'use client';

import { useMemo, useState } from 'react';
import { Upload } from 'lucide-react';
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogDescription, DialogFooter } from '@/components/ui/dialog';
import { Button } from '@/components/ui/button';
import { Label } from '@/components/ui/label';
import { RadioGroup, RadioGroupItem } from '@/components/ui/radio-group';
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from '@/components/ui/table';
import { toast } from '@/components/ui/toast';
import { plannedTabsApi } from '@/lib/api/client';
import { useLang } from '@/lib/i18n';
import { buildPreview, columnLabel, detectMapping, readSheet, type ColumnMapping, type SheetData } from '@/lib/customer-import';

const PREVIEW_ROWS = 8;

const selectClassName =
  'flex h-9 w-full rounded-md border border-input bg-background px-3 py-1 text-sm shadow-sm focus-visible:outline-none focus-visible:ring-1 focus-visible:ring-ring';

interface Props {
  venueId: string;
  open: boolean;
  onOpenChange: (open: boolean) => void;
  onImported: () => void;
}

export function ImportCustomersDialog({ venueId, open, onOpenChange, onImported }: Props) {
  const { t } = useLang();
  const [fileName, setFileName] = useState<string | null>(null);
  const [sheet, setSheet] = useState<SheetData | null>(null);
  const [mapping, setMapping] = useState<ColumnMapping | null>(null);
  const [mode, setMode] = useState<'merge' | 'replace'>('merge');
  const [submitting, setSubmitting] = useState(false);

  const preview = useMemo(() => (sheet && mapping ? buildPreview(sheet, mapping) : null), [sheet, mapping]);

  function reset() {
    setFileName(null);
    setSheet(null);
    setMapping(null);
    setMode('merge');
  }

  function handleOpenChange(next: boolean) {
    if (!next) reset();
    onOpenChange(next);
  }

  async function handleFile(file: File | undefined) {
    if (!file) return;
    try {
      const data = await readSheet(file);
      if (data.rows.length === 0) {
        toast({ title: t('import.failed'), description: t('import.empty_file'), variant: 'destructive' });
        return;
      }
      setFileName(file.name);
      setSheet(data);
      setMapping(detectMapping(data));
    } catch {
      toast({ title: t('import.failed'), description: t('import.unreadable'), variant: 'destructive' });
    }
  }

  async function submit() {
    if (!preview || preview.entries.length === 0) return;
    setSubmitting(true);
    try {
      const result = await plannedTabsApi.import(venueId, preview.entries, mode);
      toast({ title: t('import.done'), description: t('import.result', result), variant: 'success' });
      onImported();
      handleOpenChange(false);
    } catch (err: any) {
      toast({ title: t('import.failed'), description: err.message, variant: 'destructive' });
    } finally {
      setSubmitting(false);
    }
  }

  const header = sheet && mapping?.hasHeader ? sheet.rows[0] : null;
  const columnOptions = sheet
    ? Array.from({ length: sheet.columnCount }, (_, i) => ({
        value: i,
        label: header?.[i] ? `${columnLabel(i)} – ${header[i]}` : columnLabel(i),
      }))
    : [];

  function columnSelect(value: number | null, onChange: (value: number | null) => void, optional: boolean) {
    return (
      <select
        className={selectClassName}
        value={value ?? ''}
        onChange={(e) => onChange(e.target.value === '' ? null : Number(e.target.value))}
      >
        {optional && <option value="">{t('import.column_none')}</option>}
        {columnOptions.map((c) => (
          <option key={c.value} value={c.value}>{c.label}</option>
        ))}
      </select>
    );
  }

  return (
    <Dialog open={open} onOpenChange={handleOpenChange}>
      <DialogContent className="max-w-2xl max-h-[90vh] overflow-y-auto">
        <DialogHeader>
          <DialogTitle>{t('import.title')}</DialogTitle>
          <DialogDescription>{t('import.description')}</DialogDescription>
        </DialogHeader>

        <div className="space-y-5">
          <label className="flex flex-col items-center justify-center gap-2 rounded-md border border-dashed p-6 text-sm cursor-pointer hover:bg-accent">
            <Upload className="h-5 w-5 text-muted-foreground" />
            <span>{fileName ?? t('import.choose_file')}</span>
            <span className="text-xs text-muted-foreground">.xlsx, .xls, .csv</span>
            <input
              type="file"
              accept=".xlsx,.xls,.csv"
              className="sr-only"
              onChange={(e) => {
                handleFile(e.target.files?.[0]);
                e.target.value = '';
              }}
            />
          </label>

          {sheet && mapping && preview && (
            <>
              <div className="grid gap-3 sm:grid-cols-3">
                <div className="space-y-1">
                  <Label>{t('import.name_column')}</Label>
                  {columnSelect(mapping.nameColumn, (v) => setMapping({ ...mapping, nameColumn: v ?? 0 }), false)}
                </div>
                <div className="space-y-1">
                  <Label>{t('import.last_name_column')}</Label>
                  {columnSelect(mapping.lastNameColumn, (v) => setMapping({ ...mapping, lastNameColumn: v }), true)}
                </div>
                <div className="space-y-1">
                  <Label>{t('import.email_column')}</Label>
                  {columnSelect(mapping.emailColumn, (v) => setMapping({ ...mapping, emailColumn: v }), true)}
                </div>
              </div>

              <label className="flex items-center gap-2 text-sm">
                <input
                  type="checkbox"
                  checked={mapping.hasHeader}
                  onChange={(e) => setMapping({ ...mapping, hasHeader: e.target.checked })}
                />
                {t('import.has_header')}
              </label>

              <div className="space-y-2">
                <p className="text-sm">
                  {t('import.summary', {
                    count: preview.entries.length,
                    emails: preview.entries.filter((e) => e.email).length,
                  })}
                </p>
                {(preview.skippedRows > 0 || preview.invalidEmails > 0) && (
                  <p className="text-xs text-muted-foreground">
                    {t('import.warnings', { skipped: preview.skippedRows, invalid: preview.invalidEmails })}
                  </p>
                )}
                <div className="rounded-md border">
                  <Table>
                    <TableHeader>
                      <TableRow>
                        <TableHead>{t('tabs.customer')}</TableHead>
                        <TableHead>{t('import.email')}</TableHead>
                      </TableRow>
                    </TableHeader>
                    <TableBody>
                      {preview.entries.slice(0, PREVIEW_ROWS).map((entry, i) => (
                        <TableRow key={i}>
                          <TableCell className="font-medium">{entry.customerName}</TableCell>
                          <TableCell className="text-muted-foreground">{entry.email ?? '—'}</TableCell>
                        </TableRow>
                      ))}
                    </TableBody>
                  </Table>
                </div>
                {preview.entries.length > PREVIEW_ROWS && (
                  <p className="text-xs text-muted-foreground">
                    {t('import.more', { count: preview.entries.length - PREVIEW_ROWS })}
                  </p>
                )}
              </div>

              <div className="space-y-2">
                <Label className="text-base font-semibold">{t('import.mode')}</Label>
                <RadioGroup value={mode} onValueChange={(v) => setMode(v as 'merge' | 'replace')}>
                  <div className="flex items-start space-x-2">
                    <RadioGroupItem value="merge" id="import-merge" className="mt-0.5" />
                    <Label htmlFor="import-merge" className="font-normal">{t('import.mode_merge')}</Label>
                  </div>
                  <div className="flex items-start space-x-2">
                    <RadioGroupItem value="replace" id="import-replace" className="mt-0.5" />
                    <Label htmlFor="import-replace" className="font-normal">{t('import.mode_replace')}</Label>
                  </div>
                </RadioGroup>
              </div>
            </>
          )}
        </div>

        <DialogFooter>
          <Button variant="outline" onClick={() => handleOpenChange(false)} disabled={submitting}>
            {t('tabs.cancel')}
          </Button>
          <Button onClick={submit} disabled={submitting || !preview || preview.entries.length === 0}>
            {submitting ? t('import.importing') : t('import.submit', { count: preview?.entries.length ?? 0 })}
          </Button>
        </DialogFooter>
      </DialogContent>
    </Dialog>
  );
}