import React, { Component } from 'react';
import {
  Box,
  Typography,
  Button,
  Table,
  TableBody,
  TableCell,
  TableContainer,
  TableHead,
  TableRow,
  Paper,
  TextField,
  Select,
  MenuItem,
  FormControl,
  InputLabel,
  IconButton,
  Dialog,
  DialogTitle,
  DialogContent,
  DialogActions,
  Alert,
  Chip
} from '@mui/material';
import {
  Add as AddIcon,
  Delete as DeleteIcon,
  Edit as EditIcon,
  Save as SaveIcon,
  Cancel as CancelIcon
} from '@mui/icons-material';
import AuthService from '../services/AuthService';

class AccountingItemsManager extends Component {
  constructor(props) {
    super(props);
    
    this.state = {
      accountingItems: [],
      kontos: [],
      bus: [],
      loading: true,
      editingItem: null,
      showCreateDialog: false,
      showCreateKontoDialog: false,
      jtlKontierung: null,
      newItem: {
        umsatz_brutto: '',
        soll_haben_kz: 'S',
        konto: '',
        bu: '',
        rechnungsnummer: '',
        buchungstext: ''
      },
      newKonto: {
        konto: '',
        name: ''
      },
      error: null,
      saving: false
    };
    
    this.authService = new AuthService();
  }

  componentDidMount() {
    this.loadData();
    this.loadJtlKontierung();
  }

  loadData = async () => {
    try {
      // Load accounting items for this transaction
      await this.loadAccountingItems();
      
      // Load Konto and BU options
      await Promise.all([
        this.loadKontos(),
        this.loadBUs()
      ]);
      
      this.setState({ loading: false });
    } catch (error) {
      console.error('Error loading data:', error);
      this.setState({ 
        error: 'Fehler beim Laden der Daten',
        loading: false 
      });
    }
  };

  loadJtlKontierung = async () => {
    try {
      const { transaction } = this.props;
      if (!transaction || !transaction.jtlId) {
        this.setState({ jtlKontierung: undefined });
        return;
      }

      const response = await this.authService.apiCall(`/data/jtl-kontierung/${transaction.jtlId}`);
      if (!response) return;

      if (response.ok) {
        const data = await response.json();
        this.setState({ jtlKontierung: data });
      } else {
        const err = await response.json();
        console.error('Failed to load JTL Kontierung:', err);
        this.setState({ jtlKontierung: undefined });
      }
    } catch (e) {
      console.error('Error loading JTL Kontierung:', e);
      this.setState({ jtlKontierung: undefined });
    }
  }

  loadAccountingItems = async () => {
    const { transaction } = this.props;
    if (!transaction?.id) return;
    
    try {
      const response = await this.authService.apiCall(`/data/accounting-items/${transaction.id}`);
      if (response && response.ok) {
        const items = await response.json();
        this.setState({ accountingItems: items });
      }
    } catch (error) {
      console.error('Error loading accounting items:', error);
    }
  };

  loadKontos = async () => {
    try {
      const response = await this.authService.apiCall('/data/kontos');
      if (response && response.ok) {
        const kontos = await response.json();
        this.setState({ kontos });
      }
    } catch (error) {
      console.error('Error loading kontos:', error);
    }
  };

  loadBUs = async () => {
    try {
      const response = await this.authService.apiCall('/data/bus');
      if (response && response.ok) {
        const bus = await response.json();
        this.setState({ bus });
      }
    } catch (error) {
      console.error('Error loading BUs:', error);
    }
  };

  handleCreateItem = () => {
    const { transaction } = this.props;
    this.setState({
      showCreateDialog: true,
      newItem: {
        umsatz_brutto: Math.abs(transaction.numericAmount || 0).toString(),
        soll_haben_kz: (transaction.numericAmount || 0) >= 0 ? 'H' : 'S',
        konto: '',
        bu: '',
        rechnungsnummer: '',
        buchungstext: transaction.description || ''
      }
    });
  };

  handleSaveItem = async () => {
    const { transaction } = this.props;
    const { newItem } = this.state;
    
    if (!newItem.umsatz_brutto || !newItem.konto) {
      this.setState({ error: 'Betrag und Konto sind erforderlich' });
      return;
    }
    
    this.setState({ saving: true, error: null });
    
    try {
      const itemData = {
        ...newItem,
        transaction_id: transaction.isFromCSV ? null : transaction.id,
        csv_transaction_id: transaction.isFromCSV ? transaction.id : null,
        buchungsdatum: transaction.parsed_date || new Date().toISOString().split('T')[0]
      };
      
      const response = await this.authService.apiCall('/data/accounting-items', {
        method: 'POST',
        body: JSON.stringify(itemData)
      });
      
      if (response && response.ok) {
        await this.loadAccountingItems();
        this.setState({
          showCreateDialog: false,
          saving: false,
          newItem: {
            umsatz_brutto: '',
            soll_haben_kz: 'S',
            konto: '',
            bu: '',
            rechnungsnummer: '',
            buchungstext: ''
          }
        });
      } else {
        const errorData = await response.json();
        this.setState({
          error: errorData.error || 'Fehler beim Speichern',
          saving: false
        });
      }
    } catch (error) {
      console.error('Error saving accounting item:', error);
      this.setState({
        error: 'Fehler beim Speichern',
        saving: false
      });
    }
  };

  handleCreateKonto = async () => {
    const { newKonto } = this.state;
    
    if (!newKonto.konto || !newKonto.name) {
      this.setState({ error: 'Konto-Nummer und Name sind erforderlich' });
      return;
    }
    
    this.setState({ saving: true, error: null });
    
    try {
      const response = await this.authService.apiCall('/data/kontos', {
        method: 'POST',
        body: JSON.stringify(newKonto)
      });
      
      if (response && response.ok) {
        await this.loadKontos();
        this.setState({
          showCreateKontoDialog: false,
          saving: false,
          newKonto: { konto: '', name: '' }
        });
      } else {
        const errorData = await response.json();
        this.setState({
          error: errorData.error || 'Fehler beim Erstellen des Kontos',
          saving: false
        });
      }
    } catch (error) {
      console.error('Error creating konto:', error);
      this.setState({
        error: 'Fehler beim Erstellen des Kontos',
        saving: false
      });
    }
  };

  handleDeleteItem = async (itemId) => {
    if (!window.confirm('Buchungsposten wirklich löschen?')) return;
    
    try {
      const response = await this.authService.apiCall(`/data/accounting-items/${itemId}`, {
        method: 'DELETE'
      });
      
      if (response && response.ok) {
        await this.loadAccountingItems();
      }
    } catch (error) {
      console.error('Error deleting accounting item:', error);
      this.setState({ error: 'Fehler beim Löschen' });
    }
  };

  calculateTotal = () => {
    return this.state.accountingItems.reduce((sum, item) => {
      const amount = parseFloat(item.umsatz_brutto) || 0;
      return sum + (item.soll_haben_kz === 'S' ? amount : -amount);
    }, 0);
  };

  render() {
    const { transaction } = this.props;
    const {
      accountingItems,
      kontos,
      bus,
      loading,
      showCreateDialog,
      showCreateKontoDialog,
      newItem,
      newKonto,
      error,
      saving
    } = this.state;

    if (loading) {
      return <Typography>Lade Buchungsdaten...</Typography>;
    }

    const transactionAmount = transaction.numericAmount || 0;
    const currentTotal = this.calculateTotal();
    const isBalanced = Math.abs(currentTotal - Math.abs(transactionAmount)) < 0.01;

    return (
      <Box>
        <Box sx={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', mb: 2 }}>
          <Typography variant="h6">
            Buchungsposten
          </Typography>
          <Button
            variant="contained"
            startIcon={<AddIcon />}
            onClick={this.handleCreateItem}
            size="small"
          >
            Hinzufügen
          </Button>
        </Box>

        {error && (
          <Alert severity="error" sx={{ mb: 2 }}>
            {error}
          </Alert>
        )}

        <Box sx={{ mb: 2, p: 2, bgcolor: isBalanced ? '#e8f5e8' : '#fff3e0', borderRadius: 1 }}>
          <Typography variant="body2">
            <strong>Transaktionsbetrag:</strong> {Math.abs(transactionAmount).toFixed(2)} €
          </Typography>
          <Typography variant="body2">
            <strong>Summe Buchungsposten:</strong> {Math.abs(currentTotal).toFixed(2)} €
          </Typography>
          <Chip
            label={isBalanced ? "✅ Ausgeglichen" : "⚠️ Nicht ausgeglichen"}
            color={isBalanced ? "success" : "warning"}
            size="small"
            sx={{ mt: 1 }}
          />
        </Box>

        {transaction?.jtlId && (
          <Box sx={{ mb: 2, p: 2, border: '1px dashed #999', borderRadius: 1 }}>
            <Typography variant="subtitle2">Debug: tUmsatzKontierung.data</Typography>
            <Typography variant="caption" component="div" sx={{ whiteSpace: 'pre-wrap', wordBreak: 'break-word' }}>
              {this.state.jtlKontierung === undefined
                ? 'undefined'
                : this.state.jtlKontierung === null
                  ? 'null'
                  : typeof this.state.jtlKontierung === 'object'
                    ? JSON.stringify(this.state.jtlKontierung, null, 2)
                    : String(this.state.jtlKontierung)}
            </Typography>
          </Box>
        )}

        <TableContainer component={Paper}>
          <Table size="small">
            <TableHead>
              <TableRow>
                <TableCell>Betrag</TableCell>
                <TableCell>S/H</TableCell>
                <TableCell>Konto</TableCell>
                <TableCell>BU</TableCell>
                <TableCell>Buchungstext</TableCell>
                <TableCell>Aktionen</TableCell>
              </TableRow>
            </TableHead>
            <TableBody>
              {accountingItems.map((item) => (
                <TableRow key={item.id}>
                  <TableCell>{parseFloat(item.umsatz_brutto).toFixed(2)} €</TableCell>
                  <TableCell>
                    <Chip
                      label={item.soll_haben_kz}
                      color={item.soll_haben_kz === 'S' ? 'primary' : 'secondary'}
                      size="small"
                    />
                  </TableCell>
                  <TableCell>
                    {item.konto} - {item.konto_name}
                  </TableCell>
                  <TableCell>
                    {item.bu ? `${item.bu} - ${item.bu_name}` : '-'}
                  </TableCell>
                  <TableCell>{item.buchungstext || '-'}</TableCell>
                  <TableCell>
                    <IconButton
                      size="small"
                      onClick={() => this.handleDeleteItem(item.id)}
                      color="error"
                    >
                      <DeleteIcon />
                    </IconButton>
                  </TableCell>
                </TableRow>
              ))}
              {accountingItems.length === 0 && (
                <TableRow>
                  <TableCell colSpan={6} align="center">
                    <Typography color="textSecondary">
                      Keine Buchungsposten vorhanden
                    </Typography>
                  </TableCell>
                </TableRow>
              )}
            </TableBody>
          </Table>
        </TableContainer>

        {/* Create Item Dialog */}
        <Dialog open={showCreateDialog} onClose={() => this.setState({ showCreateDialog: false })} maxWidth="sm" fullWidth>
          <DialogTitle>Neuen Buchungsposten erstellen</DialogTitle>
          <DialogContent>
            <Box sx={{ display: 'flex', flexDirection: 'column', gap: 2, mt: 1 }}>
              <TextField
                label="Betrag"
                type="number"
                value={newItem.umsatz_brutto}
                onChange={(e) => this.setState({
                  newItem: { ...newItem, umsatz_brutto: e.target.value }
                })}
                required
                fullWidth
              />
              
              <FormControl fullWidth>
                <InputLabel>Soll/Haben</InputLabel>
                <Select
                  value={newItem.soll_haben_kz}
                  onChange={(e) => this.setState({
                    newItem: { ...newItem, soll_haben_kz: e.target.value }
                  })}
                >
                  <MenuItem value="S">Soll (S)</MenuItem>
                  <MenuItem value="H">Haben (H)</MenuItem>
                </Select>
              </FormControl>

              <Box sx={{ display: 'flex', gap: 1, alignItems: 'flex-end' }}>
                <FormControl fullWidth>
                  <InputLabel>Konto</InputLabel>
                  <Select
                    value={newItem.konto}
                    onChange={(e) => this.setState({
                      newItem: { ...newItem, konto: e.target.value }
                    })}
                  >
                    {kontos.map((konto) => (
                      <MenuItem key={konto.id} value={konto.konto}>
                        {konto.konto} - {konto.name}
                      </MenuItem>
                    ))}
                  </Select>
                </FormControl>
                <Button
                  variant="outlined"
                  onClick={() => this.setState({ showCreateKontoDialog: true })}
                  sx={{ minWidth: 'auto', px: 1 }}
                >
                  <AddIcon />
                </Button>
              </Box>

              <FormControl fullWidth>
                <InputLabel>BU (Steuercode)</InputLabel>
                <Select
                  value={newItem.bu}
                  onChange={(e) => this.setState({
                    newItem: { ...newItem, bu: e.target.value }
                  })}
                >
                  <MenuItem value="">Kein BU</MenuItem>
                  {bus.map((bu) => (
                    <MenuItem key={bu.id} value={bu.bu}>
                      {bu.bu} - {bu.name} ({bu.vst}%)
                    </MenuItem>
                  ))}
                </Select>
              </FormControl>

              <TextField
                label="Buchungstext"
                value={newItem.buchungstext}
                onChange={(e) => this.setState({
                  newItem: { ...newItem, buchungstext: e.target.value }
                })}
                fullWidth
                multiline
                rows={2}
              />
            </Box>
          </DialogContent>
          <DialogActions>
            <Button onClick={() => this.setState({ showCreateDialog: false })}>
              Abbrechen
            </Button>
            <Button onClick={this.handleSaveItem} variant="contained" disabled={saving}>
              {saving ? 'Speichern...' : 'Speichern'}
            </Button>
          </DialogActions>
        </Dialog>

        {/* Create Konto Dialog */}
        <Dialog open={showCreateKontoDialog} onClose={() => this.setState({ showCreateKontoDialog: false })} maxWidth="xs" fullWidth>
          <DialogTitle>Neues Konto erstellen</DialogTitle>
          <DialogContent>
            <Box sx={{ display: 'flex', flexDirection: 'column', gap: 2, mt: 1 }}>
              <TextField
                label="Konto-Nummer"
                value={newKonto.konto}
                onChange={(e) => this.setState({
                  newKonto: { ...newKonto, konto: e.target.value }
                })}
                required
                fullWidth
              />
              <TextField
                label="Konto-Name"
                value={newKonto.name}
                onChange={(e) => this.setState({
                  newKonto: { ...newKonto, name: e.target.value }
                })}
                required
                fullWidth
              />
            </Box>
          </DialogContent>
          <DialogActions>
            <Button onClick={() => this.setState({ showCreateKontoDialog: false })}>
              Abbrechen
            </Button>
            <Button onClick={this.handleCreateKonto} variant="contained" disabled={saving}>
              {saving ? 'Erstellen...' : 'Erstellen'}
            </Button>
          </DialogActions>
        </Dialog>
      </Box>
    );
  }
}

export default AccountingItemsManager;