/**
 * @ai-summary Admin Vehicle Catalog page with search-first UI
 * @ai-context Uses server-side search and pagination instead of loading all data
 */

import React, { useState, useCallback, useRef } from 'react';
import { Navigate } from 'react-router-dom';
import {
  Box,
  Button,
  Checkbox,
  CircularProgress,
  Dialog,
  DialogActions,
  DialogContent,
  DialogTitle,
  IconButton,
  InputAdornment,
  Paper,
  Table,
  TableBody,
  TableCell,
  TableContainer,
  TableHead,
  TablePagination,
  TableRow,
  TextField,
  Tooltip,
  Typography,
  Alert,
  Collapse,
} from '@mui/material';
import {
  Search,
  Delete,
  FileDownload,
  FileUpload,
  Clear,
  ExpandMore,
  ExpandLess,
} from '@mui/icons-material';
import toast from 'react-hot-toast';
import { useAdminAccess } from '../../core/auth/useAdminAccess';
import {
  useCatalogSearch,
  useExportCatalog,
  useImportPreview,
  useImportApply,
} from '../../features/admin/hooks/useCatalog';
import { adminApi } from '../../features/admin/api/admin.api';
import {
  AdminSectionHeader,
} from '../../features/admin/components';
import {
  CatalogSearchResult,
  ImportPreviewResult,
  ImportApplyResult,
} from '../../features/admin/types/admin.types';

const PAGE_SIZE_OPTIONS = [25, 50, 100];

export const AdminCatalogPage: React.FC = () => {
  const { loading: authLoading, isAdmin } = useAdminAccess();

  // Search state
  const [searchInput, setSearchInput] = useState('');
  const [searchQuery, setSearchQuery] = useState('');
  const [page, setPage] = useState(0);
  const [pageSize, setPageSize] = useState(50);

  // Selection state
  const [selectedIds, setSelectedIds] = useState<Set<number>>(new Set());

  // Dialog state
  const [deleteDialogOpen, setDeleteDialogOpen] = useState(false);
  const [deleteTarget, setDeleteTarget] = useState<CatalogSearchResult | null>(null);
  const [deleting, setDeleting] = useState(false);

  // Import state
  const [importDialogOpen, setImportDialogOpen] = useState(false);
  const [importPreview, setImportPreview] = useState<ImportPreviewResult | null>(null);
  const [importResult, setImportResult] = useState<ImportApplyResult | null>(null);
  const [errorsExpanded, setErrorsExpanded] = useState(false);
  const fileInputRef = useRef<HTMLInputElement>(null);

  // Hooks
  const { data: searchData, isLoading: searchLoading, refetch } = useCatalogSearch(
    searchQuery,
    page + 1, // API uses 1-based pages
    pageSize
  );
  const exportMutation = useExportCatalog();
  const importPreviewMutation = useImportPreview();
  const importApplyMutation = useImportApply();

  // Search handlers
  const handleSearch = useCallback(() => {
    setPage(0);
    setSelectedIds(new Set());
    setSearchQuery(searchInput);
  }, [searchInput]);

  const handleSearchKeyPress = useCallback(
    (event: React.KeyboardEvent) => {
      if (event.key === 'Enter') {
        handleSearch();
      }
    },
    [handleSearch]
  );

  const handleClearSearch = useCallback(() => {
    setSearchInput('');
    setSearchQuery('');
    setPage(0);
    setSelectedIds(new Set());
  }, []);

  // Pagination handlers
  const handlePageChange = useCallback((_: unknown, newPage: number) => {
    setPage(newPage);
    setSelectedIds(new Set());
  }, []);

  const handlePageSizeChange = useCallback(
    (event: React.ChangeEvent<HTMLInputElement>) => {
      setPageSize(parseInt(event.target.value, 10));
      setPage(0);
      setSelectedIds(new Set());
    },
    []
  );

  // Selection handlers
  const handleSelectAll = useCallback(
    (event: React.ChangeEvent<HTMLInputElement>) => {
      if (event.target.checked && searchData?.items) {
        setSelectedIds(new Set(searchData.items.map((item) => item.id)));
      } else {
        setSelectedIds(new Set());
      }
    },
    [searchData]
  );

  const handleSelectRow = useCallback((id: number) => {
    setSelectedIds((prev) => {
      const next = new Set(prev);
      if (next.has(id)) {
        next.delete(id);
      } else {
        next.add(id);
      }
      return next;
    });
  }, []);

  // Delete handlers
  const handleDeleteClick = useCallback((row: CatalogSearchResult) => {
    setDeleteTarget(row);
    setDeleteDialogOpen(true);
  }, []);

  const handleBulkDeleteClick = useCallback(() => {
    setDeleteTarget(null);
    setDeleteDialogOpen(true);
  }, []);

  const handleDeleteConfirm = useCallback(async () => {
    setDeleting(true);
    try {
      if (deleteTarget) {
        // Single delete - delete from vehicle_options
        await adminApi.deleteEngine(deleteTarget.id.toString());
        toast.success('Configuration deleted');
      } else {
        // Bulk delete
        const idsToDelete = Array.from(selectedIds);
        await Promise.all(
          idsToDelete.map((id) => adminApi.deleteEngine(id.toString()))
        );
        toast.success(`${idsToDelete.length} configurations deleted`);
        setSelectedIds(new Set());
      }
      setDeleteDialogOpen(false);
      setDeleteTarget(null);
      refetch();
    } catch (error) {
      toast.error('Failed to delete configuration(s)');
    } finally {
      setDeleting(false);
    }
  }, [deleteTarget, selectedIds, refetch]);

  // Import handlers
  const handleImportClick = useCallback(() => {
    fileInputRef.current?.click();
  }, []);

  const handleFileSelect = useCallback(
    async (event: React.ChangeEvent<HTMLInputElement>) => {
      const file = event.target.files?.[0];
      if (!file) return;

      try {
        const result = await importPreviewMutation.mutateAsync(file);
        setImportPreview(result);
        setImportDialogOpen(true);
      } catch (error) {
        // Error is handled by mutation
      }

      // Reset file input
      if (fileInputRef.current) {
        fileInputRef.current.value = '';
      }
    },
    [importPreviewMutation]
  );

  const handleImportConfirm = useCallback(async () => {
    if (!importPreview?.previewId) return;

    try {
      const result = await importApplyMutation.mutateAsync(importPreview.previewId);
      setImportResult(result);

      if (result.errors.length > 0) {
        toast.error(
          `Import completed with ${result.errors.length} error(s): ${result.created} created, ${result.updated} updated`
        );
        // Keep dialog open for error review
      } else {
        toast.success(
          `Import completed successfully: ${result.created} created, ${result.updated} updated`
        );
        // Auto-close on complete success
        setImportDialogOpen(false);
        setImportPreview(null);
        setImportResult(null);
      }

      refetch();
    } catch (error) {
      // Error is handled by mutation's onError
    }
  }, [importPreview, importApplyMutation, refetch]);

  const handleImportDialogClose = useCallback(() => {
    if (importApplyMutation.isPending) return;
    setImportDialogOpen(false);
    setImportPreview(null);
    setImportResult(null);
    setErrorsExpanded(false);
  }, [importApplyMutation.isPending]);

  // Export handler
  const handleExport = useCallback(() => {
    exportMutation.mutate();
  }, [exportMutation]);

  // Auth loading
  if (authLoading) {
    return (
      <Box
        sx={{
          display: 'flex',
          justifyContent: 'center',
          alignItems: 'center',
          minHeight: '60vh',
        }}
      >
        <CircularProgress />
      </Box>
    );
  }

  // Not admin
  if (!isAdmin) {
    return <Navigate to="/garage/settings" replace />;
  }

  const items = searchData?.items || [];
  const total = searchData?.total || 0;
  const hasResults = searchQuery.length > 0 && items.length > 0;
  const noResults = searchQuery.length > 0 && items.length === 0 && !searchLoading;

  return (
    <Box sx={{ py: 2, display: 'flex', flexDirection: 'column', gap: 3 }}>
      <AdminSectionHeader
        title="Vehicle Catalog"
        stats={[{ label: 'Total Results', value: total }]}
      />

      {/* Search and Actions Bar */}
      <Paper elevation={1} sx={{ p: 2, borderRadius: 1.5 }}>
        <Box
          sx={{
            display: 'flex',
            flexDirection: { xs: 'column', md: 'row' },
            gap: 2,
            alignItems: { xs: 'stretch', md: 'center' },
          }}
        >
          {/* Search Input */}
          <TextField
            placeholder="Search vehicles (e.g., 2024 Toyota Camry)"
            value={searchInput}
            onChange={(e) => setSearchInput(e.target.value)}
            onKeyPress={handleSearchKeyPress}
            fullWidth
            sx={{ flex: 1 }}
            InputProps={{
              startAdornment: (
                <InputAdornment position="start">
                  <Search color="action" />
                </InputAdornment>
              ),
              endAdornment: searchInput && (
                <InputAdornment position="end">
                  <IconButton size="small" onClick={handleClearSearch}>
                    <Clear />
                  </IconButton>
                </InputAdornment>
              ),
            }}
          />

          {/* Search Button */}
          <Button
            variant="contained"
            onClick={handleSearch}
            disabled={searchLoading || !searchInput.trim()}
            sx={{ textTransform: 'none', minWidth: 100 }}
          >
            {searchLoading ? <CircularProgress size={20} /> : 'Search'}
          </Button>

          {/* Action Buttons */}
          <Box sx={{ display: 'flex', gap: 1 }}>
            <Tooltip title="Import CSV">
              <Button
                variant="outlined"
                onClick={handleImportClick}
                startIcon={<FileUpload />}
                sx={{ textTransform: 'none' }}
              >
                Import
              </Button>
            </Tooltip>
            <Tooltip title="Export CSV">
              <Button
                variant="outlined"
                onClick={handleExport}
                disabled={exportMutation.isPending}
                startIcon={<FileDownload />}
                sx={{ textTransform: 'none' }}
              >
                Export
              </Button>
            </Tooltip>
          </Box>
        </Box>

        {/* Hidden file input for import */}
        <input
          type="file"
          ref={fileInputRef}
          onChange={handleFileSelect}
          accept=".csv"
          style={{ display: 'none' }}
        />
      </Paper>

      {/* Instructions when no search */}
      {!searchQuery && (
        <Paper elevation={1} sx={{ p: 4, borderRadius: 1.5, textAlign: 'center' }}>
          <Typography variant="h6" color="text.secondary" gutterBottom>
            Search for Vehicles
          </Typography>
          <Typography variant="body2" color="text.secondary">
            Enter a search term like "2024 Toyota Camry" or "Honda Civic" to find vehicles in the
            catalog.
          </Typography>
          <Typography variant="body2" color="text.secondary" sx={{ mt: 2 }}>
            Use Import/Export buttons to manage catalog data in bulk via CSV files.
          </Typography>
        </Paper>
      )}

      {/* No Results */}
      {noResults && (
        <Paper elevation={1} sx={{ p: 4, borderRadius: 1.5, textAlign: 'center' }}>
          <Typography variant="h6" color="text.secondary" gutterBottom>
            No Results Found
          </Typography>
          <Typography variant="body2" color="text.secondary">
            No vehicles match "{searchQuery}". Try a different search term.
          </Typography>
        </Paper>
      )}

      {/* Results Table */}
      {hasResults && (
        <Paper elevation={1} sx={{ borderRadius: 1.5 }}>
          {/* Bulk Actions */}
          {selectedIds.size > 0 && (
            <Box sx={{ p: 2, borderBottom: 1, borderColor: 'divider' }}>
              <Button
                variant="outlined"
                color="error"
                startIcon={<Delete />}
                onClick={handleBulkDeleteClick}
                sx={{ textTransform: 'none' }}
              >
                Delete Selected ({selectedIds.size})
              </Button>
            </Box>
          )}

          <TableContainer>
            <Table>
              <TableHead>
                <TableRow>
                  <TableCell padding="checkbox">
                    <Checkbox
                      indeterminate={selectedIds.size > 0 && selectedIds.size < items.length}
                      checked={selectedIds.size === items.length && items.length > 0}
                      onChange={handleSelectAll}
                      size="small"
                    />
                  </TableCell>
                  <TableCell>Year</TableCell>
                  <TableCell>Make</TableCell>
                  <TableCell>Model</TableCell>
                  <TableCell>Trim</TableCell>
                  <TableCell>Engine</TableCell>
                  <TableCell>Transmission</TableCell>
                  <TableCell align="right">Actions</TableCell>
                </TableRow>
              </TableHead>
              <TableBody>
                {items.map((row) => (
                  <TableRow
                    key={row.id}
                    hover
                    selected={selectedIds.has(row.id)}
                  >
                    <TableCell padding="checkbox">
                      <Checkbox
                        checked={selectedIds.has(row.id)}
                        onChange={() => handleSelectRow(row.id)}
                        size="small"
                      />
                    </TableCell>
                    <TableCell>{row.year}</TableCell>
                    <TableCell>{row.make}</TableCell>
                    <TableCell>{row.model}</TableCell>
                    <TableCell>{row.trim}</TableCell>
                    <TableCell>{row.engineName || '-'}</TableCell>
                    <TableCell>{row.transmissionType || '-'}</TableCell>
                    <TableCell align="right">
                      <Tooltip title="Delete">
                        <IconButton
                          size="small"
                          color="error"
                          onClick={() => handleDeleteClick(row)}
                        >
                          <Delete fontSize="small" />
                        </IconButton>
                      </Tooltip>
                    </TableCell>
                  </TableRow>
                ))}
              </TableBody>
            </Table>
          </TableContainer>

          <TablePagination
            component="div"
            count={total}
            page={page}
            onPageChange={handlePageChange}
            rowsPerPage={pageSize}
            onRowsPerPageChange={handlePageSizeChange}
            rowsPerPageOptions={PAGE_SIZE_OPTIONS}
          />
        </Paper>
      )}

      {/* Delete Confirmation Dialog */}
      <Dialog open={deleteDialogOpen} onClose={() => !deleting && setDeleteDialogOpen(false)}>
        <DialogTitle>
          {deleteTarget
            ? 'Delete Configuration'
            : `Delete ${selectedIds.size} Configuration${selectedIds.size > 1 ? 's' : ''}`}
        </DialogTitle>
        <DialogContent>
          {deleteTarget ? (
            <Typography>
              Are you sure you want to delete the configuration for{' '}
              <strong>
                {deleteTarget.year} {deleteTarget.make} {deleteTarget.model} {deleteTarget.trim}
              </strong>
              ?
            </Typography>
          ) : (
            <Typography>
              Are you sure you want to delete {selectedIds.size} selected configuration
              {selectedIds.size > 1 ? 's' : ''}?
            </Typography>
          )}
        </DialogContent>
        <DialogActions>
          <Button
            onClick={() => setDeleteDialogOpen(false)}
            disabled={deleting}
            sx={{ textTransform: 'none' }}
          >
            Cancel
          </Button>
          <Button
            onClick={handleDeleteConfirm}
            disabled={deleting}
            color="error"
            variant="contained"
            sx={{ textTransform: 'none' }}
          >
            {deleting ? <CircularProgress size={20} /> : 'Delete'}
          </Button>
        </DialogActions>
      </Dialog>

      {/* Import Preview/Results Dialog */}
      <Dialog
        open={importDialogOpen}
        onClose={handleImportDialogClose}
        maxWidth="md"
        fullWidth
      >
        <DialogTitle>
          {importResult ? 'Import Results' : 'Import Preview'}
        </DialogTitle>
        <DialogContent>
          {/* Preview Mode */}
          {importPreview && !importResult && (
            <Box sx={{ display: 'flex', flexDirection: 'column', gap: 2, mt: 1 }}>
              <Box sx={{ display: 'flex', gap: 3 }}>
                <Typography>
                  <strong>To Create:</strong> {importPreview.toCreate.length}
                </Typography>
                <Typography>
                  <strong>To Update:</strong> {importPreview.toUpdate.length}
                </Typography>
              </Box>

              {importPreview.errors.length > 0 && (
                <Alert severity="error">
                  <Typography variant="subtitle2" gutterBottom>
                    {importPreview.errors.length} Error(s) Found:
                  </Typography>
                  <Box component="ul" sx={{ m: 0, pl: 2 }}>
                    {importPreview.errors.slice(0, 10).map((err, idx) => (
                      <li key={idx}>
                        Row {err.row}: {err.error}
                      </li>
                    ))}
                    {importPreview.errors.length > 10 && (
                      <li>...and {importPreview.errors.length - 10} more errors</li>
                    )}
                  </Box>
                </Alert>
              )}

              {importPreview.valid ? (
                <Alert severity="success">
                  The import file is valid and ready to be applied.
                </Alert>
              ) : (
                <Alert severity="warning">
                  Please fix the errors above before importing.
                </Alert>
              )}
            </Box>
          )}

          {/* Results Mode */}
          {importResult && (
            <Box sx={{ display: 'flex', flexDirection: 'column', gap: 2, mt: 1 }}>
              <Box sx={{ display: 'flex', gap: 3 }}>
                <Typography>
                  <strong>Created:</strong> {importResult.created}
                </Typography>
                <Typography>
                  <strong>Updated:</strong> {importResult.updated}
                </Typography>
              </Box>

              {importResult.errors.length > 0 && (
                <Box sx={{ border: 1, borderColor: 'error.main', borderRadius: 1 }}>
                  <Box
                    onClick={() => setErrorsExpanded(!errorsExpanded)}
                    sx={{
                      display: 'flex',
                      justifyContent: 'space-between',
                      alignItems: 'center',
                      p: 2,
                      bgcolor: 'error.light',
                      cursor: 'pointer',
                      '&:hover': { bgcolor: 'error.main', color: 'white' },
                    }}
                  >
                    <Typography variant="subtitle2" sx={{ fontWeight: 600 }}>
                      {importResult.errors.length} Error(s) Occurred
                    </Typography>
                    <IconButton size="small" sx={{ color: 'inherit' }}>
                      {errorsExpanded ? <ExpandLess /> : <ExpandMore />}
                    </IconButton>
                  </Box>

                  <Collapse in={errorsExpanded}>
                    <Box sx={{ maxHeight: 400, overflow: 'auto', p: 2, bgcolor: 'background.paper' }}>
                      <Box component="ul" sx={{ m: 0, pl: 2 }}>
                        {importResult.errors.map((err, idx) => (
                          <Typography
                            component="li"
                            key={idx}
                            variant="body2"
                            sx={{ mb: 1, fontFamily: 'monospace', fontSize: '0.875rem' }}
                          >
                            <strong>Row {err.row}:</strong> {err.error}
                          </Typography>
                        ))}
                      </Box>
                    </Box>
                  </Collapse>
                </Box>
              )}

              {importResult.errors.length === 0 && (
                <Alert severity="success">
                  Import completed successfully with no errors.
                </Alert>
              )}
            </Box>
          )}
        </DialogContent>
        <DialogActions>
          <Button
            onClick={handleImportDialogClose}
            disabled={importApplyMutation.isPending}
            sx={{ textTransform: 'none' }}
          >
            {importResult ? 'Close' : 'Cancel'}
          </Button>
          {!importResult && (
            <Button
              onClick={handleImportConfirm}
              disabled={!importPreview?.valid || importApplyMutation.isPending}
              variant="contained"
              sx={{ textTransform: 'none' }}
            >
              {importApplyMutation.isPending ? <CircularProgress size={20} /> : 'Apply Import'}
            </Button>
          )}
        </DialogActions>
      </Dialog>
    </Box>
  );
};