import { useState, useEffect, useMemo, useRef } from "react";
import { useNavigate, useParams, Link as RouterLink } from "react-router-dom";
import { useQuery, useQueryClient } from "@tanstack/react-query";
import Box from "@mui/material/Box";
import Typography from "@mui/material/Typography";
import CircularProgress from "@mui/material/CircularProgress";
import {
  useApiMutation,
  apiErrorMessage,
  type ApiEnvelope,
} from "../lib/queries/mutations";
import { useAlert } from "../context/AlertContext";
import { useAuth } from "../context/AuthContext";
import Forbidden from "../components/Forbidden";
import RichEditor from "../components/RichEditor";
import apiFetch from "../utils/api";
import DocumentItemsEditor, {
  emptyDocumentItem,
  nextDocumentItemKey,
  type DocumentItem,
} from "../components/document/DocumentItemsEditor";
import SectionsEditor, {
  type DocumentSection,
} from "../components/document/SectionsEditor";
import LockBanner from "../components/document/LockBanner";
import { useDocumentLock } from "../hooks/useDocumentLock";
import { useUnsavedChangesGuard } from "../hooks/useUnsavedChangesGuard";
import { useDocumentPdf } from "../hooks/useDocumentPdf";
import {
  issuedOrderDetailOptions,
  issuedOrderSuppliersOptions,
  issuedOrderNextNumberOptions,
  type Supplier,
} from "../lib/queries/issued-orders";
import { companySettingsOptions } from "../lib/queries/settings";
import { numberOr, todayLocalStr } from "../utils/formatters";
import { normalizeDateStr } from "../utils/attendanceHelpers";
import {
  Button,
  Card,
  TextField,
  Select,
  DateField,
  Field,
  StatusChip,
  ConfirmDialog,
  LoadingState,
  PageEnter,
  SupplierPicker,
  headerActionsSx,
} from "../ui";
import {
  ISSUED_ORDER_STATUS,
  statusLabel,
  statusColor,
  documentNumberLabel,
} from "../lib/documentStatus";

const API_BASE = "/api/admin";

// The live (finalized) status for an issued order — assigning it (on create or
// on finalizing a draft) makes the backend consume the official PO number.
const LIVE_STATUS = "sent";

// Labels for the buttons that trigger a status transition.
const TRANSITION_LABELS: Record<string, string> = {
  sent: "Odeslat",
  confirmed: "Potvrdit",
  completed: "Dokončit",
  cancelled: "Stornovat",
};

const CURRENCY_FALLBACK = ["CZK", "EUR", "USD", "GBP"];

const BackIcon = (
  <svg
    width="20"
    height="20"
    viewBox="0 0 24 24"
    fill="none"
    stroke="currentColor"
    strokeWidth="2"
  >
    <path d="M19 12H5M12 19l-7-7 7-7" />
  </svg>
);

const FileIcon = (
  <svg
    width="16"
    height="16"
    viewBox="0 0 24 24"
    fill="none"
    stroke="currentColor"
    strokeWidth="2"
  >
    <path d="M14 2H6a2 2 0 0 0-2 2v16a2 2 0 0 0 2 2h12a2 2 0 0 0 2-2V8z" />
    <polyline points="14 2 14 8 20 8" />
  </svg>
);

interface OrderForm {
  supplier_id: number | null;
  supplier_name: string;
  currency: string;
  order_date: string;
  delivery_date: string;
  language: string;
  order_text: string;
  internal_notes: string;
  status: string;
}

interface IssuedOrderItemPayload {
  description: string;
  item_description: string;
  quantity: number;
  unit: string;
  unit_price: number;
  position: number;
}

interface IssuedOrderSectionPayload {
  title: string;
  title_cz: string;
  content: string;
  position: number;
}

interface IssuedOrderSavePayload {
  supplier_id: number | null;
  currency: string;
  order_date: string;
  delivery_date: string | null;
  language: string;
  order_text: string | null;
  internal_notes: string;
  items: IssuedOrderItemPayload[];
  sections: IssuedOrderSectionPayload[];
  status?: string;
}

export default function IssuedOrderDetail() {
  const { id } = useParams<{ id: string }>();
  const isEdit = Boolean(id);

  const navigate = useNavigate();
  const alert = useAlert();
  const { hasPermission } = useAuth();
  const queryClient = useQueryClient();

  const [form, setForm] = useState<OrderForm>({
    supplier_id: null,
    supplier_name: "",
    currency: "CZK",
    order_date: todayLocalStr(),
    delivery_date: "",
    language: "cs",
    order_text: "",
    internal_notes: "",
    status: "draft",
  });
  const [items, setItems] = useState<DocumentItem[]>(() => [
    emptyDocumentItem(),
  ]);
  const [sections, setSections] = useState<DocumentSection[]>([]);
  const [errors, setErrors] = useState<Record<string, string>>({});
  const [saving, setSaving] = useState(false);
  // Which save action is in flight ("draft" | the live status | "save"), so
  // only the clicked button shows its spinner — `saving` still disables all of
  // them to prevent a concurrent double-submit.
  const [savingAction, setSavingAction] = useState<string | null>(null);
  const [dataReady, setDataReady] = useState(false);
  const [poNumber, setPoNumber] = useState("");

  const [statusChanging, setStatusChanging] = useState<string | null>(null);
  const [statusConfirm, setStatusConfirm] = useState<{
    show: boolean;
    status: string | null;
  }>({ show: false, status: null });
  const [deleteConfirm, setDeleteConfirm] = useState(false);
  const [deleting, setDeleting] = useState(false);
  // Set to true right after a successful delete so the detail-page error
  // effect doesn't fire "Nepodařilo se načíst objednávku" on top of the
  // success toast (the 404 from a refetched-already-deleted row is expected
  // here, not a real error).
  const deletingRef = useRef(false);

  // ─── Queries ───
  const suppliersQuery = useQuery(issuedOrderSuppliersOptions());

  // The lookup returns ACTIVE suppliers only, but a saved order may reference
  // a since-deactivated one — without a fallback option the picker would
  // resolve to nothing and render the counterparty blank. The fallback is
  // built from the hydrated form state (supplier_name comes from the detail
  // response), so the name stays visible and a re-save keeps the same id.
  const suppliers = useMemo<Supplier[]>(() => {
    const activeSuppliers = suppliersQuery.data ?? [];
    if (
      form.supplier_id != null &&
      !activeSuppliers.some((s: Supplier) => s.id === form.supplier_id)
    ) {
      return [
        ...activeSuppliers,
        {
          id: form.supplier_id,
          name: form.supplier_name || `Dodavatel #${form.supplier_id}`,
          ico: null,
          dic: null,
          street: null,
          city: null,
          postal_code: null,
          country: null,
        },
      ];
    }
    return activeSuppliers;
  }, [suppliersQuery.data, form.supplier_id, form.supplier_name]);

  const companySettings = useQuery(companySettingsOptions()).data;
  // Configurable currency list from company settings (falls back to the
  // built-in list when settings are empty) — matches Offers/Invoices.
  const currencyOptions = (
    companySettings?.available_currencies || CURRENCY_FALLBACK
  ).map((c) => ({ value: c, label: c }));

  const detailQuery = useQuery(issuedOrderDetailOptions(id));
  const detail = detailQuery.data ?? null;

  const nextNumberQuery = useQuery({
    ...issuedOrderNextNumberOptions(),
    enabled: !isEdit,
  });

  // ─── Editability + shared document hooks ───
  // Fields are editable only in create mode or while draft/sent; an
  // orders.view-only holder opens everything read-only (copyable), and a
  // fresh lock held by another user forces read-only too.
  const statusEditable =
    !isEdit || form.status === "draft" || form.status === "sent";
  const {
    lockedBy,
    isLockedByOther,
    setLockedBy,
    acquire: acquireLock,
  } = useDocumentLock({
    baseUrl: isEdit && id ? `${API_BASE}/issued-orders/${id}` : null,
    enabled:
      isEdit && dataReady && statusEditable && hasPermission("orders.edit"),
  });
  const readOnly =
    isEdit &&
    (!statusEditable || isLockedByOther || !hasPermission("orders.edit"));
  const editable = !readOnly;
  const canExport = hasPermission("orders.view");

  const { isDirty, markClean } = useUnsavedChangesGuard(
    { form, items, sections },
    !isEdit || dataReady,
  );

  const { openPdf, pdfLoading } = useDocumentPdf(
    isEdit && id ? `${API_BASE}/issued-orders/${id}/file` : null,
  );

  // ─── Edit mode: hydrate form from detail (once) ───
  useEffect(() => {
    if (!isEdit || dataReady) return;
    const d = detailQuery.data;
    if (!d) return;

    const formData: OrderForm = {
      supplier_id: d.supplier_id ?? null,
      supplier_name: d.supplier_name ?? "",
      currency: d.currency || "CZK",
      order_date: normalizeDateStr(d.order_date),
      delivery_date: normalizeDateStr(d.delivery_date),
      language: d.language || "cs",
      order_text: d.order_text || "",
      internal_notes: d.internal_notes || "",
      status: d.status,
    };
    setForm(formData);
    setPoNumber(d.po_number || "");

    const mappedItems =
      d.items && d.items.length > 0
        ? d.items.map((it) => ({
            _key: nextDocumentItemKey(),
            id: it.id,
            description: it.description || "",
            item_description: it.item_description || "",
            quantity: numberOr(it.quantity, 1),
            unit: it.unit || "",
            unit_price: Number(it.unit_price) || 0,
          }))
        : [emptyDocumentItem()];
    setItems(mappedItems);

    const mappedSections =
      Array.isArray(d.sections) && d.sections.length > 0
        ? d.sections.map((s) => ({
            title: s.title || "",
            title_cz: s.title_cz || "",
            content: s.content || "",
          }))
        : [];
    setSections(mappedSections);

    setLockedBy(d.locked_by ?? null);
    // Acquire the edit lock when nobody holds it, the order is still
    // editable and the user is allowed to edit (mirrors offers).
    if (
      !d.locked_by &&
      (d.status === "draft" || d.status === "sent") &&
      hasPermission("orders.edit")
    ) {
      acquireLock();
    }

    markClean({ form: formData, items: mappedItems, sections: mappedSections });
    setDataReady(true);
  }, [
    isEdit,
    dataReady,
    detailQuery.data,
    hasPermission,
    setLockedBy,
    acquireLock,
    markClean,
  ]);

  // ─── Create mode: previewed PO number (page renders immediately) ───
  useEffect(() => {
    if (isEdit || !nextNumberQuery.data) return;
    setPoNumber(nextNumberQuery.data);
  }, [isEdit, nextNumberQuery.data]);

  // Redirect on detail fetch error (edit mode). Suppressed while deletingRef
  // is set — the in-flight refetch of a row we just deleted will 404, and we
  // don't want a "load failed" toast on top of the success toast.
  useEffect(() => {
    if (isEdit && detailQuery.isError && !deletingRef.current) {
      alert.error("Nepodařilo se načíst objednávku");
      navigate("/orders?tab=vydane");
    }
  }, [isEdit, detailQuery.isError, alert, navigate]);

  // ─── Mutations ───
  const saveMutation = useApiMutation<
    IssuedOrderSavePayload,
    ApiEnvelope<{ id: number; po_number: string | null }>
  >({
    url: () =>
      isEdit ? `${API_BASE}/issued-orders/${id}` : `${API_BASE}/issued-orders`,
    method: () => (isEdit ? "PUT" : "POST"),
    invalidate: ["issued-orders"],
    envelope: true,
  });

  const statusMutation = useApiMutation<
    { status: string },
    ApiEnvelope<{ id: number; po_number: string | null }>
  >({
    url: () => `${API_BASE}/issued-orders/${id}`,
    method: () => "PUT",
    invalidate: ["issued-orders"],
    envelope: true,
  });

  const deleteMutation = useApiMutation<void, ApiEnvelope<null>>({
    url: () => `${API_BASE}/issued-orders/${id}`,
    method: () => "DELETE",
    envelope: true,
  });

  const selectSupplier = (supplierId: number | null) => {
    const s =
      supplierId != null
        ? suppliers.find((x: Supplier) => x.id === supplierId)
        : null;
    setForm((prev) => ({
      ...prev,
      supplier_id: supplierId,
      supplier_name: s?.name || "",
    }));
    setErrors((prev) => ({ ...prev, supplier_id: "" }));
  };

  // ─── Submit (create + edit) ───
  const handleSubmit = async (targetStatus?: string) => {
    if (!editable || saving) return;
    const newErrors: Record<string, string> = {};
    if (!form.supplier_id) newErrors.supplier_id = "Vyberte dodavatele";
    if (!form.order_date) newErrors.order_date = "Zadejte datum";
    if (items.length === 0 || items.every((i) => !i.description.trim())) {
      newErrors.items = "Přidejte alespoň jednu položku";
    }
    setErrors(newErrors);
    if (Object.keys(newErrors).length > 0) return;

    setSaving(true);
    setSavingAction(targetStatus ?? "save");
    try {
      const payload: IssuedOrderSavePayload = {
        supplier_id: form.supplier_id,
        currency: form.currency,
        order_date: form.order_date,
        delivery_date: form.delivery_date || null,
        language: form.language,
        order_text: form.order_text || null,
        internal_notes: form.internal_notes,
        items: items
          .filter((i) => i.description.trim())
          .map((it, i) => ({
            description: it.description,
            item_description: it.item_description,
            // Coerce the raw typed strings back to numbers so an empty/partial
            // field never reaches the server as NaN (mirrors the totals math).
            quantity: Number(it.quantity) || 0,
            unit: it.unit,
            unit_price: Number(it.unit_price) || 0,
            position: i,
          })),
        sections: sections.map((s, i) => ({
          title: s.title,
          title_cz: s.title_cz,
          content: s.content,
          position: i,
        })),
      };
      // Only set status when a target is given (create-as-draft / create-as-live
      // / finalize). Editing a live order sends no status — the backend keeps
      // its current status. The PO number is never user-editable.
      if (targetStatus) payload.status = targetStatus;

      const result = await saveMutation.mutateAsync(payload);
      const created = result.data ?? null;
      alert.success(
        result.message ||
          (isEdit ? "Objednávka byla uložena" : "Objednávka byla vytvořena"),
      );
      // PUT/POST return po_number, so a draft→sent finalize shows the
      // assigned number immediately (no extra refetch needed).
      if (created?.po_number) setPoNumber(created.po_number);

      // Archive the PDF to NAS for any non-draft order (create-as-sent,
      // finalize draft→sent, or editing an already-live order). A draft has no
      // PO number, so it is skipped (the backend also guards on po_number).
      // Fire-and-forget: never block the success toast or navigation — but a
      // failure is surfaced, not silently swallowed.
      const recordId = isEdit ? Number(id) : created?.id;
      const effectiveStatus = targetStatus ?? form.status;
      if (recordId && effectiveStatus !== "draft") {
        apiFetch(`${API_BASE}/issued-orders-pdf/${recordId}?save=1`)
          .then((res) => {
            if (!res.ok)
              alert.error("Nepodařilo se archivovat PDF objednávky na NAS");
          })
          .catch(() =>
            alert.error("Nepodařilo se archivovat PDF objednávky na NAS"),
          );
      }
      // Reflect the just-saved status locally — on finalize (edit
      // draft→live) it flips the form out of the draft button branch without
      // waiting for a refetch (the one-shot hydration won't re-run, dataReady
      // stays true in edit mode).
      if (targetStatus) {
        setForm((prev) => ({ ...prev, status: targetStatus }));
      }
      markClean({
        form: targetStatus ? { ...form, status: targetStatus } : form,
        items,
        sections,
      });
      // On CREATE, redirect to the new order's detail. dataReady is still
      // false (it is only set by the edit-mode hydration), so the hydration
      // effect runs against the fresh detail fetch — same as offers — and
      // acquires the edit lock there.
      if (!isEdit && created?.id) {
        navigate(`/orders/issued/${created.id}`);
      }
    } catch (err) {
      alert.error(
        apiErrorMessage(
          err,
          isEdit
            ? "Nepodařilo se uložit objednávku"
            : "Nepodařilo se vytvořit objednávku",
        ),
      );
    } finally {
      setSaving(false);
      setSavingAction(null);
    }
  };

  // Native form submit (e.g. Enter): route to the right save path. Create →
  // finalize live; editing a draft → save draft (the visible primary button);
  // editing a live order → plain save (no status change).
  const handleFormSubmit = (e: React.FormEvent) => {
    e.preventDefault();
    if (!editable) return;
    if (!isEdit) void handleSubmit(LIVE_STATUS);
    else if (form.status === "draft") void handleSubmit("draft");
    else void handleSubmit();
  };

  // ─── Status transition. With unsaved edits on an editable (sent) order
  // the transition routes through handleSubmit so the edits are PERSISTED
  // with the status — a status-only payload would silently drop them, and
  // the markClean below would re-baseline the guard so even the beforeunload
  // warning disappears (the order is then read-only: edits unrecoverable).
  // Clean (or non-editable) orders keep the status-only payload — a
  // full-form resubmit on a non-editable order 400s server-side. ───
  const handleStatusChange = async () => {
    if (!statusConfirm.status || statusChanging) return;
    const newStatus = statusConfirm.status;
    if (editable && isDirty) {
      setStatusConfirm({ show: false, status: null });
      // handleSubmit validates, sends the full payload + status, archives
      // the PDF and re-baselines the guard with what was actually persisted.
      await handleSubmit(newStatus);
      return;
    }
    setStatusChanging(newStatus);
    try {
      const result = await statusMutation.mutateAsync({ status: newStatus });
      alert.success(result.message || "Stav byl změněn");
      if (result.data?.po_number) setPoNumber(result.data.po_number);
      // Mirror the new status into the form (same as handleSubmit's success
      // path): the one-shot hydration won't re-run (dataReady stays true), so
      // without this the StatusChip, the `editable` flag and the delete-button
      // gate would keep reading the stale status until a full remount.
      setForm((prev) => ({ ...prev, status: newStatus }));
      markClean({ form: { ...form, status: newStatus }, items, sections });
    } catch (err) {
      alert.error(apiErrorMessage(err, "Nepodařilo se změnit stav objednávky"));
    } finally {
      setStatusChanging(null);
      setStatusConfirm({ show: false, status: null });
    }
  };

  // ─── Delete ───
  const handleDelete = async () => {
    setDeleting(true);
    try {
      const result = await deleteMutation.mutateAsync(undefined);
      // Mark the row as gone before the list invalidation refetches the
      // detail key (which would 404 and trigger the error-toast effect).
      deletingRef.current = true;
      queryClient.removeQueries({ queryKey: ["issued-orders", id] });
      alert.success(result.message || "Objednávka byla smazána");
      await queryClient.invalidateQueries({ queryKey: ["issued-orders"] });
      navigate("/orders?tab=vydane");
    } catch (err) {
      alert.error(apiErrorMessage(err, "Nepodařilo se smazat objednávku"));
    } finally {
      setDeleting(false);
      setDeleteConfirm(false);
    }
  };

  // ─── Permission guards (AFTER all hooks) ───
  if (!isEdit && !hasPermission("orders.create")) return <Forbidden />;
  if (isEdit && !hasPermission("orders.view")) return <Forbidden />;

  // Create mode renders immediately (no full-page spinner waiting on
  // lookups); edit mode waits for the one-shot hydration.
  if (isEdit && !dataReady) {
    return <LoadingState />;
  }

  return (
    <PageEnter>
      {/* Header */}
      <Box
        sx={{
          display: "flex",
          alignItems: "flex-start",
          justifyContent: "space-between",
          flexWrap: "wrap",
          gap: 2,
          mb: 3,
        }}
      >
        {/* flexWrap: long document titles must drop below the Zpět button on
            phones instead of overflowing the viewport. */}
        <Box
          sx={{
            display: "flex",
            alignItems: "center",
            gap: 2,
            flexWrap: "wrap",
          }}
        >
          <Button
            component={RouterLink}
            to="/orders?tab=vydane"
            variant="outlined"
            color="inherit"
            startIcon={BackIcon}
          >
            Zpět
          </Button>
          <Box
            sx={{
              display: "flex",
              alignItems: "center",
              gap: 1.5,
              flexWrap: "wrap",
            }}
          >
            <Typography variant="h4">
              {isEdit ? "Objednávka vydaná" : "Nová objednávka vydaná"}
              {/* Edit mode: a draft has no PO number yet → show "Koncept".
                  Create mode: show the previewed next-number when available. */}
              {(isEdit || poNumber) && (
                <Box
                  component="span"
                  sx={{ color: "text.secondary", ml: 1, fontWeight: 400 }}
                >
                  {isEdit ? documentNumberLabel(poNumber) : poNumber}
                </Box>
              )}
            </Typography>
            {isEdit && (
              <StatusChip
                label={statusLabel(ISSUED_ORDER_STATUS, form.status)}
                color={statusColor(ISSUED_ORDER_STATUS, form.status)}
              />
            )}
          </Box>
        </Box>
        <Box sx={headerActionsSx}>
          {/* Drafts have no number yet — /file 404s for them. */}
          {isEdit && canExport && form.status !== "draft" && (
            <Button
              onClick={openPdf}
              variant="outlined"
              color="inherit"
              disabled={pdfLoading}
              startIcon={
                pdfLoading ? (
                  <CircularProgress size={16} color="inherit" />
                ) : (
                  FileIcon
                )
              }
            >
              Zobrazit objednávku
            </Button>
          )}
          {/* ── Create mode: two-button save ── */}
          {!isEdit && (
            <>
              <Button
                variant="outlined"
                color="inherit"
                onClick={() => handleSubmit("draft")}
                disabled={saving}
              >
                {savingAction === "draft" ? (
                  <CircularProgress size={16} color="inherit" />
                ) : (
                  "Uložit koncept"
                )}
              </Button>
              <Button
                onClick={() => handleSubmit(LIVE_STATUS)}
                disabled={saving}
              >
                {savingAction === LIVE_STATUS ? (
                  <>
                    <CircularProgress
                      size={16}
                      color="inherit"
                      sx={{ mr: 1 }}
                    />
                    Ukládání...
                  </>
                ) : (
                  "Vytvořit"
                )}
              </Button>
            </>
          )}

          {/* ── Edit mode, draft: save-draft + finalize (Odeslat). A draft is
              deleted rather than cancelled, so the generic transition buttons
              (sent/cancelled) are suppressed — the finalize button IS the
              draft → sent transition. ── */}
          {isEdit && editable && form.status === "draft" && (
            <>
              <Button
                variant="outlined"
                color="inherit"
                onClick={() => handleSubmit("draft")}
                disabled={saving}
              >
                {savingAction === "draft" ? (
                  <CircularProgress size={16} color="inherit" />
                ) : (
                  "Uložit koncept"
                )}
              </Button>
              <Button
                onClick={() => handleSubmit(LIVE_STATUS)}
                disabled={saving}
              >
                {savingAction === LIVE_STATUS ? (
                  <>
                    <CircularProgress
                      size={16}
                      color="inherit"
                      sx={{ mr: 1 }}
                    />
                    Ukládání...
                  </>
                ) : (
                  "Odeslat"
                )}
              </Button>
            </>
          )}

          {/* ── Edit mode, live (non-draft) order — save + transitions ── */}
          {isEdit && form.status !== "draft" && (
            <>
              {editable && (
                <Button onClick={() => handleSubmit()} disabled={saving}>
                  {savingAction === "save" ? (
                    <>
                      <CircularProgress
                        size={16}
                        color="inherit"
                        sx={{ mr: 1 }}
                      />
                      Ukládání...
                    </>
                  ) : (
                    "Uložit"
                  )}
                </Button>
              )}
              {hasPermission("orders.edit") &&
                !isLockedByOther &&
                detail?.valid_transitions?.map((status) => (
                  <Button
                    key={status}
                    onClick={() => setStatusConfirm({ show: true, status })}
                    variant={status === "cancelled" ? "outlined" : "contained"}
                    color={status === "cancelled" ? "error" : "primary"}
                    disabled={statusChanging === status}
                  >
                    {statusChanging === status ? (
                      <CircularProgress size={14} color="inherit" />
                    ) : (
                      TRANSITION_LABELS[status] || status
                    )}
                  </Button>
                ))}
            </>
          )}
          {/* A completed order is terminal/finalized — never deletable from the
              UI. draft/sent/confirmed/cancelled may be deleted. (Backend
              rejection of deleting an order is a separate hardening, out of
              scope here.) */}
          {isEdit &&
            hasPermission("orders.delete") &&
            form.status !== "completed" &&
            !isLockedByOther && (
              <Button
                onClick={() => setDeleteConfirm(true)}
                variant="outlined"
                color="error"
              >
                Smazat
              </Button>
            )}
        </Box>
      </Box>

      {/* Lock banner */}
      <LockBanner lockedBy={lockedBy} entityWord="Objednávku" />

      <form onSubmit={handleFormSubmit}>
        {/* Basic info */}
        <Card sx={{ mb: 3 }}>
          <Typography variant="subtitle2" sx={{ mb: 2, fontWeight: 600 }}>
            Základní údaje
          </Typography>
          <Box
            sx={{
              display: "grid",
              gridTemplateColumns: { xs: "1fr", md: "1fr 1fr 1fr" },
              gap: 2,
            }}
          >
            <Field label="Dodavatel" error={errors.supplier_id} required>
              <SupplierPicker
                suppliers={suppliers}
                value={form.supplier_id}
                onChange={selectSupplier}
                disabled={!editable}
                error={errors.supplier_id}
                placeholder="Vyberte dodavatele…"
              />
            </Field>
            <Field label="Datum objednávky" error={errors.order_date} required>
              <DateField
                value={form.order_date}
                disabled={!editable}
                onChange={(val) => {
                  setForm((prev) => ({ ...prev, order_date: val }));
                  setErrors((prev) => ({ ...prev, order_date: "" }));
                }}
              />
            </Field>
            <Field label="Datum dodání">
              <DateField
                value={form.delivery_date}
                disabled={!editable}
                onChange={(val) =>
                  setForm((prev) => ({ ...prev, delivery_date: val }))
                }
              />
            </Field>
          </Box>

          <Box
            sx={{
              display: "grid",
              gridTemplateColumns: { xs: "1fr", sm: "1fr 1fr" },
              gap: 2,
            }}
          >
            <Field label="Měna">
              <Select
                value={form.currency}
                disabled={!editable}
                onChange={(val) =>
                  setForm((prev) => ({ ...prev, currency: val }))
                }
                options={currencyOptions}
              />
            </Field>
            <Field label="Jazyk">
              <Select
                value={form.language}
                disabled={!editable}
                onChange={(val) =>
                  setForm((prev) => ({ ...prev, language: val }))
                }
                options={[
                  { value: "cs", label: "Čeština" },
                  { value: "en", label: "English" },
                ]}
              />
            </Field>
          </Box>

          <Field label="Text objednávky (na PDF)">
            <TextField
              value={form.order_text}
              InputProps={{ readOnly: !editable }}
              slotProps={{ htmlInput: { maxLength: 500 } }}
              onChange={(e) =>
                setForm((prev) => ({ ...prev, order_text: e.target.value }))
              }
              placeholder="Objednáváme si u Vás: (ponechte prázdné pro výchozí)"
            />
          </Field>
        </Card>

        {/* Items */}
        <DocumentItemsEditor
          items={items}
          onChange={setItems}
          currency={form.currency}
          readOnly={!editable}
          error={errors.items}
        />

        {/* Rich-text PDF sections — the free-form PDF content lives here */}
        <SectionsEditor
          sections={sections}
          onChange={setSections}
          readOnly={!editable}
          title="Obsah"
          language={form.language}
        />

        {/* Internal notes */}
        <Card sx={{ mb: 3 }}>
          <Field label="Interní poznámky" hint="Nezobrazí se na PDF.">
            <RichEditor
              value={form.internal_notes}
              readOnly={!editable}
              onChange={(val) =>
                setForm((prev) => ({ ...prev, internal_notes: val }))
              }
              placeholder="Interní poznámky..."
            />
          </Field>
        </Card>
      </form>

      {/* Status change confirm — stays open with loading during the request */}
      {isEdit && (
        <ConfirmDialog
          isOpen={statusConfirm.show}
          onClose={() => setStatusConfirm({ show: false, status: null })}
          onConfirm={handleStatusChange}
          title="Změnit stav objednávky"
          message={`Opravdu chcete změnit stav objednávky "${documentNumberLabel(
            poNumber,
          )}" na "${statusLabel(ISSUED_ORDER_STATUS, statusConfirm.status)}"?`}
          confirmText={
            TRANSITION_LABELS[statusConfirm.status || ""] || "Potvrdit"
          }
          cancelText="Zrušit"
          confirmVariant={
            statusConfirm.status === "cancelled" ? "danger" : "primary"
          }
          loading={statusChanging !== null}
        />
      )}

      {/* Delete confirm */}
      {isEdit && (
        <ConfirmDialog
          isOpen={deleteConfirm}
          onClose={() => setDeleteConfirm(false)}
          onConfirm={handleDelete}
          title="Smazat objednávku?"
          message={`Opravdu chcete smazat objednávku "${documentNumberLabel(
            poNumber,
          )}"? Tato akce je nevratná.`}
          confirmText="Smazat"
          cancelText="Zrušit"
          confirmVariant="danger"
          loading={deleting}
        />
      )}
    </PageEnter>
  );
}
