import { useState, useEffect, useMemo, useRef, type ReactNode } from "react";
import DOMPurify from "dompurify";
import { useQuery, useQueryClient } from "@tanstack/react-query";
import {
  orderDetailOptions,
  type OrderData,
  type OrderItem,
  type OrderSection,
  type OrderInvoice,
  type OrderProject,
} from "../lib/queries/orders";
import { useAlert } from "../context/AlertContext";
import { useAuth } from "../context/AuthContext";
import { useParams, useNavigate, Link } from "react-router-dom";
import { motion } from "framer-motion";
import ConfirmModal from "../components/ConfirmModal";
import OrderConfirmationModal from "../components/OrderConfirmationModal";
import FormField from "../components/FormField";
import Forbidden from "../components/Forbidden";
import { Skeleton } from "boneyard-js/react";
import OrderDetailFixture from "../fixtures/OrderDetailFixture";

import apiFetch from "../utils/api";
import { formatCurrency, formatDate } from "../utils/formatters";

const API_BASE = "/api/admin";

const STATUS_LABELS: Record<string, string> = {
  prijata: "Přijatá",
  v_realizaci: "V realizaci",
  dokoncena: "Dokončená",
  stornovana: "Stornována",
};

const STATUS_CLASSES: Record<string, string> = {
  prijata: "admin-badge-order-prijata",
  v_realizaci: "admin-badge-order-realizace",
  dokoncena: "admin-badge-order-dokoncena",
  stornovana: "admin-badge-order-stornovana",
};

const TRANSITION_LABELS: Record<string, string> = {
  v_realizaci: "Zahájit realizaci",
  dokoncena: "Dokončit",
};

const TRANSITION_CLASSES: Record<string, string> = {
  v_realizaci: "admin-btn admin-btn-primary",
  dokoncena: "admin-btn admin-btn-primary",
};

export default function OrderDetail() {
  const { id } = useParams();
  const alert = useAlert();
  const { hasPermission } = useAuth();
  const navigate = useNavigate();

  const queryClient = useQueryClient();
  const orderQuery = useQuery(orderDetailOptions(id));
  const order = orderQuery.data;
  const loading = orderQuery.isPending;

  const [notes, setNotes] = useState("");
  const [saving, setSaving] = useState(false);
  const [statusChanging, setStatusChanging] = useState<string | null>(null);
  const [statusConfirm, setStatusConfirm] = useState<{
    show: boolean;
    status: string | null;
  }>({ show: false, status: null });
  const [attachmentLoading, setAttachmentLoading] = useState(false);
  const [deleteConfirm, setDeleteConfirm] = useState(false);
  const [deleting, setDeleting] = useState(false);
  const [deleteFiles, setDeleteFiles] = useState(false);
  const [showConfirmationModal, setShowConfirmationModal] = useState(false);
  const [confirmationLoading, setConfirmationLoading] = useState(false);
  const initialNotesRef = useRef<string | null>(null);
  const formInitializedRef = useRef(false);
  const blobTimeoutsRef = useRef<ReturnType<typeof setTimeout>[]>([]);

  // Reset form sync when navigating to a different order
  useEffect(() => {
    formInitializedRef.current = false;
  }, [id]);

  // Sync order data to local form state on first load
  useEffect(() => {
    if (orderQuery.data && !formInitializedRef.current) {
      const orderData = orderQuery.data!;
      setNotes(orderData.notes || "");
      initialNotesRef.current = orderData.notes || "";
      formInitializedRef.current = true;
    }
  }, [orderQuery.data]);

  // Navigate away on fetch error
  useEffect(() => {
    if (orderQuery.error) {
      alert.error("Nepodařilo se načíst objednávku");
      navigate("/orders");
    }
  }, [orderQuery.error]); // eslint-disable-line react-hooks/exhaustive-deps

  useEffect(() => {
    return () => {
      blobTimeoutsRef.current.forEach(clearTimeout);
    };
  }, []);

  const isDirty = useMemo(() => {
    if (!initialNotesRef.current) return false;
    return notes !== initialNotesRef.current;
  }, [notes]);

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

  const totals = useMemo(() => {
    if (!order?.items) return { subtotal: 0, vatAmount: 0, total: 0 };
    const subtotal = order.items.reduce((sum, item) => {
      if (Number(item.is_included_in_total)) {
        return (
          sum + (Number(item.quantity) || 0) * (Number(item.unit_price) || 0)
        );
      }
      return sum;
    }, 0);
    const vatAmount = Number(order.apply_vat)
      ? subtotal * ((Number(order.vat_rate) || 0) / 100)
      : 0;
    return { subtotal, vatAmount, total: subtotal + vatAmount };
  }, [order]);

  if (!hasPermission("orders.view")) return <Forbidden />;

  const handleStatusChange = async () => {
    if (!statusConfirm.status) return;
    setStatusChanging(statusConfirm.status);
    setStatusConfirm({ show: false, status: null });
    try {
      const response = await apiFetch(`${API_BASE}/orders/${id}`, {
        method: "PUT",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ status: statusConfirm.status }),
      });
      const result = await response.json();
      if (result.success) {
        alert.success(result.message || "Stav byl změněn");
        queryClient.invalidateQueries({ queryKey: ["orders"] });
        queryClient.invalidateQueries({ queryKey: ["offers"] });
        queryClient.invalidateQueries({ queryKey: ["projects"] });
        queryClient.invalidateQueries({ queryKey: ["invoices"] });
      } else {
        alert.error(result.error || "Nepodařilo se změnit stav");
      }
    } catch {
      alert.error("Chyba připojení");
    } finally {
      setStatusChanging(null);
    }
  };

  const handleSaveNotes = async () => {
    setSaving(true);
    try {
      const response = await apiFetch(`${API_BASE}/orders/${id}`, {
        method: "PUT",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ notes: notes }),
      });
      const result = await response.json();
      if (result.success) {
        alert.success("Poznámky byly uloženy");
        initialNotesRef.current = notes;
        queryClient.invalidateQueries({ queryKey: ["orders"] });
        queryClient.invalidateQueries({ queryKey: ["offers"] });
        queryClient.invalidateQueries({ queryKey: ["projects"] });
        queryClient.invalidateQueries({ queryKey: ["invoices"] });
      } else {
        alert.error(result.error || "Nepodařilo se uložit poznámky");
      }
    } catch {
      alert.error("Chyba připojení");
    } finally {
      setSaving(false);
    }
  };

  const handleViewAttachment = async () => {
    const newWindow = window.open("", "_blank");
    setAttachmentLoading(true);
    try {
      const response = await apiFetch(`${API_BASE}/orders/${id}/attachment`);
      if (!response.ok) {
        newWindow?.close();
        alert.error("Nepodařilo se stáhnout přílohu");
        return;
      }
      const blob = await response.blob();
      const url = URL.createObjectURL(blob);
      if (newWindow) newWindow.location.href = url;
      const timeoutId = setTimeout(() => URL.revokeObjectURL(url), 60000);
      blobTimeoutsRef.current.push(timeoutId);
    } catch {
      newWindow?.close();
      alert.error("Chyba připojení");
    } finally {
      setAttachmentLoading(false);
    }
  };

  const handleGenerateConfirmation = async (
    lang: string,
    applyVat: boolean,
    customItems?: Array<{
      description: string;
      quantity: number;
      unit: string;
      unit_price: number;
      is_included_in_total: boolean;
      vat_rate: number;
    }>,
  ) => {
    setConfirmationLoading(true);
    try {
      const response = await apiFetch(
        `${API_BASE}/orders-pdf/${id}/confirmation`,
        {
          method: "POST",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({ lang, applyVat, items: customItems }),
        },
      );
      if (!response.ok) {
        const result = await response.json().catch(() => ({}));
        alert.error(result.error || "Nepodařilo se vygenerovat PDF");
        return;
      }
      const blob = await response.blob();
      const url = URL.createObjectURL(blob);
      const a = document.createElement("a");
      a.href = url;
      a.download = `Potvrzeni-${order?.order_number || String(id)}.pdf`;
      document.body.appendChild(a);
      a.click();
      document.body.removeChild(a);
      const timeoutId = setTimeout(() => URL.revokeObjectURL(url), 60000);
      blobTimeoutsRef.current.push(timeoutId);
    } catch {
      alert.error("Chyba připojení");
    } finally {
      setConfirmationLoading(false);
    }
  };

  const handleDelete = async () => {
    setDeleting(true);
    try {
      const response = await apiFetch(`${API_BASE}/orders/${id}`, {
        method: "DELETE",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ delete_files: deleteFiles }),
      });
      const result = await response.json();
      if (result.success) {
        alert.success(result.message || "Objednávka byla smazána");
        await queryClient.invalidateQueries({ queryKey: ["orders"] });
        await queryClient.invalidateQueries({ queryKey: ["offers"] });
        await queryClient.invalidateQueries({ queryKey: ["projects"] });
        await queryClient.invalidateQueries({ queryKey: ["invoices"] });
        navigate("/orders");
      } else {
        alert.error(result.error || "Nepodařilo se smazat objednávku");
      }
    } catch {
      alert.error("Chyba připojení");
    } finally {
      setDeleting(false);
      setDeleteConfirm(false);
    }
  };

  if (!order) return null;

  return (
    <Skeleton
      name="order-detail"
      loading={loading}
      fixture={<OrderDetailFixture />}
    >
      <div>
        {/* Header */}
        <motion.div
          className="admin-page-header"
          initial={{ opacity: 0, y: 12 }}
          animate={{ opacity: 1, y: 0 }}
          transition={{ duration: 0.25 }}
        >
          <div className="flex-row gap-4">
            <Link
              to="/orders"
              className="admin-btn-icon"
              title="Zpět"
              aria-label="Zpět"
            >
              <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>
            </Link>
            <div>
              <h1 className="admin-page-title flex-row-gap">
                <span>Objednávka {order.order_number}</span>
                <span
                  className={`admin-badge ${STATUS_CLASSES[order.status] || ""}`}
                >
                  {STATUS_LABELS[order.status] || order.status}
                </span>
              </h1>
            </div>
          </div>
          <div className="admin-page-actions">
            {order.invoice ? (
              <Link
                to={`/invoices/${order.invoice.id}`}
                className="admin-btn admin-btn-secondary"
              >
                <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>
                Faktura {order.invoice.invoice_number}
              </Link>
            ) : (
              hasPermission("invoices.create") &&
              order.status === "dokoncena" && (
                <Link
                  to={`/invoices/new?fromOrder=${order.id}`}
                  className="admin-btn admin-btn-secondary"
                >
                  <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>
                  Vytvořit fakturu
                </Link>
              )
            )}
            {hasPermission("orders.export") && (
              <button
                onClick={() => setShowConfirmationModal(true)}
                className="admin-btn admin-btn-secondary"
                disabled={confirmationLoading}
              >
                <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>
                Potvrzení objednávky
              </button>
            )}
            {hasPermission("orders.edit") &&
              order.valid_transitions?.filter((s) => s !== "stornovana")
                .length! > 0 &&
              order
                .valid_transitions!.filter((s) => s !== "stornovana")
                .map((status) => (
                  <button
                    key={status}
                    onClick={() => setStatusConfirm({ show: true, status })}
                    className={
                      TRANSITION_CLASSES[status] ||
                      "admin-btn admin-btn-secondary"
                    }
                    disabled={statusChanging === status}
                  >
                    {statusChanging === status ? (
                      <div className="admin-spinner admin-spinner-sm" />
                    ) : (
                      TRANSITION_LABELS[status] || status
                    )}
                  </button>
                ))}
            {hasPermission("orders.delete") && (
              <button
                onClick={() => setDeleteConfirm(true)}
                className="admin-btn admin-btn-primary"
              >
                Smazat
              </button>
            )}
          </div>
        </motion.div>

        {/* Info card */}
        <motion.div
          className="admin-card"
          initial={{ opacity: 0, y: 12 }}
          animate={{ opacity: 1, y: 0 }}
          transition={{ duration: 0.25, delay: 0.06 }}
        >
          <div className="admin-card-body">
            <h3 className="admin-card-title">Informace</h3>
            <div className="admin-form-row mb-2">
              <FormField label="Nabídka">
                <div>
                  <Link
                    to={`/offers/${order.quotation_id}`}
                    className="link-accent"
                  >
                    {order.quotation_number}
                  </Link>
                  {order.project_code && (
                    <span
                      className="text-tertiary"
                      style={{ marginLeft: "0.5rem" }}
                    >
                      ({order.project_code})
                    </span>
                  )}
                </div>
              </FormField>
              <FormField label="Projekt">
                <div>
                  {order.project ? (
                    <Link
                      to={`/projects/${order.project.id}`}
                      className="link-accent"
                    >
                      {order.project.project_number} — {order.project.name}
                    </Link>
                  ) : (
                    "—"
                  )}
                </div>
              </FormField>
            </div>
            <div className="admin-form-row admin-form-row-3 mb-2">
              <FormField label="Zákazník">
                <div className="fw-500">{order.customer_name || "—"}</div>
              </FormField>
              <FormField label="Číslo obj. zákazníka">
                <div>{order.customer_order_number || "—"}</div>
              </FormField>
              <FormField label="Měna">
                <div>{order.currency}</div>
              </FormField>
            </div>
            <div className="admin-form-row admin-form-row-3 mb-2">
              <FormField label="Datum vytvoření">
                <div>{formatDate(order.created_at)}</div>
              </FormField>
              <FormField label="Příloha">
                <div>
                  {order.attachment_name ? (
                    <button
                      onClick={handleViewAttachment}
                      className="admin-btn admin-btn-secondary admin-btn-sm"
                      style={{
                        display: "inline-flex",
                        alignItems: "center",
                        gap: "0.4rem",
                      }}
                      disabled={attachmentLoading}
                    >
                      {attachmentLoading ? (
                        <div className="admin-spinner admin-spinner-sm" />
                      ) : (
                        <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>
                      )}
                      {order.attachment_name}
                    </button>
                  ) : (
                    "—"
                  )}
                </div>
              </FormField>
            </div>
          </div>
        </motion.div>

        {/* Items (read-only) */}
        <motion.div
          className="admin-card"
          initial={{ opacity: 0, y: 12 }}
          animate={{ opacity: 1, y: 0 }}
          transition={{ duration: 0.25, delay: 0.12 }}
        >
          <div className="admin-card-body">
            <h3 className="admin-card-title">Položky</h3>
            {order.items?.length > 0 ? (
              <div className="admin-table-responsive">
                <table className="admin-table">
                  <thead>
                    <tr>
                      <th style={{ width: "2.5rem", textAlign: "center" }}>
                        #
                      </th>
                      <th>Popis</th>
                      <th style={{ width: "5.5rem", textAlign: "center" }}>
                        Množství
                      </th>
                      <th style={{ width: "5.5rem", textAlign: "center" }}>
                        Jednotka
                      </th>
                      <th
                        style={{
                          width: "8rem",
                          textAlign: "right",
                          whiteSpace: "nowrap",
                        }}
                      >
                        Jedn. cena
                      </th>
                      <th style={{ width: "4rem", textAlign: "center" }}>
                        V ceně
                      </th>
                      <th
                        style={{
                          width: "9rem",
                          textAlign: "right",
                          whiteSpace: "nowrap",
                        }}
                      >
                        Celkem
                      </th>
                    </tr>
                  </thead>
                  <tbody>
                    {order.items.map((item, index) => {
                      const lineTotal =
                        (Number(item.quantity) || 0) *
                        (Number(item.unit_price) || 0);
                      return (
                        <tr key={item.id || index}>
                          <td
                            style={{
                              color: "var(--text-tertiary)",
                              textAlign: "center",
                              fontWeight: 500,
                            }}
                          >
                            {index + 1}
                          </td>
                          <td>
                            <div className="fw-500">
                              {item.description || "—"}
                            </div>
                            {item.item_description && (
                              <div
                                style={{
                                  fontSize: "0.8rem",
                                  color: "var(--text-tertiary)",
                                  marginTop: "0.25rem",
                                }}
                              >
                                {item.item_description}
                              </div>
                            )}
                          </td>
                          <td style={{ textAlign: "center" }}>
                            {item.quantity}
                          </td>
                          <td style={{ textAlign: "center" }}>
                            {item.unit || "—"}
                          </td>
                          <td
                            className="admin-mono"
                            style={{ textAlign: "right", whiteSpace: "nowrap" }}
                          >
                            {formatCurrency(item.unit_price, order.currency)}
                          </td>
                          <td style={{ textAlign: "center" }}>
                            {Number(item.is_included_in_total) ? "Ano" : "Ne"}
                          </td>
                          <td
                            className="admin-mono"
                            style={{
                              textAlign: "right",
                              fontWeight: 600,
                              whiteSpace: "nowrap",
                            }}
                          >
                            {formatCurrency(lineTotal, order.currency)}
                          </td>
                        </tr>
                      );
                    })}
                  </tbody>
                </table>
              </div>
            ) : (
              <p style={{ color: "var(--text-tertiary)" }}>Žádné položky.</p>
            )}

            {/* Totals */}
            <div className="admin-totals-summary">
              <div className="admin-totals-row">
                <span>Mezisoučet:</span>
                <span>{formatCurrency(totals.subtotal, order.currency)}</span>
              </div>
              {Number(order.apply_vat) > 0 && (
                <div className="admin-totals-row">
                  <span>DPH ({order.vat_rate}%):</span>
                  <span>
                    {formatCurrency(totals.vatAmount, order.currency)}
                  </span>
                </div>
              )}
              <div className="admin-totals-row admin-totals-total">
                <span>Celkem k úhradě:</span>
                <span>{formatCurrency(totals.total, order.currency)}</span>
              </div>
            </div>
          </div>
        </motion.div>

        {/* Sections (read-only) */}
        {order.sections?.length > 0 && (
          <motion.div
            className="admin-card"
            initial={{ opacity: 0, y: 12 }}
            animate={{ opacity: 1, y: 0 }}
            transition={{ duration: 0.25, delay: 0.15 }}
          >
            <div className="admin-card-body">
              <h3 className="admin-card-title">Rozsah projektu</h3>
              {order.scope_title && (
                <div style={{ fontWeight: 500, marginBottom: "0.5rem" }}>
                  {order.scope_title}
                </div>
              )}
              {order.scope_description && (
                <div
                  style={{
                    color: "var(--text-secondary)",
                    marginBottom: "1rem",
                  }}
                >
                  {order.scope_description}
                </div>
              )}
              <div className="admin-scope-list">
                {order.sections.map((section, index) => (
                  <div
                    key={section.id || index}
                    className="admin-scope-section"
                    style={{ cursor: "default" }}
                  >
                    <div className="admin-scope-section-header">
                      <span className="admin-scope-number">{index + 1}.</span>
                      <span className="admin-scope-title">
                        {(order.language === "CZ"
                          ? section.title_cz || section.title
                          : section.title || section.title_cz) ||
                          `Sekce ${index + 1}`}
                      </span>
                    </div>
                    {section.content && (
                      <div
                        className="admin-scope-content admin-rich-text-view"
                        style={{ padding: "1rem" }}
                        dangerouslySetInnerHTML={{
                          __html: DOMPurify.sanitize(section.content),
                        }}
                      />
                    )}
                  </div>
                ))}
              </div>
            </div>
          </motion.div>
        )}

        {/* Notes (editable) */}
        <motion.div
          className="admin-card"
          initial={{ opacity: 0, y: 12 }}
          animate={{ opacity: 1, y: 0 }}
          transition={{ duration: 0.25, delay: 0.2 }}
        >
          <div className="admin-card-body">
            <h3 className="admin-card-title">Poznámky</h3>
            <FormField label="Poznámky">
              <textarea
                value={notes}
                onChange={(e) => setNotes(e.target.value)}
                className="admin-form-input"
                rows={4}
                placeholder="Interní poznámky k objednávce..."
                disabled={!hasPermission("orders.edit")}
              />
            </FormField>
            {hasPermission("orders.edit") && (
              <div className="mt-2">
                <button
                  onClick={handleSaveNotes}
                  className="admin-btn admin-btn-secondary admin-btn-sm"
                  disabled={saving}
                >
                  {saving ? "Ukládání..." : "Uložit poznámky"}
                </button>
              </div>
            )}
          </div>
        </motion.div>

        {/* Status change confirmation */}
        <ConfirmModal
          isOpen={statusConfirm.show}
          onClose={() => setStatusConfirm({ show: false, status: null })}
          onConfirm={handleStatusChange}
          title="Změnit stav objednávky"
          message={`Opravdu chcete změnit stav objednávky "${order.order_number}" na "${STATUS_LABELS[statusConfirm.status || ""]}"?${statusConfirm.status === "dokoncena" ? " Projekt bude automaticky dokončen." : ""}`}
          confirmText={
            TRANSITION_LABELS[statusConfirm.status || ""] || "Potvrdit"
          }
          cancelText="Zrušit"
          type="default"
        />

        {/* Delete confirmation */}
        <ConfirmModal
          isOpen={deleteConfirm}
          onClose={() => {
            setDeleteConfirm(false);
            setDeleteFiles(false);
          }}
          onConfirm={handleDelete}
          title="Smazat objednávku"
          message={
            <>
              Opravdu chcete smazat objednávku &quot;{order.order_number}&quot;?
              Bude smazán i přidružený projekt. Tato akce je nevratná.
              {order.project?.has_nas_folder && (
                <label
                  className="admin-form-checkbox"
                  style={{ marginTop: "1rem", display: "flex" }}
                >
                  <input
                    type="checkbox"
                    checked={deleteFiles}
                    onChange={(e) => setDeleteFiles(e.target.checked)}
                  />
                  <span>Smazat i soubory projektu na disku</span>
                </label>
              )}
            </>
          }
          confirmText="Smazat"
          cancelText="Zrušit"
          type="danger"
          loading={deleting}
        />

        {/* Order confirmation PDF modal */}
        {order && (
          <OrderConfirmationModal
            isOpen={showConfirmationModal}
            onClose={() => setShowConfirmationModal(false)}
            onGenerate={handleGenerateConfirmation}
            initialItems={order.items.map((it) => ({
              description: it.description || "",
              quantity: Number(it.quantity) || 0,
              unit: it.unit || "",
              unit_price: Number(it.unit_price) || 0,
              is_included_in_total: Number(it.is_included_in_total) !== 0,
              vat_rate: Number(order.vat_rate) || 21,
            }))}
            orderNumber={order.order_number}
            defaultVatRate={Number(order.vat_rate) || 21}
            applyVat={!!order.apply_vat}
          />
        )}
      </div>
    </Skeleton>
  );
}