,
                title: 'Herunterladen',
                loading: (row: TrusteeDocument) => downloadingId === row.id,
              },
            ]}
            onDelete={handleDeleteDoc}
            hookData={{
              refetch,
              permissions,
              pagination,
              handleDelete,
              handleInlineUpdate,
              updateOptimistically,
            }}
            emptyMessage="Keine Dokumente gefunden"
          />
        )}
      </div>

      {/* Create/Edit Modal */}
      {(editingDocument || isCreateMode) && (
        <div className={styles.modalOverlay} onClick={handleCloseModal}>
          <div className={styles.modal} onClick={e => e.stopPropagation()}>
            <div className={styles.modalHeader}>
              <h2 className={styles.modalTitle}>
                {isCreateMode ? 'Neues Dokument' : 'Dokument bearbeiten'}
              </h2>
              <button 
                className={styles.modalClose}
                onClick={handleCloseModal}
              >
                ✕
              </button>
            </div>
            <div className={styles.modalContent}>
              {formAttributes.length === 0 ? (
                <div className={styles.loadingContainer}>
                  <div className={styles.spinner} />
                  <span>Lade Formular...</span>
                </div>
              ) : (
                <FormGeneratorForm
                  attributes={formAttributes}
                  data={editingDocument || {}}
                  mode={isCreateMode ? 'create' : 'edit'}
                  onSubmit={handleFormSubmit}
                  onCancel={handleCloseModal}
                  submitButtonText={isCreateMode ? 'Erstellen' : 'Speichern'}
                  cancelButtonText="Abbrechen"
                  instanceId={instanceId}
                />
              )}
            </div>
          </div>
        </div>
      )}
    </div>
  );
};

export default TrusteeDocumentsView;
