import { lazy, Suspense, useCallback, useEffect, useMemo, useRef, useState } from "react";
import {
  ActionableNotification,
  Button,
  Column,
  Dropdown,
  Grid,
  InlineLoading,
  InlineNotification,
  Modal,
  NumberInput,
  Select,
  SelectItem,
  Table,
  TableBody,
  TableCell,
  TableHead,
  TableHeader,
  TableRow,
  Tag,
  TextArea,
  TextInput,
  Toggle,
} from "@carbon/react";
import {
  Add,
  Copy,
  DocumentAdd,
  Download,
  Keyboard,
  Save,
  TrashCan,
} from "@carbon/icons-react";
import { confirm } from "@tauri-apps/plugin-dialog";
import { api } from "../lib/api";
import { EMPTY_ITEM, INDIAN_STATES, UNIT_LABELS } from "../lib/types";
import type {
  BankAccount,
  Client,
  DraftSummary,
  Invoice,
  InvoiceInput,
  InvoiceItem,
  LineMode,
  LineUnit,
  Settings,
  TaxType,
} from "../lib/types";
import { computeLineAmount, computeTotals } from "../lib/invoice";
import { amountInWords } from "../lib/numberToWords";
import { gstinFullError } from "../lib/validators";
import { addDays, formatAmount, todayIso } from "../lib/format";
import { modelFromAssets, prefsForInvoice } from "../lib/pdf";
import { formToPreviewInvoice } from "../lib/previewInvoice";
import { fromDraftPayload, toDraftPayload, type InvoiceFormState } from "../lib/draft";
import { SHORTCUT_LIST, useShortcuts } from "../hooks/useShortcuts";
import PageSetupControls from "../components/PageSetupControls";
import { useInvoicePdf } from "../hooks/useInvoicePdf";
import { useInvoiceExport } from "../hooks/useInvoiceExport";
import ExportButton, { ExportModePicker } from "../components/ExportButton";
import ExportFeedback from "../components/ExportFeedback";
import { createExportDeps } from "../lib/exportDeps";
import { issueAndArchive, renderAndArchive } from "../lib/exportFlow";
import { loadExportMode } from "../lib/exportMode";
import type { ExportMode } from "../lib/filename";
import { parsePrefs, type RenderPrefsV1 } from "../pdf/model/prefs";
import { useUserFonts } from "../hooks/useUserFonts";
import { withUserFonts } from "../lib/fontImport";
import { ImagePicker } from "../components/ImagePicker";
import { loadLogoImages, type LogoImages } from "../lib/logo";

// pdf.js is only needed once a preview exists, so it loads on demand.
const PdfPreview = lazy(() => import("../components/PdfPreview"));

interface NewInvoiceProps {
  settings: Settings;
  onSettingsChange: () => void;
  /** Whether this view is the one on screen. It stays mounted while hidden. */
  active: boolean;
  /** Ask the shell to show this view (used by Ctrl+N from another tab). */
  onActivate: () => void;
}

const AUTOSAVE_MS = 1000;

const formatTime = (d: Date) => d.toLocaleTimeString("en-GB", { hour: "2-digit", minute: "2-digit" });
const formatStamp = (iso: string) => {
  const d = new Date(iso);
  return Number.isNaN(d.getTime()) ? iso : `${d.toLocaleDateString("en-GB")} ${formatTime(d)}`;
};

export default function NewInvoice({ settings, onSettingsChange, active, onActivate }: NewInvoiceProps) {
  const newItem = (): InvoiceItem => ({ ...EMPTY_ITEM, hsnSac: settings.defaultHsnSac });
  const blankState = (): InvoiceFormState => {
    const t = todayIso();
    return {
      invoiceDate: t,
      dueDate: addDays(t, settings.paymentTermsDays),
      clientId: null,
      clientName: "",
      clientAddress: "",
      clientGstin: "",
      poNumber: "",
      placeOfSupply: settings.vendorStateCode,
      saveClient: false,
      items: [newItem()],
      discount: 0,
      taxRate: settings.defaultTaxRate,
      reverseCharge: false,
      bankId: settings.defaultBankId,
      signaturePath: settings.signaturePath,
      notes: "",
    };
  };
  const today = todayIso();
  const [invoiceDate, setInvoiceDate] = useState(today);
  const [dueDate, setDueDate] = useState(addDays(today, settings.paymentTermsDays));
  const [number, setNumber] = useState("");

  const [clients, setClients] = useState<Client[]>([]);
  const [clientId, setClientId] = useState<number | null>(null);
  const [clientName, setClientName] = useState("");
  const [clientAddress, setClientAddress] = useState("");
  const [clientGstin, setClientGstin] = useState("");
  const [poNumber, setPoNumber] = useState("");
  const [placeOfSupply, setPlaceOfSupply] = useState(settings.vendorStateCode);
  const [saveClient, setSaveClient] = useState(false);

  const [items, setItems] = useState<InvoiceItem[]>([newItem()]);
  const [discount, setDiscount] = useState(0);

  const registered = settings.gstRegistration !== "unregistered";
  const [reverseCharge, setReverseCharge] = useState(false);
  const [taxRate, setTaxRate] = useState(settings.defaultTaxRate);

  const [banks, setBanks] = useState<BankAccount[]>([]);
  const [bankId, setBankId] = useState<number | null>(settings.defaultBankId);
  const [signaturePath, setSignaturePath] = useState<string | null>(settings.signaturePath);
  const [notes, setNotes] = useState("");

  const [logoImages, setLogoImages] = useState<LogoImages | null>(null);
  const [signatureUri, setSignatureUri] = useState<string | null>(null);

  const [saving, setSaving] = useState(false);
  const [error, setError] = useState<string | null>(null);

  // Issued invoice shown read-only after a successful issue. Its number is consumed, so the
  // form never issues again until the user starts a new one.
  const [issued, setIssued] = useState<Invoice | null>(null);
  // What the backend recorded when the issued PDF was archived; null until that worked.
  const [archive, setArchive] = useState<{ sha256: string; fingerprint: string } | null>(null);
  const [archiveError, setArchiveError] = useState<string | null>(null);
  const [archiving, setArchiving] = useState(false);
  const [exportMode, setExportMode] = useState<ExportMode>(loadExportMode);
  const locked = issued !== null;
  // The issued invoice as the export flow needs it: with its archive fields once archived.
  const exportable = useMemo<Invoice | null>(
    () => (issued ? { ...issued, archivedPdfSha256: archive?.sha256 ?? issued.archivedPdfSha256, archivedFingerprint: archive?.fingerprint ?? issued.archivedFingerprint ?? null } : null),
    [issued, archive],
  );

  // Drafts.
  const [draftId, setDraftId] = useState<number | null>(null);
  const [baseline, setBaseline] = useState<string | null>(null);
  const [savedSnapshot, setSavedSnapshot] = useState<string | null>(null);
  const [savedAt, setSavedAt] = useState<Date | null>(null);
  const [draftSaving, setDraftSaving] = useState(false);
  const [draftError, setDraftError] = useState<string | null>(null);
  const [drafts, setDrafts] = useState<DraftSummary[]>([]);
  const [noticeOpen, setNoticeOpen] = useState(false);
  const [draftsOpen, setDraftsOpen] = useState(false);
  const [helpOpen, setHelpOpen] = useState(false);

  useEffect(() => {
    let active = true;
    (async () => {
      try {
        const [next, clientList, bankList, draftList] = await Promise.all([
          api.peekNextInvoiceNumber(),
          api.listClients(),
          api.listBanks(),
          api.listDrafts(),
        ]);
        if (!active) return;
        setNumber(next);
        setClients(clientList);
        setBanks(bankList);
        setDrafts(draftList);
        setNoticeOpen(draftList.length > 0);
      } catch (e) {
        if (active) setError(String(e));
      }
    })();
    return () => {
      active = false;
    };
  }, []);

  useEffect(() => {
    let active = true;
    if (!settings.logoPath) {
      setLogoImages(null);
      return;
    }
    loadLogoImages(settings, api.readAssetDataUri)
      .then((images) => active && setLogoImages(images))
      .catch(() => {});
    return () => {
      active = false;
    };
  }, [settings.logoPath, settings.logoKnockoutPath]);

  useEffect(() => {
    let active = true;
    if (!signaturePath) {
      setSignatureUri(null);
      return;
    }
    api.readAssetDataUri(signaturePath).then((uri) => active && setSignatureUri(uri)).catch(() => {});
    return () => {
      active = false;
    };
  }, [signaturePath]);

  // Rust derives the tax type from the supplier state and the place of supply; this
  // mirrors that rule so the preview and the value sent for the cross-check agree.
  const effectiveTaxType: TaxType = !registered
    ? "none"
    : !placeOfSupply || placeOfSupply === settings.vendorStateCode
      ? "cgst_sgst"
      : "igst";
  const clientGstinError = gstinFullError(clientGstin);
  const totals = useMemo(
    () => computeTotals(items, discount, effectiveTaxType, taxRate),
    [items, discount, effectiveTaxType, taxRate],
  );
  const words = useMemo(() => amountInWords(totals.total), [totals.total]);
  const bank = useMemo(() => banks.find((b) => b.id === bankId) ?? null, [banks, bankId]);

  const payload = useMemo(
    () =>
      toDraftPayload({
        invoiceDate,
        dueDate,
        clientId,
        clientName,
        clientAddress,
        clientGstin,
        poNumber,
        placeOfSupply,
        saveClient,
        items,
        discount,
        taxRate,
        reverseCharge,
        bankId,
        signaturePath,
        notes,
      }),
    [
      invoiceDate,
      dueDate,
      clientId,
      clientName,
      clientAddress,
      clientGstin,
      poNumber,
      placeOfSupply,
      saveClient,
      items,
      discount,
      taxRate,
      reverseCharge,
      bankId,
      signaturePath,
      notes,
    ],
  );
  const snapshot = useMemo(() => JSON.stringify(payload), [payload]);

  // The untouched form is the baseline; anything else is dirty. A pristine form is never saved.
  useEffect(() => {
    setBaseline((current) => current ?? snapshot);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);
  const dirty = baseline !== null && snapshot !== baseline;
  const unsaved = !locked && dirty && snapshot !== savedSnapshot;

  const latest = useRef({ snapshot, payload });
  latest.current = { snapshot, payload };
  const draftIdRef = useRef<number | null>(null);
  const savedRef = useRef<string | null>(null);
  const issuedRef = useRef(false);
  const chain = useRef<Promise<void>>(Promise.resolve());

  const refreshDrafts = useCallback(async () => {
    try {
      setDrafts(await api.listDrafts());
    } catch {
      /* the list is a convenience; ignore */
    }
  }, []);

  const refreshNumber = async () => {
    try {
      setNumber(await api.peekNextInvoiceNumber());
    } catch {
      /* ignore */
    }
  };

  // Saves are serialised so a slow first save cannot race a second one into creating two drafts.
  const persistDraft = useCallback((): Promise<void> => {
    const run = async () => {
      if (issuedRef.current) return;
      const { snapshot: snap, payload: body } = latest.current;
      if (snap === savedRef.current) return;
      setDraftSaving(true);
      try {
        const id = await api.saveDraft(draftIdRef.current, body);
        draftIdRef.current = id;
        savedRef.current = snap;
        setDraftId(id);
        setSavedSnapshot(snap);
        setSavedAt(new Date());
        setDraftError(null);
      } finally {
        setDraftSaving(false);
      }
    };
    const next = chain.current.then(run);
    chain.current = next.catch(() => {});
    return next;
  }, []);

  useEffect(() => {
    if (!unsaved) return;
    const timer = setTimeout(() => {
      persistDraft()
        .then(refreshDrafts)
        .catch((e) => setDraftError(String(e)));
    }, AUTOSAVE_MS);
    return () => clearTimeout(timer);
  }, [unsaved, snapshot, persistDraft, refreshDrafts]);

  useEffect(() => {
    if (!unsaved) return;
    const onBeforeUnload = (event: BeforeUnloadEvent) => {
      event.preventDefault();
      event.returnValue = "";
    };
    window.addEventListener("beforeunload", onBeforeUnload);
    return () => window.removeEventListener("beforeunload", onBeforeUnload);
  }, [unsaved]);

  // Page setup for the invoice being edited; an issued invoice shows what was frozen at issue.
  const [prefs, setPrefs] = useState<RenderPrefsV1>(() => parsePrefs(settings.renderPrefs));
  useEffect(() => setPrefs(parsePrefs(settings.renderPrefs)), [settings.renderPrefs]);
  // setupPrefs is the page setup as edited (and saved as the default); activePrefs adds the imported fonts the template
  // draws, which is what renders and what is frozen on the invoice at issue. An issued invoice keeps its frozen fonts.
  const userFonts = useUserFonts();
  const setupPrefs = useMemo(() => (issued ? prefsForInvoice(issued, settings) : prefs), [issued, prefs, settings]);
  const activePrefs = useMemo(() => (issued ? setupPrefs : withUserFonts(setupPrefs, userFonts)), [issued, setupPrefs, userFonts]);

  // The preview renders the real PDF from a draft-status Invoice built from the form. It is skipped
  // while this view is hidden (it stays mounted) so typing elsewhere never starts a render.
  const previewModel = useMemo(() => {
    if (!active) return null;
    const invoice =
      issued ??
      formToPreviewInvoice(
        { invoiceDate, dueDate, clientId, clientName, clientAddress, clientGstin, poNumber, placeOfSupply, discount, taxRate, reverseCharge, signaturePath, notes, items },
        number || "DRAFT",
        settings,
        bank,
      );
    return modelFromAssets(invoice, settings, bank, logoImages, signatureUri);
  }, [active, issued, invoiceDate, dueDate, clientId, clientName, clientAddress, clientGstin, poNumber, placeOfSupply, discount, taxRate, reverseCharge, signaturePath, notes, items, number, settings, bank, logoImages, signatureUri]);
  const updateItem = (index: number, patch: Partial<InvoiceItem>) =>
    setItems((prev) => prev.map((item, i) => (i === index ? { ...item, ...patch } : item)));

  const addItem = () => setItems((prev) => [...prev, newItem()]);
  const removeItem = (index: number) =>
    setItems((prev) => (prev.length === 1 ? prev : prev.filter((_, i) => i !== index)));

  const applyClient = (selected: Client) => {
    setClientId(selected.id);
    setClientName(selected.name);
    setClientAddress(selected.address);
    setClientGstin(selected.gstin);
    setPoNumber(selected.poNumber);
    if (selected.stateCode) setPlaceOfSupply(selected.stateCode);
  };

  const applyState = (s: InvoiceFormState) => {
    setInvoiceDate(s.invoiceDate);
    setDueDate(s.dueDate);
    setClientId(s.clientId);
    setClientName(s.clientName);
    setClientAddress(s.clientAddress);
    setClientGstin(s.clientGstin);
    setPoNumber(s.poNumber);
    setPlaceOfSupply(s.placeOfSupply);
    setSaveClient(s.saveClient);
    setItems(s.items);
    setDiscount(s.discount);
    setTaxRate(s.taxRate);
    setReverseCharge(s.reverseCharge);
    setBankId(s.bankId);
    setSignaturePath(s.signaturePath);
    setNotes(s.notes);
  };

  const clearIssued = () => {
    issuedRef.current = false;
    setIssued(null);
    setArchive(null);
    setArchiveError(null);
    exp.dismiss();
    setError(null);
  };

  const detachDraft = () => {
    draftIdRef.current = null;
    savedRef.current = null;
    setDraftId(null);
    setSavedSnapshot(null);
    setSavedAt(null);
    setDraftError(null);
  };

  const resetForm = () => {
    const blank = blankState();
    applyState(blank);
    setBaseline(JSON.stringify(toDraftPayload(blank)));
    clearIssued();
    detachDraft();
    void refreshNumber();
    api.listClients().then(setClients).catch(() => {});
    void refreshDrafts();
  };

  // Keeps the work in a draft before it is replaced. Returns false if that was not possible
  // and the user chose to keep the current form.
  const parkCurrentWork = async (): Promise<boolean> => {
    if (locked || !unsaved) return true;
    try {
      await persistDraft();
      return true;
    } catch (e) {
      return confirm(`The current form could not be saved as a draft (${String(e)}). Discard it?`, {
        title: "Unsaved changes",
        kind: "warning",
      });
    }
  };

  const newInvoice = async () => {
    onActivate();
    if (!(await parkCurrentWork())) return;
    resetForm();
  };

  const duplicateAsNew = () => {
    const t = todayIso();
    clearIssued();
    detachDraft();
    setInvoiceDate(t);
    setDueDate(addDays(t, settings.paymentTermsDays));
    setSaveClient(false);
    void refreshNumber();
  };

  const saveDraftNow = async () => {
    if (locked || !dirty) return;
    try {
      await persistDraft();
      await refreshDrafts();
    } catch (e) {
      setDraftError(String(e));
    }
  };

  const discardDraft = async () => {
    const ok = await confirm(
      draftId !== null
        ? "Discard this draft and clear the form?"
        : "Clear the form? Nothing has been saved as a draft.",
      { title: "Discard draft", kind: "warning" },
    );
    if (!ok) return;
    // Wait for any in-flight save so it cannot recreate the draft after the delete.
    await chain.current;
    const id = draftIdRef.current;
    try {
      if (id !== null) await api.deleteDraft(id);
    } catch (e) {
      setDraftError(String(e));
      return;
    }
    resetForm();
  };

  const resumeDraft = async (id: number) => {
    if (id === draftIdRef.current) {
      setDraftsOpen(false);
      return;
    }
    if (!(await parkCurrentWork())) return;
    try {
      const restored = fromDraftPayload(await api.getDraft(id), blankState());
      if (restored.bankId !== null && !banks.some((b) => b.id === restored.bankId)) {
        restored.bankId = null;
      }
      applyState(restored);
      setBaseline(JSON.stringify(toDraftPayload(blankState())));
      clearIssued();
      const snap = JSON.stringify(toDraftPayload(restored));
      draftIdRef.current = id;
      savedRef.current = snap;
      setDraftId(id);
      setSavedSnapshot(snap);
      setSavedAt(null);
      setDraftError(null);
      setNoticeOpen(false);
      setDraftsOpen(false);
      void refreshNumber();
      void refreshDrafts();
    } catch (e) {
      setError(String(e));
    }
  };

  const removeDraft = async (id: number) => {
    try {
      await api.deleteDraft(id);
    } catch (e) {
      setError(String(e));
    }
    await refreshDrafts();
  };

  const noteArchived = (invoice: Invoice) => {
    if (invoice.archivedPdfSha256) {
      setArchive({ sha256: invoice.archivedPdfSha256, fingerprint: invoice.archivedFingerprint ?? "" });
      setArchiveError(null);
    }
  };

  const exp = useInvoiceExport({ settings, bank, onInvoiceUpdated: noteArchived });

  const retryArchive = async () => {
    if (!exportable || archiving) return;
    setArchiving(true);
    const outcome = await renderAndArchive(exportable, createExportDeps({ settings, bank }));
    if (outcome.archived) noteArchived(outcome.invoice);
    else setArchiveError(outcome.error ?? "The PDF could not be archived.");
    setArchiving(false);
  };

  const onSave = async () => {
    if (locked || saving) return;
    if (clientGstinError) {
      setError(`Client GSTIN: ${clientGstinError}`);
      return;
    }
    setSaving(true);
    setError(null);
    exp.dismiss();
    const mode = loadExportMode();
    let outcome: Awaited<ReturnType<typeof issueAndArchive>>;
    try {
      // Let a pending autosave land first so the issue call knows which draft to delete.
      await chain.current;
      issuedRef.current = true;
      const input: InvoiceInput = {
        invoiceDate,
        dueDate,
        clientId,
        clientName,
        clientAddress,
        clientGstin,
        poNumber,
        placeOfSupplyStateCode: placeOfSupply,
        discount,
        taxType: effectiveTaxType,
        taxRate,
        reverseCharge: registered && reverseCharge,
        bankAccountId: bankId,
        signaturePath,
        notes,
        saveClient,
        draftId: draftIdRef.current,
        items: items.map((item, index) => ({ ...item, sortOrder: index })),
      };
      outcome = await issueAndArchive(input, activePrefs, createExportDeps({ settings, bank }));
    } catch (e) {
      issuedRef.current = false;
      setError(String(e));
      setSaving(false);
      return;
    }
    // The number is consumed from here on. A failed archive or export must never lead to a second issue.
    setIssued(outcome.invoice);
    if (outcome.archived) noteArchived(outcome.invoice);
    else setArchiveError(outcome.error ?? "The PDF could not be archived.");
    detachDraft();
    api.listClients().then(setClients).catch(() => {});
    void refreshDrafts();
    // Unarchived invoices export by rendering and archiving first (see exportInvoice), so this still works.
    await exp.start(outcome.invoice, mode, "original");
    setSaving(false);
  };

  useShortcuts({
    onNew: () => void newInvoice(),
    onSaveDraft: () => active && void saveDraftNow(),
    onIssue: () => active && !locked && void onSave(),
    onAddLine: () => active && !locked && addItem(),
    onHelp: () => active && setHelpOpen(true),
  });

  const otherDrafts = drafts.filter((d) => d.id !== draftId);
  const busy = saving || exp.busy || archiving;
  // Yield the shared render worker to the export; the model changes back when it is done and re-renders.
  const pdf = useInvoicePdf({ model: busy ? null : previewModel, prefs: activePrefs });

  return (
    <>
    <div className="voiced-page" hidden={!active}>
      <Grid>
        <Column sm={4} md={8} lg={16}>
          <div style={{ display: "flex", justifyContent: "space-between", alignItems: "flex-end", gap: "1rem", flexWrap: "wrap" }}>
            <div>
              <h1 className="voiced-page__title">{locked ? `Invoice ${issued.number}` : "New invoice"}</h1>
              <p className="voiced-page__subtitle" style={{ marginBottom: 0 }}>
                {locked ? (
                  "Issued and read-only. Use the actions below to continue."
                ) : (
                  <>
                    Next number: <strong>{number || "—"}</strong>
                  </>
                )}
              </p>
            </div>
            {locked ? null : (
              <div className="voiced-header-action" style={{ flexWrap: "wrap" }}>
                {draftSaving ? (
                  <InlineLoading status="active" description="Saving draft…" />
                ) : savedAt && !unsaved ? (
                  <InlineLoading status="finished" description={`Draft saved ${formatTime(savedAt)}`} />
                ) : unsaved ? (
                  <Tag type="gray" size="sm">
                    Unsaved changes
                  </Tag>
                ) : null}
                {drafts.length > 0 ? (
                  <Button kind="ghost" onClick={() => setDraftsOpen(true)} disabled={busy}>
                    {`Drafts (${drafts.length})`}
                  </Button>
                ) : null}
                <Button kind="ghost" renderIcon={Keyboard} hasIconOnly iconDescription="Keyboard shortcuts (?)" tooltipPosition="bottom" onClick={() => setHelpOpen(true)} />
                {dirty || draftId !== null ? (
                  <Button kind="ghost" onClick={discardDraft} disabled={busy}>
                    Discard draft
                  </Button>
                ) : null}
                <Button kind="tertiary" renderIcon={Save} onClick={saveDraftNow} disabled={busy || !dirty}>
                  Save draft
                </Button>
                <div className="voiced-export-split">
                  <Button renderIcon={Download} onClick={onSave} disabled={busy} title={`Issues the invoice and exports the ${exportMode} PDF`}>
                    {saving ? "Issuing…" : "Issue & export"}
                  </Button>
                  <ExportModePicker mode={exportMode} onChange={setExportMode} disabled={busy} />
                </div>
              </div>
            )}
          </div>
          {error ? (
            <InlineNotification
              kind="error"
              lowContrast
              title="Could not save invoice"
              subtitle={error}
              onCloseButtonClick={() => setError(null)}
            />
          ) : null}
          {draftError ? (
            <InlineNotification
              kind="warning"
              lowContrast
              title="Draft not saved"
              subtitle={draftError}
              onCloseButtonClick={() => setDraftError(null)}
            />
          ) : null}
          {!locked && noticeOpen && !dirty && otherDrafts.length > 0 ? (
            <ActionableNotification
              inline
              kind="info"
              lowContrast
              title={`You have ${otherDrafts.length} unfinished draft${otherDrafts.length === 1 ? "" : "s"}`}
              subtitle="Pick up where you left off."
              actionButtonLabel="Resume latest"
              onActionButtonClick={() => void resumeDraft(otherDrafts[0].id)}
              onCloseButtonClick={() => setNoticeOpen(false)}
            />
          ) : null}
          {locked && exportable ? (
            <>
              {!exportable.archivedPdfSha256 ? (
                <ActionableNotification
                  inline
                  kind="warning"
                  lowContrast
                  hideCloseButton
                  title="Issued — PDF not archived yet"
                  subtitle={`${archiveError ?? "The PDF was not archived."} The invoice is safe; it is not issued again. You can still export.`}
                  actionButtonLabel={archiving ? "Archiving…" : "Render & archive"}
                  onActionButtonClick={() => void retryArchive()}
                />
              ) : null}
              <ExportFeedback exp={exp} />
              <div className="voiced-header-action" style={{ flexWrap: "wrap", marginTop: "0.5rem" }}>
                <ExportButton onExport={(mode) => void exp.start(exportable, mode, "original")} disabled={busy} />
                <Button kind="tertiary" renderIcon={Copy} onClick={duplicateAsNew} disabled={busy}>
                  Duplicate as new
                </Button>
                <Button kind="tertiary" renderIcon={DocumentAdd} onClick={() => void newInvoice()} disabled={busy}>
                  New invoice
                </Button>
              </div>
            </>
          ) : null}
          <div style={{ marginTop: "1.5rem" }} />
        </Column>

        <Column sm={4} md={8} lg={9} className="voiced-stack">
          <Grid narrow>
            <Column sm={4} md={4} lg={5}>
              <TextInput
                id="invoiceDate"
                disabled={locked}
                type="date"
                labelText="Invoice date"
                value={invoiceDate}
                onChange={(e) => {
                  setInvoiceDate(e.target.value);
                  setDueDate(addDays(e.target.value, settings.paymentTermsDays));
                }}
              />
            </Column>
            <Column sm={4} md={4} lg={5}>
              <TextInput
                id="dueDate"
                disabled={locked}
                type="date"
                labelText={`Due date (net ${settings.paymentTermsDays} days)`}
                value={dueDate}
                onChange={(e) => setDueDate(e.target.value)}
              />
            </Column>
            <Column sm={4} md={8} lg={6}>
              <TextInput id="invoiceNumber" labelText="Invoice number" value={issued?.number ?? number} readOnly />
            </Column>

            <Column sm={4} md={8} lg={8}>
              <Dropdown
                id="savedClient"
                disabled={locked}
                titleText="Saved client (optional)"
                label="Select a saved client to autofill"
                items={clients}
                itemToString={(item) => (item ? item.name : "")}
                selectedItem={clients.find((c) => c.id === clientId) ?? null}
                onChange={({ selectedItem }) => selectedItem && applyClient(selectedItem)}
              />
            </Column>
            <Column sm={4} md={8} lg={8}>
              <TextInput
                id="clientName"
                disabled={locked}
                labelText="Client name"
                value={clientName}
                onChange={(e) => {
                  setClientName(e.target.value);
                  setClientId(null);
                }}
              />
            </Column>
            <Column sm={4} md={8} lg={16}>
              <TextArea
                id="clientAddress"
                disabled={locked}
                labelText="Client address"
                rows={3}
                value={clientAddress}
                onChange={(e) => setClientAddress(e.target.value)}
              />
            </Column>
            <Column sm={4} md={4} lg={5}>
              <TextInput
                id="clientGstin"
                disabled={locked}
                labelText="Client GSTIN (optional)"
                value={clientGstin}
                onChange={(e) => setClientGstin(e.target.value.toUpperCase())}
                invalid={Boolean(clientGstinError)}
                invalidText={clientGstinError}
              />
            </Column>
            <Column sm={4} md={4} lg={5}>
              <TextInput
                id="poNumber"
                disabled={locked}
                labelText="PO number (optional)"
                value={poNumber}
                onChange={(e) => setPoNumber(e.target.value)}
              />
            </Column>
            <Column sm={4} md={8} lg={6}>
              <Select
                id="placeOfSupply"
                disabled={locked}
                labelText="Place of supply"
                value={placeOfSupply}
                onChange={(e) => setPlaceOfSupply(e.target.value)}
              >
                {INDIAN_STATES.map((s) => (
                  <SelectItem key={s.code} value={s.code} text={`${s.code} — ${s.name}`} />
                ))}
              </Select>
            </Column>
            <Column sm={4} md={8} lg={16}>
              <Toggle
                id="saveClient"
                disabled={locked}
                labelText="Save this client for next time"
                toggled={saveClient}
                onToggle={setSaveClient}
              />
            </Column>
          </Grid>

          <div>
            <h3 style={{ marginBottom: "0.75rem" }}>Line items</h3>
            {items.map((item, index) => (
              <div
                key={index}
                style={{
                  display: "flex",
                  flexWrap: "wrap",
                  gap: "0.5rem",
                  alignItems: "flex-end",
                  padding: "0.75rem",
                  border: "1px solid var(--cds-border-subtle-01)",
                  marginBottom: "0.5rem",
                }}
              >
                <div style={{ flex: "3 1 240px" }}>
                  <TextInput
                    id={`desc-${index}`}
                    disabled={locked}
                    labelText="Particulars / description"
                    value={item.description}
                    onChange={(e) => updateItem(index, { description: e.target.value })}
                  />
                </div>
                {registered ? (
                  <div style={{ flex: "0 1 120px" }}>
                    <TextInput
                      id={`hsn-${index}`}
                      disabled={locked}
                      labelText="HSN/SAC"
                      value={item.hsnSac ?? ""}
                      onChange={(e) => updateItem(index, { hsnSac: e.target.value })}
                    />
                  </div>
                ) : null}
                <div style={{ flex: "0 1 150px" }}>
                  <Select
                    id={`mode-${index}`}
                    disabled={locked}
                    labelText="Type"
                    value={item.mode}
                    onChange={(e) => updateItem(index, { mode: e.target.value as LineMode })}
                  >
                    <SelectItem value="fixed" text="Fixed amount" />
                    <SelectItem value="rate" text="Rate × quantity" />
                  </Select>
                </div>
                {item.mode === "rate" ? (
                  <>
                    <div style={{ flex: "0 1 130px" }}>
                      <NumberInput
                        id={`rate-${index}`}
                        disabled={locked}
                        label="Rate (₹)"
                        min={0}
                        step={1}
                        value={item.rate}
                        onChange={(_e, { value }) => updateItem(index, { rate: Number(value) || 0 })}
                      />
                    </div>
                    <div style={{ flex: "0 1 140px" }}>
                      <Select
                        id={`unit-${index}`}
                        disabled={locked}
                        labelText="Unit"
                        value={item.unit}
                        onChange={(e) => updateItem(index, { unit: e.target.value as LineUnit })}
                      >
                        {Object.entries(UNIT_LABELS).map(([value, text]) => (
                          <SelectItem key={value} value={value} text={text} />
                        ))}
                      </Select>
                    </div>
                    <div style={{ flex: "0 1 110px" }}>
                      <NumberInput
                        id={`qty-${index}`}
                        disabled={locked}
                        label="Quantity"
                        min={0}
                        step={1}
                        value={item.quantity}
                        onChange={(_e, { value }) => updateItem(index, { quantity: Number(value) || 0 })}
                      />
                    </div>
                  </>
                ) : (
                  <div style={{ flex: "0 1 150px" }}>
                    <NumberInput
                      id={`amount-${index}`}
                      disabled={locked}
                      label="Amount (₹)"
                      min={0}
                      step={1}
                      value={item.amount}
                      onChange={(_e, { value }) => updateItem(index, { amount: Number(value) || 0 })}
                    />
                  </div>
                )}
                <div style={{ flex: "0 0 auto", paddingBottom: "0.4rem" }}>
                  <strong>₹{formatAmount(computeLineAmount(item))}</strong>
                </div>
                <Button
                  kind="ghost"
                  size="sm"
                  hasIconOnly
                  renderIcon={TrashCan}
                  iconDescription="Remove line"
                  onClick={() => removeItem(index)}
                  disabled={locked || items.length === 1}
                />
              </div>
            ))}
            <Button kind="tertiary" size="sm" renderIcon={Add} onClick={addItem} disabled={locked}>
              Add line
            </Button>
          </div>

          <Grid narrow>
            <Column sm={4} md={4} lg={8}>
              <NumberInput
                id="discount"
                disabled={locked}
                label="Discount (₹)"
                min={0}
                step={1}
                value={discount}
                onChange={(_e, { value }) => setDiscount(Number(value) || 0)}
              />
            </Column>
            {registered ? (
              <>
                <Column sm={4} md={8} lg={16}>
                  <p className="voiced-page__subtitle" style={{ marginBottom: 0 }}>
                    {effectiveTaxType === "igst"
                      ? "IGST (inter-state supply)"
                      : "CGST + SGST (supply within the supplier's state)"}
                  </p>
                </Column>
                <Column sm={4} md={4} lg={8}>
                  <NumberInput
                    id="taxRate"
                    disabled={locked}
                    label="Tax rate (%)"
                    min={0}
                    max={100}
                    step={0.5}
                    value={taxRate}
                    onChange={(_e, { value }) => setTaxRate(Number(value) || 0)}
                  />
                </Column>
                <Column sm={4} md={8} lg={16}>
                  <Toggle
                    id="reverseCharge"
                    disabled={locked}
                    labelText="Tax payable on reverse charge"
                    toggled={reverseCharge}
                    onToggle={setReverseCharge}
                  />
                </Column>
              </>
            ) : null}
          </Grid>

          <Select
            id="bankAccount"
            disabled={locked}
            labelText="Bank account (Pay To)"
            value={bankId ?? ""}
            onChange={(e) => setBankId(e.target.value ? Number(e.target.value) : null)}
          >
            <SelectItem value="" text="No bank details" />
            {banks.map((b) => (
              <SelectItem
                key={b.id ?? 0}
                value={String(b.id)}
                text={`${b.bankName} · ${b.accountNo}`}
              />
            ))}
          </Select>

          <ImagePicker
            kind="signature"
            label="Signature for this invoice (optional)"
            value={signaturePath}
            onChange={setSignaturePath}
            disabled={locked}
          />

          <TextArea
            id="notes"
            disabled={locked}
            labelText="Notes (optional)"
            rows={2}
            value={notes}
            onChange={(e) => setNotes(e.target.value)}
          />
        </Column>

        <Column sm={4} md={8} lg={7}>
          <div style={{ position: "sticky", top: "3rem" }}>
            <h3 style={{ marginBottom: "0.75rem" }}>Preview</h3>
            <PageSetupControls prefs={setupPrefs} onChange={setPrefs} settings={settings} onSaved={onSettingsChange} disabled={locked} />
            <Suspense fallback={<InlineLoading description="Loading preview…" />}>
              <PdfPreview
                bytes={pdf.bytes}
                pages={pdf.pages}
                issues={pdf.issues}
                rendering={pdf.rendering}
                mode={pdf.mode}
                error={pdf.error}
              />
            </Suspense>
          </div>
        </Column>
      </Grid>
    </div>

    <Modal
      open={draftsOpen}
      passiveModal
      size="md"
      modalHeading="Unfinished drafts"
      onRequestClose={() => setDraftsOpen(false)}
    >
      <Table size="md" aria-label="Drafts">
        <TableHead>
          <TableRow>
            <TableHeader>Client</TableHeader>
            <TableHeader>Last edited</TableHeader>
            <TableHeader>Actions</TableHeader>
          </TableRow>
        </TableHead>
        <TableBody>
          {drafts.map((d) => (
            <TableRow key={d.id}>
              <TableCell>{d.clientName || "—"}</TableCell>
              <TableCell>{formatStamp(d.updatedAt)}</TableCell>
              <TableCell>
                {d.id === draftId ? (
                  <Tag type="blue" size="sm">
                    Open now
                  </Tag>
                ) : (
                  <div className="voiced-header-action">
                    <Button kind="ghost" size="sm" onClick={() => void resumeDraft(d.id)}>
                      Resume
                    </Button>
                    <Button
                      kind="ghost"
                      size="sm"
                      hasIconOnly
                      renderIcon={TrashCan}
                      iconDescription="Delete draft"
                      onClick={() => void removeDraft(d.id)}
                    />
                  </div>
                )}
              </TableCell>
            </TableRow>
          ))}
        </TableBody>
      </Table>
      {drafts.length === 0 ? <p style={{ marginTop: "1rem" }}>No drafts.</p> : null}
    </Modal>

    <Modal
      open={helpOpen}
      passiveModal
      size="sm"
      modalHeading="Keyboard shortcuts"
      onRequestClose={() => setHelpOpen(false)}
    >
      <Table size="md" aria-label="Keyboard shortcuts">
        <TableHead>
          <TableRow>
            <TableHeader>Keys</TableHeader>
            <TableHeader>Action</TableHeader>
          </TableRow>
        </TableHead>
        <TableBody>
          {SHORTCUT_LIST.map((row) => (
            <TableRow key={row.keys}>
              <TableCell>
                <strong>{row.keys}</strong>
              </TableCell>
              <TableCell>{row.action}</TableCell>
            </TableRow>
          ))}
        </TableBody>
      </Table>
    </Modal>
    </>
  );
}