BillTracker/client/pages/DataPage.jsx

import React, { useState, useEffect, useRef, useMemo } from 'react';
import { toast } from 'sonner';
import {
  Upload, FileSpreadsheet, Database, Download, CheckCircle2, XCircle,
  AlertTriangle, Loader2, RefreshCw, Clock, ChevronDown,
  ChevronUp, SkipForward, Plus, CheckCheck, Sparkles,
  List, Building2, ChevronLeft, FileText,
} from 'lucide-react';
import { api } from '@/api';
import { cn } from '@/lib/utils';
import { Button } from '@/components/ui/button';
import { Input } from '@/components/ui/input';
import { Switch } from '@/components/ui/switch';
import {
  AlertDialog,
  AlertDialogAction,
  AlertDialogCancel,
  AlertDialogContent,
  AlertDialogDescription,
  AlertDialogFooter,
  AlertDialogHeader,
  AlertDialogTitle,
  AlertDialogTrigger,
} from '@/components/ui/alert-dialog';

// ─── User export availability flag ───────────────────────────────────────────
// Flip to true when GET /api/export/user-db and GET /api/export/user-excel exist.
const USER_EXPORTS_AVAILABLE = true;

// ─── Utilities ────────────────────────────────────────────────────────────────

function fmt(isoStr) {
  if (!isoStr) return '—';
  const d = new Date(isoStr);
  return d.toLocaleDateString(undefined, { month: 'short', day: 'numeric', year: 'numeric' })
    + ' ' + d.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' });
}

function groupRowsBySheet(rows) {
  const map = new Map();
  for (const row of rows) {
    const key = row.sheet_name || '(unknown sheet)';
    if (!map.has(key)) map.set(key, []);
    map.get(key).push(row);
  }
  return Array.from(map.entries()).map(([name, rows]) => ({ name, rows }));
}

function initialDecisionFromRecommendation(row) {
  const rec = row.recommendation || {};
  const action = rec.action === 'ambiguous' ? null : (rec.action || row.proposed_action || null);

  if (!action || row.requires_user_decision) return { action: null };
  if (action === 'skip_row') return { action: 'skip_row' };
  if (action === 'match_existing_bill') {
    return {
      action,
      bill_id: rec.bill_id ?? row.possible_bill_matches?.[0]?.bill_id ?? null,
      bill_name: null,
      due_day: rec.due_day ?? null,
      actual_amount: rec.actual_amount ?? row.detected_amount ?? null,
      payment_amount: rec.payment_amount ?? row.detected_payment_amount ?? null,
      payment_date: rec.payment_date ?? row.detected_paid_date ?? null,
      notes: row.detected_notes ?? null,
    };
  }
  if (action === 'create_new_bill') {
    return {
      action,
      bill_id: null,
      bill_name: rec.bill_name || row.detected_bill_name || '',
      category_id: rec.category_id ?? null,
      due_day: rec.due_day ?? null,
      expected_amount: rec.expected_amount ?? row.detected_amount ?? null,
      actual_amount: rec.actual_amount ?? row.detected_amount ?? null,
      payment_amount: rec.payment_amount ?? row.detected_payment_amount ?? null,
      payment_date: rec.payment_date ?? row.detected_paid_date ?? null,
      notes: row.detected_notes ?? null,
    };
  }
  return { action };
}

function safeRawBillName(row) {
  const raw = row.raw_values?.find((v) => {
    const text = String(v || '').trim();
    if (!text || text.length > 80) return false;
    if (/^(?:total|subtotal|sum|grand\s*total)$/i.test(text)) return false;
    if (/^\$?\(?\d[\d,]*(?:\.\d{1,2})?\)?$/.test(text)) return false;
    if (/^\d{1,2}\/\d{1,2}(?:\/\d{2,4})?$/.test(text)) return false;
    if (/^\d{4}-\d{2}-\d{2}$/.test(text)) return false;
    return true;
  });
  return raw ? String(raw).trim() : '';
}

function buildCreateNewDecision(row, currentDecision = {}) {
  const rec = row.recommendation || {};
  const billName = currentDecision.bill_name
    || row.detected_bill_name
    || rec.bill_name
    || safeRawBillName(row);

  return {
    ...currentDecision,
    action: 'create_new_bill',
    previous_match_bill_id: currentDecision.bill_id ?? currentDecision.previous_match_bill_id ?? rec.bill_id ?? row.possible_bill_matches?.[0]?.bill_id ?? null,
    bill_id: null,
    bill_name: billName,
    category_id: currentDecision.category_id ?? rec.category_id ?? null,
    due_day: currentDecision.due_day ?? rec.due_day ?? null,
    expected_amount: currentDecision.expected_amount ?? rec.expected_amount ?? row.detected_amount ?? null,
    actual_amount: currentDecision.actual_amount ?? rec.actual_amount ?? row.detected_amount ?? null,
    payment_amount: currentDecision.payment_amount ?? rec.payment_amount ?? row.detected_payment_amount ?? null,
    payment_date: currentDecision.payment_date ?? rec.payment_date ?? row.detected_paid_date ?? null,
    notes: currentDecision.notes ?? row.detected_notes ?? null,
  };
}

function buildInitialDecisions(rows) {
  const d = {};
  for (const row of rows) {
    const hasError = row.errors?.length > 0;
    if (hasError || row.proposed_action === 'skip_row') {
      d[row.row_id] = { action: 'skip_row' };
    } else {
      d[row.row_id] = initialDecisionFromRecommendation(row);
    }
  }
  return d;
}

function isDecisionComplete(action, decision) {
  if (!action) return false;
  if (action === 'skip_row') return true;
  if (action === 'create_new_bill') return !!(decision?.bill_name?.trim());
  if (['match_existing_bill', 'update_monthly_state', 'add_monthly_note', 'create_payment'].includes(action)) {
    return !!decision?.bill_id;
  }
  return true;
}

// ─── Badges ───────────────────────────────────────────────────────────────────

function SourceBadge({ source }) {
  const MAP = {
    row_date:   'bg-emerald-500/15 text-emerald-600 dark:text-emerald-400',
    sheet_name: 'bg-blue-500/15 text-blue-600 dark:text-blue-400',
    default:    'bg-amber-500/15 text-amber-600 dark:text-amber-500',
    ambiguous:  'bg-red-500/15 text-red-600 dark:text-red-400',
  };
  const LABELS = { row_date: 'date cell', sheet_name: 'tab name', default: 'default', ambiguous: 'ambiguous' };
  return (
    <span className={cn('inline-flex items-center rounded-full px-1.5 py-0.5 text-[10px] font-medium', MAP[source] ?? MAP.ambiguous)}>
      {LABELS[source] ?? source}
    </span>
  );
}

function ConfidenceBadge({ confidence }) {
  const MAP = { high: 'text-emerald-600 dark:text-emerald-400', medium: 'text-amber-600 dark:text-amber-500', low: 'text-red-500' };
  return <span className={cn('text-[10px] font-semibold uppercase', MAP[confidence] ?? '')}>{confidence}</span>;
}

function actionLabel(action) {
  const MAP = {
    match_existing_bill: 'Match existing bill',
    create_new_bill: 'Create new bill',
    skip_row: 'Skip row',
    ambiguous: 'Needs decision',
    update_monthly_state: 'Update monthly record',
    add_monthly_note: 'Add monthly note',
    create_payment: 'Record as payment',
  };
  return MAP[action] || (action ? action.replace(/_/g, ' ') : 'Needs decision');
}

function importErrorState(err, fallback) {
  const data = err?.data || {};
  return {
    message: err?.message || data.message || data.error || fallback,
    error: data.error || fallback,
    code: data.code || err?.code || null,
    details: Array.isArray(data.details) ? data.details : (Array.isArray(err?.details) ? err.details : []),
    error_id: data.error_id || null,
  };
}

function SheetStatusBadge({ status }) {
  const MAP = {
    parsed:            'bg-emerald-500/15 text-emerald-600',
    parsed_month_only: 'bg-amber-500/15 text-amber-600',
    ambiguous:         'bg-orange-500/15 text-orange-600',
    skipped:           'bg-muted text-muted-foreground',
  };
  const LABELS = {
    parsed: 'parsed', parsed_month_only: 'month only', ambiguous: 'ambiguous', skipped: 'skipped',
  };
  return (
    <span className={cn('inline-flex items-center rounded-full px-2 py-0.5 text-[10px] font-medium', MAP[status] ?? MAP.ambiguous)}>
      {LABELS[status] ?? status}
    </span>
  );
}

// ─── Shared SectionCard ───────────────────────────────────────────────────────

function SectionCard({ title, subtitle, children, className }) {
  return (
    <div className={cn('table-surface mb-6', className)}>
      <div className="px-6 py-4 border-b border-border/50">
        <h2 className="text-xs font-bold uppercase tracking-widest text-muted-foreground">{title}</h2>
        {subtitle && <p className="text-sm text-muted-foreground mt-1">{subtitle}</p>}
      </div>
      <div className="divide-y divide-border/50">{children}</div>
    </div>
  );
}

// ─── Section 2: Download My Data ─────────────────────────────────────────────

function ExportCard({ icon: Icon, title, description, filename, endpoint }) {
  const [loading, setLoading] = useState(false);

  const handleDownload = async () => {
    setLoading(true);
    try {
      const res = await fetch(endpoint, { credentials: 'include' });
      if (!res.ok) {
        let data = {};
        try { data = await res.json(); } catch {}
        throw new Error(data.error || `HTTP ${res.status}`);
      }
      const disposition = res.headers.get('Content-Disposition');
      const match = disposition?.match(/filename="?([^"]+)"?/i);
      const name = match ? match[1] : filename;
      const blob = await res.blob();
      const url = URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url; a.download = name; a.click();
      URL.revokeObjectURL(url);
      toast.success(`${title} downloaded.`);
    } catch (err) {
      toast.error(err.message || 'Download failed.');
    } finally {
      setLoading(false);
    }
  };

  const disabled = !USER_EXPORTS_AVAILABLE || loading;
  return (
    <div className="px-6 py-5 flex items-start justify-between gap-6">
      <div className="flex items-start gap-4 flex-1 min-w-0">
        <div className="mt-0.5 h-9 w-9 rounded-lg bg-primary/10 flex items-center justify-center shrink-0">
          <Icon className="h-5 w-5 text-primary" />
        </div>
        <div className="flex-1 min-w-0">
          <div className="flex items-center gap-2 mb-0.5 flex-wrap">
            <p className="text-sm font-medium">{title}</p>
            {!USER_EXPORTS_AVAILABLE && (
              <span className="inline-flex items-center rounded-full bg-muted border border-border px-2 py-0.5 text-[10px] font-medium text-muted-foreground">
                Coming soon
              </span>
            )}
          </div>
          <p className="text-xs text-muted-foreground">{description}</p>
        </div>
      </div>
      <div className="shrink-0 pt-0.5">
        <Button size="sm" variant="outline" disabled={disabled}
          onClick={USER_EXPORTS_AVAILABLE ? handleDownload : undefined}>
          {loading ? <><Loader2 className="h-3.5 w-3.5 mr-1.5 animate-spin" />Downloading…</>
            : <><Download className="h-3.5 w-3.5 mr-1.5" />{USER_EXPORTS_AVAILABLE ? 'Download' : 'Not Available Yet'}</>}
        </Button>
      </div>
    </div>
  );
}

export function DownloadMyDataSection() {
  return (
    <SectionCard
      title="Download My Data"
      subtitle="Export your bill tracker data for your own records. These exports include only your data — not a full system backup."
    >
      <ExportCard icon={Database} title="SQLite Data Export"
        description="Download a portable SQLite database containing your bill tracker data."
        filename="bill-tracker-user-export.sqlite" endpoint="/api/export/user-db" />
      <ExportCard icon={FileSpreadsheet} title="Excel Databook"
        description="Download an Excel workbook with sheets for bills, payments, categories, monthly state, and summary data."
        filename="bill-tracker-databook.xlsx" endpoint="/api/export/user-excel" />
      <div className="px-6 py-3 rounded-md bg-amber-50 dark:bg-amber-950/30 border border-amber-200 dark:border-amber-800/40 flex items-start gap-2.5 mx-6 mt-2">
        <AlertTriangle className="h-4 w-4 text-amber-600 dark:text-amber-400 shrink-0 mt-0.5" />
        <p className="text-xs text-amber-700 dark:text-amber-300">Exports may contain sensitive account metadata (website URLs, usernames, account info). Store exported files securely and avoid sharing them unencrypted.</p>
      </div>
      <div className="px-6 py-5 grid grid-cols-1 sm:grid-cols-2 gap-3">
        <div className="rounded-lg bg-muted/40 border border-border/60 p-4">
          <p className="text-[10px] font-bold uppercase tracking-widest text-muted-foreground mb-2.5">What's included</p>
          <ul className="space-y-1.5">
            {['Bills','Payments','Categories','Monthly bill state','Monthly starting amounts','History ranges','Notes','Export metadata'].map(i => (
              <li key={i} className="flex items-center gap-2 text-xs text-foreground/80">
                <CheckCircle2 className="h-3.5 w-3.5 text-emerald-500 shrink-0" />{i}
              </li>
            ))}
          </ul>
        </div>
        <div className="rounded-lg bg-muted/40 border border-border/60 p-4">
          <p className="text-[10px] font-bold uppercase tracking-widest text-muted-foreground mb-2.5">What's not included</p>
          <ul className="space-y-1.5">
            {['Passwords','Sessions','Admin settings','Server configuration',"Other users' data",'Full system backup files'].map(i => (
              <li key={i} className="flex items-center gap-2 text-xs text-muted-foreground">
                <XCircle className="h-3.5 w-3.5 text-muted-foreground/40 shrink-0" />{i}
              </li>
            ))}
          </ul>
        </div>
      </div>
    </SectionCard>
  );
}

function CountPill({ label, value }) {
  return (
    <div className="rounded-lg border border-border/60 bg-muted/25 px-3 py-2">
      <p className="text-[10px] font-bold uppercase tracking-widest text-muted-foreground">{label}</p>
      <p className="mt-1 text-sm font-semibold tabular-nums">{value ?? 0}</p>
    </div>
  );
}

// ─── Section 1: Import Transaction CSV ───────────────────────────────────────

const CSV_MAPPING_FIELDS = [
  'posted_date',
  'amount',
  'debit_amount',
  'credit_amount',
  'description',
  'payee',
  'memo',
  'category',
  'account',
  'transaction_id',
  'transaction_type',
  'currency',
  'transacted_at',
];

function compactMapping(mapping) {
  return Object.fromEntries(
    Object.entries(mapping || {}).filter(([, value]) => value),
  );
}

function canCommitCsvMapping(mapping) {
  return !!mapping?.posted_date && !!(mapping.amount || mapping.debit_amount || mapping.credit_amount);
}

function CsvMappingSelect({ field, label, headers, mapping, onChange }) {
  const current = mapping[field] || '';
  const used = new Set(Object.entries(mapping)
    .filter(([key, value]) => key !== field && value)
    .map(([, value]) => value));

  return (
    <label className="space-y-1.5">
      <span className="flex items-center gap-1.5 text-xs font-medium text-muted-foreground">
        {label}
        {field === 'posted_date' && <span className="text-destructive">*</span>}
        {field === 'amount' && !mapping.debit_amount && !mapping.credit_amount && (
          <span className="text-destructive">*</span>
        )}
      </span>
      <select
        value={current}
        onChange={e => onChange(field, e.target.value)}
        className="h-9 w-full rounded-md border border-input bg-background px-2 text-sm focus:outline-none focus:ring-1 focus:ring-ring"
      >
        <option value="">Not mapped</option>
        {headers.map(header => (
          <option key={header} value={header} disabled={used.has(header)}>
            {header}
          </option>
        ))}
      </select>
    </label>
  );
}

function CsvSampleTable({ preview }) {
  const headers = preview?.headers || [];
  const sampleRows = preview?.sampleRows || [];
  const visibleHeaders = headers.slice(0, 8);
  const hiddenCount = Math.max(0, headers.length - visibleHeaders.length);

  if (sampleRows.length === 0) {
    return <p className="py-4 text-center text-sm text-muted-foreground">No sample rows found.</p>;
  }

  return (
    <div className="overflow-x-auto rounded-lg border border-border/60">
      <table className="w-full text-xs">
        <thead>
          <tr className="border-b border-border/50 bg-muted/40 text-muted-foreground">
            {visibleHeaders.map(header => (
              <th key={header} className="px-3 py-2 text-left font-medium whitespace-nowrap">{header}</th>
            ))}
            {hiddenCount > 0 && (
              <th className="px-3 py-2 text-left font-medium whitespace-nowrap">+{hiddenCount}</th>
            )}
          </tr>
        </thead>
        <tbody className="divide-y divide-border/30">
          {sampleRows.map((row, index) => (
            <tr key={index} className="hover:bg-muted/20">
              {visibleHeaders.map(header => (
                <td key={header} className="max-w-48 truncate px-3 py-2 text-muted-foreground">
                  {row[header] || '—'}
                </td>
              ))}
              {hiddenCount > 0 && (
                <td className="px-3 py-2 text-muted-foreground">more columns</td>
              )}
            </tr>
          ))}
        </tbody>
      </table>
    </div>
  );
}

export function ImportTransactionCsvSection({ onHistoryRefresh }) {
  const fileRef = useRef(null);
  const [file, setFile] = useState(null);
  const [preview, setPreview] = useState({ status: 'idle', data: null, error: null });
  const [mapping, setMapping] = useState({});
  const [commitState, setCommitState] = useState({ status: 'idle', result: null, error: null });

  const reset = () => {
    setFile(null);
    setPreview({ status: 'idle', data: null, error: null });
    setMapping({});
    setCommitState({ status: 'idle', result: null, error: null });
    if (fileRef.current) fileRef.current.value = '';
  };

  const handleMappingChange = (field, header) => {
    setMapping(prev => {
      const next = { ...prev };
      if (header) next[field] = header;
      else delete next[field];
      return next;
    });
    setCommitState({ status: 'idle', result: null, error: null });
  };

  const handlePreview = async () => {
    if (!file) {
      toast.error('Choose a CSV file first.');
      return;
    }
    setPreview({ status: 'loading', data: null, error: null });
    setMapping({});
    setCommitState({ status: 'idle', result: null, error: null });
    try {
      const data = await api.previewCsvTransactionImport(file);
      setPreview({ status: 'ready', data, error: null });
      setMapping(compactMapping(data.suggestedMapping || {}));
      toast.success('CSV preview ready.');
    } catch (err) {
      const errorState = importErrorState(err, 'CSV preview failed.');
      setPreview({ status: 'error', data: null, error: errorState });
      toast.error(errorState.message || 'CSV preview failed.');
    }
  };

  const handleCommit = async () => {
    if (!preview.data?.import_session_id || !canCommitCsvMapping(mapping)) return;
    setCommitState({ status: 'loading', result: null, error: null });
    try {
      const result = await api.commitCsvTransactionImport({
        import_session_id: preview.data.import_session_id,
        mapping: compactMapping(mapping),
      });
      setCommitState({ status: 'done', result, error: null });
      toast.success(`CSV imported — ${result.imported} imported, ${result.skipped} skipped.`);
      onHistoryRefresh?.();
    } catch (err) {
      const errorState = importErrorState(err, 'CSV import failed.');
      setCommitState({ status: 'error', result: null, error: errorState });
      toast.error(errorState.message || 'CSV import failed.');
    }
  };

  const fields = preview.data?.fields || {};
  const mappingFields = CSV_MAPPING_FIELDS.filter(field => fields[field]);
  const canCommit = preview.status === 'ready'
    && preview.data?.import_session_id
    && canCommitCsvMapping(mapping)
    && commitState.status !== 'loading'
    && commitState.status !== 'done';
  const failedRows = (commitState.result?.details || []).filter(d => d.result === 'failed').slice(0, 5);
  const skippedRows = (commitState.result?.details || []).filter(d => d.result === 'skipped_duplicate').slice(0, 5);

  return (
    <SectionCard
      title="Import Transaction CSV"
      subtitle="Upload a bank or credit-card CSV, map its columns, then save normalized transactions for matching later."
    >
      <div className="px-6 py-5 space-y-5">
        <div className="rounded-lg border border-border/60 bg-muted/25 p-4">
          <div className="flex items-start gap-3">
            <FileText className="mt-0.5 h-5 w-5 text-primary shrink-0" />
            <div>
              <p className="text-sm font-medium">Import transaction rows from CSV.</p>
              <p className="mt-1 text-xs text-muted-foreground">
                This importer creates shared transaction records only. It does not match transactions to bills yet.
              </p>
            </div>
          </div>
        </div>

        <div className="flex flex-col gap-3 sm:flex-row sm:items-end">
          <label className="flex-1 space-y-1.5">
            <span className="text-xs font-medium text-muted-foreground">CSV file</span>
            <Input
              ref={fileRef}
              type="file"
              accept=".csv,text/csv"
              onChange={e => {
                setFile(e.target.files?.[0] || null);
                setPreview({ status: 'idle', data: null, error: null });
                setMapping({});
                setCommitState({ status: 'idle', result: null, error: null });
              }}
            />
          </label>
          <div className="flex gap-2">
            <Button size="sm" variant="outline" type="button" onClick={reset}>
              Clear
            </Button>
            <Button size="sm" type="button" disabled={!file || preview.status === 'loading'} onClick={handlePreview}>
              {preview.status === 'loading'
                ? <><Loader2 className="h-3.5 w-3.5 mr-1.5 animate-spin" />Previewing…</>
                : <><Upload className="h-3.5 w-3.5 mr-1.5" />Preview</>}
            </Button>
          </div>
        </div>

        {preview.status === 'error' && (
          <div className="rounded-lg border border-destructive/30 bg-destructive/10 p-3 text-sm text-destructive">
            <AlertTriangle className="mr-1.5 inline h-4 w-4" />
            {preview.error?.message || 'CSV preview failed.'}
            {preview.error?.details?.length > 0 && (
              <ul className="mt-2 list-disc pl-5 text-xs">
                {preview.error.details.map((d, i) => (
                  <li key={i}>{d.message || JSON.stringify(d)}</li>
                ))}
              </ul>
            )}
          </div>
        )}

        {preview.status === 'ready' && preview.data && (
          <div className="space-y-5">
            <div className="flex flex-wrap gap-2">
              <CountPill label="Rows" value={preview.data.rowCount} />
              <CountPill label="Columns" value={preview.data.headers?.length || 0} />
              <CountPill label="Issues" value={preview.data.errors?.length || 0} />
            </div>

            {preview.data.errors?.length > 0 && (
              <div className="rounded-lg border border-amber-500/30 bg-amber-500/5 p-3">
                <p className="text-xs font-semibold uppercase tracking-widest text-amber-600 dark:text-amber-400">Review mapping</p>
                <ul className="mt-2 space-y-1 text-xs text-amber-700 dark:text-amber-300">
                  {preview.data.errors.map((issue, i) => (
                    <li key={i} className="flex items-start gap-1.5">
                      <AlertTriangle className="mt-0.5 h-3.5 w-3.5 shrink-0" />
                      <span>{issue.message || JSON.stringify(issue)}</span>
                    </li>
                  ))}
                </ul>
              </div>
            )}

            <div className="space-y-3">
              <div className="flex items-center justify-between gap-3">
                <p className="text-sm font-medium">Column mapping</p>
                <span className="text-xs text-muted-foreground">
                  Posted date and one amount mapping are required.
                </span>
              </div>
              <div className="grid gap-3 sm:grid-cols-2 lg:grid-cols-3">
                {mappingFields.map(field => (
                  <CsvMappingSelect
                    key={field}
                    field={field}
                    label={fields[field]}
                    headers={preview.data.headers || []}
                    mapping={mapping}
                    onChange={handleMappingChange}
                  />
                ))}
              </div>
              {!canCommitCsvMapping(mapping) && (
                <p className="text-xs text-destructive">
                  Map a posted date column and either amount, debit amount, or credit amount before importing.
                </p>
              )}
            </div>

            <div className="space-y-3">
              <p className="text-sm font-medium">Sample rows</p>
              <CsvSampleTable preview={preview.data} />
            </div>

            <div className="rounded-lg border border-border/60 bg-muted/25 px-4 py-3 flex items-center justify-between gap-3 flex-wrap">
              <p className="text-xs text-muted-foreground">
                Duplicate rows are skipped using a CSV transaction ID when available, otherwise a stable row hash.
              </p>
              {commitState.status === 'done' ? (
                <Button size="sm" variant="outline" type="button" onClick={reset}>
                  <Plus className="h-3.5 w-3.5 mr-1.5" />New CSV import
                </Button>
              ) : (
                <Button size="sm" type="button" disabled={!canCommit} onClick={handleCommit}>
                  {commitState.status === 'loading'
                    ? <><Loader2 className="h-3.5 w-3.5 mr-1.5 animate-spin" />Importing…</>
                    : <><CheckCheck className="h-3.5 w-3.5 mr-1.5" />Commit Import</>}
                </Button>
              )}
            </div>
          </div>
        )}

        {commitState.status === 'done' && commitState.result && (
          <div className="rounded-lg border border-emerald-500/30 bg-emerald-500/5 p-4">
            <div className="flex items-center gap-2">
              <CheckCircle2 className="h-5 w-5 text-emerald-500" />
              <p className="text-sm font-medium text-emerald-600">CSV transaction import complete</p>
            </div>
            <div className="mt-3 grid grid-cols-3 gap-2 text-xs">
              <CountPill label="Imported" value={commitState.result.imported} />
              <CountPill label="Skipped" value={commitState.result.skipped} />
              <CountPill label="Failed" value={commitState.result.failed} />
            </div>
            {skippedRows.length > 0 && (
              <div className="mt-3 text-xs text-muted-foreground">
                <p className="font-medium text-foreground">Skipped duplicates</p>
                <ul className="mt-1 space-y-0.5">
                  {skippedRows.map(row => (
                    <li key={row.row}>Row {row.row}: {row.provider_transaction_id}</li>
                  ))}
                </ul>
              </div>
            )}
            {failedRows.length > 0 && (
              <div className="mt-3 text-xs text-destructive">
                <p className="font-medium">Failed rows</p>
                <ul className="mt-1 space-y-0.5">
                  {failedRows.map(row => (
                    <li key={row.row}>Row {row.row}: {row.message}</li>
                  ))}
                </ul>
              </div>
            )}
          </div>
        )}

        {commitState.status === 'error' && (
          <div className="rounded-lg border border-destructive/30 bg-destructive/10 p-3 text-sm text-destructive">
            <AlertTriangle className="mr-1.5 inline h-4 w-4" />
            {commitState.error?.message || 'CSV import failed.'}
            {commitState.error?.details?.length > 0 && (
              <ul className="mt-2 list-disc pl-5 text-xs">
                {commitState.error.details.map((d, i) => (
                  <li key={i}>{d.message || JSON.stringify(d)}</li>
                ))}
              </ul>
            )}
          </div>
        )}
      </div>
    </SectionCard>
  );
}

// ─── Section 3: Import My Data Export ────────────────────────────────────────

export function ImportMyDataSection({ onHistoryRefresh }) {
  const fileRef = useRef(null);
  const [file, setFile] = useState(null);
  const [preview, setPreview] = useState({ status: 'idle', data: null, error: null });
  const [applyState, setApplyState] = useState({ status: 'idle', result: null, error: null });
  const [confirmOpen, setConfirmOpen] = useState(false);

  const reset = () => {
    setFile(null);
    setPreview({ status: 'idle', data: null, error: null });
    setApplyState({ status: 'idle', result: null, error: null });
    if (fileRef.current) fileRef.current.value = '';
  };

  const handlePreview = async () => {
    if (!file) {
      toast.error('Choose a SQLite data export first.');
      return;
    }
    setPreview({ status: 'loading', data: null, error: null });
    setApplyState({ status: 'idle', result: null, error: null });
    try {
      const data = await api.previewUserDbImport(file);
      setPreview({ status: 'ready', data, error: null });
      toast.success('SQLite export preview ready.');
    } catch (err) {
      setPreview({ status: 'error', data: null, error: importErrorState(err, 'SQLite import preview failed.') });
      toast.error(err.message || 'SQLite import preview failed.');
    }
  };

  const handleApply = () => {
    if (!preview.data?.import_session_id) return;
    setConfirmOpen(true);
  };

  const handleConfirmImport = async () => {
    setConfirmOpen(false);
    setApplyState({ status: 'loading', result: null, error: null });
    try {
      const result = await api.applyUserDbImport({
        import_session_id: preview.data.import_session_id,
        options: { overwrite: false },
      });
      setApplyState({ status: 'done', result, error: null });
      toast.success('SQLite data import applied.');
      onHistoryRefresh?.();
    } catch (err) {
      setApplyState({ status: 'error', result: null, error: importErrorState(err, 'SQLite import apply failed.') });
      toast.error(err.message || 'SQLite import apply failed.');
    }
  };

  const counts = preview.data?.counts || {};
  const summary = preview.data?.summary || {};

  return (
    <>
      <SectionCard title="Import My Data Export"
        subtitle="Restore data from a SQLite export created by this app for your account.">
      <div className="px-6 py-5">
        <div className="rounded-lg border border-border/60 bg-muted/25 p-4">
          <div className="flex items-start gap-3">
            <Database className="mt-0.5 h-5 w-5 text-primary shrink-0" />
            <div>
              <p className="text-sm font-medium">Import a SQLite data export created by this app.</p>
              <p className="mt-1 text-xs text-muted-foreground">
                This is not a full system restore. Existing records are skipped by default, and admin/system data is never imported.
              </p>
            </div>
          </div>
        </div>

        <div className="mt-4 flex flex-col gap-3 sm:flex-row sm:items-end">
          <label className="flex-1 space-y-1.5">
            <span className="text-xs font-medium text-muted-foreground">SQLite export file</span>
            <Input
              ref={fileRef}
              type="file"
              accept=".sqlite,.db,application/octet-stream,application/x-sqlite3,application/vnd.sqlite3"
              onChange={e => {
                setFile(e.target.files?.[0] || null);
                setPreview({ status: 'idle', data: null, error: null });
                setApplyState({ status: 'idle', result: null, error: null });
              }}
            />
          </label>
          <div className="flex gap-2">
            <Button size="sm" variant="outline" type="button" onClick={reset}>
              Clear
            </Button>
            <Button size="sm" type="button" disabled={!file || preview.status === 'loading'} onClick={handlePreview}>
              {preview.status === 'loading'
                ? <><Loader2 className="h-3.5 w-3.5 mr-1.5 animate-spin" />Previewing…</>
                : <><Upload className="h-3.5 w-3.5 mr-1.5" />Preview</>}
            </Button>
          </div>
        </div>

        {preview.status === 'error' && (
          <div className="mt-4 rounded-lg border border-destructive/30 bg-destructive/10 p-3 text-sm text-destructive">
            <AlertTriangle className="inline h-4 w-4 mr-1.5" />
            {preview.error?.message || 'SQLite import preview failed.'}
            {preview.error?.details?.length > 0 && (
              <ul className="mt-2 list-disc pl-5 text-xs">
                {preview.error.details.map((d, i) => (
                  <li key={i}>{d.message || d.table || JSON.stringify(d)}</li>
                ))}
              </ul>
            )}
          </div>
        )}

        {preview.status === 'ready' && preview.data && (
          <div className="mt-4 space-y-4">
            <div className="rounded-lg border border-border/60 bg-background/50 p-4">
              <div className="flex items-start justify-between gap-3">
                <div>
                  <p className="text-sm font-medium">Preview ready</p>
                  <p className="mt-1 text-xs text-muted-foreground">
                    Exported {fmt(preview.data.metadata?.exported_at)} · {preview.data.source_filename || 'SQLite export'}
                  </p>
                </div>
                <span className="rounded-full border border-border bg-muted px-2 py-0.5 text-[10px] font-semibold uppercase text-muted-foreground">
                  User data only
                </span>
              </div>
              <div className="mt-4 grid gap-2 sm:grid-cols-2 xl:grid-cols-5">
                <CountPill label="Bills" value={counts.bills} />
                <CountPill label="Categories" value={counts.categories} />
                <CountPill label="Payments" value={counts.payments} />
                <CountPill label="Monthly" value={counts.monthly_bill_state} />
                <CountPill label="Notes" value={counts.notes} />
              </div>
              <div className="mt-4 grid gap-2 sm:grid-cols-2">
                {Object.entries(summary).filter(([, v]) => v && typeof v === 'object').map(([key, value]) => (
                  <div key={key} className="rounded-lg border border-border/50 bg-muted/20 px-3 py-2 text-xs">
                    <p className="font-semibold capitalize">{key.replace(/_/g, ' ')}</p>
                    <p className="mt-1 text-muted-foreground">
                      create {value.create || 0} · skip {value.skip || 0} · conflict {value.conflict || 0}
                    </p>
                  </div>
                ))}
              </div>
              {preview.data.warnings?.length > 0 && (
                <div className="mt-4 space-y-1">
                  {preview.data.warnings.map((warning, i) => (
                    <p key={i} className="text-xs text-amber-600 dark:text-amber-400">
                      <AlertTriangle className="mr-1 inline h-3.5 w-3.5" />{warning}
                    </p>
                  ))}
                </div>
              )}
            </div>

            <div className="flex items-center justify-between gap-3">
              <p className="text-xs text-muted-foreground">Review the preview before applying. Nothing is imported until you confirm.</p>
              <Button size="sm" type="button" disabled={applyState.status === 'loading'} onClick={handleApply}>
                {applyState.status === 'loading'
                  ? <><Loader2 className="h-3.5 w-3.5 mr-1.5 animate-spin" />Applying…</>
                  : 'Apply Import'}
              </Button>
            </div>
          </div>
        )}

        {applyState.status === 'done' && applyState.result && (
          <div className="mt-4 rounded-lg border border-emerald-500/30 bg-emerald-500/5 p-4">
            <p className="text-sm font-medium text-emerald-600">SQLite import applied</p>
            <div className="mt-3 grid grid-cols-2 gap-2 text-xs sm:grid-cols-4">
              <CountPill label="Created" value={applyState.result.rows_created} />
              <CountPill label="Skipped" value={applyState.result.rows_skipped} />
              <CountPill label="Conflicts" value={applyState.result.rows_conflicted} />
              <CountPill label="Errors" value={applyState.result.rows_errored} />
            </div>
          </div>
        )}

        {applyState.status === 'error' && (
          <div className="mt-4 rounded-lg border border-destructive/30 bg-destructive/10 p-3 text-sm text-destructive">
            <AlertTriangle className="inline h-4 w-4 mr-1.5" />{applyState.error?.message || 'SQLite import apply failed.'}
          </div>
        )}
      </div>
    </SectionCard>
    {/* Import confirmation dialog */}
    <AlertDialog open={confirmOpen} onOpenChange={setConfirmOpen}>
      <AlertDialogContent>
        <AlertDialogHeader>
          <AlertDialogTitle>Import SQLite data export?</AlertDialogTitle>
          <AlertDialogDescription>
            Import this SQLite data export into your account? Existing records will be skipped by default.
          </AlertDialogDescription>
        </AlertDialogHeader>
        <AlertDialogFooter>
          <AlertDialogCancel>Cancel</AlertDialogCancel>
          <AlertDialogAction onClick={handleConfirmImport}>
            Confirm Import
          </AlertDialogAction>
        </AlertDialogFooter>
      </AlertDialogContent>
    </AlertDialog>
    </>
  );
}

// ─── Section 4: Import History ────────────────────────────────────────────────

export function ImportHistorySection({ history, loading, onRefresh }) {
  if (loading) {
    return (
      <SectionCard title="Import History">
        <div className="px-6 py-6 text-sm text-muted-foreground">Loading…</div>
      </SectionCard>
    );
  }

  const rows = history ?? [];

  return (
    <SectionCard title="Import History">
      <div className="px-6 py-4 flex items-center justify-between">
        <p className="text-xs text-muted-foreground">
          {rows.length === 0 ? 'No imports yet.' : `${rows.length} import${rows.length === 1 ? '' : 's'}`}
        </p>
        <Button size="sm" variant="ghost" onClick={onRefresh} className="h-7 text-xs gap-1.5">
          <RefreshCw className="h-3 w-3" />Refresh
        </Button>
      </div>
      {rows.length > 0 && (
        <div className="overflow-x-auto">
          <table className="w-full text-xs">
            <thead>
              <tr className="border-b border-border/50 text-muted-foreground">
                {['Date','File','Sheet','Parsed','Created','Updated','Skipped','Errors'].map(h => (
                  <th key={h} className="px-4 py-2 text-left font-medium whitespace-nowrap">{h}</th>
                ))}
              </tr>
            </thead>
            <tbody className="divide-y divide-border/30">
              {rows.map(r => (
                <tr key={r.id} className="hover:bg-muted/20 transition-colors">
                  <td className="px-4 py-2 whitespace-nowrap text-muted-foreground">
                    <span className="flex items-center gap-1"><Clock className="h-3 w-3" />{fmt(r.imported_at)}</span>
                  </td>
                  <td className="px-4 py-2 text-muted-foreground">{r.source_filename || '—'}</td>
                  <td className="px-4 py-2 text-muted-foreground">{r.sheet_name || '—'}</td>
                  <td className="px-4 py-2 tabular-nums">{r.rows_parsed}</td>
                  <td className="px-4 py-2 tabular-nums text-emerald-600">{r.rows_created}</td>
                  <td className="px-4 py-2 tabular-nums text-blue-600">{r.rows_updated}</td>
                  <td className="px-4 py-2 tabular-nums text-muted-foreground">{r.rows_skipped}</td>
                  <td className="px-4 py-2 tabular-nums text-red-500">{r.rows_errored}</td>
                </tr>
              ))}
            </tbody>
          </table>
        </div>
      )}
    </SectionCard>
  );
}

// ─── XLSX Import: Workbook Summary ────────────────────────────────────────────

function WorkbookSummaryCard({ workbook }) {
  const isMulti = workbook.parse_mode === 'all_sheets';

  return (
    <div className="rounded-lg border border-border bg-muted/30 p-4 mb-4 space-y-3">
      <div className="flex items-center justify-between flex-wrap gap-2">
        <p className="text-xs font-semibold uppercase tracking-wider text-muted-foreground">Workbook Summary</p>
        <span className="text-xs text-muted-foreground">
          {isMulti ? `${workbook.total_row_count} rows across ${workbook.sheet_names.length} tabs` : `${workbook.row_count} rows · ${workbook.selected_sheet}`}
        </span>
      </div>
      {isMulti && workbook.sheets?.length > 0 && (
        <div className="grid grid-cols-1 sm:grid-cols-2 gap-1.5">
          {workbook.sheets.map(s => (
            <div key={s.name} className={cn(
              'flex items-center justify-between rounded px-3 py-1.5 text-xs',
              s.is_non_month_sheet || s.status === 'skipped' ? 'bg-muted/50 text-muted-foreground/60' : 'bg-background border border-border/60'
            )}>
              <span className="font-medium truncate mr-2">{s.name}</span>
              <div className="flex items-center gap-2 shrink-0">
                {s.detected_year && s.detected_month && (
                  <span className="tabular-nums text-muted-foreground">
                    {String(s.detected_month).padStart(2,'0')}/{s.detected_year}
                  </span>
                )}
                <SheetStatusBadge status={s.status} />
                {s.status !== 'skipped' && <span className="text-muted-foreground">{s.row_count} rows</span>}
              </div>
            </div>
          ))}
        </div>
      )}
    </div>
  );
}

// ─── XLSX Import: Row Decision Controls ──────────────────────────────────────

const ACTIONS_NEEDING_BILL = new Set(['match_existing_bill','update_monthly_state','add_monthly_note','create_payment']);

function RowDecisionRow({ row, decision, onDecisionChange, allBills, categories, selected, onSelectedChange }) {
  const [expanded, setExpanded] = useState(row.requires_user_decision || !decision?.action);

  const action   = decision?.action ?? null;
  const isSkip   = action === 'skip_row';
  const hasError = row.errors?.length > 0;
  const complete = isDecisionComplete(action, decision);
  const rec = row.recommendation || {};

  const suggestedBills = row.possible_bill_matches ?? [];
  const suggestedIds   = new Set(suggestedBills.map(b => b.bill_id));
  const otherBills     = allBills.filter(b => !suggestedIds.has(b.id));

  const handleAction = (val) => {
    const next = { ...decision, action: val };
    if (val === 'create_new_bill') {
      Object.assign(next, buildCreateNewDecision(row, decision));
    } else if (ACTIONS_NEEDING_BILL.has(val)) {
      next.bill_name = null;
      next.bill_id = decision?.bill_id ?? decision?.previous_match_bill_id ?? rec.bill_id ?? suggestedBills[0]?.bill_id ?? null;
      next.actual_amount = decision?.actual_amount ?? rec.actual_amount ?? row.detected_amount ?? null;
      next.payment_amount = decision?.payment_amount ?? rec.payment_amount ?? row.detected_payment_amount ?? null;
      next.payment_date = decision?.payment_date ?? rec.payment_date ?? row.detected_paid_date ?? null;
    } else {
      next.bill_id = null;
      next.bill_name = null;
    }
    onDecisionChange(row.row_id, next);
    if (val === 'skip_row') setExpanded(false);
  };

  const handleBill = (e) => {
    onDecisionChange(row.row_id, { ...decision, bill_id: parseInt(e.target.value, 10) || null });
  };

  const handleBillName = (e) => {
    onDecisionChange(row.row_id, { ...decision, bill_name: e.target.value });
  };

  const handleDecisionField = (field, value) => {
    onDecisionChange(row.row_id, { ...decision, [field]: value });
  };

  return (
    <div className={cn(
      'border-b border-border/40 last:border-0',
      isSkip && 'opacity-50',
      !complete && action !== null && 'bg-amber-500/5',
    )}>
      {/* Main row */}
      <div
        className="flex items-start gap-3 px-4 py-3 cursor-pointer hover:bg-muted/20 transition-colors"
        onClick={() => setExpanded(e => !e)}
      >
        {/* Selection */}
        <div className="mt-0.5 shrink-0" onClick={e => e.stopPropagation()}>
          <input
            type="checkbox"
            checked={selected}
            onChange={e => onSelectedChange(row.row_id, e.target.checked)}
            aria-label={`Select row ${row.source_row_number}`}
            className="h-4 w-4 rounded border-border accent-primary"
          />
        </div>

        {/* Status icon */}
        <div className="mt-0.5 shrink-0">
          {hasError      ? <XCircle   className="h-4 w-4 text-muted-foreground/40" /> :
           isSkip        ? <SkipForward className="h-4 w-4 text-muted-foreground/40" /> :
           complete      ? <CheckCircle2 className="h-4 w-4 text-emerald-500" /> :
           action !== null ? <AlertTriangle className="h-4 w-4 text-amber-500" /> :
                            <AlertTriangle className="h-4 w-4 text-orange-500" />}
        </div>

        {/* Content */}
        <div className="flex-1 min-w-0">
          <div className="flex items-center gap-2 flex-wrap">
            <span className="text-xs text-muted-foreground tabular-nums">#{row.source_row_number}</span>
            {row.sheet_name && <span className="text-xs text-muted-foreground">{row.sheet_name}</span>}
            {row.detected_year && row.detected_month && (
              <span className="text-xs text-muted-foreground tabular-nums">
                {String(row.detected_month).padStart(2,'0')}/{row.detected_year}
              </span>
            )}
            {row.year_month_source && <SourceBadge source={row.year_month_source} />}
          </div>
          <div className="flex items-baseline gap-3 mt-0.5 flex-wrap">
            <span className={cn('text-sm font-medium', !row.detected_bill_name && 'italic text-muted-foreground/60')}>
              {row.detected_bill_name || '(no bill name)'}
            </span>
            {row.detected_amount != null && (
              <span className="text-xs text-muted-foreground tabular-nums">
                ${row.detected_amount.toFixed(2)}
              </span>
            )}
            {row.detected_paid_date && (
              <span className="text-xs text-emerald-500 tabular-nums">
                paid {row.detected_paid_date}
              </span>
            )}
            {row.detected_labels?.length > 0 && (
              <span className="text-xs text-muted-foreground/70">{row.detected_labels.join(', ')}</span>
            )}
            {row.detected_notes && (
              <span className="text-xs text-muted-foreground/70 italic truncate max-w-[200px]">{row.detected_notes}</span>
            )}
          </div>
        </div>

        {/* Right: action status + expand */}
        <div className="flex items-center gap-2 shrink-0">
          {action === null ? (
            <span className="text-xs font-medium text-orange-500">Needs decision</span>
          ) : isSkip ? (
            <span className="text-xs text-muted-foreground">Skipped</span>
          ) : (
            <span className="text-xs text-muted-foreground capitalize">{action.replace(/_/g,' ')}</span>
          )}
          {action !== 'skip_row' && (
            expanded ? <ChevronUp className="h-3.5 w-3.5 text-muted-foreground" /> : <ChevronDown className="h-3.5 w-3.5 text-muted-foreground" />
          )}
        </div>
      </div>

      {/* Expanded decision controls */}
      {expanded && !hasError && (
        <div className="px-11 pb-4 space-y-3">
          {/* Recommendation */}
          {rec.action && (
            <div className="rounded-md border border-border bg-muted/30 px-3 py-2 space-y-1.5">
              <div className="flex items-center gap-2 flex-wrap">
                <span className="text-xs font-medium">Recommended: {actionLabel(rec.action)}</span>
                {rec.bill_name && rec.action === 'match_existing_bill' && (
                  <span className="text-xs text-muted-foreground">→ {rec.bill_name}</span>
                )}
                {rec.category_name && (
                  <span className="text-xs text-muted-foreground">Category: {rec.category_name}</span>
                )}
                {rec.due_day && <span className="text-xs text-muted-foreground">Due day: {rec.due_day}</span>}
                {rec.actual_amount != null && <span className="text-xs text-muted-foreground">${Number(rec.actual_amount).toFixed(2)}</span>}
                <ConfidenceBadge confidence={rec.confidence} />
              </div>
              {rec.reason && <p className="text-xs text-muted-foreground">Reason: {rec.reason}</p>}
            </div>
          )}

          {/* Warnings */}
          {(rec.warnings?.length > 0 || row.warnings?.length > 0) && (
            <div className="space-y-1">
              {Array.from(new Set([...(rec.warnings || []), ...(row.warnings || [])])).map((w, i) => (
                <p key={i} className="text-xs text-amber-600 flex items-start gap-1.5">
                  <AlertTriangle className="h-3.5 w-3.5 shrink-0 mt-0.5" />{w}
                </p>
              ))}
            </div>
          )}

          {/* Possible matches hint */}
          {suggestedBills.length > 0 && (
            <div className="flex flex-wrap gap-1.5">
              <span className="text-xs text-muted-foreground self-center">Suggested:</span>
              {suggestedBills.slice(0, 3).map(b => (
                <button key={b.bill_id} type="button"
                  onClick={() => {
                    onDecisionChange(row.row_id, {
                      ...decision,
                      action: 'match_existing_bill',
                      bill_id: b.bill_id,
                      previous_match_bill_id: b.bill_id,
                      bill_name: null,
                    });
                    setExpanded(false);
                  }}
                  className="text-xs px-2 py-0.5 rounded-full border border-border bg-background hover:bg-muted transition-colors">
                  {b.bill_name}
                  {b.match_confidence === 'high' && <CheckCircle2 className="inline h-2.5 w-2.5 ml-1 text-emerald-500" />}
                </button>
              ))}
            </div>
          )}

          {/* Action selector */}
          <div className="flex items-center gap-3 flex-wrap">
            <label className="text-xs text-muted-foreground w-14 shrink-0">Action</label>
            <select
              value={action ?? ''}
              onChange={e => handleAction(e.target.value || null)}
              className="text-sm border border-input bg-background rounded-md px-2 py-1 focus:outline-none focus:ring-1 focus:ring-ring"
            >
              <option value="">— choose action —</option>
              <option value="match_existing_bill">Match existing bill</option>
              <option value="create_new_bill">Create new bill</option>
              <option value="update_monthly_state">Update monthly record</option>
              <option value="add_monthly_note">Add monthly note</option>
              <option value="create_payment">Record as payment</option>
              <option value="skip_row">Skip this row</option>
            </select>
          </div>

          {/* Bill selector (for actions that need a bill) */}
          {ACTIONS_NEEDING_BILL.has(action) && (
            <div className="flex items-center gap-3 flex-wrap">
              <label className="text-xs text-muted-foreground w-14 shrink-0">Bill</label>
              <select
                value={decision?.bill_id ?? ''}
                onChange={handleBill}
                className="text-sm border border-input bg-background rounded-md px-2 py-1 flex-1 min-w-[200px] focus:outline-none focus:ring-1 focus:ring-ring"
              >
                <option value="">— select bill —</option>
                {suggestedBills.length > 0 && (
                  <optgroup label="Suggested matches">
                    {suggestedBills.map(b => (
                      <option key={b.bill_id} value={b.bill_id}>
                        {b.bill_name}{b.expected_amount ? ` ($${b.expected_amount})` : ''} · {b.match_confidence}
                      </option>
                    ))}
                  </optgroup>
                )}
                {otherBills.length > 0 && (
                  <optgroup label={suggestedBills.length ? 'All other bills' : 'All bills'}>
                    {otherBills.map(b => (
                      <option key={b.id} value={b.id}>{b.name}</option>
                    ))}
                  </optgroup>
                )}
              </select>
            </div>
          )}

          {/* Bill name input for create_new_bill */}
          {action === 'create_new_bill' && (
            <div className="space-y-2">
              <div className="flex items-center gap-3">
                <label className="text-xs text-muted-foreground w-14 shrink-0">Name</label>
                <Input
                  value={decision?.bill_name ?? ''}
                  onChange={handleBillName}
                  placeholder="Bill name"
                  className="h-8 text-sm flex-1 max-w-sm"
                />
              </div>
              <div className="flex items-center gap-3 flex-wrap">
                <label className="text-xs text-muted-foreground w-14 shrink-0">Category</label>
                <select
                  value={decision?.category_id ?? ''}
                  onChange={e => handleDecisionField('category_id', parseInt(e.target.value, 10) || null)}
                  className="text-sm border border-input bg-background rounded-md px-2 py-1 min-w-[180px] focus:outline-none focus:ring-1 focus:ring-ring"
                >
                  <option value="">No category</option>
                  {categories.map(c => <option key={c.id} value={c.id}>{c.name}</option>)}
                </select>
                {rec.category_name && <span className="text-xs text-muted-foreground">Suggested: {rec.category_name}</span>}
              </div>
              <div className="flex items-center gap-3 flex-wrap">
                <label className="text-xs text-muted-foreground w-14 shrink-0">Details</label>
                <Input
                  type="number"
                  min="1"
                  max="31"
                  value={decision?.due_day ?? ''}
                  onChange={e => handleDecisionField('due_day', e.target.value ? parseInt(e.target.value, 10) : null)}
                  placeholder="Due day"
                  className="h-8 text-sm w-24"
                />
                <Input
                  type="number"
                  min="0"
                  step="0.01"
                  value={decision?.expected_amount ?? ''}
                  onChange={e => handleDecisionField('expected_amount', e.target.value === '' ? null : parseFloat(e.target.value))}
                  placeholder="Expected amount"
                  className="h-8 text-sm w-40"
                />
              </div>
            </div>
          )}

          {action && action !== 'skip_row' && (
            <div className="flex items-center gap-3 flex-wrap">
              <label className="text-xs text-muted-foreground w-14 shrink-0">Paid</label>
              <Input
                type="date"
                value={decision?.payment_date ?? ''}
                onChange={e => handleDecisionField('payment_date', e.target.value || null)}
                className="h-8 text-sm w-40"
              />
              <Input
                type="number"
                min="0"
                step="0.01"
                value={decision?.payment_amount ?? ''}
                onChange={e => handleDecisionField('payment_amount', e.target.value === '' ? null : parseFloat(e.target.value))}
                placeholder="Paid amount"
                className="h-8 text-sm w-36"
              />
            </div>
          )}

          {/* Quick skip */}
          {action !== 'skip_row' && (
            <button type="button"
              onClick={() => { handleAction('skip_row'); setExpanded(false); }}
              className="text-xs text-muted-foreground hover:text-foreground flex items-center gap-1 transition-colors">
              <SkipForward className="h-3 w-3" />Skip this row
            </button>
          )}
        </div>
      )}
    </div>
  );
}

// ─── XLSX Import: Preview Table ───────────────────────────────────────────────

function PreviewTable({ rows, decisions, onDecisionChange, allBills, categories, selectedRows, onSelectedChange }) {
  const groups   = groupRowsBySheet(rows);
  const multiTab = groups.length > 1;

  return (
    <div>
      {groups.map(({ name, rows: groupRows }) => (
        <div key={name}>
          {multiTab && (
            <div className="px-4 py-2 bg-muted/40 border-b border-border/60 flex items-center gap-2">
              <FileSpreadsheet className="h-3.5 w-3.5 text-muted-foreground" />
              <span className="text-xs font-semibold text-muted-foreground">{name}</span>
              <span className="text-xs text-muted-foreground/60">· {groupRows.length} rows</span>
            </div>
          )}
          {groupRows.map(row => (
            <RowDecisionRow
              key={row.row_id}
              row={row}
              decision={decisions[row.row_id]}
              onDecisionChange={onDecisionChange}
              allBills={allBills}
              categories={categories}
              selected={selectedRows.has(row.row_id)}
              onSelectedChange={onSelectedChange}
            />
          ))}
        </div>
      ))}
    </div>
  );
}

function BulkActionBar({
  rows,
  selectedRows,
  onSelectAll,
  onClearSelection,
  onBulkSkip,
  onBulkCreateNew,
  onBulkReset,
}) {
  const allSelected = rows.length > 0 && rows.every(r => selectedRows.has(r.row_id));
  const selectedCount = selectedRows.size;

  return (
    <div className="border-b border-border bg-muted/25 px-4 py-3">
      <div className="flex items-center justify-between gap-3 flex-wrap">
        <label className="flex items-center gap-2 text-xs text-muted-foreground cursor-pointer">
          <input
            type="checkbox"
            checked={allSelected}
            onChange={e => e.target.checked ? onSelectAll() : onClearSelection()}
            className="h-4 w-4 rounded border-border accent-primary"
          />
          Select all visible
        </label>

        <div className="flex items-center gap-2 flex-wrap">
          {selectedCount > 0 && (
            <span className="text-xs font-medium text-foreground">{selectedCount} row{selectedCount === 1 ? '' : 's'} selected</span>
          )}
          {selectedCount > 0 && (
            <>
              <Button size="sm" variant="outline" onClick={onBulkSkip} className="h-8 text-xs">
                Skip selected
              </Button>
              <Button size="sm" variant="outline" onClick={onBulkCreateNew} className="h-8 text-xs">
                Create new bills
              </Button>
              <Button size="sm" variant="ghost" onClick={onBulkReset} className="h-8 text-xs">
                Reset to recommendation
              </Button>
              <Button size="sm" variant="ghost" onClick={onClearSelection} className="h-8 text-xs text-muted-foreground">
                Clear selection
              </Button>
            </>
          )}
        </div>
      </div>
    </div>
  );
}

// ─── Section 1: Import Spreadsheet History ────────────────────────────────────

const INITIAL_OPTIONS = {
  parseAllSheets: true,
  defaultYear: new Date().getFullYear(),
  defaultMonth: '',
};

// ─── Bill History Import helpers ──────────────────────────────────────────────

function ConfidenceDot({ level }) {
  const cls = level === 'high'   ? 'bg-emerald-500'
            : level === 'medium' ? 'bg-amber-500'
            :                      'bg-muted-foreground/30';
  return <span className={cn('h-2 w-2 rounded-full shrink-0 inline-block', cls)} />;
}

function useBillGroups(previewRows, allBills) {
  return useMemo(() => {
    const billMap = new Map(allBills.map(b => [b.id, b]));
    const groups  = new Map();

    for (const row of previewRows) {
      for (const match of (row.possible_bill_matches ?? [])) {
        if (!billMap.has(match.bill_id)) continue;
        if (!groups.has(match.bill_id)) {
          groups.set(match.bill_id, {
            bill:   billMap.get(match.bill_id),
            rows:   [],
            counts: { high: 0, medium: 0, low: 0 },
          });
        }
        const g = groups.get(match.bill_id);
        if (!g.rows.find(r => r.row_id === row.row_id)) {
          g.rows.push({ ...row, _match: match });
          g.counts[match.match_confidence] = (g.counts[match.match_confidence] || 0) + 1;
        }
      }
    }
    return [...groups.values()].sort((a, b) =>
      b.rows.length !== a.rows.length ? b.rows.length - a.rows.length : b.counts.high - a.counts.high
    );
  }, [previewRows, allBills]);
}

function rowDateLabel(row) {
  if (row.detected_year && row.detected_month)
    return `${row.detected_year}-${String(row.detected_month).padStart(2, '0')}`;
  return row.detected_paid_date ?? '—';
}

function billImportProgress(rows, importResult) {
  const completedRowIds = importResult?.completedRowIds ?? new Set();
  const remainingRows = rows.filter(row => !completedRowIds.has(row.row_id));
  return {
    completedCount: rows.length - remainingRows.length,
    remainingRows,
    remainingCount: remainingRows.length,
  };
}

function detailImportedAnything(detail) {
  return ['created', 'updated', 'overwritten', 'imported'].includes(detail?.result)
    || detail?.payment === 'created';
}

function detailCompletesImport(detail) {
  if (!detail?.row_id) return false;
  if (['error', 'ambiguous', 'skipped_conflict'].includes(detail.result)) return false;
  if (detail.result === 'skipped') return false;
  return detailImportedAnything(detail)
    || detail.result === 'skipped_duplicate'
    || detail.payment === 'skipped_duplicate';
}

function BillDetailView({ group, onBack, onImport, isImporting, importResult }) {
  const { bill, rows } = group;
  const { completedCount, remainingCount } = billImportProgress(rows, importResult);
  const sorted = [...rows].sort((a, b) => {
    const da = (a.detected_year ?? 0) * 100 + (a.detected_month ?? 0);
    const db = (b.detected_year ?? 0) * 100 + (b.detected_month ?? 0);
    return da - db;
  });

  return (
    <div>
      <div className="px-4 py-2.5 border-b border-border/50 flex items-center justify-between gap-3">
        <button type="button" onClick={onBack}
          className="inline-flex items-center gap-1 text-xs text-muted-foreground hover:text-foreground transition-colors">
          <ChevronLeft className="h-3.5 w-3.5" /> All bills
        </button>
        <span className="text-sm font-medium truncate">{bill.name}</span>
        <div className="flex items-center gap-2 shrink-0">
          {importResult && (
            <div className="text-right">
              <span className={`text-xs font-medium ${
                completedCount === rows.length ? 'text-emerald-500' : 'text-amber-400'
              }`}>
                {completedCount === rows.length
                  ? 'All imported'
                  : `${completedCount} imported · ${remainingCount} remaining`}
                {importResult.duplicates > 0
                  && ` · ${importResult.duplicates} dupes`}
              </span>
              {importResult.duplicates > 0 && importResult.earliestDup && (
                <p className="text-[10px] text-muted-foreground/70 mt-0.5">
                  {importResult.duplicates} dup{importResult.duplicates > 1 ? 's' : ''} · recorded{' '}
                  {importResult.earliestDup.toLocaleDateString(undefined, { month: 'short', day: 'numeric', year: 'numeric' })}
                </p>
              )}
            </div>
          )}
          <Button size="sm" onClick={onImport} disabled={isImporting || remainingCount === 0} className="h-7 text-xs px-3 shrink-0 gap-1.5">
            {isImporting && <Loader2 className="h-3 w-3 animate-spin" />}
            {remainingCount === 0 ? 'All imported' : `Import all ${remainingCount}`}
          </Button>
        </div>
      </div>
      <div className="divide-y divide-border/30 max-h-80 overflow-y-auto">
        {sorted.map(row => (
          <div key={row.row_id} className="px-4 py-2 flex items-center gap-3">
            <ConfidenceDot level={row._match.match_confidence} />
            <span className="text-xs tabular-nums text-muted-foreground w-16 shrink-0">{rowDateLabel(row)}</span>
            <span className="text-xs font-mono tabular-nums w-16 shrink-0">
              {row.detected_amount != null ? `$${Number(row.detected_amount).toFixed(2)}` : '—'}
            </span>
            <span className="text-xs text-muted-foreground truncate flex-1">{row.detected_name ?? '—'}</span>
            <span className={cn('text-[10px] shrink-0',
              row._match.match_confidence === 'high'   ? 'text-emerald-500' :
              row._match.match_confidence === 'medium' ? 'text-amber-500'   : 'text-muted-foreground/40')}>
              {row._match.match_confidence}
            </span>
          </div>
        ))}
      </div>
    </div>
  );
}

function BillHistoryView({ previewRows, allBills, importingBillId, billImportResults, onImportBill }) {
  const [selectedBillId, setSelectedBillId] = useState(null);
  const billGroups = useBillGroups(previewRows, allBills);

  if (billGroups.length === 0) {
    return (
      <div className="px-4 py-10 text-center text-sm text-muted-foreground">
        No existing bills matched rows in this file.
      </div>
    );
  }

  if (selectedBillId) {
    const group = billGroups.find(g => g.bill.id === selectedBillId);
    return group
      ? <BillDetailView group={group}
          isImporting={importingBillId === group.bill.id}
          importResult={billImportResults.get(group.bill.id) ?? null}
          onBack={() => setSelectedBillId(null)}
          onImport={() => onImportBill(group)} />
      : null;
  }

  return (
    <div className="divide-y divide-border/50">
      {billGroups.map(g => {
        const { bill, rows, counts } = g;
        const isImporting  = importingBillId === bill.id;
        const importResult = billImportResults.get(bill.id) ?? null;
        const { completedCount, remainingCount } = billImportProgress(rows, importResult);

        const sorted3 = [...rows]
          .sort((a, b) => {
            const da = (a.detected_year ?? 0) * 100 + (a.detected_month ?? 0);
            const db = (b.detected_year ?? 0) * 100 + (b.detected_month ?? 0);
            return da - db;
          })
          .slice(0, 3);

        return (
          <div key={bill.id} className="px-4 py-3 flex items-start gap-3">
            <div className="flex-1 min-w-0">
              <div className="flex items-center gap-2 flex-wrap">
                <span className="text-sm font-medium truncate">{bill.name}</span>
                <span className="text-[10px] text-muted-foreground border border-border/50 rounded px-1.5 py-0.5 shrink-0">
                  {rows.length} row{rows.length !== 1 ? 's' : ''}
                </span>
                {counts.high   > 0 && <span className="text-[10px] text-emerald-500">{counts.high} high</span>}
                {counts.medium > 0 && <span className="text-[10px] text-amber-500">{counts.medium} med</span>}
                {counts.low    > 0 && <span className="text-[10px] text-muted-foreground/50">{counts.low} low</span>}
                {importResult && (() => {
                  const allImported = completedCount === rows.length;
                  const fmtDate   = d => d?.toLocaleDateString(undefined, { month: 'short', day: 'numeric', year: 'numeric' });
                  const dupDate   = importResult.earliestDup ? ` · ${fmtDate(importResult.earliestDup)}` : '';
                  return (
                    <div className="space-y-0.5">
                      <span className={`text-[10px] font-medium ${allImported ? 'text-emerald-500' : 'text-amber-400'}`}>
                        {allImported ? 'All imported' : `${completedCount} imported · ${remainingCount} remaining`}
                        {importResult.duplicates > 0 && ` · ${importResult.duplicates} dupes`}
                        {importResult.errored > 0 && ` · ${importResult.errored} errors`}
                      </span>
                      {importResult.duplicates > 0 && (
                        <p className="text-[10px] text-muted-foreground/70">
                          {importResult.duplicates} duplicate{importResult.duplicates > 1 ? 's' : ''}{dupDate}
                        </p>
                      )}
                    </div>
                  );
                })()}
              </div>
              <div className="mt-1.5 space-y-0.5">
                {sorted3.map(row => (
                  <div key={row.row_id} className="flex items-center gap-2 text-xs text-muted-foreground">
                    <ConfidenceDot level={row._match.match_confidence} />
                    <span className="tabular-nums w-16 shrink-0">{rowDateLabel(row)}</span>
                    {row.detected_amount != null && (
                      <span className="tabular-nums">${Number(row.detected_amount).toFixed(2)}</span>
                    )}
                    {row.detected_name &&
                      row.detected_name.toLowerCase() !== bill.name.toLowerCase() && (
                      <span className="truncate italic opacity-60">"{row.detected_name}"</span>
                    )}
                  </div>
                ))}
                {rows.length > 3 && (
                  <button type="button" onClick={() => setSelectedBillId(bill.id)}
                    className="text-[10px] text-primary/70 hover:text-primary transition-colors">
                    +{rows.length - 3} more — view all
                  </button>
                )}
              </div>
            </div>
            <div className="flex flex-col gap-1 shrink-0 pt-0.5">
              {importResult ? (
                <Button size="sm" variant="outline" onClick={() => onImportBill(g)}
                  disabled={!!importingBillId || remainingCount === 0} className="h-7 text-xs px-3 gap-1.5">
                  {remainingCount === 0 ? 'All imported' : `Import ${remainingCount}`}
                </Button>
              ) : (
                <Button size="sm" onClick={() => onImportBill(g)}
                  disabled={!!importingBillId} className="h-7 text-xs px-3 gap-1.5">
                  {isImporting && <Loader2 className="h-3 w-3 animate-spin" />}
                  Import {rows.length}
                </Button>
              )}
              <Button size="sm" variant="ghost" onClick={() => setSelectedBillId(bill.id)}
                disabled={!!importingBillId} className="h-7 text-xs px-3">
                Review
              </Button>
            </div>
          </div>
        );
      })}
    </div>
  );
}

// ─────────────────────────────────────────────────────────────────────────────

export function ImportSpreadsheetSection({ onHistoryRefresh }) {
  const fileRef = useRef(null);
  const [file,    setFile]    = useState(null);
  const [options, setOptions] = useState(INITIAL_OPTIONS);
  const [preview, setPreview] = useState({ status: 'idle', data: null, error: null });
  const [decisions, setDecisions]  = useState({});
  const [applyState, setApplyState] = useState({ status: 'idle', result: null, error: null });
  const [allBills, setAllBills]    = useState([]);
  const [categories, setCategories] = useState([]);
  const [selectedRows, setSelectedRows] = useState(new Set());
  const [viewMode, setViewMode]    = useState('rows'); // 'rows' | 'bills'
  const [importingBillId,  setImportingBillId]  = useState(null);
  const [billImportResults, setBillImportResults] = useState(new Map()); // bill_id → { created, updated, errored }

  // Load bills/categories for the decision controls
  useEffect(() => {
    api.bills().then(setAllBills).catch(() => {});
    api.categories().then(setCategories).catch(() => {});
  }, []);

  const opt = (k, v) => setOptions(prev => ({ ...prev, [k]: v }));

  // ── Preview ──────────────────────────────────────────────────────────────────
  const handlePreview = async () => {
    if (!file) return;
    setPreview({ status: 'loading', data: null, error: null });
    setDecisions({});
    setSelectedRows(new Set());
    setApplyState({ status: 'idle', result: null, error: null });
    setViewMode('rows');
    setImportingBillId(null);
    setBillImportResults(new Map());
    try {
      const data = await api.previewSpreadsheetImport(file, {
        parseAllSheets: options.parseAllSheets,
        defaultYear:    options.defaultYear ? parseInt(options.defaultYear, 10) : null,
        defaultMonth:   options.defaultMonth ? parseInt(options.defaultMonth, 10) : null,
      });
      setPreview({ status: 'ready', data, error: null });
      setDecisions(buildInitialDecisions(data.rows));
    } catch (err) {
      setPreview({ status: 'error', data: null, error: importErrorState(err, 'Preview failed.') });
    }
  };

  // ── Decision update ──────────────────────────────────────────────────────────
  const handleDecisionChange = (rowId, decision) => {
    setDecisions(prev => ({ ...prev, [rowId]: decision }));
  };

  const handleSelectedChange = (rowId, selected) => {
    setSelectedRows(prev => {
      const next = new Set(prev);
      if (selected) next.add(rowId);
      else next.delete(rowId);
      return next;
    });
  };

  const clearSelection = () => setSelectedRows(new Set());

  // ── Bill-history direct import ────────────────────────────────────────────
  // Applies all matching rows for a bill immediately — no queue, no review step.
  const handleDirectImportBill = async (group) => {
    const sessionId = preview.data?.import_session_id;
    if (!sessionId || importingBillId) return;

    const previousResult = billImportResults.get(group.bill.id) ?? null;
    const rowsToImport = billImportProgress(group.rows, previousResult).remainingRows;
    if (rowsToImport.length === 0) {
      toast.info(`All rows for "${group.bill.name}" have already been imported.`);
      return;
    }

    setImportingBillId(group.bill.id);
    try {
      const decisionsList = rowsToImport.map(row => ({
        row_id:         row.row_id,
        action:         'match_existing_bill',
        bill_id:        group.bill.id,
        actual_amount:  row.detected_amount ?? null,
        payment_amount: row.detected_payment_amount ?? row.detected_amount ?? null,
        payment_date:   row.detected_paid_date ?? null,
      }));

      const result = await api.applySpreadsheetImport({
        import_session_id: sessionId,
        decisions:         decisionsList,
        options:           {},
      });

      const created    = result.rows_created    ?? 0;
      const updated    = result.rows_updated    ?? 0;
      const errored    = result.rows_errored    ?? 0;
      const details    = result.details ?? [];
      const duplicateRowIds = new Set(
        details
          .filter(d => d.result === 'skipped_duplicate' || d.payment === 'skipped_duplicate')
          .map(d => d.row_id)
          .filter(Boolean),
      );
      const duplicates = duplicateRowIds.size || (result.rows_duplicates ?? 0);

      // Collect created_at dates from duplicate detail entries so we can show
      // when the existing payments were originally recorded.
      const dupDates = details
        .filter(d => (d.result === 'skipped_duplicate' || d.payment === 'skipped_duplicate') && d.existing_created_at)
        .map(d => new Date(d.existing_created_at))
        .filter(d => !isNaN(d.getTime()))
        .sort((a, b) => a - b);

      const earliestDup = dupDates[0]   ?? null;
      const latestDup   = dupDates.at(-1) ?? null;
      const completedRowIds = new Set(previousResult?.completedRowIds ?? []);
      const erroredRowIds = new Set(previousResult?.erroredRowIds ?? []);

      for (const detail of details) {
        if (detailCompletesImport(detail)) {
          completedRowIds.add(detail.row_id);
          erroredRowIds.delete(detail.row_id);
        } else if (['error', 'ambiguous', 'skipped_conflict'].includes(detail?.result)) {
          erroredRowIds.add(detail.row_id);
        }
      }

      const mergedResult = {
        created:    (previousResult?.created ?? 0) + created,
        updated:    (previousResult?.updated ?? 0) + updated,
        errored:    erroredRowIds.size,
        duplicates: (previousResult?.duplicates ?? 0) + duplicates,
        earliestDup: previousResult?.earliestDup && earliestDup
          ? (previousResult.earliestDup < earliestDup ? previousResult.earliestDup : earliestDup)
          : (previousResult?.earliestDup ?? earliestDup),
        latestDup: previousResult?.latestDup && latestDup
          ? (previousResult.latestDup > latestDup ? previousResult.latestDup : latestDup)
          : (previousResult?.latestDup ?? latestDup),
        completedRowIds,
        erroredRowIds,
      };

      setBillImportResults(prev => new Map(prev).set(group.bill.id, mergedResult));

      const imported = created + updated;
      const fmtDate  = d => d?.toLocaleDateString(undefined, { month: 'short', day: 'numeric', year: 'numeric' });
      const remainingCount = billImportProgress(group.rows, mergedResult).remainingCount;

      if (imported === 0 && duplicates > 0) {
        const dateHint = earliestDup
          ? ` (first recorded ${fmtDate(earliestDup)})`
          : '';
        toast.warning(
          remainingCount === 0
            ? `All rows for "${group.bill.name}" are now imported${dateHint}.`
            : `${duplicates} row${duplicates > 1 ? 's' : ''} for "${group.bill.name}" already exist${dateHint}. ${remainingCount} remaining.`,
        );
      } else {
        const parts = [`${imported} entr${imported === 1 ? 'y' : 'ies'} imported`];
        if (duplicates > 0) {
          const dateHint = earliestDup ? ` (recorded ${fmtDate(earliestDup)})` : '';
          parts.push(`${duplicates} already existed${dateHint}`);
        }
        if (errored > 0) parts.push(`${errored} error${errored > 1 ? 's' : ''}`);
        if (remainingCount > 0) parts.push(`${remainingCount} remaining`);
        toast.success(`${group.bill.name} — ${parts.join(' · ')}`);
      }
      onHistoryRefresh?.();
    } catch (err) {
      toast.error(err.message || `Import failed for "${group.bill.name}"`);
    } finally {
      setImportingBillId(null);
    }
  };

  const selectAllVisibleRows = () => {
    setSelectedRows(new Set((preview.data?.rows || []).map(r => r.row_id)));
  };

  const selectedPreviewRows = () => {
    const selected = selectedRows;
    return (preview.data?.rows || []).filter(r => selected.has(r.row_id));
  };

  const handleBulkSkip = () => {
    const rows = selectedPreviewRows();
    setDecisions(prev => {
      const next = { ...prev };
      rows.forEach(row => {
        next[row.row_id] = { ...(next[row.row_id] || {}), action: 'skip_row', bill_id: null, bill_name: null };
      });
      return next;
    });
    toast.success(`${rows.length} row${rows.length === 1 ? '' : 's'} marked skipped.`);
  };

  const handleBulkCreateNew = () => {
    const rows = selectedPreviewRows();
    let missingNames = 0;
    setDecisions(prev => {
      const next = { ...prev };
      rows.forEach(row => {
        const decision = buildCreateNewDecision(row, next[row.row_id] || {});
        if (!decision.bill_name?.trim()) missingNames++;
        next[row.row_id] = decision;
      });
      return next;
    });
    if (missingNames > 0) {
      toast.warning(`${missingNames} selected row${missingNames === 1 ? '' : 's'} still need a bill name.`);
    } else {
      toast.success(`${rows.length} row${rows.length === 1 ? '' : 's'} set to create new bills.`);
    }
  };

  const handleBulkReset = () => {
    const rows = selectedPreviewRows();
    setDecisions(prev => {
      const next = { ...prev };
      rows.forEach(row => {
        next[row.row_id] = initialDecisionFromRecommendation(row);
      });
      return next;
    });
    toast.success(`${rows.length} row${rows.length === 1 ? '' : 's'} reset to recommendation.`);
  };

  const buildApplyDecision = (row, d) => {
    if (!d?.action) return null;

    const base = {
      row_id:        row.row_id,
      action:        d.action,
      actual_amount: d.actual_amount ?? row.detected_amount ?? undefined,
      year:          row.detected_year ?? undefined,
      month:         row.detected_month ?? undefined,
      notes:         d.notes ?? row.detected_notes ?? undefined,
      payment_amount: d.payment_amount ?? row.detected_payment_amount ?? undefined,
      payment_date:   d.payment_date ?? row.detected_paid_date ?? undefined,
    };

    if (d.action === 'create_new_bill') {
      return {
        ...base,
        bill_name:       d.bill_name?.trim() || undefined,
        category_id:     d.category_id ?? undefined,
        due_day:         d.due_day ?? undefined,
        expected_amount: d.expected_amount ?? undefined,
      };
    }

    if (ACTIONS_NEEDING_BILL.has(d.action)) {
      return {
        ...base,
        bill_id: d.bill_id ?? undefined,
      };
    }

    return base;
  };

  // ── Apply ────────────────────────────────────────────────────────────────────
  const handleApply = async () => {
    if (!preview.data) return;
    setApplyState({ status: 'loading', result: null, error: null });
    try {
      const decisionsList = preview.data.rows
        .map(row => {
          const d = decisions[row.row_id];
          if (d?.action === 'skip_row') return null;
          return buildApplyDecision(row, d);
        })
        .filter(Boolean);

      if (decisionsList.length === 0) {
        throw new Error('No rows are selected to import. Choose at least one row to match or create, or keep the preview for review.');
      }

      const result = await api.applySpreadsheetImport({
        import_session_id: preview.data.import_session_id,
        decisions:         decisionsList,
        options:           { reviewed_skipped_count: skipRows.length },
      });
      setApplyState({ status: 'done', result, error: null });
      setSelectedRows(new Set());
      toast.success(`Import applied — ${result.rows_created} created, ${result.rows_updated} updated.`);
      onHistoryRefresh();
    } catch (err) {
      const errorState = importErrorState(err, 'Apply failed.');
      setApplyState({ status: 'error', result: null, error: errorState });
      toast.error(errorState.message || 'Apply failed.');
    }
  };

  // ── Reset ────────────────────────────────────────────────────────────────────
  const handleReset = () => {
    setFile(null);
    setOptions(INITIAL_OPTIONS);
    setPreview({ status: 'idle', data: null, error: null });
    setDecisions({});
    setSelectedRows(new Set());
    setApplyState({ status: 'idle', result: null, error: null });
    setViewMode('rows');
    setImportingBillId(null);
    setBillImportResults(new Map());
    if (fileRef.current) fileRef.current.value = '';
  };

  // ── Derived state ────────────────────────────────────────────────────────────
  const previewRows    = preview.data?.rows ?? [];
  const unresolvedRows = previewRows.filter(r => {
    const d = decisions[r.row_id];
    return !d?.action || !isDecisionComplete(d.action, d);
  });
  const pendingRows    = previewRows.filter(r => decisions[r.row_id]?.action && decisions[r.row_id]?.action !== 'skip_row');
  const skipRows       = previewRows.filter(r => decisions[r.row_id]?.action === 'skip_row');
  const canApply       = unresolvedRows.length === 0 && pendingRows.length > 0 && applyState.status !== 'loading';

  // ── Render ────────────────────────────────────────────────────────────────────
  return (
    <SectionCard
      title="Import Spreadsheet History"
      subtitle='Export your Google Sheet as .xlsx, upload it here, review the matches, then apply only the rows you approve.'
    >

      {/* ── Upload panel ──────────────────────────────────────────────────────── */}
      <div className="px-6 py-5 space-y-5">

        {/* File picker */}
        <div className="space-y-1.5">
          <label className="text-xs font-medium text-muted-foreground">XLSX File</label>
          <div className="flex items-center gap-3">
            <input ref={fileRef} type="file" accept=".xlsx,application/vnd.openxmlformats-officedocument.spreadsheetml.sheet"
              className="hidden" id="xlsx-upload"
              onChange={e => setFile(e.target.files?.[0] ?? null)} />
            <label htmlFor="xlsx-upload">
              <Button size="sm" variant="outline" asChild>
                <span className="cursor-pointer gap-2">
                  <Upload className="h-3.5 w-3.5" />
                  {file ? 'Change file' : 'Choose .xlsx file'}
                </span>
              </Button>
            </label>
            {file && (
              <span className="text-sm text-muted-foreground truncate max-w-[260px]">
                <FileSpreadsheet className="inline h-3.5 w-3.5 mr-1" />{file.name}
              </span>
            )}
          </div>
        </div>

        {/* Options */}
        <div className="flex flex-wrap items-center gap-x-8 gap-y-3">
          <div className="flex items-center gap-2.5">
            <Switch checked={options.parseAllSheets} onCheckedChange={v => opt('parseAllSheets', v)}
              id="parse-all" />
            <label htmlFor="parse-all" className="text-sm cursor-pointer">Parse all sheet tabs</label>
          </div>
          <div className="flex items-center gap-2">
            <label className="text-xs text-muted-foreground">Default year</label>
            <Input type="number" min="2000" max="2100" placeholder="2026"
              value={options.defaultYear}
              onChange={e => opt('defaultYear', e.target.value)}
              className="w-24 h-8 text-sm" />
          </div>
          {!options.parseAllSheets && (
            <div className="flex items-center gap-2">
              <label className="text-xs text-muted-foreground">Default month</label>
              <Input type="number" min="1" max="12" placeholder="1–12"
                value={options.defaultMonth}
                onChange={e => opt('defaultMonth', e.target.value)}
                className="w-20 h-8 text-sm" />
            </div>
          )}
        </div>

        {/* Preview button */}
        <div className="flex items-center gap-3">
          <Button size="sm" onClick={handlePreview}
            disabled={!file || preview.status === 'loading'}
            className="gap-2">
            {preview.status === 'loading'
              ? <><Loader2 className="h-3.5 w-3.5 animate-spin" />Parsing…</>
              : <><FileSpreadsheet className="h-3.5 w-3.5" />Preview Import</>}
          </Button>
          {(preview.status === 'ready' || preview.status === 'error' || applyState.status !== 'idle') && (
            <Button size="sm" variant="ghost" onClick={handleReset} className="text-muted-foreground">
              New import
            </Button>
          )}
        </div>

        {/* Error from preview */}
        {preview.status === 'error' && (
          <div className="rounded-lg bg-destructive/10 border border-destructive/30 p-3 text-sm text-destructive">
            <AlertTriangle className="inline h-4 w-4 mr-1.5" />{preview.error?.message || preview.error || 'Preview failed.'}
            {preview.error?.details?.length > 0 && (
              <ul className="mt-2 space-y-1 text-xs">
                {preview.error.details.map((d, i) => (
                  <li key={i}>{d.row_id ? `${d.row_id}: ` : ''}{d.message}</li>
                ))}
              </ul>
            )}
          </div>
        )}
      </div>

      {/* ── Preview results ────────────────────────────────────────────────────── */}
      {preview.status === 'ready' && preview.data && !['loading', 'done'].includes(applyState.status) && (
        <div className="px-6 pb-5 space-y-4">

          {/* Workbook summary */}
          <WorkbookSummaryCard workbook={preview.data.workbook} />

          {/* Row decision table */}
          {previewRows.length > 0 ? (
            <div className="rounded-lg border border-border overflow-hidden bg-background">
              {/* Tab header */}
              <div className="px-4 py-3 border-b border-border bg-muted/40 flex items-center justify-between gap-3 flex-wrap">
                <div className="flex items-center gap-1 bg-background rounded-md border border-border p-0.5">
                  <button type="button" onClick={() => setViewMode('rows')}
                    className={cn('inline-flex items-center gap-1.5 rounded px-3 py-1.5 text-xs font-medium transition-colors',
                      viewMode === 'rows'
                        ? 'bg-primary text-primary-foreground shadow-sm'
                        : 'text-muted-foreground hover:text-foreground')}>
                    <List className="h-3.5 w-3.5" />
                    Rows ({previewRows.length})
                  </button>
                  <button type="button" onClick={() => setViewMode('bills')}
                    className={cn('inline-flex items-center gap-1.5 rounded px-3 py-1.5 text-xs font-medium transition-colors',
                      viewMode === 'bills'
                        ? 'bg-primary text-primary-foreground shadow-sm'
                        : 'text-muted-foreground hover:text-foreground')}>
                    <Building2 className="h-3.5 w-3.5" />
                    Bills
                  </button>
                </div>
                <span className="text-xs text-muted-foreground">
                  {viewMode === 'rows'
                    ? 'Select rows, apply bulk decisions, then import.'
                    : 'Click a bill to queue its entire history from this file.'}
                </span>
              </div>

              {/* Rows view */}
              {viewMode === 'rows' && (
                <>
                  <BulkActionBar
                    rows={previewRows}
                    selectedRows={selectedRows}
                    onSelectAll={selectAllVisibleRows}
                    onClearSelection={clearSelection}
                    onBulkSkip={handleBulkSkip}
                    onBulkCreateNew={handleBulkCreateNew}
                    onBulkReset={handleBulkReset}
                  />
                  <PreviewTable
                    rows={previewRows}
                    decisions={decisions}
                    onDecisionChange={handleDecisionChange}
                    allBills={allBills}
                    categories={categories}
                    selectedRows={selectedRows}
                    onSelectedChange={handleSelectedChange}
                  />
                </>
              )}

              {/* Bills view */}
              {viewMode === 'bills' && (
                <BillHistoryView
                  previewRows={previewRows}
                  allBills={allBills}
                  importingBillId={importingBillId}
                  billImportResults={billImportResults}
                  onImportBill={handleDirectImportBill}
                />
              )}
            </div>
          ) : (
            <p className="text-sm text-muted-foreground text-center py-4">No data rows found in this file.</p>
          )}

          {/* Apply bar */}
          {previewRows.length > 0 && (
            <div className="rounded-lg border border-border bg-muted/30 px-4 py-3 flex items-center justify-between flex-wrap gap-3">
              <div className="flex items-center gap-4 text-xs text-muted-foreground flex-wrap">
                <span className="text-foreground font-medium">{previewRows.length} rows reviewed</span>
                <span className="text-emerald-600">{pendingRows.length} to apply</span>
                <span>{skipRows.length} skipped</span>
                {unresolvedRows.length > 0 && (
                  <span className="text-orange-500 font-medium">{unresolvedRows.length} need a decision</span>
                )}
              </div>
              <Button size="sm" onClick={handleApply} disabled={!canApply} className="gap-2">
                <CheckCheck className="h-3.5 w-3.5" />
                Apply {pendingRows.length} rows
              </Button>
            </div>
          )}
        </div>
      )}

      {/* ── Applying ──────────────────────────────────────────────────────────── */}
      {applyState.status === 'loading' && (
        <div className="px-6 py-8 flex items-center justify-center gap-3 text-muted-foreground">
          <Loader2 className="h-5 w-5 animate-spin" />
          <span className="text-sm">Applying import…</span>
        </div>
      )}

      {/* ── Apply result ──────────────────────────────────────────────────────── */}
      {applyState.status === 'done' && applyState.result && (
        <div className="px-6 pb-6 space-y-4">
          <div className="rounded-lg border border-emerald-500/30 bg-emerald-500/5 p-4">
            <div className="flex items-center gap-2 mb-3">
              <CheckCircle2 className="h-5 w-5 text-emerald-500" />
              <p className="text-sm font-medium text-emerald-600">Import applied successfully</p>
            </div>
            <div className="grid grid-cols-2 sm:grid-cols-4 gap-3">
              {[
                { label: 'Created',   value: applyState.result.rows_created,  color: 'text-emerald-600' },
                { label: 'Updated',   value: applyState.result.rows_updated,  color: 'text-blue-600'    },
                { label: 'Skipped',   value: applyState.result.rows_skipped,  color: 'text-muted-foreground' },
                { label: 'Errors',    value: applyState.result.rows_errored,  color: 'text-red-500'     },
              ].map(({ label, value, color }) => (
                <div key={label} className="text-center">
                  <p className={cn('text-xl font-bold tabular-nums', color)}>{value}</p>
                  <p className="text-xs text-muted-foreground">{label}</p>
                </div>
              ))}
            </div>
          </div>
          <Button size="sm" variant="outline" onClick={handleReset} className="gap-2">
            <Plus className="h-3.5 w-3.5" />New Import
          </Button>
        </div>
      )}

      {/* ── Apply error ───────────────────────────────────────────────────────── */}
      {applyState.status === 'error' && (
        <div className="px-6 pb-5">
          <div className="rounded-lg bg-destructive/10 border border-destructive/30 p-3 text-sm text-destructive">
            <AlertTriangle className="inline h-4 w-4 mr-1.5" />{applyState.error?.message || applyState.error || 'Apply failed.'}
            {applyState.error?.details?.length > 0 && (
              <ul className="mt-2 space-y-1 text-xs">
                {applyState.error.details.map((d, i) => (
                  <li key={i}>
                    {d.row_id ? `${d.row_id}: ` : ''}
                    {d.field ? `${d.field} - ` : ''}
                    {d.message}
                  </li>
                ))}
              </ul>
            )}
            {applyState.error?.error_id && (
              <p className="mt-2 text-xs opacity-80">Error ID: {applyState.error.error_id}</p>
            )}
          </div>
        </div>
      )}
    </SectionCard>
  );
}

// ─── DataPage ─────────────────────────────────────────────────────────────────

function SeedDemoDataSection({ onSeeded }) {
  const [loading, setLoading] = useState(false);
  const [seeded, setSeeded] = useState(false);
  const [counts, setCounts] = useState({ bills: 0, categories: 0 });
  const [clearing, setClearing] = useState(false);
  const [showClearConfirm, setShowClearConfirm] = useState(false);
  const [statusLoading, setStatusLoading] = useState(true);

  useEffect(() => {
    api.seededStatus()
      .then(data => {
        setSeeded(data.seeded);
        if (data.seeded) setCounts({ bills: data.seededBills || 0, categories: data.seededCategories || 0 });
      })
      .catch(err => console.error('Failed to check seeded status:', err))
      .finally(() => setStatusLoading(false));
  }, []);

  const handleSeed = async () => {
    setLoading(true);
    try {
      const data = await api.seedDemoData();
      if (!data || typeof data !== 'object') throw new Error('Invalid response from server');
      setCounts({ bills: data.billsCreated || 0, categories: data.categoriesCreated || 0 });
      setSeeded(true);
      toast.success(`Created ${data.billsCreated || 0} demo bills successfully.`);
      setTimeout(() => onSeeded?.(), 100);
    } catch (err) {
      console.error('Seed error:', err);
      toast.error(err?.message || err?.error || 'Failed to seed demo data.');
    } finally {
      setLoading(false);
    }
  };

  const handleClearDemoData = async () => {
    setClearing(true);
    try {
      const data = await api.clearDemoData();
      setSeeded(false);
      setCounts({ bills: 0, categories: 0 });
      setShowClearConfirm(false);
      toast.success(`Removed ${data.billsDeleted || 0} demo bills and ${data.categoriesDeleted || 0} demo categories.`);
      onSeeded?.();
    } catch (err) {
      toast.error(err.message || 'Failed to clear demo data.');
    } finally {
      setClearing(false);
    }
  };

  return (
    <SectionCard title="Demo Data" subtitle="Seed your database with demo data for testing" icon={Sparkles}>
      <div className="rounded-lg border border-border/60 bg-background/50 p-4">
        {statusLoading ? (
          <p className="text-sm text-muted-foreground">Loading…</p>
        ) : seeded ? (
          <>
            <p className="text-sm font-medium text-emerald-600 dark:text-emerald-400">Demo data seeded</p>
            <div className="mt-3 grid grid-cols-2 gap-4 text-xs sm:grid-cols-4">
              <div>
                <p className="text-muted-foreground">Bills</p>
                <p className="font-semibold">{counts.bills}</p>
              </div>
              <div>
                <p className="text-muted-foreground">Categories</p>
                <p className="font-semibold">{counts.categories}</p>
              </div>
            </div>
          </>
        ) : (
          <p className="text-sm text-muted-foreground">
            Create 20 realistic demo bills and 8 demo categories for testing purposes.
            The data will be associated with your account.
          </p>
        )}

        <div className="mt-4 flex items-center justify-between gap-3 border-t border-border pt-4">
          <Button size="sm" variant="outline" onClick={handleSeed} disabled={loading || seeded || statusLoading}>
            {loading ? <><Loader2 className="h-3.5 w-3.5 mr-1.5 animate-spin" />Seeding…</> : 'Seed Demo Data'}
          </Button>

          <AlertDialog open={showClearConfirm} onOpenChange={setShowClearConfirm}>
            <AlertDialogTrigger asChild>
              <Button size="sm" variant="destructive" disabled={!seeded || clearing || statusLoading}>
                {clearing ? <><Loader2 className="h-3.5 w-3.5 mr-1.5 animate-spin" />Clearing…</> : 'Clear Demo Data'}
              </Button>
            </AlertDialogTrigger>
            <AlertDialogContent>
              <AlertDialogHeader>
                <AlertDialogTitle>Clear Demo Data</AlertDialogTitle>
                <AlertDialogDescription>
                  This will remove {counts.bills} demo bills and {counts.categories} demo categories from your account. This cannot be undone.
                </AlertDialogDescription>
              </AlertDialogHeader>
              <AlertDialogFooter>
                <AlertDialogCancel>Cancel</AlertDialogCancel>
                <AlertDialogAction onClick={handleClearDemoData} className="bg-destructive text-destructive-foreground hover:bg-destructive/90">
                  {clearing ? <><Loader2 className="h-3.5 w-3.5 mr-1.5 animate-spin" />Clearing…</> : 'Clear Data'}
                </AlertDialogAction>
              </AlertDialogFooter>
            </AlertDialogContent>
          </AlertDialog>
        </div>
      </div>
    </SectionCard>
  );
}

export default function DataPage() {
  const [history, setHistory] = useState(null);
  const [historyLoading, setHistoryLoading] = useState(true);

  const loadHistory = async () => {
    setHistoryLoading(true);
    try {
      const { history } = await api.importHistory();
      setHistory(history);
    } catch {
      setHistory([]);
    } finally {
      setHistoryLoading(false);
    }
  };

  useEffect(() => { loadHistory(); }, []);

  return (
    <div className="mx-auto w-full max-w-6xl space-y-5">
      <div className="flex flex-col gap-2 sm:flex-row sm:items-end sm:justify-between">
        <div>
          <h1 className="text-2xl font-bold tracking-tight">Data</h1>
          <p className="text-sm text-muted-foreground mt-0.5">
            Import, export, and review your user-owned bill tracker records.
          </p>
        </div>
        <div className="rounded-full border border-border/70 bg-card/80 px-3 py-1.5 text-xs font-medium text-muted-foreground">
          User data only
        </div>
      </div>

      <div className="space-y-5">
        <ImportTransactionCsvSection onHistoryRefresh={loadHistory} />
        <ImportSpreadsheetSection onHistoryRefresh={loadHistory} />
        <ImportMyDataSection onHistoryRefresh={loadHistory} />
      </div>
      <SeedDemoDataSection onSeeded={loadHistory} />
      <DownloadMyDataSection />
      <ImportHistorySection history={history} loading={historyLoading} onRefresh={loadHistory} />
    </div>
  );
}