import { Component, createRef } from 'react';
import Alert from '@mui/material/Alert';
import Box from '@mui/material/Box';
import Button from '@mui/material/Button';
import CircularProgress from '@mui/material/CircularProgress';
import Divider from '@mui/material/Divider';
import IconButton from '@mui/material/IconButton';
import LinearProgress from '@mui/material/LinearProgress';
import Stack from '@mui/material/Stack';
import Typography from '@mui/material/Typography';
import CloudDownloadOutlinedIcon from '@mui/icons-material/CloudDownloadOutlined';
import CloudUploadOutlinedIcon from '@mui/icons-material/CloudUploadOutlined';
import InsertDriveFileOutlinedIcon from '@mui/icons-material/InsertDriveFileOutlined';
import CheckCircleOutlineIcon from '@mui/icons-material/CheckCircleOutlined';
import CloseIcon from '@mui/icons-material/Close';
import { enqueueSnackbar } from 'notistack';
import { company } from '../../api';
import categoryAutomat from '../../automats/categoryAutomat';
import articleIndexAutomat from '../../automats/articleIndexAutomat';
import companyAutomat from '../../automats/companyAutomat';
import { orderAutomat } from '../../automats/orderAutomat';
import SkeleHashImage from './SkeleHashImage';

function formatBytes(bytes) {
  if (bytes == null || isNaN(bytes) || bytes === 0) return '0 B';
  const units = ['B', 'KB', 'MB', 'GB', 'TB'];
  const i = Math.floor(Math.log(bytes) / Math.log(1024));
  return `${(bytes / Math.pow(1024, i)).toFixed(1)} ${units[i]}`;
}

function isZipFile(file) {
  if (!file) return false;
  const name = (file.name || '').toLowerCase();
  return (
    name.endsWith('.zip') ||
    file.type === 'application/zip' ||
    file.type === 'application/x-zip-compressed'
  );
}

// Counter-based phases emitted by the `progress` event.
const PROGRESS_PHASES = [
  { key: 'categories', label: 'Kategorien', totalKey: 'categoriestotal', doneKey: 'categoriesdone' },
  { key: 'articles', label: 'Artikel', totalKey: 'articlestotal', doneKey: 'articlesdone' },
  { key: 'images', label: 'Medien', totalKey: 'imagestotal', doneKey: 'imagesdone' },
  { key: 'receipts', label: 'Belege', totalKey: 'receiptstotal', doneKey: 'receiptsdone' },
];

export default class ImportExportSettingsPanel extends Component {
  constructor(props) {
    super(props);
    this.state = {
      isAdmin: companyAutomat.state.current?.role === 'admin',
      // Export state
      downloading: false,
      downloadProgress: null, // null = unknown, number 0-100
      downloadStatus: null,
      downloadError: null,

      // Import state (SSE streaming & upload tracking)
      selectedFile: null,
      uploading: false,
      uploadStage: 'idle', // 'idle' | 'upload' | 'server'
      uploadProgress: 0,
      uploadLoaded: 0,
      uploadTotal: 0,
      importProgress: null, // raw counters from the `progress` event
      // Latest SkeleHash shown (first hash of the most recent images batch)
      streamedHash: null,
      importedImageCount: 0,
      statusMessage: null,
      importStats: null,
      uploadError: null,
      uploadSuccess: null,
    };

    this.fileInputRef = createRef();
    this.uploadAbortController = null;
    this.abortController = null;

    this.handleStartDownload = this.handleStartDownload.bind(this);
    this.handleCancelDownload = this.handleCancelDownload.bind(this);
    this.handleFileChange = this.handleFileChange.bind(this);
    this.handleStartUpload = this.handleStartUpload.bind(this);
    this.handleCancelUpload = this.handleCancelUpload.bind(this);
  }

  componentDidMount() {
    this.unsub = companyAutomat.subscribe(this, (state) => ({
      isAdmin: state.current?.role === 'admin',
    }));
  }

  componentWillUnmount() {
    this.unsub?.();
    if (this.uploadAbortController) {
      this.uploadAbortController.abort();
    }
    if (this.abortController) {
      this.abortController.abort();
    }
  }

  async handleStartDownload() {
    this.setState({
      downloading: true,
      downloadProgress: null,
      downloadStatus: null,
      downloadError: null,
    });

    this.abortController = new AbortController();

    try {
      await company.exportCatalog(
        {
          onStatus: (message) => {
            this.setState({ downloadStatus: message });
          },
          onProgress: (progress) => {
            const percent = typeof progress?.percent === 'number' ? progress.percent : null;
            const stage = progress?.stage;
            this.setState((prev) => ({
              downloadProgress: percent ?? prev.downloadProgress,
              downloadStatus: stage
                ? `Verarbeite ${stage} (${percent != null ? `${percent}%` : '...'})`
                : prev.downloadStatus,
            }));
          },
          onError: (errMessage) => {
            this.setState({ downloadError: errMessage });
          },
        },
        { signal: this.abortController.signal, triggerDownload: true }
      );

      enqueueSnackbar('Katalog-Export erfolgreich heruntergeladen.', { variant: 'success' });
      this.setState({ downloading: false, downloadProgress: 100, downloadStatus: null });
    } catch (err) {
      if (err.name === 'AbortError') {
        enqueueSnackbar('Download abgebrochen.', { variant: 'info' });
      } else {
        this.setState({ downloadError: err.message || String(err) });
      }
    } finally {
      this.setState({ downloading: false });
      this.abortController = null;
    }
  }

  handleCancelDownload() {
    if (this.abortController) {
      this.abortController.abort();
    }
  }

  handleFileChange(event) {
    if (!this.state.isAdmin) return;
    const file = event.target.files?.[0];
    if (file) {
      if (!isZipFile(file)) {
        this.setState({
          selectedFile: null,
          uploadError: 'Nur ZIP-Dateien (.zip) sind für den Import zulässig.',
          uploadSuccess: null,
          uploadProgress: 0,
        });
        if (this.fileInputRef.current) this.fileInputRef.current.value = '';
        return;
      }
      this.setState({
        selectedFile: file,
        uploadError: null,
        uploadSuccess: null,
        uploadProgress: 0,
      });
    }
  }

  async handleStartUpload() {
    if (!this.state.isAdmin) return;
    const { selectedFile } = this.state;
    if (!selectedFile) return;

    this.uploadAbortController = new AbortController();

    this.setState({
      uploading: true,
      uploadStage: 'upload',
      uploadProgress: 0,
      uploadLoaded: 0,
      uploadTotal: selectedFile.size,
      importProgress: null,
      streamedHash: null,
      importedImageCount: 0,
      statusMessage: null,
      importStats: null,
      uploadError: null,
      uploadSuccess: null,
    });

    try {
      await company.importCatalog(
        selectedFile,
        {
          onUploadProgress: (p) => {
            this.setState({
              uploadStage: 'upload',
              uploadProgress: p.percent,
              uploadLoaded: p.loaded,
              uploadTotal: p.total,
            });
          },
          onStatus: (message) => {
            this.setState({
              uploadStage: 'server',
              statusMessage: message,
            });
          },
          onProgress: (progress) => {
            if (!progress || typeof progress !== 'object') return;
            // Counter-based protocol: { categoriestotal, categoriesdone, ... }
            this.setState({ uploadStage: 'server', importProgress: progress });
          },
          onImages: (images) => {
            const list = Array.isArray(images) ? images.filter(Boolean) : [];
            if (!list.length) return;
            // Only the first hash of each batch; it replaces the previously
            // shown placeholder.
            const first = list[0];
            const hash = typeof first === 'string' ? first : (first?.skelehash ?? null);
            this.setState((prev) => ({
              uploadStage: 'server',
              streamedHash: hash,
              importedImageCount: prev.importedImageCount + list.length,
              statusMessage: null,
            }));
          },
          onDone: (stats) => {
            this.setState({
              uploading: false,
              uploadStage: 'idle',
              importStats: stats,
              uploadSuccess: 'Import erfolgreich abgeschlossen.',
              statusMessage: null,
              importProgress: null,
              selectedFile: null,
            });
            if (this.fileInputRef.current) this.fileInputRef.current.value = '';
            enqueueSnackbar('Import erfolgreich abgeschlossen.', { variant: 'success' });
            void categoryAutomat.actions.loadTree();
            void articleIndexAutomat.actions.reload?.();
            void companyAutomat.actions.loadBrands?.();
            if (stats?.ordersImported) {
              void orderAutomat.actions.reload?.();
            }
          },
          onError: (message) => {
            this.setState({
              uploading: false,
              uploadStage: 'idle',
              uploadError: message,
            });
            enqueueSnackbar(message || 'Fehler beim Importieren', { variant: 'error' });
          },
        },
        { signal: this.uploadAbortController.signal },
      );
    } catch (err) {
      if (err.name === 'AbortError') {
        this.setState({ uploading: false, uploadStage: 'idle', statusMessage: null });
        enqueueSnackbar('Import abgebrochen.', { variant: 'info' });
        return;
      }
      this.setState({
        uploading: false,
        uploadStage: 'idle',
        uploadError: err?.message || 'Upload fehlgeschlagen.',
      });
      enqueueSnackbar(err?.message || 'Upload fehlgeschlagen.', { variant: 'error' });
    } finally {
      this.uploadAbortController = null;
    }
  }

  handleCancelUpload() {
    if (this.uploadAbortController) {
      this.uploadAbortController.abort();
      this.uploadAbortController = null;
    }
  }

  render() {
    const {
      isAdmin,
      downloading,
      downloadProgress,
      downloadStatus,
      downloadError,
      selectedFile,
      uploading,
      uploadStage,
      uploadProgress,
      uploadLoaded,
      uploadTotal,
      importProgress,
      streamedHash,
      importedImageCount,
      statusMessage,
      importStats,
      uploadError,
      uploadSuccess,
    } = this.state;

    const phaseRows = PROGRESS_PHASES.map((phase) => {
      const total = importProgress?.[phase.totalKey] ?? 0;
      const done = importProgress?.[phase.doneKey] ?? 0;
      return {
        ...phase,
        total,
        done,
        percent: total > 0 ? Math.min(100, Math.round((done / total) * 100)) : 0,
      };
    }).filter((row) => row.total > 0);

    const totalUnits = phaseRows.reduce((sum, row) => sum + row.total, 0);
    const doneUnits = phaseRows.reduce((sum, row) => sum + Math.min(row.done, row.total), 0);
    const overallPercent =
      totalUnits > 0 ? Math.min(100, Math.round((doneUnits / totalUnits) * 100)) : null;

    return (
      <Box sx={{ maxWidth: 680, mx: 'auto', py: 2 }}>
        <Stack spacing={4}>
          {/* SECTION 1: EXPORT (DOWNLOAD) */}
          <Box
            sx={{
              p: 2.5,
              borderRadius: 2,
              border: '1px solid',
              borderColor: 'divider',
              bgcolor: 'background.paper',
            }}
          >
            <Box sx={{ display: 'flex', alignItems: 'center', gap: 1.5, mb: 1.5 }}>
              <CloudDownloadOutlinedIcon color="primary" sx={{ fontSize: 28 }} />
              <Box>
                <Typography variant="subtitle1" fontWeight={600}>
                  Katalog exportieren (Download)
                </Typography>
                <Typography variant="caption" color="text.secondary">
                  Exportiert den vollständigen Mandantenbestand (Kategorien, Artikel, Varianten, Marken, Pfand und Bilder) als ZIP-Archiv.
                </Typography>
              </Box>
            </Box>

            <Divider sx={{ my: 1.5 }} />

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

            {downloading && (
              <Box sx={{ mb: 2, p: 1.5, bgcolor: 'action.hover', borderRadius: 1.5 }}>
                <Box sx={{ display: 'flex', justifyContent: 'space-between', mb: 0.5 }}>
                  <Typography variant="caption" color="text.secondary">
                    {downloadStatus
                      ? (downloadProgress != null ? `${downloadStatus} (${downloadProgress}%)` : downloadStatus)
                      : (downloadProgress != null ? `${downloadProgress}% geladen...` : 'Export wird vorbereitet...')}
                  </Typography>
                  <Button
                    size="small"
                    color="error"
                    onClick={this.handleCancelDownload}
                    sx={{ p: 0, minWidth: 'auto', fontSize: '0.75rem' }}
                  >
                    Abbrechen
                  </Button>
                </Box>
                <LinearProgress
                  variant={downloadProgress != null ? 'determinate' : 'indeterminate'}
                  value={downloadProgress ?? undefined}
                />
              </Box>
            )}

            <Box sx={{ display: 'flex', justifyContent: 'flex-end', gap: 1 }}>
              <Button
                variant="contained"
                startIcon={
                  downloading ? (
                    <CircularProgress size={16} color="inherit" />
                  ) : (
                    <CloudDownloadOutlinedIcon />
                  )
                }
                disabled={downloading}
                onClick={this.handleStartDownload}
              >
                {downloading ? 'Exportieren...' : 'Katalog exportieren'}
              </Button>
            </Box>
          </Box>

          {/* SECTION 2: IMPORT (UPLOAD) */}
          <Box
            sx={{
              p: 2.5,
              borderRadius: 2,
              border: '1px solid',
              borderColor: 'divider',
              bgcolor: 'background.paper',
            }}
          >
            <Box sx={{ display: 'flex', alignItems: 'center', gap: 1.5, mb: 1.5 }}>
              <CloudUploadOutlinedIcon color="primary" sx={{ fontSize: 28 }} />
              <Typography variant="subtitle1" fontWeight={600}>
                Import
              </Typography>
            </Box>

            <Divider sx={{ my: 1.5 }} />

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

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

            {/* Import statistics breakdown on done */}
            {importStats && (
              <Box
                sx={{
                  p: 2,
                  bgcolor: 'background.default',
                  border: '1px solid',
                  borderColor: 'divider',
                  borderRadius: 2,
                  mb: 2,
                }}
              >
                <Box sx={{ display: 'flex', alignItems: 'center', gap: 1, mb: 1.5 }}>
                  <CheckCircleOutlineIcon color="success" />
                  <Typography variant="subtitle2" fontWeight={600}>
                    Import-Statistik
                  </Typography>
                </Box>
                <Box
                  sx={{
                    display: 'grid',
                    gridTemplateColumns: 'repeat(auto-fit, minmax(130px, 1fr))',
                    gap: 1.5,
                  }}
                >
                  <Box
                    sx={{
                      p: 1.5,
                      bgcolor: 'background.paper',
                      borderRadius: 1.5,
                      border: '1px solid',
                      borderColor: 'divider',
                    }}
                  >
                    <Typography variant="caption" color="text.secondary">
                      Kategorien
                    </Typography>
                    <Typography variant="h6" fontWeight={700}>
                      {importStats.categories ?? 0}
                    </Typography>
                    {importStats.categoriesCreated != null && (
                      <Typography variant="caption" color="success.main" display="block">
                        +{importStats.categoriesCreated} neu
                      </Typography>
                    )}
                  </Box>
                  <Box
                    sx={{
                      p: 1.5,
                      bgcolor: 'background.paper',
                      borderRadius: 1.5,
                      border: '1px solid',
                      borderColor: 'divider',
                    }}
                  >
                    <Typography variant="caption" color="text.secondary">
                      Artikel
                    </Typography>
                    <Typography variant="h6" fontWeight={700}>
                      {importStats.articlesTotal ??
                        ((importStats.articlesImported ?? 0) +
                          (importStats.articlesUpdated ?? 0))}
                    </Typography>
                    <Typography variant="caption" color="text.secondary" display="block">
                      {importStats.articlesImported ?? 0} neu / {importStats.articlesUpdated ?? 0} akt.
                    </Typography>
                  </Box>
                  <Box
                    sx={{
                      p: 1.5,
                      bgcolor: 'background.paper',
                      borderRadius: 1.5,
                      border: '1px solid',
                      borderColor: 'divider',
                    }}
                  >
                    <Typography variant="caption" color="text.secondary">
                      Varianten
                    </Typography>
                    <Typography variant="h6" fontWeight={700}>
                      {importStats.variantsLinked ?? 0}
                    </Typography>
                    <Typography variant="caption" color="text.secondary" display="block">
                      verknüpft
                    </Typography>
                  </Box>
                  <Box
                    sx={{
                      p: 1.5,
                      bgcolor: 'background.paper',
                      borderRadius: 1.5,
                      border: '1px solid',
                      borderColor: 'divider',
                    }}
                  >
                    <Typography variant="caption" color="text.secondary">
                      Bilder
                    </Typography>
                    <Typography variant="h6" fontWeight={700}>
                      {importStats.articlePictures ?? 0}
                    </Typography>
                    {importStats.categoryPictures != null && (
                      <Typography variant="caption" color="text.secondary" display="block">
                        +{importStats.categoryPictures} Kat-Bilder
                      </Typography>
                    )}
                  </Box>
                  {importStats.brands != null && (
                    <Box
                      sx={{
                        p: 1.5,
                        bgcolor: 'background.paper',
                        borderRadius: 1.5,
                        border: '1px solid',
                        borderColor: 'divider',
                      }}
                    >
                      <Typography variant="caption" color="text.secondary">
                        Marken
                      </Typography>
                      <Typography variant="h6" fontWeight={700}>
                        {importStats.brands ?? 0}
                      </Typography>
                      <Typography variant="caption" color="text.secondary" display="block">
                        {importStats.brandsCreated != null ? `+${importStats.brandsCreated} neu` : ''}
                        {importStats.brandPictures ? ` (${importStats.brandPictures} Logos)` : ''}
                      </Typography>
                    </Box>
                  )}
                  {importStats.ordersImported != null && (
                    <Box
                      sx={{
                        p: 1.5,
                        bgcolor: 'background.paper',
                        borderRadius: 1.5,
                        border: '1px solid',
                        borderColor: 'divider',
                      }}
                    >
                      <Typography variant="caption" color="text.secondary">
                        Aufträge
                      </Typography>
                      <Typography variant="h6" fontWeight={700}>
                        {importStats.ordersImported}
                      </Typography>
                      <Typography variant="caption" color="text.secondary" display="block">
                        {importStats.ordersSkipped ? `+${importStats.ordersSkipped} übersprungen` : 'importiert'}
                      </Typography>
                    </Box>
                  )}
                </Box>
              </Box>
            )}

            <input
              ref={this.fileInputRef}
              type="file"
              accept=".zip,application/zip,application/x-zip-compressed"
              style={{ display: 'none' }}
              onChange={this.handleFileChange}
              disabled={!isAdmin || uploading}
            />

            {!selectedFile ? (
              <Box sx={{ mb: 2 }}>
                <Button
                  variant="outlined"
                  startIcon={<InsertDriveFileOutlinedIcon />}
                  onClick={() => this.fileInputRef.current?.click()}
                  disabled={!isAdmin || uploading}
                >
                  ZIP-Datei auswählen
                </Button>
              </Box>
            ) : (
              <Box
                sx={{
                  display: 'flex',
                  alignItems: 'center',
                  justifyContent: 'space-between',
                  p: 1.5,
                  mb: 2,
                  borderRadius: 1.5,
                  border: '1px solid',
                  borderColor: 'divider',
                  bgcolor: 'background.default',
                }}
              >
                <Box sx={{ display: 'flex', alignItems: 'center', gap: 1.5, minWidth: 0 }}>
                  <InsertDriveFileOutlinedIcon color="primary" />
                  <Box sx={{ minWidth: 0 }}>
                    <Typography variant="body2" fontWeight={600} noWrap>
                      {selectedFile.name}
                    </Typography>
                    <Typography variant="caption" color="text.secondary">
                      Größe: {formatBytes(selectedFile.size)}
                    </Typography>
                  </Box>
                </Box>
                {!uploading && (
                  <IconButton
                    size="small"
                    disabled={!isAdmin}
                    onClick={() => {
                      this.setState({ selectedFile: null });
                      if (this.fileInputRef.current) this.fileInputRef.current.value = '';
                    }}
                  >
                    <CloseIcon fontSize="small" />
                  </IconButton>
                )}
              </Box>
            )}

            {/* Real-time Streaming Progress Ticker */}
            {uploading && (
              <Box sx={{ mb: 2, p: 2, bgcolor: 'action.hover', borderRadius: 2, border: '1px solid', borderColor: 'divider' }}>
                {uploadStage === 'upload' ? (
                  <>
                    <Box sx={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', mb: 1 }}>
                      <Typography variant="body2" fontWeight={600} color="primary.main">
                        Datei wird übertragen…
                      </Typography>
                      <Button
                        size="small"
                        color="error"
                        onClick={this.handleCancelUpload}
                        sx={{ minWidth: 'auto', fontSize: '0.75rem', px: 1, py: 0.25 }}
                      >
                        Abbrechen
                      </Button>
                    </Box>
                    <Box sx={{ display: 'flex', justifyContent: 'space-between', mb: 0.5 }}>
                      <Typography variant="caption" color="text.secondary">
                        {uploadProgress}% ({formatBytes(uploadLoaded)} von {formatBytes(uploadTotal)})
                      </Typography>
                    </Box>
                    <LinearProgress
                      variant="determinate"
                      value={uploadProgress}
                      sx={{ height: 8, borderRadius: 1 }}
                    />
                  </>
                ) : (
                  <>
                    <Box sx={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', mb: 1 }}>
                      <Typography variant="body2" fontWeight={600} color="primary.main">
                        {statusMessage || 'Daten werden verarbeitet…'}
                        {overallPercent != null ? ` · ${overallPercent}%` : ''}
                      </Typography>
                      <Button
                        size="small"
                        color="error"
                        onClick={this.handleCancelUpload}
                        sx={{ minWidth: 'auto', fontSize: '0.75rem', px: 1, py: 0.25 }}
                      >
                        Abbrechen
                      </Button>
                    </Box>
                    {phaseRows.length > 0 ? (
                      <Stack spacing={1}>
                        {phaseRows.map((row) => (
                          <Box key={row.key}>
                            <Box sx={{ display: 'flex', justifyContent: 'space-between', mb: 0.25 }}>
                              <Typography variant="caption" color="text.secondary">
                                {row.label}
                              </Typography>
                              <Typography variant="caption" fontWeight={600} color="text.secondary">
                                {row.done} / {row.total} ({row.percent}%)
                              </Typography>
                            </Box>
                            <LinearProgress
                              variant="determinate"
                              value={row.percent}
                              sx={{ height: 6, borderRadius: 1 }}
                            />
                          </Box>
                        ))}
                      </Stack>
                    ) : (
                      <>
                        {statusMessage && (
                          <Typography variant="caption" color="text.secondary" display="block" sx={{ mb: 0.5 }}>
                            {statusMessage}
                          </Typography>
                        )}
                        <LinearProgress sx={{ height: 8, borderRadius: 1 }} />
                      </>
                    )}

                    {/* Latest decoded SkeleHash placeholder (replaces previous) */}
                    {streamedHash && (
                      <Box
                        sx={{
                          display: 'flex',
                          alignItems: 'center',
                          gap: 1,
                          mt: 2,
                          pt: 2,
                          borderTop: '1px dashed',
                          borderColor: 'divider',
                        }}
                      >
                        <Box
                          title={streamedHash}
                          sx={{
                            width: 18,
                            height: 18,
                            flex: '0 0 auto',
                            borderRadius: 0.5,
                            overflow: 'hidden',
                            border: '1px solid',
                            borderColor: 'divider',
                            bgcolor: 'background.paper',
                          }}
                        >
                          <SkeleHashImage hash={streamedHash} />
                        </Box>
                        <Typography variant="caption" color="text.secondary">
                          {importedImageCount} Bild(er) verarbeitet
                        </Typography>
                      </Box>
                    )}
                  </>
                )}
              </Box>
            )}

            <Box sx={{ display: 'flex', justifyContent: 'flex-end', gap: 1 }}>
              <Button
                variant="contained"
                startIcon={
                  uploading ? (
                    <CircularProgress size={16} color="inherit" />
                  ) : (
                    <CloudUploadOutlinedIcon />
                  )
                }
                disabled={!isAdmin || uploading || !selectedFile}
                onClick={this.handleStartUpload}
              >
                {uploading ? 'Import läuft…' : 'Upload & Import starten'}
              </Button>
            </Box>
          </Box>
        </Stack>
      </Box>
    );
  }
}